Biochemistry Quiz on Metabolites
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Biochemistry Quiz on Metabolites

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Questions and Answers

Which of the following is NOT classified as a primary metabolite?

  • Atropine (correct)
  • Citric acid
  • L-lactate
  • Ethanol

    • Primary metabolites play a crucial role in an organism's growth and reproduction.

    True

    What is the role of secondary metabolites in organisms?

    Ecological functions such as defense mechanisms and antibiotic production.

    ___ is a secondary metabolite derived from various plants with important clinical uses.

    <p>Atropine</p> Signup and view all the answers

    Which organism is known for producing citric acid?

    <p>Aspergillus niger</p> Signup and view all the answers

    Secondary metabolites are formed primarily during the growth phase of an organism.

    <p>False</p> Signup and view all the answers

    Name one example of a secondary metabolite used in industry.

    <p>Erythromycin or Bacitracin</p> Signup and view all the answers

    Match the following primary metabolites with their uses:

    <p>Ethanol = Used for large-scale production in industrial microbiology Citric acid = Widely used in food production L-glutamate = Commonly used as a dietary supplement L-lysine = Important amino acid for nutrition</p> Signup and view all the answers

    What type of receptors does atropine act on?

    <p>Muscarinic receptors</p> Signup and view all the answers

    Erythromycin is produced from organisms classified under Bacillus subtilis.

    <p>False</p> Signup and view all the answers

    What is the primary process by which plants convert light energy into chemical energy?

    <p>Photosynthesis</p> Signup and view all the answers

    The light-dependent reactions of photosynthesis occur in the ______ of the chloroplast.

    <p>thylakoid membranes</p> Signup and view all the answers

    Match the following steps of the Calvin cycle with their descriptions:

    <p>Carbon fixation = Combines CO2 with RuBP Reduction = Converts 3-PGA into G3P Regeneration = Recycles G3P to regenerate RuBP</p> Signup and view all the answers

    Which of the following substances is produced during the light reactions of photosynthesis?

    <p>NADPH</p> Signup and view all the answers

    Bacitracin is commonly used as an oral antibiotic.

    <p>False</p> Signup and view all the answers

    What is the final product of glycolysis?

    <p>Pyruvate</p> Signup and view all the answers

    The chemical equation for the light reaction of photosynthesis can be simplified to: 2H2O + 2NADP+ + 3ADP + 3Pi → O2 + ______ + 3ATP

    <p>2NADPH</p> Signup and view all the answers

    Match the following biochemical pathways with their description:

    <p>Glycolysis = Converts glucose into pyruvate Citric Acid Cycle = Oxidizes acetyl-CoA to produce ATP Calvin Cycle = Incorporates CO2 into sugar molecules</p> Signup and view all the answers

    Which of the following is a reactant in the dark reactions of photosynthesis?

    <p>ATP</p> Signup and view all the answers

    Which of the following vitamins is classified as water soluble?

    <p>Vitamin C</p> Signup and view all the answers

    Chlorophyll a is the main pigment in most green plants.

    <p>True</p> Signup and view all the answers

    Vitamins can be synthesized by the body.

    <p>False</p> Signup and view all the answers

    What is the initial acceptor molecule in the Calvin cycle?

    <p>Ribulose-1,5-bisphosphate (RuBP)</p> Signup and view all the answers

    The Krebs cycle takes place in the ______ of the mitochondria.

    <p>matrix</p> Signup and view all the answers

    What is the primary natural form of Vitamin A?

    <p>Retinol</p> Signup and view all the answers

    Excessive intake of _______ soluble vitamins may be toxic.

    <p>fat</p> Signup and view all the answers

    Which vitamin is referred to as the 'sunshine vitamin'?

    <p>Vitamin D</p> Signup and view all the answers

    Beta-carotene can be converted into Vitamin A by the body.

    <p>True</p> Signup and view all the answers

    What is the role of Vitamin D in the body?

    <p>It assists in the absorption of calcium and phosphorus.</p> Signup and view all the answers

    Vitamin _______ is essential for vision, growth, and immune function.

    <p>A</p> Signup and view all the answers

    Which of the following dietary sources is rich in Vitamin E?

    <p>Nuts and seeds</p> Signup and view all the answers

    Match the following vitamins with their primary deficiency states:

    <p>Vitamin A = Xerophthalmia Vitamin D = Rickets Vitamin C = Scurvy Vitamin B = Beriberi</p> Signup and view all the answers

    How are fat-soluble vitamins absorbed in the body?

    <p>With lipids</p> Signup and view all the answers

    Vitamin E is a specific term for one particular form of tocopherol.

    <p>False</p> Signup and view all the answers

    What condition can arise from Vitamin D deficiency in adults?

    <p>Osteomalacia</p> Signup and view all the answers

    The vitamins can be classified as either _______ soluble or water soluble.

    <p>fat</p> Signup and view all the answers

    Which vitamin is primarily derived from plant sources such as mushrooms?

    <p>Vitamin D2</p> Signup and view all the answers

    What is the primary location where the Krebs cycle occurs?

    <p>Matrix of mitochondria</p> Signup and view all the answers

    The shikimic acid pathway is utilized by plants only for synthesizing fatty acids.

    <p>False</p> Signup and view all the answers

    What are the two substrates that start the shikimic acid pathway?

    <p>Phosphoenolpyruvate and erythrose-4-phosphate</p> Signup and view all the answers

    The main product of the mevalonate pathway is __________.

    <p>cholesterol</p> Signup and view all the answers

    Match the following metabolic pathways with their main products:

    <p>Shikimate pathway = Phenolic compounds and aromatic amino acids Malonate pathway = Fatty acids Mevalonate pathway = Cholesterol and isoprenoids</p> Signup and view all the answers

    Which of these compounds is considered a building block in biosynthesis?

    <p>Acetyl CoA</p> Signup and view all the answers

    The acetate pathway is primarily for synthesizing amino acids.

    <p>False</p> Signup and view all the answers

    What are the main intermediates produced by the mevalonate pathway?

    <p>Isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP)</p> Signup and view all the answers

    C2 building blocks in biosynthesis are derived from __________.

    <p>acetyl-CoA</p> Signup and view all the answers

    Match the following pathways with their type of secondary metabolites:

    <p>Shikimate pathway = Alkaloids and phenolic compounds Malonate pathway = Fatty acids Mevalonate pathway = Terpenes and steroids</p> Signup and view all the answers

    What initiates the shikimic acid pathway reactions?

    <p>Phosphoenolpyruvate</p> Signup and view all the answers

    Environmental stresses do not influence the expression of secondary metabolites.

    <p>False</p> Signup and view all the answers

    Name an enzyme involved in the shikimic acid pathway.

    <p>DAHP synthase</p> Signup and view all the answers

    Malonyl-CoA is formed from __________ by the addition of CO2.

    <p>acetyl-CoA</p> Signup and view all the answers

    Which acid is a key precursor in the biosynthesis of aromatic amino acids?

    <p>Shikimic acid</p> Signup and view all the answers

    Which of the following is a common dietary source of Vitamin E?

    <p>Wheat germ oil</p> Signup and view all the answers

    Vitamin K is primarily involved in blood clotting and can help in the metabolism of bone proteins.

    <p>True</p> Signup and view all the answers

    Name one symptom of Vitamin E deficiency.

    <p>Muscle weakness</p> Signup and view all the answers

    Vitamin B1 is also known as _____ .

    <p>thiamine</p> Signup and view all the answers

    Match the following vitamins with their primary functions:

    <p>Vitamin K = Blood clotting Vitamin B2 = Energy metabolism Vitamin B3 = Neurological protection Vitamin E = Antioxidant activity</p> Signup and view all the answers

    What is a major health consequence of Vitamin K deficiency?

    <p>Hemorrhage</p> Signup and view all the answers

    Riboflavin is sensitive to light and can change to lumichrome or lumiflavin.

    <p>True</p> Signup and view all the answers

    What is the common deficiency condition associated with Vitamin B3?

    <p>Pellagra</p> Signup and view all the answers

    Vitamin B2 is also known as _____ .

    <p>riboflavin</p> Signup and view all the answers

    Which vitamin is described as a lipid-soluble antioxidant?

    <p>Vitamin E</p> Signup and view all the answers

    Thiamine is stable in an acidic environment but decomposes above pH 5.0.

    <p>True</p> Signup and view all the answers

    Identify one dietary source of Vitamin B1.

    <p>Whole grains</p> Signup and view all the answers

    Niacin is also called _____ .

    <p>nicotinic acid</p> Signup and view all the answers

    Match the following vitamins with sources:

    <p>Vitamin E = Plant oils Vitamin K = Green leafy vegetables Vitamin B1 = Legumes Vitamin B2 = Yeast</p> Signup and view all the answers

    Which plant is known for containing cardiac glycosides and has historically been considered poisonous?

    <p>Nerium oleander</p> Signup and view all the answers

    Ouabagenin has an aldehydic group at C-10.

    <p>False</p> Signup and view all the answers

    What is the main therapeutic effect of Strophanthin when administered intravenously?

    <p>It acts as a cardiotonic.</p> Signup and view all the answers

    The sugar component of Ouabagenin is ______.

    <p>rhamnose</p> Signup and view all the answers

    What vitamin is known for its role in energy metabolism and synthesis of lipids?

    <p>Vitamin B5</p> Signup and view all the answers

    Match the following substances with their properties or uses:

    <p>Oleanderin = Used for treating cardiac insufficiency Red squill = Used as rat poison Strophanthidin = Cardiotonic used I.V. Squill glycosides = Expectorant properties</p> Signup and view all the answers

    Vitamin B6 is primarily found in animal tissues and is used for amino acid metabolism.

    <p>True</p> Signup and view all the answers

    What condition can arise from a deficiency of Vitamin B12?

    <p>Pernicious anemia</p> Signup and view all the answers

    Vitamin C is essential for the synthesis of __________.

    <p>collagen</p> Signup and view all the answers

    Match the vitamin to its key use:

    <p>Vitamin B5 = Energy metabolism Vitamin B9 = DNA synthesis Vitamin B7 = Fat metabolism Vitamin C = Antioxidant activity</p> Signup and view all the answers

    Which vitamin is primarily involved in mood improvement and red blood cell formation?

    <p>Vitamin B6</p> Signup and view all the answers

    Deficiency in Vitamin B7 can lead to fatigue and dermatitis.

    <p>True</p> Signup and view all the answers

    List one major food source of Vitamin C.

    <p>Citrus fruits</p> Signup and view all the answers

    Vitamin B9 is particularly important during __________ to prevent birth defects.

    <p>early pregnancy</p> Signup and view all the answers

    Which vitamin is known for aiding in the absorption of iron?

    <p>Vitamin C</p> Signup and view all the answers

    Glycosides are organic compounds that contain a sugar and a non-sugar moiety.

    <p>True</p> Signup and view all the answers

    What vitamin helps in the maintenance of nerve fibers?

    <p>Vitamin B12</p> Signup and view all the answers

    Vitamin B12 is also referred to as __________.

    <p>cobalamin</p> Signup and view all the answers

    Match the vitamin with its deficiency symptoms:

    <p>Vitamin B6 = Peripheral neuropathy Vitamin B5 = Fatigue and sleep disturbances Vitamin C = Scurvy Vitamin B9 = Megaloblastic anemia</p> Signup and view all the answers

    Which form of glycosides predominates in plants?

    <p>β-glycosides</p> Signup and view all the answers

    Most glycosides are soluble in non-polar organic solvents.

    <p>False</p> Signup and view all the answers

    What are the two main components of glycosides?

    <p>glycone and aglycone</p> Signup and view all the answers

    The acidic hydrolysis of glycosides results in the cleavage of the ________ linkages.

    <p>glycosidic</p> Signup and view all the answers

    Match the following types of glycosides with their examples:

    <p>O-glycosides = Senna C-glycosides = Cascaroside S-glycosides = Sinigrin N-glycosides = Glycoalkaloid</p> Signup and view all the answers

    Which enzyme specifically hydrolyzes most β-glycoside linkages?

    <p>Emulsin</p> Signup and view all the answers

    Glycosides can be classified based on the chemical nature of the aglycon.

    <p>True</p> Signup and view all the answers

    What is the primary role of the glycone part of glycosides in biological systems?

    <p>solubility properties</p> Signup and view all the answers

    Glycosides derived from digitalis are commonly used for ________ effects.

    <p>cardiac</p> Signup and view all the answers

    What is the taste characteristic of most glycosides?

    <p>Bitter</p> Signup and view all the answers

    Enzymatic hydrolysis of glycosides can occur within the same plant.

    <p>True</p> Signup and view all the answers

    Name one glycoside that is used as a laxative.

    <p>Senna</p> Signup and view all the answers

    ________ glycosides are classified based on the type of glycosidic linkage.

    <p>α and β</p> Signup and view all the answers

    Match the following glycoside types with their respective sugars:

    <p>Glucoside = Glucose Galactoside = Galactose Mannoside = Mannose Arabinoside = Arabinose</p> Signup and view all the answers

    Which of the following is a process involved in the purification of plant material from seeds?

    <p>Defatting</p> Signup and view all the answers

    Cardioactive glycosides are only derived from plants in the Scrophulariaceae family.

    <p>False</p> Signup and view all the answers

    What type of sugars can the glycone portion at position C-3 of cardiac glycosides contain?

    <p>mono, di, tri, or tetra saccharides</p> Signup and view all the answers

    The compounds containing a five-membered lactone ring are known as __________.

