vitamin c & b5

(ASCORBIC AND PANTOTHENIC ACIDS) : 

(ASCORBIC AND PANTOTHENIC ACIDS) VITAMIN C & VITAMIN B5 BY ANAND C.R. Ist MSc BIOTECHNOLOGY

VITAMIN C : 

VITAMIN C 1747 – James Lind, Scottish Naval surgeon, discovered a nutrient in citrus fruit prevented scurvy Waugh, Albert Szent-Gyorgyi, and Charles Glen King discovered structure and importance Also known as ascorbic acid, a- (meaning no) and scorbuticus (scurvy)

BIOSYNTHESIS OF ASCORBIC ACID : 

BIOSYNTHESIS OF ASCORBIC ACID All plants and most animals except some mammals and few birds synthesize Vitamin C from glucose. Some animals have lost the enzyme L-gulonolactone oxidase –catalyzes conversion of L-gulonolactone to L-3-ketogulonolactone

ABSORPTION OF VITAMIN C : 

ABSORPTION OF VITAMIN C Absorbed through active transport and simple diffusion Two transporters :- 1) Sodium – dependent vitamin C transporter (SVCT) 2) GLUT transporters SVCT1 and SVCT2 import reduced from, ascorbate, across plasma membrane GLUT1,GLUT3 and GLUT4 only transfer dehydroascorbic acid from of ascorbic acid.

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Susceptible to oxidation to dehydroascorbic acid Ascorbic acid Dehydroascorbic acid

OXIDATION OF VITAMIN C : 

OXIDATION OF VITAMIN C Ascorbic acid oxidized by two successive loses of single electron First monovalent oxidation – formation of ascorbyl free radical; reversible reaction Further oxidized to form dehydroascorbic acid which undergoes irreversible hydrolysis to form 2,3-diketo-L-gulonic acid

METABOLIC FUNCTION OF VITAMIN C : 

METABOLIC FUNCTION OF VITAMIN C 1) Electron transport Loses electrons easily because of reversible monovalent oxidation to ascorbyl radical Involved in many electron transport reactions Ascorbic acid regenerated – ascorbyl ion reduced by two enzymes dehydroascorbate reductase ascorbate cytochrome-b5.

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O HO O O O L-Ascorbate Anion O HO O O - H O O H O CH2OH O O O -e- , -H + +e- , +H + -e- +2 e - , +2H + Dehydro Ascorbic Acid Reductase Ascorbyl free radical Dehydroascorbic Acid • CH2OH CH2OH

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2) Antioxidant functions Antioxidant Activity Reacts and removes active oxygen species Pro-oxidant Activity Reduces metals to their pro-oxidant forms

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3)Collagen synthesis Helps in hydroxylation of proline and lysine in procollagen molecule Catalyzed by prolyl hydroxylase and lysyl hydroxylase Hydroxylation of procollagen necessary for folding into triple helical structure

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4) Catecholamine biosynthesis Serves as electron donor for dopamine ß –monooxygenase 5) Carnitine synthesis Ascorbic acid has a cofactor of two Fe2+ containing hydroxylases involved in synthesis of carnitine

CATECHOLAMINE BIOSYNTHESIS : 

CATECHOLAMINE BIOSYNTHESIS Dopamine-ß-Monooxygenase Cu+ Cu2+ Ascorbate Ascorbyl free radical

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6) Tyrosine metabolism Oxidative degradation of tyrosine by 2 oxidases :- 4-hydroxyphenylpyruvate dioxygenase and homogentisate 1,2-dioxygenase Former catalyzes oxidation and decarboxylation of 4-hydroxylphenylpyruvate to homogentisic acid Latter requires ascorbate for tyrosine degradation

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7) Absorption of iron Keeps iron in ferrous form (Fe2+) 8) Immune function Stimulate production of interferons Antibody IgG and IgM Megadose of vitamin C – 10g/day, prevent common cold

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Gingivitis

VITAMIN C DEFICIENCY : 

VITAMIN C DEFICIENCY Scurvy Vitamin C- required for collagen synthesis Defective collagen fibrillogenesis impair wound healing; bone formation affected; bleeding gums with loss of teeth; fragile capillaries and abnormal bleeding.

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Bone Formation in Guinea Pigs Section of costochondral junction from a guinea pig dying of scurvy. Silver stain was used to bring out any reticulum but there are none - only the nuclei of the impotent osteoblasts stain. Severely scorbutic animal after 72 h of ascorbic acid treatment; fibers of reticulum have appeared between the nuclei & have fused in some areas to form asteoid matrix.

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In children, called Moller-Barlow disease, seen in non-breastfed infants VITAMIN C DEFICIENCY Show lethargy, fatigue, rheumatic pains in legs, muscular atrophy, skin lesions, hemorrhages in many organs

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Vitamin C – Scurvy in Human Scorbutic Rosary Enlarged costochondral junctions of scurvy resembles rickets - lesions may feel sharper & may be tender X-ray of a child with scurvy

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Vitamin C – Scurvy in Human Child in scorbutic position. Because movement is painful, infant usually lies on its back, makes little attempt to lift leg or arm – hurts. Legs may be tender and sometimes both arms as well. Usually first sign of scurvy.

