Carbohydrates And Natural Products - Lecture 3 PDF

PHARMACOGNOSY Module code: PHA 2001 Lecturer: Desireé Gyles Lynch, MSc., BSc. Contact: [email protected] Carbohydrates and Natural Products Natural Products  4 What is a Natural Product? A natural product is a substance obtained from a organic (natu...

PHARMACOGNOSY Module code: PHA 2001 Lecturer: Desireé Gyles Lynch, MSc., BSc. Contact: [email protected] Carbohydrates and Natural Products Natural Products  4 What is a Natural Product? A natural product is a substance obtained from a organic (natural) source.  5 Uses Of Natural Products 1. Asdrugs for the treatment of a wide range of diseases, eg. Morphine, atropine, digoxin, hormones, antibiotics, etc.. 2. Aspharmaceutical aids in the pharmaceutical Industry, eg. Suspending & emulsifying agents, suppository bases, binders, excipients, sweetening & colouring agents, etc...  6 Uses Of Natural Products 3. In cosmetics as flavouring & colouring agents, etc. 4. In culture media for the propagation of microorganisms in microbiology laboratories & biotechnology. 5. General uses eg. In food industries: as dusting powders, as indicators and in perfumery.  7 Crude Drugs This is the harvested and usually dried plant or animal sources of pharmaceutically or medicinally useful products before they have undergone extensive processing or modification. I.e. It is used for those natural products such as plants or part of plants, extracts and exudates which are not pure compounds  8 Crude Drugs ❖ Crude drugs are derived from the mineral, vegetable and animal kingdoms. ❖ Crude drugs of vegetable, animal and mineral origin form the subject matter with which pharmacognosy is concerned.  9 Examples of Crude Drugs ◆ Entire plants or animals: Mentha, Lobelia, Cantharidis, Cochineal. ❖ Entire organs of plants or animals: Senna, Clove, Fennel, Linseed, Quassia, Cinchona, Liquorice, Thyroid gland. ◆ Minerals: chalk, kaolin, talc. ◆ Organised drugs: fruit, seeds, root, leaves  10 Types Of Drugs Derived From Plants 1. Herbal drugs, derived from specific parts of a medicinal plant 2. Compounds isolated from nature 3. Nutraceuticals, or “functional foods”  11 Official And Unofficial Drugs Official drug is one that is listed/recognized and described as being a definite therapeutic agent in the pharmacopoeia. Unofficial drug is that one that are not recognized in the pharmacopoeia and is used as therapeutic agent.  Collection Of Crude Drugs The potency of the bioactive substances in particular crude drugs are often dependent on one or more of the following:  Time of the year (seasonal varieties)  Time of the day.  Stage of maturity and age.  Plant Organs  13 Plant organs ❑Flowers are collected in dry weather. ❑Leaves are collected when plant is flowering. ❑Fruits and seeds when fully mature but unripe. ❑Underground organs when aerial parts die down. ❑Barks in spring (when they are easily separated). ❑Unorganized drugs in dry weather (not rainy).  14 Evaluation of Crude Drugs Means to identify and to determine quality, safety and purity. 1. It has to be certain of identity of the collected plant from proper source by matching to authentic plant sample 2. Preparation by proper cleaning, drying and garbling. 3. Proper preservation of cleaned, dried, pure drug against contamination. Evaluation of drugs involves 15 the following methods: 1. Organoleptic 2. Microscopic 3. Chemical 4. Physical  16 Organoleptic Evaluation Organoleptic refers to evaluation by means of the organs of sense which includes: - The macroscopic appearance of the drug, - Its odour and taste and the feel of the drug to the touch. Description of the macroscopic characteristics of a drug include: 1. Shape and size. 2. Colour and external markings 3. Fracture and internal colour. 4. Odour and taste.  17 Chemical Evaluation Chemical tests are employed to identify crude plant drugs. To ascertain the purity of certain drugs and to determine potency. Eg. to detect the presence of inorganic substances iodine in thyroid tablets  18 Physical Evaluation Typical physical constants is very rare. The specific gravity is used with nutgalls, where the galls that will not sink in H2O are considered to be of inferior quality, In jalap and clove, the specific gravity should be higher than that of water. The elasticity of certain fibers, such as cotton, is a physical constant of importance.  19 Physical Evaluation ▪Alkaloids aconitine (light blue), berberine (yellow), emetine (orange). ▪Alkaloid quinine has blue fluroscence in acid solution in UV or even in daylight. ▪The use of physical constants on active constituents.: ▪Solubility, specific gravity, optical rotation, melting point etc.  20 Crude drugs - Parts of the plant ◆ Plant organs are the most important to crude drug production. They are classified as follows: 1. Aerial parts or herb (herba) 5. Bark (cortex) 2. Leaf (folia) 6. Root (radix) 3. Flower (flos) 7. Rhizome (rhizoma) 4. Fruit (fructus) 8. Bulb (bulbus) Carbohydrates  Carbohydrates Carbohydrates are:  Compounds composed of the elements C, H, and O made by photosynthesis.  