    <p>cardenolides</p> Signup and view all the answers

    Match the following components with their corresponding terms:

    <p>Cardenolides = Aglycones with 23 carbons Bufadienolides = Aglycones with 24 carbons Digitalis purpurea = Source of Digitoxin Strophanthus kombe = Source of K-strophanthoside</p> Signup and view all the answers

    What is a key medicinal compound derived from Digitalis purpurea?

    <p>Digitoxin</p> Signup and view all the answers

    Bufadienolides have a five-membered lactone ring.

    <p>False</p> Signup and view all the answers

    What enzyme do cardioactive glycosides primarily inhibit?

    <p>Na+/K+ ATPase</p> Signup and view all the answers

    The aglycone part of cardioactive glycosides is referred to as __________.

    <p>cardiac genin</p> Signup and view all the answers

    Which of the following statements correctly describes a feature of cardioactive glycosides?

    <p>They contain a β-OH group at position C-3.</p> Signup and view all the answers

    The average concentration of glycosides in Digitalis purpurea is around 0.16%.

    <p>True</p> Signup and view all the answers

    What is the main glycoside found in Strophanthus kombe?

    <p>K-strophanthoside</p> Signup and view all the answers

    Glycosides derived from Digitoxigenin include Lanatoside A, Acetyl-digitoxin, and __________.

    <p>Digitoxin</p> Signup and view all the answers

    Match the type of glycoside with the description:

    <p>Cardenolides = Contain a butenolide ring Bufadienolides = Contain a pentadienolide ring Aglycone with 23 carbons = Digitoxigenin Aglycone with 24 carbons = Scilladienolide</p> Signup and view all the answers

    What is the primary role of primary metabolites?

    <p>Support in growth and reproduction</p> Signup and view all the answers

    Secondary metabolites are primarily produced during the growth phase.

    <p>False</p> Signup and view all the answers

    What type of organism is known for producing erythromycin?

    <p>Streptomyces</p> Signup and view all the answers

    Atropine is derived from __________ and has important clinical uses.

    <p>various plants</p> Signup and view all the answers

    Which of the following is commonly used in food production?

    <p>Citric Acid</p> Signup and view all the answers

    Match the following secondary metabolites with their uses:

    <p>Erythromycin = Antibiotic treatment Atropine = Dilating pupils in eye exams Bacitracin = Topical anti-infection Pigments = Coloring agents in food</p> Signup and view all the answers

    Primary metabolites are typically produced during the stationary phase of growth.

    <p>False</p> Signup and view all the answers

    The significant amino acids like L-glutamate are produced from ________ species.

    <p>Corynebacteria</p> Signup and view all the answers

    Which of the following vitamins is classified as fat-soluble?

    <p>Vitamin A</p> Signup and view all the answers

    Water-soluble vitamins can be stored in the body.

    <p>False</p> Signup and view all the answers

    What is a primary function of Vitamin D in the body?

    <p>Assists in the absorption of calcium and phosphorus</p> Signup and view all the answers

    Vitamin A is essential for _______ and immune function.

    <p>vision</p> Signup and view all the answers

    Match the following vitamins with their primary deficiencies:

    <p>Vitamin A = Xerophthalmia Vitamin D = Rickets Vitamin C = Scurvy Vitamin K = Bleeding disorders</p> Signup and view all the answers

    Which of the following vitamins has a major form known as tocopherol?

    <p>Vitamin E</p> Signup and view all the answers

    Vitamin D3 is derived solely from plant sources.

    <p>False</p> Signup and view all the answers

    What is one common dietary source of Vitamin A?

    <p>Fish liver oils</p> Signup and view all the answers

    The two primary forms of Vitamin D are D2 (ergocalciferol) and D3 (_______).

    <p>cholecalciferol</p> Signup and view all the answers

    Match the following vitamin deficiencies with their conditions:

    <p>Vitamin A = Nyctalopia Vitamin D = Osteomalacia Vitamin C = Hyperkeratosis Vitamin K = Increased bleeding tendency</p> Signup and view all the answers

    Which vitamin can be converted to its active form from provitamin A substances?

    <p>Vitamin A</p> Signup and view all the answers

    Excessive intake of fat-soluble vitamins can lead to toxicity.

    <p>True</p> Signup and view all the answers

    What condition results from a deficiency of Vitamin D in children?

    <p>Rickets</p> Signup and view all the answers

    Vitamin E is essential for protecting _______ from oxidative damage.

    <p>cells</p> Signup and view all the answers

    Which of the following compounds is a precursor for the shikimic acid pathway?

    <p>Phosphoenol pyruvate</p> Signup and view all the answers

    What is the primary product formed during the light-dependent reactions of photosynthesis?

    <p>Oxygen</p> Signup and view all the answers

    The mevalonate pathway is responsible for synthesizing secondary metabolites in all organisms.

    <p>False</p> Signup and view all the answers

    Erythromycin is derived from Saccharopolyspora erythraea.

    <p>True</p> Signup and view all the answers

    Name one environmental stress that can trigger the expression of secondary metabolites.

    <p>Pathogens, herbivores attack, inappropriate pH, temperature changes, UV radiation, saline stress, or heavy metal stress.</p> Signup and view all the answers

    The pathway responsible for the synthesis of aromatic amino acids is known as the __________ pathway.

    <p>shikimic acid</p> Signup and view all the answers

    What role does chlorophyll play in photosynthesis?

    <p>Captures light energy</p> Signup and view all the answers

    The Calvin cycle primarily occurs in the ______ of the chloroplast.

    <p>stroma</p> Signup and view all the answers

    Match the following pathways with their primary product:

    <p>Shikimic Acid Pathway = Aromatic Amino Acids Malonate Pathway = Fatty Acids Mevalonate Pathway = Cholesterol</p> Signup and view all the answers

    Match the following processes of photosynthesis with their descriptors:

    <p>Light-dependent reactions = Convert light energy to chemical energy Calvin cycle = Convert carbon dioxide into glucose Glycolysis = Convert glucose into pyruvate Krebs cycle = Oxidize acetyl-CoA to produce ATP</p> Signup and view all the answers

    Which compound is a building block derived from acetyl-CoA?

    <p>Malonic acid</p> Signup and view all the answers

    What is the main carbon source for the dark reactions in photosynthesis?

    <p>Carbon dioxide</p> Signup and view all the answers

    Acetyl-CoA is a direct precursor for the growing fatty acid chain in fatty acid synthesis.

    <p>True</p> Signup and view all the answers

    What is the function of 5-enolpyruvylshikimate-3-phosphate synthase in the shikimic acid pathway?

    <p>Catalyzes the transformation of shikimate-3-phosphate and phosphoenolpyruvate.</p> Signup and view all the answers

    Bacitracin is commonly administered orally.

    <p>False</p> Signup and view all the answers

    Malonate is formed from acetyl-CoA by the addition of __________.

    <p>CO2</p> Signup and view all the answers

    Name the enzyme that catalyzes the reaction in the Calvin cycle.

    <p>RuBisCO</p> Signup and view all the answers

    During glycolysis, glucose is converted to ______.

    <p>pyruvate</p> Signup and view all the answers

    Match the following building blocks with their derived sources:

    <p>C1 = S-methyl of L-methionine C2 = Acetyl-CoA C5 = Isoprene units C6-C3 = Phenylpropyl from phenylalanine</p> Signup and view all the answers

    Which enzyme catalyzes the ATP dependent phosphorylation of shikimate?

    <p>Shikimate kinase</p> Signup and view all the answers

    Match the following antibiotics with their descriptions:

    <p>Erythromycin = Wide antimicrobial spectrum antibiotic Bacitracin = Topical antibiotic from Bacillus subtilis</p> Signup and view all the answers

    What are the two types of photosystems involved in the light reactions?

    <p>Photosystem I and II</p> Signup and view all the answers

    The acetyl-CoA carboxylase enzyme is involved in the formation of malonyl-CoA.

    <p>True</p> Signup and view all the answers

    What type of secondary metabolites does the shikimic acid pathway specifically produce?

    <p>Phenolic compounds and alkaloids.</p> Signup and view all the answers

    The Krebs cycle occurs in the mitochondrial matrix.

    <p>True</p> Signup and view all the answers

    The main intermediates produced in the mevalonate pathway include __________ and its isomer.

    <p>Isopentenyl pyrophosphate</p> Signup and view all the answers

    What is the overall reaction for the Krebs cycle in relation to glucose?

    <p>C6H12O6 + 6CO2 + 38 ADP + 38 Pi → 6H2O + 6CO2 + 38 ATP</p> Signup and view all the answers

    Photosynthesis requires ______, water, and carbon dioxide.

    <p>light energy</p> Signup and view all the answers

    Which of the following is produced in the light-dependent reaction but not in the dark reaction of photosynthesis?

    <p>Oxygen</p> Signup and view all the answers

    All plants have chlorophyll b.

    <p>False</p> Signup and view all the answers

    Which vitamin plays a crucial role in blood clotting?

    <p>Vitamin K</p> Signup and view all the answers

    Vitamin E is primarily a water-soluble vitamin.

    <p>False</p> Signup and view all the answers

    What is a common deficiency symptom of Vitamin B1?

    <p>Wernicke encephalopathy</p> Signup and view all the answers

    Vitamin _______ is known for protecting cell membranes from oxidation.

    <p>E</p> Signup and view all the answers

    Match the following vitamins with their primary sources:

    <p>Vitamin B2 = Yeast Vitamin B3 = Meats Vitamin E = Plant oils Vitamin K = Green leafy vegetables</p> Signup and view all the answers

    Which vitamin is essential for the metabolism of bone proteins?

    <p>Vitamin K</p> Signup and view all the answers

    Riboflavin is sensitive to light and may change to lumichrome or lumiflavin when exposed.

    <p>True</p> Signup and view all the answers

    Name a deficiency condition associated with Vitamin B3.

    <p>Pellagra</p> Signup and view all the answers

    Thiamine deficiency can lead to ________, a syndrome affecting the nervous system.

    <p>beriberi</p> Signup and view all the answers

    Match the following vitamins with their primary functions:

    <p>Vitamin B1 = Energy metabolism Vitamin B2 = Coenzyme in oxidation-reduction reactions Vitamin B3 = Lowering LDL cholesterol Vitamin K = Blood clotting</p> Signup and view all the answers

    Which vitamin is vital for immune function boosting?

    <p>Vitamin E</p> Signup and view all the answers

    Vitamin K can be obtained from the intestinal microflora.

    <p>True</p> Signup and view all the answers

    What dietary sources are rich in Vitamin K?

    <p>Green leafy vegetables</p> Signup and view all the answers

    The primary use of Riboflavin (Vitamin B2) is as a _______ in energy metabolism.

    <p>coenzyme</p> Signup and view all the answers

    What is a primary use of ouabain (G-strophanthin)?

    <p>Cardiotonic for prompt therapeutic effect</p> Signup and view all the answers

    Oleander is considered non-toxic and can be safely consumed in any amounts.

    <p>False</p> Signup and view all the answers

    What two types of sugars make up the trisaccharide in strophanthidin?

    <p>cymarose, β-glucose and α-glucose</p> Signup and view all the answers

    The main constituent of Nerium oleander is ______.

    <p>oleanderin</p> Signup and view all the answers

    Match the following compounds to their uses:

    <p>Ouabain = Cardiotonic, administered I.V. Oleanderin = Potential anticancer treatment Red squill = Used as rat poison Squill glycosides = Expectorant with diuretic properties</p> Signup and view all the answers

    What is the primary purpose of treating plant material with lead acetate?

    <p>To precipitate tannins and non-glycosidal impurities</p> Signup and view all the answers

    Cardioactive glycosides exclusively contain a four-membered lactone ring.

    <p>False</p> Signup and view all the answers

    What are the two types of genin identified in cardioactive glycosides?

    <p>Cardenolides and bufadienolides</p> Signup and view all the answers

    The enzyme Na+/K+ ATPase is inhibited by cardioactive glycosides, leading to increased levels of __________ inside the cell.

    <p>Calcium ions</p> Signup and view all the answers

    Match the following cardiac glycosides with their sources:

    <p>Digitalis purpurea = Foxglove Strophanthus kombe = Dried ripe seeds Digitalis lanata = Dried leaves Digitalis glycosides = Various medicinal applications</p> Signup and view all the answers

    Which of the following structural features is NOT characteristic of cardioactive glycosides?

    <p>Lactone ring must be saturated</p> Signup and view all the answers

    The principal glycosides in Digitalis purpurea include digitoxin, gitoxin, and gitaloxin.

    <p>True</p> Signup and view all the answers

    Name one method used to purify crude glycosides.

    <p>Chromatography or crystallization</p> Signup and view all the answers

    Bufadienolides are condensation products involving a C21 steroid and a __________ unit.

    <p>C3</p> Signup and view all the answers

    Which of the following is a function of cardioactive glycosides?

    <p>Increase cardiac muscle tone</p> Signup and view all the answers

    All cardioactive glycosides are derived from cholesterol.

    <p>False</p> Signup and view all the answers

    What configuration must be denoted when naming cardioactive glycosides?

    <p>The configuration of functional groups and whether they are α or β</p> Signup and view all the answers

    The glycone portion of cardiac glycosides can contain up to __________ monosaccharide molecules linked in series.

    <p>four</p> Signup and view all the answers

    What is one of the primary functions of pantothenic acid (Vitamin B5)?

    <p>Turn food into energy</p> Signup and view all the answers

    Which compound is associated with the dried leaves of Digitalis lanata?

    <p>Digitoxin</p> Signup and view all the answers

    Deficiency of Vitamin B6 can lead to peripheral neuropathy.

    <p>True</p> Signup and view all the answers

    What is a common dietary source of Vitamin B7?