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Bone Lesions - Scurvy Calcified cartilage at costachondral junction Fractures between epiphysis and shafts of femur, tibia and fibula Fracture at lower end of tibia

Rebound Scurvy : 

Rebound Scurvy When high doses of vitamin C are taken, body excretes it rapidly When abruptly stopped, the body is unable to immediately reduce rapid excretion rate Potentially results in vitamin C deficiency

Ascorbate Toxicity : 

Ascorbate Toxicity Nausea, abdominal cramps and diarrhea Oxalate kidney stones Decreases uric acid reabsorption resulting in increased risk of gout Interference with medical diagnostic tests False positive or false negative to detect diabetes Individuals taking anti-clotting medication may counteract the effect if they take high doses of vitamin C Dangerous for people with iron overload UL adults: 2000mg/d

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summary

Other Potential Functions : 

Other Potential Functions Reduce stress (e.g. infections, smoking) Mechanism unknown, but vitamin C requirements increase during stress Common cold? Disease prevention? Cancer, heart disease: inconclusive…

PANTOTHENIC ACID : 

PANTOTHENIC ACID Derived from the Greek word pántothen, meaning from all quarters (everywhere) R.J. Williams and coworkers isolated and named it pantothenic acid in 1933 Critical role in metabolism since it plays important role as acylation factors coenzyme-A (CoA) and acyl-carrier protein (ACP)

SOURCES OF PANTOTHENIC ACID : 

SOURCES OF PANTOTHENIC ACID Meat- liver and heart particularly Mushrooms, avocados, broccoli and some yeast Whole grains- localized in the outer layer Richest source of this vitamin – coldwater fish ovaries (2.3mg/g) and royal jelly (0.5mg/g) 15-50% loss from cooking meat and 37-78% from heat processing vegetables

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RDA FOR PANTOTHENIC ACID

ABSORPTION OF PANTOTHENIC ACID : 

ABSORPTION OF PANTOTHENIC ACID Occurs in food mainly as CoA and ACP Degraded in lumen of intestine to release 4’-phosphopantetheine It is then dephosphorylated to yield pantetheine which is rapidly converted to pantothenic acid by pantetheinase

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pantetheinase

METABOLISM OF PANTOTHENIC ACID : 

METABOLISM OF PANTOTHENIC ACID Coenzyme A biosynthesis Synthesize CoA from pantothenic acid Four moles of ATP required In cytosol Pantothenic acid 4’- phosphopantothenic acid 4’- phosphopantothenic acid 4’-phosphopantothenylcysteine Pantothenate kinase ATP dependent Phosphopantothenylcysteine synthase ATP dependent

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4’-phospho 4’-phospho pantothenylcysteine pantetheine In the mitochondrial inner membrane 4’-phospho dephospho pantetheine CoA Dephospho CoA CoA Phosphopantetheinyl cysteine decarboxylase Phosphopantetheine adenyltransferase Dephospho CoA kinase ATP dependent ATP dependent

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FUNCTIONS OF CoA In TCA cycle, assist formation of succinyl CoA used for synthesis of fatty acids (eg: cholesterol) used in oxidation of amino acids used in acetylation of alcohols, amines and amino acids used in acetylation of proteins like histones

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b) Acyl-Carrier Protein biosynthesis ACP synthesized as apoprotein lacking prosthetic group Require pantothenic acid in the form of prosthetic group, 4’-phosphopantetheine That group, 4’-phosphopantetheine, transferred to ACP from CoA by action of 4’-phophopantetheineapoACP transferase

Pantothenic Acid - Deficiency : 

Pantothenic Acid - Deficiency Deficiency is rare; “the burning feet” Goose stepping - swine Cannot bend hock joint (nervous system degeneration) Reduced growth, dermatitis, diarrhea

Deficiency : 

Deficiency Very rare in humans and common in animals like dogs, chicken etc Tissue CoA levels are not altered in pantothenate deficiency Nausea, abdominal pain, headache and numbness or tingling in the limbs and extremities Muscle cramping and lack of coordination

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Pantothenic acid deficiency - Chick Dermatitis in chick on pantothenic acid deficient diet Three weeks after calcium pantothenate added to diet, skin lesions cured

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Pantothenic acid An essential vitamin to humans and animals for proper growth, reproduction, and common physiological conditions. Involved in multiple metabolic pathways that uses the coenzymes of CoA and acyl carrier protein. summary

Water Soluble Vitamins : 

Water Soluble Vitamins Eight B vitamins, Vitamin C Absorbed via blood Transported freely in blood Excesses excreted in the urine Toxicity with over supplementation Must be consumed on a regular basis Steam rather than boil vegetables

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To minimize vitamin losses, wrap cut fruits and vegetables or store them in airtight containers.

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Try topical vitamin C. Vitamin C can increase collagen production, protect against damage from UVA and UVB rays, correct pigmentation problems, and improve inflammatory skin conditions. Most research points to L-ascorbic acid as the most potent for wrinkle relief.

Despite his critics …Linus Pauling was right. : 

The Nobel Prize winning scientist Linus Pauling was the first to claim that vitamin C could extend your life. Dr. Pauling took between 12,000 and 18,000 mg of vitamin C every day for 40 years. Despite his critics …Linus Pauling was right.

The telomere preserving, anti-aging benefit of vitamin C appears to begin at about 500 mg, twice a day. : 

In 1998 Japanese study tested vitamin C’s effect on telomeres. It was found that raising the level of vitamin C in the cells could slow down the loss of telomeres up to 62% The telomere preserving, anti-aging benefit of vitamin C appears to begin at about 500 mg, twice a day.

Take it with food to avoid an upset stomach!! : 

Take it with food to avoid an upset stomach!! CAREFUL!!!!!

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“An in vivo study supports earlier research showing that adding ascorbic acid and sugar to green tea may increase the amount of antioxidants the body is able to absorb”, - Mario Ferruzzi, associate professor of food science and nutrition.

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Research is still being developed to support the many advantages that these vitamins plays in our diet.

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Fortify Your Diet With Vitamins FOR A HEALTHY LIFE

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THANK YOU