part 1-6 Vitamins and their functions

• PH112 explores the structures, names, relationships to coenzymes, functions, deficiency consequences, sources, and daily requirements of Vitamins A, B, C, D, E, and K.

Contents

• Introduction to vitamins and coenzymes.
• Definitions of coenzymes and vitamins.
• Classes of vitamins.
• Detailed exploration of Vitamin B (B1, B2, B3, B5, B6, B7, B9, B12).
• Vitamin C.
• Vitamin A
• Vitamin D (D2 & D3).
• Vitamin E.
• Vitamin K (K1 & K2).

Aims and Objectives

• Introduce the structures and names of vitamins in groups A, B, C, D, E, and K.
• Show the relationships between vitamins and the coenzymes they form.
• Demonstrate the essential functions of vitamins and the consequences of deficiency diseases.
• Overview the sources of vitamins and daily requirements.

Cofactors

• Cofactors are required to activate enzymes
• Cofactors include essential ions and coenzymes
• Essential ions such as Na+ and K+ can act as cofactors
• Coenzymes are non-protein organic compounds produced in living cells and activate enzymes
• Co-substrates, like ATP and NADH, are loosely bound and altered during reactions, then regenerated by another reaction.
• Prosthetic groups are tightly bound to the enzyme but still need to be regenerated.
• Apoenzyme is the large protein molecule that forms the bulk of the enzyme molecule.
• Holoenzyme is the catalytically active form of the enzyme
• The substrate binds to the holoenzyme and a reaction occurs, but without a cofactor, no reaction happens even if the substrate binds to the apoenzyme.

Coenzyme Reactions

• Describes how coenzymes interact with enzymes and other molecules.
• Functional group X it's cleaved from molecule A by an enzyme and bound to the coenzyme, producing coenzyme-X.
• Coenzyme-X acts as a coenzyme for another enzymes, which allows to transfer a functional group X onto molecule B.
• Coenzymes, unlike enzymes, are often structurally altered during reactions and are regularly regenerated to continuously act as coenzymes.

Vitamins

• Vitamins are essential organic substances needed for normal metabolic processes
• Vitamins aren't produced naturally by the body
• A vitamin deficiency in the diet will cause problems with normal function
• Many coenzymes are synthesized using vitamins from dietary precursors
• Vitamins are required for growth, reproduction, and normal body function.
• The term "vitamin" comes from "vital amine" to describe a compound in rice husks that treated beriberi, with later discoveries using the term despite not being amines.

Classes of Vitamins

• Water-soluble vitamins are readily excreted through urine, require daily intake, and include vitamins B and C.
• Lipid-soluble vitamins are stored in the liver and excessive intake can cause toxicity; they include vitamins A, D, E, and K.

B Group Vitamins

• B vitamins were originally thought to be a single vitamin, but are understood as multiple vitamins that form coenzymes and are found in similar foods.
• B Vitamins are named in order of discovery and some have since been found to be created by the body and are no longer classified vitamins
• Some B vitamins are synthesized via intestinal flora.

Vitamin B1 (Thiamine)

• Found in cells therefore in natural foods
• Thiamine produces the coenzyme thiamine pyrophosphate (TPP)
• TPP assists enzymes in carbohydrate metabolism, helping release energy from food, and in conduction of action potentials in neurons and neuro-muscular transmission.
• Prevalent in eastern Asia due to low thiamine in white rice and in malnourished chronic alcoholics
• Supplements may be needed for athletes, pregnant, or lactating women due to increased carbohydrate consumption.
• Beriberi which can affect the cardiovascular and peripheral nervous system
• Wet beriberi causes cardiovascular problems like cardiac failure, dyspnea, and oedema.
• Dry beriberi causes peripheral neuritis, paralysis, and wastage; a severe form known as Wernicke-Korsakoff syndrome, causes paralysis of eye.

Vitamin B2 (Riboflavin)

• Structure: a complex organic compound as shown in the image
• Found in dairy, eggs, veg, and almonds
• Coenzymes produced are flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)
• The heterocyclic system functions as a hydrogen acceptor or donor.
• They are prosthetic groups on oxidoreductase enzymes known as flavoproteins
• Involved in processing fats, carbs, and proteins, with role in processing other vitamins like conversion of vitamin B6 into coenzyme
• Deficiency in developed countries is rare thanks to fortified foods, but common in developing countries due to malnutrition; symptoms include inflammation of the mouth and lips (stomatitis), similar to pellagra.
• It can reduce iron absorption, causing normocytic anaemia.

Vitamin B3 (Niacin)

• Structure: Nicotinamide and Niacin
• Sources: Meat, fish, and nuts
• Nicotinamide is also used in acne treatments.
• Coenzymes Produced Nicotinamide adenine dinucleotide (NAD) and Nicotinamide adenine dinucleotide phosphate (NADP)
• Important roles in oxidoreductase enzyme reactions where NAD(P)+ is an oxidising agent while NAD(P)H is reducing agent
• NADPH is important in anabolic processes (e.g., lipid and nucleic acid synthesis) while NAD+ is vital to catabolic processes (e.g., metabolism of energy sources like fatty acids and glucose)
• The body is not entirely dependant on dietary intake as nicotinic acid can be produced from dietary tryptophan in vivo
• Deficiency common in areas in which maize is the principal foodstuff (as it is low in both nicotinic acid and tryptophan)
• Pellagra – characterised by 'dermatitis, diarrhoea and dementia'
• Chronic alcoholics also at risk of B3 deficiency.
• Side effects of excess include skin flushes, liver damage
• Nicotinamide may be given as an alternative to the flush