    <p>Eggs</p> Signup and view all the answers

    Match the glycosides with their respective structural characteristics:

    <p>Cardenolides = Aglycones with 23 carbons Bufadienolides = Aglycones with 24 carbons Butenolide = 4 carbons attached to C17 Pentadienolide = 5 carbons with two double bonds</p> Signup and view all the answers

    Vitamin B9 is crucial during early pregnancy to reduce the risk of __________.

    <p>birth defects</p> Signup and view all the answers

    Match the following vitamins with their associated deficiencies:

    <p>Vitamin B5 = Fatigue and sleep disturbances Vitamin B6 = Peripheral neuropathy Vitamin B9 = Megaloblastic anemia Vitamin C = Scurvy</p> Signup and view all the answers

    Which vitamin is essential for the synthesis of red blood cells?

    <p>Vitamin B12</p> Signup and view all the answers

    Vitamin C is the most stable of all vitamins.

    <p>False</p> Signup and view all the answers

    Which of the following is true regarding the structure of glycosides?

    <p>The glycone part generally confers solubility properties.</p> Signup and view all the answers

    List one function of Vitamin C.

    <p>Antioxidant activity</p> Signup and view all the answers

    Vitamin C helps in the synthesis of __________.

    <p>collagen</p> Signup and view all the answers

    β-glycosides are predominantly found in plants.

    <p>True</p> Signup and view all the answers

    What type of compound is a glycoside?

    <p>An organic compound</p> Signup and view all the answers

    What type of linkage connects the glycone and aglycone parts in glycosides?

    <p>Glycosidic linkage</p> Signup and view all the answers

    Glycosides derived from digitalis are primarily used as _______ agents.

    <p>cardiac</p> Signup and view all the answers

    Biotin is involved only in carbohydrate metabolism.

    <p>False</p> Signup and view all the answers

    Match each type of glycoside with its respective aglycone component:

    <p>Senna = O-glycoside Cascara = C-glycoside Black mustard = N-glycoside Saponin = S-glycoside</p> Signup and view all the answers

    What is one food source of Vitamin B12?

    <p>Beef liver</p> Signup and view all the answers

    Pyridoxine is the term usually used for __________ in pharmacy and medicine.

    <p>pyridoxol</p> Signup and view all the answers

    Which of the following is NOT a property of glycosides?

    <p>They are volatile and aromatic.</p> Signup and view all the answers

    Enzymatic hydrolysis of glycosides can only be carried out by one specific enzyme for all types of glycosides.

    <p>False</p> Signup and view all the answers

    Which of the following vitamins aids in the production of DNA and RNA?

    <p>Vitamin B9</p> Signup and view all the answers

    Match the following vitamins with key roles:

    <p>Vitamin B5 = Energy metabolism Vitamin B6 = Neurotransmitter synthesis Vitamin B12 = DNA synthesis Vitamin C = Iron absorption</p> Signup and view all the answers

    Name a therapeutic class that glycosides can be derived from.

    <p>Cardiac drugs</p> Signup and view all the answers

    The hydroxyl group on the anomeric carbon is ______ in the α-form of glycosides.

    <p>down</p> Signup and view all the answers

    Match the glycoside with its corresponding feature:

    <p>Flavonoids = Yellow color Anthraquinones = Red or orange color Saponin = Odorless Rhubarb = Bitter taste</p> Signup and view all the answers

    Which of the following substances predominantly increases the water solubility of glycosides?

    <p>The sugar moiety</p> Signup and view all the answers

    Glycosides are relatively stable in alkaline conditions.

    <p>True</p> Signup and view all the answers

    What is the primary role of the aglycone part in glycosides?

    <p>Responsible for pharmacological activity</p> Signup and view all the answers

    The process by which plants inactivate hydrolyzing enzymes for glycosides involves putting them into _______ water or alcohol.

    <p>boiling</p> Signup and view all the answers

    What is a common primary metabolite produced by the organism Aspergillus niger?

    <p>Citric acid</p> Signup and view all the answers

    Secondary metabolites are primarily formed during the growth phase of an organism.

    <p>False</p> Signup and view all the answers

    Name one example of a primary metabolite used for large-scale production in industrial microbiology.

    <p>Ethanol</p> Signup and view all the answers

    ___ is an example of a secondary metabolite with important clinical uses derived from various plants.

    <p>Atropine</p> Signup and view all the answers

    Match the following metabolites with their classifications:

    <p>Ethanol = Primary metabolite Erythromycin = Secondary metabolite Citric acid = Primary metabolite Bacitracin = Secondary metabolite</p> Signup and view all the answers

    Which of the following best describes a primary metabolite?

    <p>Organic compound involved in growth and reproduction.</p> Signup and view all the answers

    L-glutamate is an example of a secondary metabolite.

    <p>False</p> Signup and view all the answers

    What role do secondary metabolites play in ecological functions?

    <p>Defense mechanism, including serving as antibiotics.</p> Signup and view all the answers

    Which vitamin is essential for vision and immune function?

    <p>Vitamin A</p> Signup and view all the answers

    Water-soluble vitamins are stored in the body and can lead to toxicity if taken in excess.

    <p>False</p> Signup and view all the answers

    Name one condition that can result from Vitamin A deficiency.

    <p>nyctalopia</p> Signup and view all the answers

    Vitamin D3 is primarily obtained from _______ sources.

    <p>animal</p> Signup and view all the answers

    Match the following vitamins with their primary deficiency states:

    <p>Vitamin A = Xerophthalmia Vitamin D = Rickets Vitamin C = Scurvy Vitamin E = Neurological issues</p> Signup and view all the answers

    Which food is a natural source of Vitamin E?

    <p>Sunflower seeds</p> Signup and view all the answers

    Vitamin D3 is synthesized in the skin through exposure to UVB light.

    <p>True</p> Signup and view all the answers

    What are the two classes of vitamins?

    <p>Fat-soluble and water-soluble</p> Signup and view all the answers

    Vitamin _______ is critical for bone and calcium homeostasis.

    <p>D</p> Signup and view all the answers

    Which vitamin is also known as the 'sunshine vitamin'?

    <p>Vitamin D</p> Signup and view all the answers

    Excessive intake of fat-soluble vitamins is generally safe.

    <p>False</p> Signup and view all the answers

    List one dietary source of Vitamin C.

    <p>Oranges</p> Signup and view all the answers

    Vitamin K is important for _______ in blood clotting.

    <p>coagulation</p> Signup and view all the answers

    Match the vitamin with its natural source:

    <p>Vitamin A = Carrots Vitamin D3 = Oily fish Vitamin C = Berries Vitamin E = Nuts</p> Signup and view all the answers

    What process do plants use to capture light energy?

    <p>Photosynthesis</p> Signup and view all the answers

    Atropine is a competitive antagonist for nicotinic receptors.

    <p>False</p> Signup and view all the answers

    What is the main pigment involved in the light-dependent reactions of photosynthesis?

    <p>Chlorophyll-a</p> Signup and view all the answers

    The overall reaction of glycolysis converts glucose into ______.

    <p>pyruvate</p> Signup and view all the answers

    Match the following antibiotics with their source:

    <p>Erythromycin = Saccharopolyspora erythraea Bacitracin = Bacillus subtilis</p> Signup and view all the answers

    Which of the following substances is generated during the light-dependent reactions?

    <p>Oxygen</p> Signup and view all the answers

    The dark reaction of photosynthesis requires light to proceed.

    <p>False</p> Signup and view all the answers

    What are the two main stages of photosynthesis?

    <p>Light-dependent reaction and Light-independent reaction</p> Signup and view all the answers

    The Calvin cycle primarily occurs in the ______ of the chloroplast.

    <p>stroma</p> Signup and view all the answers

    Match the following stages of the Calvin cycle with their functions:

    <p>Carbon fixation = Formation of 3-PGA from RuBP and CO2 Reduction = Conversion of 3-PGA to G3P Regeneration = Restoration of RuBP from G3P</p> Signup and view all the answers

    What is the main product formed during the dark reactions of photosynthesis?

    <p>Glucose</p> Signup and view all the answers

    Photosystems are located in the cytosol of plant cells.

    <p>False</p> Signup and view all the answers

    What enzyme catalyzes the reaction in the carbon fixation stage of the Calvin cycle?

    <p>Rubisco</p> Signup and view all the answers

    During glycolysis, a net gain of ______ molecules of ATP is produced.

    <p>two</p> Signup and view all the answers

    What is the main function of the shikimic acid pathway?

    <p>Biosynthesis of phenolic compounds and aromatic amino acids</p> Signup and view all the answers

    The mevalonate pathway is crucial for cholesterol biosynthesis.

    <p>True</p> Signup and view all the answers

    What are the two starting substrates of the shikimic acid pathway?

    <p>Phosphoenol pyruvate and erythrose-4-phosphate</p> Signup and view all the answers

    C2 building blocks in biosynthesis are derived from __________.

    <p>acetyl-CoA</p> Signup and view all the answers

    Match the following metabolic pathways with their primary products:

    <p>Shikimic acid pathway = Aromatic amino acids Malonate pathway = Fatty acids Mevalonate pathway = Cholesterol and isoprenoids Acetate pathway = Acyl thioesters</p> Signup and view all the answers

    Which intermediate is produced from the mevalonate pathway?

    <p>Farnesyl pyrophosphate</p> Signup and view all the answers

    Environmental stresses do not affect the expression of secondary metabolites.

    <p>False</p> Signup and view all the answers

    What type of acid is malonate?

    <p>Three-carbon dicarboxylic acid</p> Signup and view all the answers

    The building blocks produced from photosynthesis are mainly used in __________.

    <p>biosynthesis of secondary metabolites</p> Signup and view all the answers

    Which of the following compounds is NOT derived from the shikimic acid pathway?

    <p>Cholesterol</p> Signup and view all the answers

    The acetate pathway directly synthesizes fatty acids.

    <p>True</p> Signup and view all the answers

    What are the main building blocks for secondary metabolite production categorized by carbon units?

    <p>C1, C2, C5, C6-C3</p> Signup and view all the answers

    Match the following compounds with their carbon unit classification:

    <p>Acetyl-CoA = C2 S-methyl of L-methionine = C1 Isoprene units = C5 Phenylalanine = C6-C3</p> Signup and view all the answers

    Which of the following describes the role of shikimic acid?

    <p>Intermediary in aromatic amino acid production</p> Signup and view all the answers

    Which of the following is a major dietary source of Vitamin E?

    <p>Wheat germ oil</p> Signup and view all the answers

    Vitamin K is primarily involved in energy metabolism.

    <p>False</p> Signup and view all the answers

    What are the symptoms of Vitamin B1 (thiamine) deficiency?

    <p>Wernicke encephalopathy and beriberi</p> Signup and view all the answers

    Vitamin ___ is essential for blood clotting.

    <p>K</p> Signup and view all the answers

    Match the following vitamins to their primary roles:

    <p>Vitamin E = Lipid-soluble antioxidant Vitamin K = Blood clotting Vitamin B3 = Energy transfer reactions Vitamin B1 = Nerve and muscle activity</p> Signup and view all the answers

    What is a common symptom of Vitamin E deficiency?

    <p>Muscle weakness</p> Signup and view all the answers

    Which of the following is a cardiotonic agent used intravenously?

    <p>Ouabin</p> Signup and view all the answers

    Alcohol can enhance the absorption of Vitamin B1.

    <p>False</p> Signup and view all the answers

    What are the three D's associated with niacin deficiency?

    <p>Dementia, dermatitis, diarrhea</p> Signup and view all the answers

    Oleander can be safely consumed in large amounts without toxicity.

    <p>False</p> Signup and view all the answers

    Vitamin B2 is also known as __________.

    <p>riboflavin</p> Signup and view all the answers

    What is the main constituent of Nerium oleander known for its medicinal use?

    <p>Oleanderin</p> Signup and view all the answers

    Match the B-vitamins with their sources:

    <p>B1 = Whole grains and legumes B2 = Dairy products and eggs B3 = Meats and fish B5 = Meats and whole grains</p> Signup and view all the answers

    Strophanthidin is coupled to a trisaccharide consisting of cymarose, β-glucose, and ______.

    <p>α-glucose</p> Signup and view all the answers

    Which vitamin contributes to the formation of myelin sheaths?

    <p>Vitamin B1</p> Signup and view all the answers

    Match the following cardiac glycosides with their sources or uses:

    <p>Ouabin = S. grantus Oleanderin = Nerium oleander Red Squill = Urginea maritima Squill = Expectorant and diuretic</p> Signup and view all the answers

    Riboflavin is stable during cooking in the absence of light.

    <p>True</p> Signup and view all the answers

    Why is Vitamin K important for bone health?

    <p>It helps osteocalcin bind to minerals.</p> Signup and view all the answers

    Niacin is also referred to as __________.

    <p>Vitamin B3</p> Signup and view all the answers

    Which of the following vitamins is known for its antihemorrhagic activity?

    <p>Vitamin K</p> Signup and view all the answers

    Vitamin E is primarily water-soluble.

    <p>False</p> Signup and view all the answers

    What is a primary source of pantothenic acid?

    <p>Cereal grains</p> Signup and view all the answers

    Vitamin B6 is necessary for amino acid metabolism.

    <p>True</p> Signup and view all the answers

    What deficiency can result from a lack of vitamin B9?

    <p>Megaloblastic anemia or macrocytic anemia</p> Signup and view all the answers

    Vitamin C is essential for the synthesis of ______.

    <p>collagen</p> Signup and view all the answers

    Match the following vitamins with their primary benefits:

    <p>Vitamin B5 = Helps in energy metabolism Vitamin B7 = Involved in fat metabolism Vitamin B12 = Prevents pernicious anemia Vitamin C = Antioxidant properties</p> Signup and view all the answers

    Which vitamin is essential for the production of red blood cells?