Such as glucose are synthesized in plants from CO2, H2O, and energy from the sun (photosynthesis).  6 CO2 + 6 H2O + energy (light energy)↔ C6H12O6 + 6 O2  A major source of energy from the diet.  Dietary Sources of carbohydrates ▪ Rice ▪ Maize ▪ Wheat ▪ Potato ▪ Arrowroot Carbohydrates  Also called saccharides, which means “sugars.”  All are aldehydes or ketones  All contain many hydroxyl groups (OH)  They are oxidized in living cells …by what process?  Carbohydrates  glucose provides energy for the brain and ½ of energy for muscles and tissues  glycogen is stored glucose  glucose is immediate energy  glycogen is reserve energy  Classification of carbohydrates  Carbohydrates are made up of units of sugar called saccharide units  Simple sugars ◦ Monosaccharide (glucose & fructose) ◦ Disaccharide (sucrose)  Complex carbohydrates ◦ Starch ◦ Glycogen ◦ Cellulose Structures  Simple Carbohydrates  sugars  monosaccharides – single sugars  disaccharides – 2 monosaccharides  Sugars  Oligosaccharides - a few monosaccharides covalently linked.  Polysaccharides - polymers consisting of chains of monosaccharide or disaccharide units.  Simple Carbs  monosaccharides  all are 6 carbon hexes 6 carbons  12 hydrogens  6 oxygens  arrangement differs  accounts for varying sweetness  glucose, fructose, galactose  Glucose  mild sweet flavor  known as blood sugar  essential energy source  found in every disaccharide and polysaccharide  Fructose  sweetest sugar  found in fruits and honey  added to soft drinks, cereals, deserts  Galactose  hardly tastes sweet  rarely found naturally as a single sugar Carbohydrates (glycans) have the following basic composition: I (CH2O)n or H - C - OH I  Monosaccharides - simple sugars with multiple OH groups. Based on number of carbons (3, 4, 5, 6), a monosaccharide is a triose, tetrose, pentose or hexose.  Disaccharides - 2 monosaccharides covalently linked.  Monosaccharides Aldoses (e.g., glucose) have an Ketoses (e.g., fructose) have aldehyde group at one end. a keto group, usually at C2. H O C CH2OH H C OH C O HO C H HO C H H C OH H C OH H C OH H C OH CH2OH CH2OH D-glucose D-fructose D glucose D-glucose is  Found in fruits, corn syrup, and honey.  An aldohexose with the formula C6H12O6.  Known as blood sugar in the body.  The monosaccharide in polymers of starch, cellulose, and glycogen. D- fructose D-fructose  Is a ketohexose C6H12O6.  Is the sweetest carbohydrate.  Is found in fruit juices and honey. CH2OH  Converts to glucose in the C O body. HO C H H C OH H C OH CH2OH D-Fructose  Chemical tests of carbohydrates Benedicts test for glucose (glucose is a reducing sugar ▪ Benedicts reagent:  Copper sulfate + sodium hydroxide + tartaric acid ▪ Mix benedicts reagent with glucose Iodine test for starch ▪ Iodine-KI reagent:  Dissolving iodine in water in the presence of potassium iodide ▪ Add Iodine-KI reagent to starch  Disaccharides  pairs of monosaccharides  glucose is always present  2nd of the pair could be fructose, galactose or another glucose  taken apart by hydrolysis  put together by condensation  hydrolysis and condensation occur with all energy nutrients  maltose, sucrose, lactose  Complex Carbohydrates  starches and fibers  polysaccharides chains of monosaccharides  Maltose  2 glucose units  produced when starch breaks down by amylases  not abundant  Maltose  The breakdown of starch  Malting – germination of to maltose takes place in barley is stimulated animal and germinating which results in the seeds. breakdown of starch to  The latter is used maltose. industrially in the production of beer  Sucrose  fructose and glucose  tastes sweet ▪ fruit, vegetables, grains  table sugar is refined sugarcane and sugar beets  Found in brown, white and powdered sugar.  Sucrose  It is the most abundant  It is also relatively unreactive disaccharide in nature. chemically.  It is transported in large quantities by  It does not take part in plants via the phloem metabolism when being tubes. transported  It is a good transport sugar because it is very soluble  Lactose  Glucose and galactose  main carbohydrate in milk (energy source for young mammals)  known as milk sugar.  It can only be digested slowly inorder to release energy slowly.  Condensation  Disaccharide synthesis. ❑ chemical reaction linking 2 monosaccharides (residues) via the release of a water molecule ❑ The bond formed is called a glycosidic bond. ❑ A glycosidic bond is usually formed between C1 and C4 of neighbouring units. Thus it is specifically called a 1,4- glycosidic bond or linkage Glycosidic bond  Hydrolysis  Breaking a disaccharide requiring water.  watermolecule splits it into its constituent monosaccharides.  