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WATER SOLUBLE VITAMINS

WATER SOLUBLE VITAMINS. Dr Greeshma Dept., of Biochemistry. VITAMINS: CLASSIFICATION. Vitamins are micronutrients that are required for normal growth and maintainence of good health Fat soluble vitamins vitamin A vitamin D vitamin E v itamin K

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WATER SOLUBLE VITAMINS

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  1. WATER SOLUBLE VITAMINS DrGreeshma Dept., of Biochemistry

  2. VITAMINS: CLASSIFICATION • Vitamins are micronutrients that are required for normal growth and maintainence of good health Fat soluble vitamins • vitamin A • vitamin D • vitamin E • vitamin K Water soluble vitamins - vitamin B complex - vitamin C • o health

  3. VITAMINS

  4. VITAMINS • Synonyms • Chemistry • Coenzyme Forms • Functions • Nutritional Aspects: Sources RDA • Deficiency Manifestations • Antivitamins

  5. WATER SOLUBLE VITAMINS Vitamin B complex - • Thiamine (VitaminB1) • Riboflavin (Vitamin B2) • Niacin(Vitamin B3) • Pantothenic acid • Pyridoxine (Vitamin B6) • Biotin • Folic acid • Cobalamin (Vitamin B12) Vitamin C

  6. WATER SOLUBLE VITAMINS

  7. VITAMIN B1(THIAMINE) • Aneurine • Anti beri-beri factor PyrimidineThiazole ring

  8. VITAMIN B1(THIAMINE) Thiamine pyrophosphate(TPP) • Coenzyme form : • Involved mainly in carbohydrate metabolism ATP AMP Thiamine TPP TPP transferase

  9. VITAMIN B1(THIAMINE) • Oxidative decarboxylation reactions pyruvate dehydrogenase α-ketoglutarate dehydrogenase α-keto acid dehydrogenase • Transketolase reactions in HMP pathway • Neurotransmission

  10. VITAMIN B1(THIAMINE) • Transketolase reaction Ribose-5 –phosphate + xylulose -5-phosphate Transketolase-TPP Sedoheptulose-7-phosphate + glyceraldehyde-3-phosphate

  11. VITAMIN B1(THIAMINE) • Transketolase reaction Xylulose-5-phosphate+ Erythrose-4-phosphate Transketolase-TPP Fructose – 6 - Phosphate+Glyceraldehyde-3-Phosphate • Transfers 2 carbon units from ketose to aldose and simultaneously converts aldose to ketose • Reaction generates NADPH

  12. VITAMIN B1(THIAMINE) PDH Complex Pyruvate Acetyl CoA + CO2 TPP,NAD,FAD, CoASH, Lipoic acid

  13. VITAMIN B1(THIAMINE) • α-ketoglutarate dehydrogenase α-ketoglutaratesuccinyl CoA + CO2 TPP,NAD,FAD, CoASH, Lipoicacid • α-keto acid dehydrogenase Branch chain amino acids acyl CoA + CO2 TPP,NAD,FAD, CoASH, Lipoic acid

  14. VITAMIN B1(THIAMINE) Neurotransmission • ↑acetyl choline synthesis and utilization • ↑ neurotransmitter levels in brain

  15. VITAMIN B1(THIAMINE) Sources • Vegetarian :Outer layer of cereals – unpolished (parboiled) rice • Pulses, Oil seeds, nuts and yeast • Animal sources: pork ,liver, heart, kidney & milk • RDA: 1 – 1.5 mg/ day • During Pregnancy & lactation (+0.3mg)

  16. VITAMIN B1DEFICIENCY • Low dietary intake • Intake of polished cereals • Chronic alcoholism Other factors • Carbohydrate rich diet • Impaired intestinal absorption • Excessive demand – pregnancy & lactation

  17. VITAMIN B1DEFICIENCY BeriBeri Dry BeriBeri -Neuropsychiatric manifestations Peripheral neuropathy, psychosis, Muscular weakness Infantile BeriBeri Restlessness, Sleeplessness, convulsions, vomiting Wet BeriBeri -cardiovascular manifestations Palpitations, Breathlessness edema • Cerebral • ( Wernicke’s –korsakoff syndrome) • - Chronic alcholics • Psychosis • encephalopathy

  18. VITAMIN B1 Antivitamins: • Tannin: excessive tea consumption • Pyrithiamine and oxythiamine (sulfa drugs-antibiotics)

  19. VITAMIN B2 (RIBOFLAVIN) • Riboflavin • Warburg’s yellow enzyme • Heat stable, Light sensitive • Act as both oxidant and antioxidant ribitol Isoalloxazine ring

  20. RIBOFLAVIN- coenzyme FMN: Flavin adenine mononucleotide FAD : Flavin adenine dinucleotide FAD synthase Flavokinase Riboflavin FAD FMN ATP PPi ADP ATP liver Intestinal mucosal cell

  21. RIBOFLAVIN • Enzyme cofactor for: Oxidation – reduction reactions Metabolism of lipids / carbohydrates Drug metabolism • FAD transfers reducing equivalents for ATP production by oxidative phosphorylation