    <p>Vitamin B12</p> Signup and view all the answers

    All types of glycosides yield the same number of sugars upon hydrolysis.

    <p>False</p> Signup and view all the answers

    Name a key deficiency symptom of vitamin C.

    <p>Scurvy</p> Signup and view all the answers

    Fatty acid synthesis requires the presence of ______.

    <p>biotin</p> Signup and view all the answers

    Match the vitamins with their primary food sources:

    <p>Vitamin B6 = Fish and poultry Vitamin B9 = Beans and whole grains Vitamin B5 = Animal organs Vitamin C = Citrus fruits</p> Signup and view all the answers

    What is a potential consequence of vitamin B12 deficiency?

    <p>Mood swings</p> Signup and view all the answers

    Pyridoxine is the primary form of vitamin B6 found in plant sources.

    <p>True</p> Signup and view all the answers

    List one role of biotin in the body.

    <p>Transfer of carbon dioxide in metabolism</p> Signup and view all the answers

    Vitamin B7 helps in the metabolism of ______.

    <p>carbohydrates</p> Signup and view all the answers

    What occurs during the purification of plant material from seeds?

    <p>Defatting or purification of the plant material</p> Signup and view all the answers

    Cardioactive glycosides have a specific action on cardiac muscle that increases excitability and contractility.

    <p>True</p> Signup and view all the answers

    What type of chemical structure is primarily associated with cardioactive glycosides?

    <p>Steroidal structure with lactone rings</p> Signup and view all the answers

    The main glycoside in both S. kombe and S. hispidus is known as __________.

    <p>K-strophanthoside</p> Signup and view all the answers

    Match the following glycosides with their corresponding characteristics:

    <p>Digitoxin = Derived from Digitalis purpurea K-strophanthoside = Main glycoside in S. kombe Bufotoxin = Derived from bufadienolides Scillarenin = Derived from scilladienolides</p> Signup and view all the answers

    What method is used to precipitate tannins during the purification process?

    <p>Treatment with lead acetate</p> Signup and view all the answers

    The glycone portion at position C-3 of cardiac glycosides may contain four monosaccharide molecules linked in series.

    <p>True</p> Signup and view all the answers

    What is the mechanism of action for cardioactive glycosides?

    <p>Inhibition of Na+/K+ ATPase enzyme</p> Signup and view all the answers

    Cardiac glycosides are proposed to arise from the condensation of a C21 steroid with a C2 unit, with bufadienolides arising from a C21 steroid and a __________ unit.

    <p>C3</p> Signup and view all the answers

    Match the following digitalis glycosides with their derivatives:

    <p>Lanatoside A = Derived from Digitoxigenin Digitoxin = Derived from Digitoxigenin Gitaloxin = Derived from Digitoxigenin Gluco-gitaloxin = Derived from Digitoxigenin</p> Signup and view all the answers

    Which of the following correctly describes cardenolides?

    <p>Contain one double bond</p> Signup and view all the answers

    Bufadienolides contain a five-membered lactone ring.

    <p>False</p> Signup and view all the answers

    How many different glycosides have been identified in the leaves of Digitalis lanata?

    <p>Nearly 70</p> Signup and view all the answers

    The presence of another β-OH group at C-14 is a characteristic feature of ______________.

    <p>cardioactive glycosides</p> Signup and view all the answers

    What is the primary difference between α and β glycosides?

    <p>The position of the hydroxyl group on the anomeric carbon</p> Signup and view all the answers

    Glycosides are always insoluble in water.

    <p>False</p> Signup and view all the answers

    Identify one therapeutic agent derived from glycosides.

    <p>Digitalis</p> Signup and view all the answers

    Glycosides can be hydrolyzed by heating with a dilute ______.

    <p>acid</p> Signup and view all the answers

    Match the type of glycosidic linkage with its corresponding type:

    <p>α-glycosides = Hydroxyl group down β-glycosides = Hydroxyl group up C-glycosides = Aglycone with carbon linkage O-glycosides = Aglycone with hydroxyl group linkage</p> Signup and view all the answers

    Which enzymes are primarily responsible for hydrolyzing β-glycoside linkages?

    <p>Emulsin</p> Signup and view all the answers

    The aglycone part of glycosides is responsible for solubility properties.

    <p>False</p> Signup and view all the answers

    What is one function of glycosides in plants?

    <p>Defense against microorganisms</p> Signup and view all the answers

    The sugar moiety in glycosides enhances ______ solubility.

    <p>water</p> Signup and view all the answers

    Match the glycoside with its corresponding source or type:

    <p>Senna = Laxative drug Glycyrrhizin = From saponins Frangula = Contains anthraquinones Digitalis = Cardiac glycoside</p> Signup and view all the answers

    What role do glycosides play in plant metabolism?

    <p>Waste products</p> Signup and view all the answers

    Most glycosides are volatile compounds.

    <p>False</p> Signup and view all the answers

    What is the effect of sugar residues on glycoside solubility?

    <p>Increase water solubility</p> Signup and view all the answers

    Glycosides can be classified depending on the chemical group of the ______.

    <p>aglycone</p> Signup and view all the answers

    Match the glycoside to its corresponding property:

    <p>Bitter taste = Most glycosides Colorless = General glycosides Yellow = Flavonoids Red or orange = Anthraquinones</p> Signup and view all the answers

    Study Notes

    Metabolism

    • Metabolism is the chemical transformation that occurs in cells of living organisms.
    • Primary metabolites are involved in growth, development and reproduction.
    • Examples of primary metabolites include ethanol, lactic acid, and certain amino acids.
    • Secondary metabolites are derived from primary metabolites and are not directly involved in growth.
    • Examples of secondary metabolites include antibiotics like erythromycin and bacitracin.

    Photosynthesis

    • Photosynthesis is the process that converts light energy into chemical energy stored in glucose.
    • Occurs in chloroplasts and other parts of green organisms.
    • Requires carbon dioxide, water and light energy.
    • Produces glucose and oxygen as byproducts.
    • Consists of two stages: light-dependent reaction and light-independent reaction.
    • Light reaction captures light energy and converts it into ATP and NADPH.
    • Dark reaction uses ATP and NADPH to convert carbon dioxide into glucose.

    Glycolysis

    • The metabolic pathway that converts glucose into pyruvate.
    • Occurs in the cytosol and is oxygen-independent.
    • Produces ATP and pyruvate.

    Citric Acid Cycle

    • Also known as the Krebs cycle or TCA cycle.
    • A series of enzyme-catalyzed reactions that occur in the mitochondrial matrix.
    • Oxidizes acetyl-CoA to form carbon dioxide and reduced coenzymes.
    • Generates ATP via the electron transport chain.

    Biosynthesis of Secondary Metabolites

    • A multi-step process involving enzymes that convert substrates into more complex products.
    • Simple compounds are modified, converted, or joined together to form macromolecules.
    • Building blocks are derived from primary metabolites.
    • Important building blocks include acetyl CoA, shikimic acid, mevalonic acid, and malonic acid.

    Shikimic-Acid Pathway

    • The basis for biosynthesis of phenolic compounds, alkaloids, and other aromatic compounds.
    • Occurs in chloroplast plant cells.
    • Triggered by environmental stresses like pathogens, herbivores, pH, temperature, UV radiation, and heavy metals.
    • Provides the building blocks for aromatic amino acids (phenylalanine, tyrosine, and tryptophan).

    Malonic-Acid Pathway

    • Involved in the synthesis of fatty acids.
    • Uses acetyl CoA and malonyl CoA.
    • Malonyl CoA is formed from acetyl CoA by adding CO2.

    Mevalonic-Acid Pathway

    • Synthesizes isoprenoid compounds.
    • Produces isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP).
    • IPP and DMAPP form the basic building blocks of isoprenoid compounds.
    • Leads to the production of cholesterol and other compounds like triterpenoids.

    Introduction to Vitamins

    • Organic substances not synthesized within the body.
    • Essential in small amounts for normal metabolic functions.
    • Does not provide energy or building units for cellular structure.
    • Lack of specific vitamins lead to deficiency states like beriberi, rickets, scurvy, and xerophthalmia.

    Classification of Vitamins

    • Fat-soluble vitamins: A, D, E, and K.
    • Water-soluble vitamins: C and B complex.

    Fat-Soluble Vitamins

    • Stored in the body.
    • Deficiencies are rare; excessive intakes may be toxic.
    • Absorbed along with lipids.
    • Deficiency states can be caused by conditions that impair fat absorption.

    Vitamin A

    • Also known as retinol.
    • Important for vision, growth development, immune function, red blood cell formation, skin and bone formation.
    • Deficiency leads to night blindness, xerophthalmia, hyperkeratosis, growth retardation, and decreased resistance to infection.

    Vitamin D

    • Essential for calcium absorption and utilization.
    • Two forms: D2 (ergocalciferol) and D3 (cholecalciferol).
    • Vitamin D3 is formed in the skin by exposure to UVB radiation.
    • Vitamins D2 and D3 can be obtained from food or supplements.
    • Important for bone health, muscle function, immune system function, and cell function in general.
    • Deficiency leads to rickets in children and osteomalacia in adults.

    Vitamin E

    • Refers to various forms of α-tocopherol.

    Vitamin E

    • Several structurally related tocopherol analogs, including B, gamma, and S-tocopherols, occur in nature, but these substances possess only low levels of vitamin E activity.
    • Vitamin E is widely distributed in nature, and the body's requirements are normally satisfied by dietary sources.
    • Plant oils, green vegetables, whole grains, egg yolks, and meats are common dietary sources of this vitamin.
    • Wheat germ oil is a traditional natural source of vitamin E for therapeutic purposes.
    • Vitamin E is the major lipid-soluble antioxidant protecting cell membranes, proteins, and DNA from oxidation, thereby contributing to cellular health.
    • Vitamin E prevents oxidation of polyunsaturated fatty acids and lipids in the cells.
    • Vitamin E deficiency can cause nerve and muscle damage that results in loss of feeling in the arms and legs, loss of body movement control, muscle weakness, and vision problems.
    • A weakened immune system is another sign of vitamin E deficiency.

    Vitamin K

    • Vitamin K is a term that refers to 2-methyl-1,4-naphthoquinone and derivatives of this compound.
    • Vitamin K is distributed widely in dairy products and many fruits and vegetables, green leafy vegetables being especially good dietary sources.
    • The intestinal microflora also provides a significant portion of the normal human supply of this vitamin.
    • Vitamin K acts primarily in blood clotting (antihemorrhagic activity).
    • Vitamin K is used in treatments for bleeding events caused by overdose of the anticoagulant drug warfarin.
    • Vitamin K helps in the metabolism of bone proteins (osteocalcin).
    • Without vitamin K, osteocalcin cannot bind to the minerals that normally form bones, resulting in poor bone mineralization.
    • Vitamin K helps regulate blood calcium levels.
    • Hemorrhage is the most common symptom in Vitamin K deficiency.

    Vitamin B1

    • Thiamine or vitamin B1 has substituted pyrimidine and thiazole rings linked by a methylene bridge.
    • The vitamin is stable in an acidic environment but decomposes readily above pH 5.0.
    • It is estimated that about 50% of the vitamin in foods is destroyed during cooking.
    • Whole grains, legumes, and meats are good dietary sources of thiamine.
    • Alcohol inhibits its absorption from the small intestine.
    • Thiamin is a sulfur-containing vitamin that participates in energy metabolism.
    • Thiamin is involved in converting carbohydrates, lipids and proteins into energy.
    • It plays a key role in nerve and muscle activity.
    • Thiamin may be helpful to people with Alzheimer's disease.
    • Thiamin contributes to the development of myelin sheaths and improves brain function.
    • Vitamin B1 (thiamine) deficiency can cause several clinical syndromes, including Wernicke encephalopathy and beriberi.
    • Risk factors for deficiency include alcohol dependence, malabsorption, and a diet low in thiamine.

    Vitamin B2

    • Riboflavin or vitamin B2 is a yellow, heat-stable substance that is slightly soluble in water.
    • Riboflavin is sensitive to light and will change into lumichrome or lumiflavin, depending on whether the irradiated solution is acidic or alkaline; neither lumichrome nor lumiflavin possesses physiologic activity.
    • Yeast is the richest natural source of riboflavin.
    • Dairy products, eggs, legumes, and meats are the main dietary sources of this vitamin.
    • Small amounts are provided by cereal grains, fruits, and green vegetables.
    • Riboflavin is stable during cooking in the absence of light.
    • Riboflavin occurs in foods in the free form and as riboflavin 5'-phosphate (Flavin mononucleotide or FMN) and flavin adenine dinucleotide (FAD).
    • The nucleotides are hydrolyzed to riboflavin in the upper gastrointestinal tract.
    • Free riboflavin is absorbed readily into cells of the intestinal mucosa by an active transport system that is enhanced by bile salt.
    • Riboflavin functions as a coenzyme in numerous oxidation-reduction reactions, which are necessary for releasing energy from carbohydrates, fats and proteins.
    • Riboflavin stimulates growth and reproduction.
    • It plays a role in vision.
    • Riboflavin plays a role in the conversion of vitamins B6, folic acid, and niacin into their active coenzyme forms.
    • Riboflavin neutralizes free radicals hence acts as an antioxidant.
    • Riboflavin deficiency can cause stomatitis and dermatitis.