occurs during digestion by enzymes.  May be done in a test tube by heating with concentrated acid.  Complex Carbohydrates  polysaccharides  glycogen and starch  built entirely of glucose  Fiber (cellulose)  variety ofmonosaccharides and other carbohydrate derivatives  What makes these polysaccharides different?  Glycogen Not a dietary source of carbohydrate  all glucose is stored as glycogen  long chains allow for hydrolysis and release of energy  Starches  stored in plant cells  body hydrolyzes plant starch to glucose  Fiber  structural parts of plants ❑ found in all plant derived food  bonds of fibers cannot be broken down during the digestive process ❑ minimal or no energy available  Cellulose  Fiber  pectins  lignins  resistant starches ❑ classified as fibers ❑ escape digestion and absorption  Fiber Characteristics  soluble fibers, viscous, fermentable ❑ easily digested by bacteria in colon ❑ associated with protection against heart disease and diabetes ▪ lower cholesterol and glucose levels ❑ found in legumes and fruits  Fiber  insoluble and not easily fermented ❖ promote bowel movements ❖ alleviate constipation ❖ found in grains and vegetables  distinguish fibers by source ❖ dietary fibers: naturally in intact plants ❖ functional fibers: extracted from plants or manufactured ❖ total fiber: sum of the 2  Carbohydrate Digestion  Carbohydrates are broken down into glucose body is able to absorb and use for energy  large starch molecules extensive breakdown of large polysaccharide chains  disaccharides broken once  monosaccharides don’t need to be broken down  Carbohydrate Digestion  begins in mouth ❖ chewing releases saliva ❖ enzyme amylase hydrolyzes starch to polysaccharides and maltose  stomach ❖ no enzymes available to break down starch ❖ acid does some breakdown ❖ fibers in starch provide feeling of fullness  Carbohydrate Digestion  small intestine ❑ majority of carbohydrate digestion takes place here ❑ pancreatic amylase reduces carbs to glucose chains or disaccharides  specific enzymes chemically break down sugars. maltASE ❖ Breaks down maltOSE into 2 glucose molecules in the small intestine. sucrASE ❖ Breaks down sucrOSE into glucOSE and fructOSE lactASE ❖ Breaks down lactOSE into glucOSE and galactOSE  Carbohydrate Digestion  large intestine ❖ 1-4 hours for sugars and starches to be digested ❖ only fibers remain attract water, which softens stool ❖ bacteria ferment some fibers water, gas, short-chain fatty acids (used for energy)  Carbohydrate Absorption  glucose can be absorbed in the mouth  majority absorbed in small intestine ❖ active transport: glucose and galactose. ❖ facilitated diffusion: fructose  smaller rise in blood glucose  Nutritional Content Of Starch Component (per 100g portion) Rice Maize Wheat Potato water 12 76 11 82 energy 1527 360 1506 288 protein 7 3 23 1.7 fat 1 1 10 0.1 carbohydrate 79 19 52 16 sugars >0.1 3 0.1 1.2 iron 0.8 0.5 6.3 0.5 calcium 28 2 39 9  Glucose Homeostasis  maintaining an even balance of glucose is controlled by insulin and glucagon ❑ insulin ✓ moves glucose from the blood to cells ❑ glucagon ✓ brings glucose out of glycogen storage  Glucose Imbalance  diabetes ❑ after food intake, blood glucose rises and is not regulated because insulin is inadequate  hypoglycemia ❑ blood glucose drops dramatically too much insulin, activity, inadequate food intake, illness diet adjustment includes fiber-rich carbs and protein  Intestine 1 When a person eats, blood glucose rises. 2 Pancreas High blood glucose stimulates the pancreas to release insulin. Insulin 3 Insulin stimulates the uptake of glucose into cells and storage Maintaining Liver as glycogen in the liver and muscles. Insulin also stimulates Blood the conversion of excess glucose into fat for storage. Glucose Fat cell Muscle Homeostasis 4 As the body's cells use glucose, blood levels decline. Pancreas 5 Low blood glucose stimulates the pancreas to release Glucagon glucagon into the bloodstream. 6 Glucagon stimulates liver cells to break down glycogen Glucose and release glucose into the blood.a Insulin Glucagon Liver Glycogen a The stress hormone epinephrine and other hormones 7 Blood glucose begins to also bring glucose out of storage. rise.  Glycemic Index  way of classifying food according to their ability to raise blood glucose levels.  Particularly important for diabetics.  Carbohydrate Drugs  There are for main starches in the British Pharmacopiea:  Maize (Zea mays)  Potato (Solanum tuberosum f. )  Rice (Oryza Sativa)  Wheat (Triticum oestivum)  Cassava  Starches are used as various thickening agents in the food and pharmaceutical industries.  Eg. Acacia, Dextrose, Agar  Uses Of Starch In Pharmaceutical Industry  Starches are used in the pharmaceutical industry for a wide variety of reasons: ❑ such as an excipients, ❑ tablet and capsule diluents, ❑ tablet and capsule disintegrants ❑ glidants, ❑ binders.