Vitamin B5 (Pantothenic Acid)

• Structure: Defined organic compound
• Sources: Dairy, eggs, avocado, mushrooms
• Milling grains lowers pantothenic acid
• Produces Coenzyme A
• Coenzyme A is needed for synthesis and breakdown of acids
• Coenzyme A involved in the oxidation of pyruvate as part of Krebs cycle
• Vitamin B5 Deficiency is extremely rare and understudied

Vitamin B6 (Pyridoxine, Pyridoxal, Pyridoxamine)

• Structures: distinct, yet convertible
• Sources: Most foods
• Source origin (veg pyridoxine) and animal (pyridoxal, pyridoxamine)
• All coenzymes are interconvertible
• The final coenzyme product is pyridoxal-5'-phosphate
• Serves as the co-enzyme for metabolism of Tryptophan, meaning that a B6 risk increases the risk pf B3 deficiency
• Production of neurotransmitters is B6 dependent
• B6 constitutes around 4% of all needed enzymes
• B6 levels are maintained well in most diets, with synthesis aiding
• Poor diet and synthesise will lead to disorders of CNS (central nervous system )
• Patients on Isoniazid will benefit from additional B6 supplements, this will help combat any increase pyridoxine excretion
• Additional supplementation will lead to motor function and nerve problems

Vitamin B7 (Biotin)

• A defined organic structure,
• Sourced from, avocado, yeast, and egg and fresh veg
• No true coenzyme produced (Biotin is a co-enzyme on it's own)
• Required for carboxylase enzyme processes, these include, amino,fatty and glucose production from fat digestion
• Severe deficiencies in the standard diet are virtually rare
  • deficiency symptoms include neurological problems, brittle nails, and hair, and sometimes rare in pregnant, lactating and general consumer of egg whites

Vitamin B9 (Folic Acid)

• Has a complex compound
• Seeds, chickpeas, veg and nuts are strong source
• As added vitamin to flour it's very common
• Tetrahydrofolate, is the common enzyme produced
• Necessary for proper carbon group conversions
• Also key in synthesis of amino acids
• Essential for DNA formation
• Deficiencies occur most noticeably in pregnant women where additional demands are placed
• Many cancer treatments interfere with processing, causing deficiencies Low weight, premature birth and defects are all pregnancy deficits
• Leukaemia and several drug deficiencies are supplementation use cases
• Anemia arises from deficit multiplication of red blood cells

Vitamin B12 (Cobalamin)

• Complicated organic base compound
• Exclusively in animal origin
• Some rare forms in seaweed and fermented plant dishes
• Key enzymes provided are methylcobalamin and adenosylcobalamin
• It is cofactor for some synthase, used to create, folic acids
• It enables molecular rearrangement to some amino acids, those in CNS
• Deficiencies commonly cause pernicious anaemia, alongside multiple additional GI and neurological problems
• Folic-acid excess, can mask other B12 deficits in testing

Vitamin C (Ascorbic Acid)

• Found in many citrus fruits such as guava, sprouts and broccoli
• The first ever clinical trial involved ascorbic acid to combat scurvy
• An powerful reducing agent found often in tissue
• The agent for H bonding and hydroxylation of proline
• Able to balance cofactor ions, or ionic states, an example of this is activating active sites of hydroxylase through F.e
• Co factor for steroid and norepinephrine creation

Vitamin A (Retinol)

• Mainly from cod oil, dairy, butter and eggs
• Carotenoids in tomatoes and the like, enable natural synthesis instead
• N/A co enzymes provided ( retinol not able to form)
• Retinol converts to retinal then to an acid derivative where RPE65 Enzyme is activated
• RPE65 enables correct wavelength usage during isomerisation,
• Retinoic acids, are required or a health, growth and development system
• Psoriasis a result of deficiency, supplementation is also possible for cases that cannot absorb
• Hypervitaminosis A happens if liver supplementation is unchecked, and over active
• A deficiency causes Corneal damage, with night blindness a potential symptom.

Vitamin D (Calciferol)

• Found in fungi, fish oils and egg yolk
• Not strongly linked to dietary dependency because precursors in the body
• D3 happens from precursors in light
• Calcideliol will stimulate synthesis of various key proteins
• Calcidiol and calcitriol support calcium balance in the proper areas
• If synthesis occurs, a rickets state can arise, mainly distortion of key spine and leg bones
• Over supplementation, can also cause toxicity.

Vitamin E (Tocopherol, Tocotrienol)

• Sources are primarily in oils
• Non enzyme creator
• Fat soluable, protects via antioxidation
• Support smooth muscle and maintenance of tissue,
• Side effects and main toxicity cases result in fat malabsorption and a strong increase risk in bleeding

Vitamin K (Phytomenadione, Menaquinone )

• Present in leafy vegetables and intestines( flora creates form meat)
• co enzyme n/a, acts as main cofactor
• Aids the reactions needed, gamma carboxyglutamate formation proteins, prothrombin, procoagulants
• Deficiencies stem from damage, not lack, anticoagulants
• Anemia, bleeding and bruising are symptoms of deficiency
• Toxicity is usually not as much problem and toxicity levels are mild

Explores the roles of vitamins like E, K, and C, and their impact on health. It covers deficiency symptoms, food sources, and the importance of vitamins in processes like collagen synthesis and enzyme function. It also touches on risks associated with certain dietary habits.