    Vitamin B3

    • Niacin, nicotinic acid, or vitamin B3 is a simple, naturally occurring pyridine derivative that prevents pellagra.
    • Niacinamide or nicotinamide also occurs naturally, has antipellagra activity, and is used for dietary and therapeutic purposes.
    • Niacin and niacinamide are readily absorbed from the gastrointestinal tract under normal circumstances.
    • Meats, fish, and dairy products are good dietary sources of niacin.
    • The roasting of coffee beans results in the release of a significant quantity of niacin as well as the development of a characteristic flavor.
    • Tryptophan is also converted to niacin in the body.
    • Niacin acts as a coenzyme in energy-transfer reactions.
    • Niacin is similar to the riboflavin coenzymes in that it carries hydrogen during metabolic reactions.
    • Niacin protects against neurological degeneration and Alzheimer’s disease.
    • Niacin helps lower LDL cholesterol.
    • Niacin lowers the risk of cardiovascular diseases and eases arthritis.
    • Pellagra is the classic niacin-deficiency condition.
    • Symptoms of deficiency involve the nervous system, the skin, and the gastrointestinal tract and are sometimes summarized as the 3D's—dementia, dermatitis, and diarrhea.
    • Oral lesions, especially angular stomatitis and a red tongue, are more distinctive than the other symptoms.

    Vitamin B5

    • Pantothenic acid or vitamin B5 is a component of the vitamin B complex that is sometimes known as the “chick antidermatitis factor” (based on a prior bioassay procedure).
    • Pantothenic acid is a naturally occurring compound that upon hydrolysis yields β-alanine and pantoic acid, a substituted butyric acid derivative.
    • Animal organs (heart, kidney, and liver) and cereal grains are rich dietary sources of pantothenic acid.
    • Pantothenic acid helps to turn food into energy.
    • It is involved in the synthesis of lipids, neurotransmitters, steroid hormones, and hemoglobin.
    • Pantothenic acid aids in maintenance and repair of tissues and cells of the skin and hair.
    • It helps in the healing of wounds and lesions.
    • Pantothenic acid normalizes the blood lipid profile.
    • Pantothenic acid deficiency can cause fatigue and sleep disturbances.

    Vitamin B6

    • Vitamin B6 is a term that is applied to pyridoxol, pyridoxal, and pyridoxamine, three closely related, naturally occurring, highly substituted pyridine derivatives with comparable physiologic activity.
    • Pyridoxine, the most stable of these substances, is synthesized for exogenous dietary supplementation and therapeutic purposes.
    • Beef liver, tuna, salmon, fortified cereals, chickpeas, poultry, and some vegetables and fruits are good sources of vitamin B6.
    • Vitamin B6 improves mood.
    • It is required for biological reactions including amino acid metabolism, neurotransmitter synthesis, and red blood cell formation.
    • Vitamin B6 acts as a critical cofactor for a diverse range of biochemical reactions that regulate basic cellular metabolism.
    • Vitamin B6 deficiency can cause peripheral neuropathy.
    • Symptoms of vitamin B6 deficiency somewhat resemble those of niacin and riboflavin deficiencies, including neurological abnormalities, skin lesions, and hypochromic microcytic anemia.

    Vitamin B7

    • Foods that contain the most biotin include eggs, fish, meat, seeds, nuts, and certain vegetables (such as sweet potatoes).
    • Biotin plays an important role in metabolism as a coenzyme that transfers carbon dioxide.
    • This role is critical in the breakdown of food (carbohydrates, fats and proteins) into energy.
    • Biotin is involved in many cellular reactions, particularly in fat and protein metabolism of hair roots, finger nails, and skin.
    • It is used in fatty acid synthesis.
    • Biotin deficiency can cause fatigue, depression and dermatitis.

    Vitamin B9

    • Folic acid, folacin, pteroylglutamic acid, and occasionally vitamin B9 are terms that refer to a material with anti-anemia properties.
    • Beans, peanuts, sunflower seeds, fresh fruits, fruit juices, whole grains, and liver are good sources of folic acid.
    • Folate is essential for brain development and function.
    • Folate aids in the production of DNA and RNA.
    • It plays a role in the metabolism of vitamins and amino acids.
    • Folate is crucial during early pregnancy to reduce the risk of birth defects of the brain and spine.
    • Folate is required for the synthesis of glycine, methionine, nucleotides T & U.
    • Deficiency causes megaloblastic and macrocytic anemias and glossitis.

    Vitamin B12

    • Vitamin B12 (cobalamins) are terms that refer to a series of porphyrin-related corrinoid derivatives that function as extrinsic factors to prevent pernicious anemia.
    • Cyanocobalamin, a red crystalline material, is the most stable of the cobalamins and is frequently utilized in therapy.
    • Hydroxocobalamin, in which the cyano group is replaced with a hydroxyl substituent, is also used therapeutically.
    • Vitamin B12 acts as a coenzyme in the conversion of homocysteine to methionine.
    • It plays a role in the metabolism of fatty acids and amino acids.
    • Vitamin B12 contributes to the production of neurotransmitters.
    • Vitamin B12 maintains a special lining that surrounds and protects nerve fibers.
    • Bone cell activity depends on vitamin B12.
    • Vitamin B12 plays a significant role in DNA synthesis.
    • It helps in brain function and the synthesis of red blood cells.
    • Deficiencies usually involve rapidly dividing cells of the hematopoietic system (e.g., megaloblastic anemia) and irreversible neurological damage (e.g., defective myelin nerve sheaths).
    • Symptoms include irritability, weakness, memory loss, mood swings, and a sensation of tingling or numbness of the arms and legs.

    Vitamin C

    • Vitamin C or L-ascorbic acid is a naturally occurring vitamin substance that prevents scurvy and has useful antioxidant properties.
    • It occurs in equilibrium with dehydro-L-ascorbic acid, an oxidized form, which also has antiscorbutic properties.
    • Vitamin C is the least stable of all the vitamins.
    • Good dietary sources of ascorbic acid include citrus fruits, tomatoes, strawberries, and other fresh fruits and vegetables.
    • Although vitamin C content is preserved on freezing, up to 50% of the vitamin C content is lost upon cooking.
    • One of the important properties of Vitamin C is its antioxidant activity.
    • Vitamin C functions in enzyme activation and oxidative stress reduction.
    • It plays roles in the synthesis of collagen and absorption of iron.
    • Vitamin C aids defense against infections and inflammation.
    • Vitamin C helps to prevent certain diseases such as cancer, the common cold, cardiovascular diseases, and cataracts.
    • Vitamin C deficiency causes scurvy.

    Glycosides

    • A glycoside is an organic compound, usually of plant origin, that is composed of a sugar portion linked to a non-sugar moiety by a glycosidic bond.
    • The sugar portion is called the glycon.
    • The non-sugar portion is called the aglycon or genin.
    • There are four basic classes of glycosides: C-glycosides, in which the sugar is attached to the aglycone through a C-C bond, and O-glycosides in which the sugar is connected to the aglycone through a oxygen-carbon bond, S-glycosides, and N-glycosides.
    • Glycosides yield one or more sugars among the products upon enzymatic or acid hydrolysis.
    • The sugar component of glycosides may be mono-, di-, tri- or tetrasaccharides.
    • Sugars in glycosides exist in isomeric α and β forms so both α and β glycosides are theoretically possible, but the β-form is the one that occurs in plants.
    • The two diastereoisomers differ in configuration about the anomeric carbon (C-1).
    • The hydroxyl group on the anomeric carbon is down in relation to the cyclic structure for the α anomer while the hydroxyl group on the anomeric carbon is up in relation to the cyclic structure for the β anomer.
    • Chemically the glycosides are acetals in which the hydroxyl group (OH) of the glycone is condensed with the hydroxyl group of the aglycone.
    • Sugars exist predominantly as cyclic hemiacetals (R-O-C-OH group), while glycosides are usually mixed acetals (R-O-C-O-R) group.
    • Inside the body, glycosides will be cleaved to glycone and aglycone parts.
    • The glycone part confers on the molecule solubility properties, thus is important in the absorption and distribution in the body.
    • The aglycone part is responsible for the pharmacological activity.

    Physical and Chemical Properties of Glycosides

    • Because of the complexity of the structure of naturally occurring glycosides, no generalizations are possible with regard to their stability.
    • There are differences in their solubility properties.
    • Most glycosides are soluble in water or hydroalcoholic solutions and insoluble or less soluble in non-polar organic solvents because the solubility properties of the sugar residues exert a considerable effect; i.e. the sugar moiety increases water solubility.
    • The aglycon part is soluble in non-polar (organic) solvents such as benzene, ether, and chloroform.
    • Glycosides can be hydrolyzed by heating with a dilute acid where by the glycosidic linkages are cleaved.
    • Glycosides are relatively stable towards alkalis.
    • Glycosides can be hydrolyzed by appropriate enzymes, which are usually found in the same plant, in separate compartments.
    • There is a specific enzyme for each glycoside to exert a hydrolytic action on it.
    • The same enzyme is capable to hydrolyze different glycosides, but α and β stereo-isomers of the same glycoside are usually not hydrolyzed by the same enzyme.
    • Emulsin is found to hydrolyze most β-glycoside linkages while maltase and invertase are α-glycosidases, capable of hydrolyzing.
    • Glycosides are solid, amorphous and non-volatile.
    • Glycosides are colorless except flavonoids which are yellow and anthraquinones which are red or orange.
    • Most glycosides have a bitter taste.
    • Glycosides are odorless except saponin (glycyrrhizin).

    Importance of Glycosides

    • Glycosides play an important role in the life of the plant and are involved in different functions:
    • Sugar reserves.
    • Waste products of plant metabolism.
    • Mean of detoxification.
    • Regulating osmosis.
    • Regulating the supply of substances of importance in metabolism.
    • Defense against the invasion of tissues by microorganisms.
    • Many therapeutic agents are derived from glycosides.
    • Some of our most valuable cardiac glycosides are from digitalis, strophanthus, squill, and others.
    • Laxative drugs, such as senna, aloe, rhubarb, cascara sagrada, and frangula, contain emodin and other anthraquinone glycosides.
    • Sinigrin, a glycoside from black mustard, yields allyl isothiocyanate, a powerful local irritant.

    Classification of Glycosides

    • Glycosides can be classified according to the following:
    • The type of glycosidic linkage (α-glycosides or β-glycosides).
    • The chemical group of the aglycon involved in the formation of glycoside linkage (O-glycosides, C-glycosides, S-glycosides, and N-glycosides).
    • The chemical nature of the aglycon (cardioactive group, anthraquinone group, saponin group, cyanophore group, isothiocyanate group, flavonol group, alcohol group, aldehyde group, phenol group).
    • The nature of the simple sugar component of the glycoside (glucoside, galactoside, mannoside, arabinoside).

    Biosynthesis of Glycosides

    • Biosynthetic pathways are widely variable depending on the type of aglycone as well as the glycone units.
    • The aglycone and the sugar parts are biosynthesized separately, and then coupled to form a glycoside.
    • The coupling of the two parts occurs via phosphorylation of a sugar to yield a sugar 1-phosphate which reacts with a uridine triphosphate to form a uridine diphosphate sugar (UDP-sugar) and inorganic phosphate.
    • This UDP-sugar reacts with the aglycone to form the glycoside and a free UDP.

    Extraction of Glycosides

    • Since glycosides are accompanied by specific hydrolyzing enzymes, these enzymes must be inactivated by putting the plant in boiling water or alcohol.
    • Defatting or purification of the plant material in case of seeds.
    • Treatment with lead acetate to precipitate tannins and other non-glycosidal impurities.
    • Removal of any excess of lead acetate by passing hydrogen sulfide H2S gas through the solution.
    • The extract is filtered and concentrated to get the crude glycoside.
    • Purification of the crude glycosides by chromatography or crystallization.

    Cardioactive Glycosides

    • The glycosides of this group are characterized by their highly specific action on cardiac muscle, increasing tone, excitability, and contractility.
    • The aglycones of these glycosides are referred to as "cardiac genin".
    • They are steroidal in nature, specifically, they are derivatives of cyclopentaphenanthrene containing an unsaturated lactone ring attached to C17.
    • Two types of genin may be distinguished according to whether there is a five- or six-membered lactone ring.
    • These types are known respectively as cardenolides (e.g., digitoxigenin) and bufanolides or bufadienolides (e.g., scillarenin).
    • In the cardenolide (aglycones with 23 carbons), the lactone ring attached at C17 is a butenolide (4 carbons), which is also referred as α,β-unsaturated lactone ring. (e.g., the glycosides of digitalis and strophanthus species).
    • The lactone ring attached at C17 in the scilladienolide (aglycone with 24 carbons) is a pentadienolide (5 carbons with two double bonds), also called a pentenolide. (e.g. the squill glycosides and, Bufotoxin).

    Bufadienolides

    • Bufadienolides are a group of cardiac glycosides, which are naturally occurring compounds that affect the heart.
    • They are characterized by their specific chemical structure, including a 6-membered doubly unsaturated lactone ring at position C-17 and at least one double bond in the steroid nucleus.
    • They are found in plants like squill bulbs (Urginea maritima), which are used medicinally for their expectorant, emetic, cardiotonic, and diuretic properties.
    • Bufadienolides are often used as rat poison due to their toxic effects.

    Cardioactive Glycosides

    • These are a class of natural compounds found in plants that exert a strong effect on the heart.
    • They are characterized by the presence of a specific structure: a β-OH group at positions C-3 and C-14, an unsaturated 5 or 6-membered lactone ring at position C-17, and additional OH groups at positions C-5, C-11, and C-16.
    • They are classified into different types based on the number of double bonds present: cardenolides (one double bond), dienolides (two double bonds), cardanolides (no double bond), and bufanolides (no double bond).

    Digitalis

    • Digitalis is a dried leaf of the plant Digitalis purpurea (Foxglove).
    • It contains a large number of cardiac glycosides, with the most important ones being digitoxin, gitoxin, and gitaloxin.
    • Digitalis has been used in the treatment of congestive heart failure.

    Strophanthus

    • Strophanthus is a dried ripe seed of the plant Strophanthus kombe or Strophanthus hispidus.
    • It contains cardiac glycosides, particularly K-strophanthoside, K-strophanthin-B, and cymarin.
    • Strophanthus is used intravenously (I.V.) as a cardiotonic agent.

    Oleander

    • Oleander is derived from the plant Nerium oleander.
    • It contains cardiac glycosides, especially oleanderin, which is considered a promising agent for anticancer treatment.
    • Oleander is known to be poisonous, particularly to animals, if consumed in large quantities.

    Squill

    • Squill refers to the bulb of the plant Urginea maritima (white or Mediterranean squill) or Urginea indica (Indian squill).
    • Squill glycosides differ from cardenolides in having a six-membered doubly unsaturated lactone ring at position C-17 and at least one double bond in the steroid nucleus.
    • Squill is used as an expectorant, but it also possesses emetic, cardiotonic, and diuretic properties.
    • Red squill, derived from the bulb of the red variety of Urginea maritima, is used as a rat poison.

    Mechanism of Action

    • Cardioactive glycosides inhibit the Na+/K+ ATPase enzyme, a membrane-bound enzyme responsible for maintaining potassium (K+) levels inside the cell and sodium (Na+) levels outside the cell.
    • Inhibition of this enzyme disrupts ion balance, leading to increased calcium (Ca+2) entry into the cell.
    • Increased intracellular calcium promotes the contraction of actin and myosin, leading to stronger heart contractions.

    Important Facts

    • The glycone portion of cardiac glycosides can contain up to four monosaccharide molecules linked in series.
    • Cardioactive glycosides are primarily derived from mevalonic acid, with the final molecules arising from a condensation of a C21 steroid with a C2 or C3 unit.
    • Digitalis (foxglove) contains numerous cardiac glycosides, including digitoxin, gitoxin, and gitaloxin.
    • Strophanthus contains K-strophanthoside, K-strophanthin-B, and cymarin, which are based on the genin strophanthidin.
    • Oleander contains oleanderin, a potential anticancer agent.
    • Squill glycosides differ from cardenolides in their structure and have expectorant, emetic, cardiotonic, and diuretic properties.

    Metabolism

    • Metabolism refers to all chemical processes in living organisms.
    • Metabolites are products of metabolic processes and include primary and secondary metabolites.
    • Primary metabolites are involved in essential functions during growth, development, and reproduction, like energy metabolism, while secondary metabolites don't have a central role and are often produced during the stationary phase of growth.

    Primary Metabolites

    • Primary metabolites include ethanol, lactic acid, and certain amino acids.
    • Primary metabolites like amino acids (L-glutamate, L-lysine) and citric acid are commonly used in industrial microbiology.
    • L-glutamate and L-lysine are produced by Corynebacteria glutamicum, while citric acid is produced by Aspergillus niger.

    Secondary Metabolites

    • Secondary metabolites are formed by modifying primary metabolite synthases and often serve ecological functions, like defense mechanisms, by producing antibiotics and pigments.
    • Atropine, erythromycin, and bacitracin are examples of secondary metabolites used industrially.
    • Atropine, derived from plants, is a muscarinic acetylcholine receptor antagonist used to treat bradycardia.
    • Erythromycin, produced by Saccharopolyspora erythraea, is a broad-spectrum antibiotic commonly administered orally.
    • Bacitracin, produced by Bacillus subtilis, is a topical antibiotic.

    Photosynthesis

    • Photosynthesis converts light energy into chemical energy stored in glucose.
    • The process occurs in chloroplasts of green organisms.
    • Photosynthesis depends on carbon dioxide, water, and light energy, producing glucose, oxygen, and water.
    • Pigments like chlorophyll a, chlorophyll b, and carotenoids are involved in capturing light energy, with chlorophyll a as the main pigment.

    Light Reaction

    • This reaction uses light energy to generate ATP and NADPH in the thylakoid membranes of chloroplasts.
    • Photosystems I and II, within the grana, gather light and play a key role in the light-dependent reactions.

    Dark Reaction

    • This reaction is also called the carbon-fixing reaction and is light-independent.
    • It occurs in the stroma of the chloroplast, using NADPH and ATP from the light reaction to synthesize sugar molecules.
    • The Calvin cycle is a crucial part of the dark reaction, incorporating carbon dioxide from the atmosphere to form glucose.

    Glycolysis

    • This pathway converts glucose into pyruvate in the cytosol with a net gain of two ATP molecules.
    • This process can occur in both aerobic and anaerobic conditions.

    Citric Acid Cycle

    • This cycle takes place in the mitochondrial matrix and oxidizes acetyl-CoA to carbon dioxide, producing reduced coenzymes that generate ATP in the electron transport chain.

    Biosynthesis of Secondary Metabolites

    • Biosynthesis involves multi-step enzyme-catalyzed processes, converting substrates into more complex products using primary metabolites as building blocks.
    • Important building blocks include acetyl CoA, shikimic acid, mevalonic acid, and malonic acid, derived from photosynthesis, glycolysis, and the Krebs cycle.

    Shikimic Acid Pathway

    • This pathway is essential for the biosynthesis of phenolic compounds, alkaloids, and other aromatic compounds.
    • It occurs in chloroplasts of plant cells and involves phenylpropanoid precursors.
    • It is a seven-step pathway used by bacteria, archaea, fungi, algae, some protozoans, and plants for the synthesis of folates and aromatic amino acids (phenylalanine, tyrosine, and tryptophan).

    Malonic Acid Pathway

    • This pathway works with acyl carrier protein (ACP) to produce fatty acyl thioesters of ACP, which are important intermediates in fatty acid synthesis.
    • Acetyl CoA units are used to synthesize fatty acids of varying chain lengths.

    Mevalonic Acid Pathway

    • This pathway is also known as the isoprenoid pathway and is involved in the synthesis of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR).
    • The pathway is crucial for cholesterol biosynthesis, protein synthesis, membrane cell structure, steroid hormone production, and other functions.
    • The pathway produces isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), which are important building blocks for isoprenoid compounds.

    Vitamin E

    • Several tocopherol analogs, including B, y, and S-tocopherols, exist in nature, but possess low levels of vitamin E activity.
    • Vitamin E is widely distributed in nature, and dietary sources typically meet the body's requirements.
    • Plant oils, green vegetables, whole grains, egg yolks, and meats are common dietary sources.
    • Wheat germ oil is a traditional natural source of vitamin E for therapeutic purposes.
    • Vitamin E is the major lipid-soluble antioxidant, protecting cell membranes, proteins, and DNA from oxidation.
    • Vitamin E prevents oxidation of polyunsaturated fatty acids and lipids in cells.
    • Vitamin E deficiency can lead to nerve and muscle damage resulting in loss of feeling in extremities, movement control, muscle weakness, and vision problems.
    • A weakened immune system is another sign of deficiency.

    Vitamin K

    • Vitamin K refers to 2-methyl-1,4-naphthoquinone and its derivatives.
    • Dairy products, various fruits and vegetables, and green leafy vegetables are good sources of vitamin K.
    • The intestinal microflora also provide a significant portion of the normal human supply of vitamin K.
    • Vitamin K's primary function is in blood clotting (antihemorrhagic activity).
    • Vitamin K is used in treatments for bleeding events caused by warfarin overdose.
    • Vitamin K assists in metabolism of bone proteins (osteocalcin), crucial for bone mineralization.
    • Vitamin K deficiency leads to hemorrhage, the most common symptom.

    Water-Soluble Vitamins

    • Water-soluble vitamins are a group of essential nutrients that dissolve in water.

    B-complex Vitamins

    • These vitamins are a group of eight essential nutrients involved in various metabolic processes.
    Vitamin B1 (Thiamine)
    • Thiamine contains substituted pyrimidine and thiazole rings linked by a methylene bridge.
    • Commercial thiamine is prepared by chemical synthesis and is usually used as the hydrochloride salt.
    • Thiamine is stable in acidic environments but decomposes readily above pH 5.0.
    • About 50% of thiamine in food is destroyed during cooking.
    • Whole grains, legumes, and meats are good sources of thiamine.
    • Alcohol inhibits thiamine absorption.
    • Thiamine is involved in energy metabolism, converting carbohydrates, lipids, and proteins into energy.
    • Plays a key role in nerve and muscle activity.
    • May be helpful for people with Alzheimer's disease.
    • Involved in development of myelin sheaths and improves brain function.
    • Deficiency can cause Wernicke encephalopathy and beriberi.
    • Risk factors include alcohol dependence, malabsorption, and a thiamine-deficient diet.
    Vitamin B2 (Riboflavin)
    • Riboflavin is a yellow, heat-stable substance slightly soluble in water. It is sensitive to light.
    • Yeast is the richest natural source of riboflavin.
    • Dairy products, eggs, legumes, and meats are the main dietary sources.
    • Riboflavin is stable during cooking in the absence of light.
    • Riboflavin exists in foods as free form or as riboflavin 5'-phosphate (FMN) and flavin adenine dinucleotide (FAD).
    • These nucleotides are hydrolyzed to free riboflavin in the upper gastrointestinal tract.
    • Free riboflavin is readily absorbed into cells by an active transport system enhanced by bile salts.
    • Riboflavin acts as a coenzyme in numerous oxidation-reduction reactions, essential for energy release from carbohydrates, fats, and proteins.
    • It stimulates growth and reproduction.
    • Plays a role in vision.
    • Involved in conversion of vitamins B6, folic acid, and niacin into their active coenzyme forms.
    • Acts as an antioxidant by neutralizing free radicals.
    • Deficiency causes stomatitis and dermatitis.
    Vitamin B3 (Niacin)
    • Niacin, nicotinic acid, or vitamin B3 is a naturally occurring pyridine derivative that prevents pellagra.
    • Niacinamide or nicotinamide also occurs naturally and has anti-pellagra activity, being used for dietary and therapeutic purposes.
    • They are readily absorbed from the gastrointestinal tract under normal circumstances.
    • Meats, fish, and dairy products are good dietary sources of niacin.
    • Roasting coffee beans releases significant amounts of niacin.
    • Tryptophan can be converted to niacin in the body.
    • Niacin acts as a coenzyme in energy-transfer reactions.
    • Similar to riboflavin coenzymes, it carries hydrogen during metabolic reactions.
    • Protects against neurological degeneration and Alzheimer's disease.
    • Helps lower LDL cholesterol.
    • Lowers cardiovascular disease risk and eases arthritis.
    • Deficiency causes pellagra, characterized by symptoms affecting the nervous system, skin, and gastrointestinal tract (dementia, dermatitis, and diarrhea).
    Vitamin B5 (Pantothenic acid)
    • Pantothenic acid is a component of the vitamin B complex, sometimes known as the "chick antidermatitis factor."
    • Hydrolysis of pantothenic acid yields β-alanine and pantoic acid.
    • Animal organs (heart, kidney, and liver) and cereal grains are rich dietary sources of pantothenic acid.
    • Pantothenic acid facilitates the conversion of food into energy.
    • Involved in the synthesis of lipids, neurotransmitters, steroid hormones, and hemoglobin.
    • Maintains and repairs tissues and cells of the skin and hair.
    • Helps heal wounds and lesions.
    • Normalizes blood lipid profiles.
    • Deficiency causes fatigue and sleep disturbances.
    Vitamin B6 (Pyridoxine)
    • Vitamin B6 refers to pyridoxol, pyridoxal, and pyridoxamine, three related pyridine derivatives with comparable physiological activity.
    • Pyridoxine is the predominant form of vitamin B6 in plants, while pyridoxal and pyridoxamine occur in animal tissues.
    • Synthetically prepared pyridoxine is typically used for dietary supplementation.
    • Beef liver, tuna, salmon, fortified cereals, chickpeas, poultry, and some vegetables and fruits are good sources of Vitamin B6.
    • Vitamin B6 is required for biological reactions, including amino acid metabolism, neurotransmitter synthesis, and red blood cell formation.
    • Acts as a coenzyme for biochemical reactions regulating cellular metabolism.
    Vitamin B7 (Biotin)

    • Foods rich in biotin include eggs, fish, meat, seeds, nuts, and vegetables like sweet potatoes.

    • Biotin plays a crucial role in metabolism as a coenzyme that transfers carbon dioxide.

    • Essential for the breakdown of food (carbohydrates, fats, and proteins) into energy.

    • Involved in numerous cellular reactions, particularly fat and protein metabolism of hair, nails, and skin.

    • Used in fatty acid synthesis.

    • Deficiency causes fatigue, depression, and dermatitis.

    Vitamin B9 (Folic Acid)
    • Folic acid, folacin, pteroylglutamic acid, and vitamin B9 are terms referencing a material with anti-anemia properties.
    • Beans, peanuts, sunflower seeds, fresh fruits, fruit juices, whole grains, and liver are good sources of folic acid.
    • Folic acid is essential for brain development and function.
    • Aids in the production of DNA and RNA.
    • Involved in the metabolism of vitamins and amino acids.
    • Crucial during early pregnancy to reduce the risk of birth defects.
    • Required for the synthesis glycine, methionine, and nucleotides T and U.
    • Deficiency causes megaloblastic and macrocytic anemias and glossitis.
    Vitamin B12 (Cobalamin)
    • Vitamin B12 (cobalamins) are a series of porphyrin-related corrinoid derivatives that function as extrinsic factors preventing pernicious anemia.
    • Cyanocobalamin is the most stable cobalamin, commonly used therapeutically.
    • Hydroxocobalamin, with a hydroxyl group replacing the cyano group, is also used therapeutically.
    • Vitamin B12 acts as a coenzyme in the conversion of homocysteine to methionine.
    • It plays a role in the metabolism of fatty acids and amino acids.
    • Involved in the production of neurotransmitters.
    • Maintains the lining surrounding and protecting nerve fibers.
    • Bone cell activity depends on vitamin B12.
    • Plays a significant role in DNA synthesis.
    • Essential for brain function and red blood cell synthesis.
    • Deficiency affects rapidly dividing cells in the hematopoietic system (e.g., megaloblastic anemia) and can cause irreversible neurological damage (e.g., defective myelin nerve sheaths).

    Vitamin C

    • Vitamin C, or L-ascorbic acid, prevents scurvy and has antioxidant properties. 
    • It exists in equilibrium with dehydro-L-ascorbic acid, an oxidized form with antiscorbutic properties.
    • Vitamin C is the least stable of all vitamins.
    • Citrus fruits, tomatoes, strawberries, and other fresh fruits and vegetables are good dietary sources.
    • Freezing preserves the vitamin content, but cooking can lead to a 50% loss of vitamin C.
    • Vitamin C has significant antioxidant activity.
    • Functions in enzyme activation and oxidative stress reduction.
    • Plays a role in collagen synthesis and iron absorption.
    • Important for defense against infections and inflammation.
    • Helps prevent diseases like cancer, the common cold, cardiovascular diseases, and cataracts.
    • Deficiency causes scurvy.

    Bufadienolides

    • Bufadienolides are a type of cardiac glycoside with a six-membered doubly unsaturated lactone ring at position C-17
    • They have at least one double bond in the steroid nucleus
    • Squill glycosides (R1=OH, R2=H) and Bufotoxin (R1 & R2 = ester group) are examples of bufadienolides

    Cardiac Glycosides

    • All cardioactive glycosides have a β-OH group at position C-3, which is involved in a glycosidic linkage to a mono, di, tri, or tetrasaccharide
    • They also have a β-OH group at C-14
    • They have an unsaturated 5 or 6-membered lactone ring at position C-17, also in the β configuration
    • They may have additional OH groups at C-5, C-11, and C-16

    Nomenclature

    • The sequence of nomenclature for cardioactive glycosides is as follows:
      • Arrange the functional groups and denote their configuration
      • Denote whether the configuration is α or β
      • Denote the type of glycoside
      • Denote the position of the double bonds
    • If the compound has one double bond, it is called a cardenolide
    • If it has two double bonds, it is called a dienolide
    • If it has no double bond, it is called a cardanolide or bufanolide

    Biosynthesis

    • Aglycones of cardiac glycosides are derived from mevalonic acid
    • The final molecules arise from a condensation of a C21 steroid with a C2 unit (the source of C-22 and C-23).
    • Bufadienolides are condensation products of a C21 steroid and a C3 unit

    Drugs containing cardioactive glycosides

    • Digitalis or foxglove
      • It's the dried leaf of Digitalis purpurea (Scrophulariaceae)
      • Contains a large number of glycosides, the most important being digitoxin, gitoxin, and gitaloxin
      • The average concentration of glycosides in the leaf is about 0.16%
      • Nearly 30 other glycosides have been identified in the drug, including purpurea glycosides A and B, gluco-gitaloxin, and gluco-digitoxigenin
      • Primary glycosides with acetylated sugar moieties
    • Digitalis lanata
      • Nearly 70 different glycosides have been detected in the leaves of Digitalis lanata
      • All are derivatives of five different aglycones, three of which (digitoxigenin, gitoxigenin, and gitaloxigenin) also occur in Digitalis purpurea
      • The other two types of glycosides are derived from digoxigenin and diginatigenin, which occur in Digitalis lanata but not in Digitalis purpurea
      • The leaves of Digitalis lanata are used as a source of the glycosides digoxin and lanatoside C
      • Lantoside A, B, and E are acetyl derivatives of purpurea A, B, and E, respectively
    • Glycosides derived from Digitoxigenin:
      • Lanatoside A = Digitoxigenin---DX---DX----DX(AC)---G
      • Acetyl-digitoxin = Digitoxigenin---DX---DX----DX---(AC)
      • Digitoxin = Digitoxigenin------DX---DX----DX
      • Purpurea gly A = Digitoxigenin---DX---DX----DX---G
      • DX = Digitoxose, DX (AC)=Acetyldigitoxose, G = Glucose
    • Strophanthus
      • It's the dried ripe seeds of Strophanthus kombe or Strophanthus hispidus (Apocyanaceae)
      • Principal glycosides are K-strophanthoside, K-strophanthin-B, and cymarin, all based on the genin strophanthidin
      • K-strophanthoside, also known as strophoside, is the main glycoside in both S.kombe and S.hispidus
      • It's composed of the genin strophanthidin coupled to a trisaccharide consisting of cymarose, β-glucose, and α-glucose
      • Strophanthin is used intravenously as a cardiotonic
    • Ouabin (G-strophanthin)
      • It's obtained from Strophanthus gratus (Apocynaceae)
      • It's a highly polar cardioactive glycoside
      • Acts as a cardiotonic and is administered intravenously for prompt therapeutic effect
      • It's absorbed so slowly and irregularly from the alimentary canal that oral administration is not recommended and is considered unsafe
    • Oleander
      • The leaves of Nerium oleander (Apocynaceae) have been used to treat cardiac insufficiency
      • The main constituent is oleanderin, which is a promising agent for anticancer treatment
      • Oleander has historically been considered a poisonous plant because some of its compounds may exhibit toxicity, especially to animals, when consumed in large amounts
    • Squill bulb
      • The white variety of Urginea maritima is known as white or Mediterranean squill
      • Urginea indica is known as Indian squill (Liliaceae)
      • Squill glycosides have a six-membered doubly unsaturated lactone ring at position C-17
      • They have at least one double bond in the steroid nucleus
      • Used as an expectorant and possesses emetic, cardiotonic, and diuretic properties
    • Red squill
      • It consists of the bulb of the red variety of Urginea maritima and is mostly used as rat poison

    Mechanism of Action

    • Cardiac glycosides act by inhibiting the Na+/K+ ATPase enzyme
    • This enzyme maintains the concentration of K+ inside the cell and Na+ outside the cell
    • Inhibition of the enzyme blocks K+ transport back into the cell, increasing its concentration in the extracellular fluid
    • At the same time, Na+ ions enter the cell, facilitating the entry of Ca+2 which is essential for the contraction of actin and myosin
    • Therefore, cardiac glycosides are used in the treatment of congestive heart failure.

    Side Effects

    • Cardiac glycosides can cause various side effects, including:
      • Nausea
      • Vomiting
      • Diarrhea
      • Loss of appetite
      • Arrhythmias
      • Heart block
      • Visual disturbances
    • It is important to monitor patients carefully for these side effects and adjust the dosage as needed.

    Metabolism

    • Metabolism refers to all chemical transformations occurring in living organisms, essential for their survival.
    • Metabolites are the end products and intermediates formed during metabolic processes.
    • Primary metabolites directly contribute to normal growth, development, and reproduction.
    • Primary metabolites are produced during the growth phase due to energy metabolism, and are crucial for proper growth.
    • Primary metabolites include alcohols (ethanol, lactic acid), amino acids (L-glutamate, L-lysine), and citric acid.
    • Secondary metabolites are organic compounds formed through the modification of primary metabolite synthases, typically during the stationary phase of growth.
    • Secondary metabolites play a role in ecological functions:
      • Defense mechanisms (antibiotics, pigmentation)
      • Ecological interactions

    Biosynthesis of Secondary Metabolites

    • Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products.
    • Simple compounds are modified, converted, or joined to form macromolecules, often involving metabolic pathways.
    • Building blocks for secondary metabolites are derived from primary metabolites, mainly from photosynthesis, glycolysis, and the Krebs cycle.
    • Key building block molecules include:
      • Acetyl CoA
      • Shikimic acid
      • Mevalonic acid
      • Malonic acid

    Shikimic Acid Pathway

    • The shikimic acid pathway is the foundation for the biosynthesis of phenolic compounds, alkaloids, and other secondary metabolites.
    • This pathway takes place in chloroplast plant cells and utilizes phenylpropanoid precursors.
    • Aromatic compounds, a type of secondary metabolite, are abundant in plants and their expression is triggered by environmental stresses (pathogens, herbivores, pH, temperature, UV, salinity, heavy metals).
    • The shikimic acid pathway is also known as the chorismate pathway.
    • The pathway starts with two substrates: phosphoenol pyruvate and erythrose-4-phosphate, and ends with chorismate, a precursor for the synthesis of three aromatic amino acids.
    • Aromatic amino acids (phenylalanine, tyrosine, tryptophan) are produced by the shikimate pathway and serve as building blocks for proteins, alkaloids, phenols, and other biosynthesis processes.
    • The shikimate pathway links central and specialized metabolism in plant cells and carbon degradation during the synthesis of secondary metabolites.

    Malonic Acid (Malonate/Acetate) Pathway

    • The acetate pathway operates with the involvement of acyl carrier protein (ACP) to produce fatty acylthioesters of ACP.
    • These acyl thioesters are crucial intermediates in fatty acid synthesis.
    • Acetyl CoA units produce fatty acids with even numbers of carbons, ranging from butyric to arachidic acid.
    • Malonyl CoA, formed from acetyl CoA by the addition of CO2, is the primary substrate for fatty acid synthase.

    Mevalonic Acid (Mevalonate) Pathway

    • The mevalonic acid (MVA) pathway, or isoprenoid pathway, involves the synthesis of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR).
    • This pathway plays a critical role in cellular metabolism in eukaryotes, archaea, and some bacteria, including cholesterol biosynthesis and protein production.
    • Cholesterol is used to build cell membrane structure, steroid hormones, myelin sheaths in the nervous system, vitamin D precursors, and synaptic vesicles.
    • The MVA pathway produces isopentenyl pyrophosphate (IPP) and its isomer dimethylallyl pyrophosphate (DMAPP).
    • These two intermediates are the basic building blocks of isoprenoid compounds.
    • They build various isoprenoid compounds, including:
      • Geranyl pyrophosphate (C10-monoterpenes)
      • Farnesyl pyrophosphate (C15-sesquiterpenes)
      • Geranyl-geranyl pyrophosphate (C20-diterpenes)
    • Farnesyl pyrophosphate is used to produce squalene, and its subsequent cyclization generates cholesterol and triterpenoids.

    Vitamin E

    • Structurally related tocopherol analogs, including B, gamma, and delta-tocopherols, occur in nature but possess low vitamin E activity.
    • Dietary sources include plant oils, green vegetables, whole grains, egg yolks, and meats.
    • Wheat germ oil is a traditional source of vitamin E for therapeutic purposes.
    • Vitamin E is a major lipid-soluble antioxidant that protects cell membranes, proteins, and DNA from oxidation.
    • Prevents oxidation of polyunsaturated fatty acids and lipids in cells.
    • Contributes to cellular health.
    • Deficiency can lead to nerve and muscle damage, resulting in loss of feeling in arms and legs, loss of body movement control, muscle weakness, and vision problems.
    • A weakened immune system is another sign of deficiency.

    Vitamin K

    • Refers to 2-methyl-1,4-naphthoquinone and its derivatives.
    • Widely distributed in dairy products, many fruits and vegetables, especially green leafy vegetables.
    • The intestinal microflora provides a significant portion of the normal human supply of vitamin K.
    • Primarily acts in blood clotting (antihemorrhagic activity).
    • Treatment for bleeding events caused by warfarin (anticoagulant drug) overdose.
    • Helps in the metabolism of bone proteins (osteocalcin).
    • Without vitamin K, osteocalcin cannot bind to minerals needed for bone formation, resulting in poor bone mineralization.
    • Regulates blood calcium levels.
    • Hemorrhage is the most common symptom in vitamin K deficiency.

    Vitamin B-Complex

    Vitamin B1 (Thiamine)

    • Thiamine or vitamin B1 consists of substituted pyrimidine and thiazole rings linked by a methylene bridge.
    • Commercial supplies are prepared by chemical synthesis and often used as the hydrochloride salt.
    • Stable in acidic environments but readily decomposes above pH 5.0.
    • Approximately 50% of the vitamin in foods is destroyed during cooking.
    • Good dietary sources are whole grains, legumes, and meats.
    • Alcohol inhibits its absorption.
    • Participates in energy metabolism by converting carbohydrates, lipids, and proteins into energy.
    • Plays a key role in nerve and muscle activity.
    • May be helpful for those with Alzheimer’s disease.
    • Promotes brain function and the development of myelin sheaths.
    • Deficiency can cause several clinical syndromes, including Wernicke encephalopathy and beriberi.
    • Risk factors include alcohol dependence, malabsorption, and a thiamine-deficient diet.

    Vitamin B2 (Riboflavin)

    • Yellow, heat-stable substance slightly soluble in water.
    • Sensitive to light and can change into lumichrome or lumiflavin, depending on the acidity or alkalinity of the irradiated solution; neither form has physiological activity.
    • Yeast is the richest natural source.
    • Main dietary sources include dairy products, eggs, legumes, and meats.
    • Small amounts are found in cereal grains, fruits, and green vegetables.
    • Stable during cooking when protected from light.
    • Occurs in foods in free form and as riboflavin 5'-phosphate (Flavin mononucleotide or FMN) and flavin adenine dinucleotide (FAD).
    • Nucleotides are hydrolyzed to riboflavin in the upper gastrointestinal tract.
    • Free riboflavin is readily absorbed into cells of the intestinal mucosa by an active transport system enhanced by bile salts.
    • Acts as a coenzyme in numerous oxidation-reduction reactions essential for energy release from carbohydrates, fats, and proteins.
    • Stimulates growth and reproduction.
    • Plays a role in vision.
    • Involved in the conversion of vitamins B6, folic acid, and niacin into their active coenzyme forms.
    • Neutralizes free radicals, acting as an antioxidant.
    • Deficiency can cause stomatitis and dermatitis.

    Vitamin B3 (Niacin)

    • Simple pyridine derivative that prevents pellagra.
    • Niacinamide also has anti-pellagra activity and is used for dietary and therapeutic purposes.
    • Readily absorbed from the gastrointestinal tract under normal circumstances.
    • Good dietary sources are meats, fish, and dairy products.
    • Roasting coffee beans releases significant amounts of niacin and develops a characteristic flavor.
    • Tryptophan is converted to niacin in the body.
    • Acts as a coenzyme in energy-transfer reactions.
    • Similar to riboflavin coenzymes in carrying hydrogen during metabolic reactions.
    • Protects against neurological degeneration and Alzheimer’s disease.
    • Helps lower LDL cholesterol.
    • Lowers the risk of cardiovascular diseases and eases arthritis.
    • Pellagra is the classic niacin-deficiency condition.
    • Symptoms involve the nervous system, skin, and gastrointestinal tract, often summarized as the 3Ds: dementia, dermatitis, and diarrhea.
    • Oral lesions, especially angular stomatitis and red tongue, are more distinct than other symptoms.

    Vitamin B5 (Pantothenic Acid)

    • Component of the vitamin B complex, sometimes known as the “chick antidermatitis factor".
    • Naturally occurring compound that yields β-alanine and pantoic acid upon hydrolysis.
    • Animal organs (heart, kidney, and liver) and cereal grains are rich dietary sources.
    • Turns food into energy.
    • Involved in the synthesis of lipids, neurotransmitters, steroid hormones, and hemoglobin.
    • Maintains and repairs skin and hair tissues and cells.
    • Helps heal wounds and lesions.
    • Normalizes blood lipid profile.
    • Deficiency can cause fatigue and sleep disturbances.

    Vitamin B6

    • Term applied to pyridoxol, pyridoxal, and pyridoxamine, three closely related, naturally occurring pyridine derivatives with comparable physiological activity.
    • Pyridoxine (pyridoxol) is the predominant form in plants, and the term used in pharmacy and medicine.
    • Pyridoxal and pyridoxamine occur in animal tissues.
    • Pyridoxine is the most stable, so synthetically prepared pyridoxine is usually used in exogenous dietary supplementation and therapeutic purposes.
    • Good dietary sources include beef liver, tuna, salmon, fortified cereals, chickpeas, and poultry.
    • Some vegetables and fruits, especially dark leafy greens, pineapple, papaya, oranges, and cantaloupe, also contain vitamin B6.
    • Required for biological reactions like amino acid metabolism, neurotransmitter synthesis, and red blood cell formation.
    • Acts as a crucial co-factor for diverse biochemical reactions that regulate basic cellular metabolism.
    • Deficiency can cause peripheral neuropathy.
    • Symptoms resemble those of niacin and riboflavin deficiencies and include neurological abnormalities, skin lesions, and hypochromic microcytic anemia.

    Vitamin B7 (Biotin)

    • Found in eggs, fish, meat, seeds, nuts, and certain vegetables (sweet potatoes).
    • Plays an important role in metabolism as a coenzyme that transfers carbon dioxide.
    • Crucial for breaking down food (carbohydrates, fats, and proteins) into energy.
    • Involved in many cellular reactions, particularly in fat and protein metabolism of hair roots, fingernails, and skin.
    • Used in fatty acid synthesis.
    • Deficiency can cause fatigue, depression, and dermatitis.

    Vitamin B9 (Folate)

    • Terms include folic acid, folacin, pteroylglutamic acid, and vitamin B9.
    • Sources include beans, peanuts, sunflower seeds, fresh fruits, fruit juices, whole grains, and liver.
    • Essential for brain development and function.
    • Aids in the production of DNA and RNA.
    • Involved in the metabolism of vitamins and amino acids.
    • Crucial during early pregnancy to reduce the risk of birth defects of the brain and spine.
    • Required for the synthesis of glycine, methionine, and nucleotides T and U.
    • Deficiency states include megaloblastic and macrocytic anemias and glossitis.

    Vitamin B12 (cobalamins)

    • Refer to a series of porphyrin-related corrinoid derivatives that function as extrinsic factors to prevent pernicious anemia.
    • Cyanocobalamin is the most stable form and is frequently used in therapy.
    • Hydroxocobalamin also finds some therapeutic use, with the cyano group replaced by a hydroxyl substituent.
    • Acts as a coenzyme in the conversion of homocysteine to methionine.
    • Plays a role in the metabolism of fatty acids and amino acids.
    • Involved in the production of neurotransmitters.
    • Maintains the lining surrounding and protecting nerve fibers.
    • Bone cell activity depends on vitamin B12.
    • Plays a significant role in DNA synthesis.
    • Helps in brain function and the synthesis of red blood cells.
    • Deficiency usually involves rapidly dividing cells of the hematopoietic system (megaloblastic anemia) and irreversible neurological damage (defective myelin nerve sheaths).
    • Symptoms include irritability, weakness, memory loss, mood swings, and a tingling or numbness sensation in the arms and legs.

    Vitamin C (L-Ascorbic Acid)

    • Naturally occurring vitamin that prevents scurvy and has antioxidant properties.
    • Exists in equilibrium with dehydro-L-ascorbic acid, an oxidized form, which also has antiscorbutic properties.
    • Least stable of all vitamins.
    • Good dietary sources include citrus fruits, tomatoes, strawberries, and other fresh fruits and vegetables.
    • Content is preserved on freezing, but up to 50% is lost upon cooking.
    • One of its important properties is antioxidant activity.
    • Functions in enzyme activation and oxidative stress reduction.
    • Plays a role in collagen synthesis and iron absorption.
    • Provides defense against infections and inflammation.
    • Helps prevent certain diseases like cancer, the common cold, cardiovascular diseases, and cataracts.
    • Deficiency causes scurvy.

    Glycosides

    • Organic compounds, usually of plant origin, composed of a sugar portion linked to a non-sugar moiety by a glycosidic bond.
    • Sugar portion is called glycon.
    • Non-sugar portion is called aglycon or genin.
    • Four basic classes: C-glycosides, O-glycosides, S-glycosides, and N-glycosides.
    • Yield one or more sugars upon enzymatic or acid hydrolysis.
    • Sugar component can be mono-, di-, tri-, or tetrasaccharides.

    Alpha and Beta Glycosides

    • Sugars exist in isomeric α and β forms, so both are theoretically possible.
    • β-form is the one that predominantly occurs in plants.
    • Diastereoisomers differ in configuration about the anomeric carbon (C-1).
    • α anomer has a hydroxyl group on the anomeric carbon down in relation to the cyclic structure.
    • β anomer has a hydroxyl group on the anomeric carbon up in relation to the cyclic structure.
    • Chemically, glycosides are acetals with the hydroxyl group (OH) of the glycon condensed with the hydroxyl group of the aglycone.
    • Sugars exist as cyclic hemiacetals (R-O-C-OH group), while glycosides are mixed acetals (R-O-C-O-R group).
    • Glycosides are cleaved in the body to glycon and aglycone parts.
    • Glycon confers solubility properties, important for absorption and distribution.
    • Aglycone is responsible for the pharmacological activity.

    Physical and Chemical Properties of Glycosides

    • No generalizations are possible regarding stability due to structural complexity.
    • There are differences in their solubility properties.
    Solubility
    • Most are soluble in water or hydroalcoholic solutions and insoluble or less soluble in non-polar organic solvents because the sugar residues increase water solubility.
    • Aglycone part is soluble in non-polar organic solvents like benzene, ether, and chloroform.
    Stability and Hydrolytic Cleavage
    • Acids and alkali: Glycosides are hydrolyzed by heating with dilute acid, cleaving the glycosidic linkages. They are relatively stable towards alkalis.
    • Enzyme hydrolysis: Specific enzymes, usually found in the same plant, in separate compartments, can hydrolyze glycosides. One enzyme can hydrolyze different glycosides, but α and β stereo-isomers of the same glycoside usually are not hydrolyzed by the same enzyme. Emulsin hydrolyzes most β-glycoside linkages, while maltase and invertase are α-glycosidases.
    Shape, Color, Taste, and Odor:
    • Shape: Glycosides are solid, amorphous, and nonvolatile.
    • Color: Colorless except for flavonoids (yellow) and anthraquinones (red or orange).
    • Taste: Most are bitter.
    • Odor: Odorless except for saponin (glycyrrhizin).

    Importance of Glycosides

    • Play an important role in plant life.
    • Serve as sugar reserves, waste products of plant metabolism, a means of detoxification, regulators of osmosis, regulators of the supply of important substances in metabolism, and a defense against microbial invasion. Aglycones are sometimes suggested to be antiseptics and bactericidal.
    • Many therapeutic agents are derived from glycosides, contributing to almost every therapeutic class. Examples include:
      • Cardioactive glycosides: Digitalis, strophanthus, squill.
      • Laxative drugs: Senna, aloe, rhubarb, cascara sagrada, frangula.
      • Sinigrin: From black mustard, yields allyl isothiocyanate (irritant).

    Biosynthesis of Glycosides

    • Pathways are variable depending on the aglycone and glycone units.
    • Aglycone and sugar parts are biosynthesized separately and then coupled to form a glycoside.
    • Coupling occurs by phosphorylation of a sugar to yield a sugar 1-phosphate, which reacts with uridine triphosphate to form a uridine diphosphate sugar (UDP-sugar) and inorganic phosphate.
    • UDP-sugar reacts with the aglycone to form the glycoside and a free UDP.

    Extraction of Glycosides

    • Inactivate hydrolyzing enzymes by putting the plant in boiling water or alcohol.
    • Defatting or purification of the plant material (seeds).
    • Treatment with lead acetate: Precipitates tannins and other non-glycosidal impurities.
    • Removal of excess lead acetate: By passing hydrogen sulfide (H2S) gas through the solution.
    • Filter and concentrate the extract: To obtain the crude glycoside.
    • Purify the crude glycosides: By chromatography or crystallization.

    Cardioactive Glycosides

    • Characterized by their specific action on cardiac muscle, increasing tone, excitability, and contractility.
    • Aglycones are referred to as "cardiac genin" and are steroidal in nature.
    • Derivatives of cyclopentaphenanthrene, with an unsaturated lactone ring attached to C17.

    Structure of Glycosides

    • Cardenolide: Contains a five-membered lactone ring. Examples include digitoxigenin and glycosides of digitalis and strophanthus species.
    • Scilladienolide (Bufadienolide): Contains a six-membered lactone ring. Examples include scillarenin, squill glycosides, and bufotoxin.

    Cardenolide Structure (C23)

    • Possesses a butenolide (4 carbons) attached at C17, also known as an α,β-unsaturated lactone ring.

    Scilladienolide Structure (C24)

    • Possesses a pentadienolide (5 carbons with two double bonds) attached at C17, also known as a pentenolide.

    Color Tests

    • The two types of lactone rings (cardenolide and scilladienolide) give different reactions to certain color tests.

    Bufadienolides

    • Bufadienolides are a type of cardiac glycoside
    • The glycone portion of cardiac glycosides can contain up to four sugar molecules
    • Bufadienolides contain a C3 unit (in addition to the C21 steroid)
    • Bufadienolides are condensation products of a C21 steroid and a C3 unit.
    • In the nomenclature of cardioactive glycosides, the configuration of functional groups is denoted first
    • The type of glycoside (e.g., cardenolide, dienolide, cardanolide, bufanolide) is denoted based on the number of double bonds in the molecule

    Cardiac Glycosides

    • Cardiac glycosides contain a β-OH group at position C-3 that is glycosidically linked to a mono, di, tri, or tetrasaccharide.
    • Cardiac glycosides also contain a β-OH group at position C-14.
    • Cardiac glycosides contain an unsaturated 5 or 6-membered lactone ring at position C-17 in the β configuration.

    Digitalis

    • Digitalis is derived from the dried leaves of Digitalis purpurea
    • Digitalis contains various glycosides, including digitoxin, gitoxin, and gitaloxin
    • Digitalis acts through inhibiting the sodium-potassium ATPase enzyme
    • It is used in the treatment of congestive heart failure
    • Digitalis lanata also contains various glycosides including digitoxin, gitoxin, and gitaloxin.

    Strophanthus

    • Strophanthus is derived from the dried seeds of Strophanthus kombe or Strophanthus hispidus
    • Strophanthus is a cardiotonic
    • Strophanthus contains various glycosides including k-strophanthoside, k-strophanthin-B and cymarin.

    Oleander

    • Oleander is derived from the leaves of Nerium oleander
    • Oleander is used to treat cardiac insufficiency
    • Oleanderin is a constituent of oleander and is studied for anticancer treatment

    Squill

    • Squill is derived from the bulbs of Urginea maritima or Urginea indica
    • Squill glycosides differ from cardiac glycosides in having a six-membered, doubly unsaturated lactone ring in position C-17.
    • Squill glycosides also have at least one double bond in the steroid nucleus
    • Squill has expectorant, emetic, cardiotonic and diuretic properties.

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