  22. RIBOFLAVIN FMN acts as a coenzyme of: • L-amino acid keto acid • L- amino acid oxidase • 2. NADH dehydrogenase – Complex I of ETC has FMN

  23. RIBOFLAVIN FAD dependant reactions: • Oxidative decarboxyation:- • PDH complex pyruvate CO2 Acetyl CoA + TPP, NAD, FAD. CoASH, Lipoic acid TCA cycle: succinate dehydrogenase Fumarate Succinate FAD FADH2

  24. VITAMIN B2: SOURCES • Animal: Liver Kidney Yeast Egg Meat Fish • Veg: Cereals Pulses Milk Fruits Green Leafy Vegetables • RDA: 1.5 mg/ day. • Increased in pregnancy and lactation

  25. VITAMIN B2: DEFICIENCY • Symptoms involves skin and mucosal membranes • Cheilosis (inflamed lips) • Angular stomatitis • Glossitis • Seborrheic dermatitis • Corneal vascularization

  26. ANTIVITAMINS Isoriboflavin Galactoflavin Araboflavin

  27. VITAMIN B3: NIACIN Pellagra preventing factor of Goldberger Pyridine derivative 2 forms: Nicotinic acid & Nicotinamide

  28. NIACIN • 60 mg of tryptophan can synthesize 1mg of niacin TPP Cu2+ Tryptophan N-formylkynurenine 3-OH-kynurenine Kynurenine PLP Kynureninase 3-OH-anthranallic acid Quinolinicacid NMN Niacin NAD FADD Fe2+ QPRT(rate-limiting step)

  29. NIACIN : COENZYME FORM • Nicotinamide adenine dinucleotide (NAD+ ) • Nicotinamide adenine dinucleotide phosphate (NADP + ) Functions: • NAD+ collects reducing equivalents for ATP production in the mitochondria by oxidative phosphorylation.

  30. NIACIN : COENZYME FORM NAD+ + H2 NADH + H + • Cofactor for dehydrogenation reactions • Enters electron transport chain→ ATP synthesis NADP + + H2 NADPH + H + • Used for biosynthetic reactions

  31. NIACIN : FUNCTION • NAD+ dependent enzymes (NADH generating reactions) • NADP+ dependent enzymes (NADPH generating reactions)

  32. NIACIN : FUNCTION NAD dependantreactions: • Pyruvate dehydrogenase • Pyruvate Acetyl CoA + CO2 TPP, NAD, FAD. CoASH, Lipoic acid • Glyceraldehyde-3-phosphate dehydogenase • Lactate dehydrogenase Lactate Pyruvate NAD+ NADH+H+ GLYCOLYSIS

  33. NAD DEPENDANT REACTIONS • α-ketoglutarate dehydrogenase • Isocitrate dehydrogenase TCA Cycle • Malate dehydrogenase • βhydroxy acyl CoA dehydrogenase ( β oxidation) β-OH-acyl CoA β-ketoacyl CoA

  34. NADP DEPENDANT REACTIONS • Glucose 6 phosphate dehydrogenase Glucose-6-phosphate NADP + NADPH+H+ 6-phosphogluconolactone • Malic enzyme • malate pyruvate

  35. NIACIN : SOURCES Yeast Liver Meat Fish Legumes Cereals (outer coats) Peanuts Sweet potato - Niacin is formed in humans during catabolism of tryptophan. It provides only 10% of the requirement. Remainder must come from the diet • Every 60 mg of tryptophan =1 mg of niacin • RDA: 20mg/day

  36. NIACIN : DEFICIENCY • 1. Diet poor in niacin & tryptophan • - seen in populations dependanton maize as staple food. • Maize deficient in tryptophan, niacin present. • in bound form in maize →niacin unavailable • 2. Hartnupsdisease: defective intestinal absorption and renal tubular reabsorption of tryptophan • 3. Inability to convert tryptophan to niacin

  37. NIACIN : DEFICIENCY • Pellagra : Disease of 3Ds( involves skin, GIT & CNS) • Dermatitis: bright red erythema and increase pigmentation around neck(Casal’s necklace), ankle, feet and face exposed to sunlight • Diarrhea: chronic inflammation of intestinal mucosa • Dementia: degeneration of nervous tissue – irritability, inability to concentrate, poor memory

  38. NIACIN : DEFICIENCY

  39. NIACIN : ANTAGONISTS • 3 Acetyl pyridine • Isoniazid

  40. 1.Explain the following aspects of thiamine. a) Coenzyme form b) Biochemical functions/ metabolic role and c) Deficiency 2.TPP as a coenzyme in three metabolic reactions of the body. 3. Write coenzyme forms of and one reaction for each a) Niacin b) Riboflavin 4. Deficiency manifestations of Niacin. 5. Explain the biochemical basis: a) Intake of polished cereals as staple food may cause Beriberi b) Pellagra is more common in population dependent on maize as the staple food

  41. VITAMIN B5: PANTOTHENIC ACID- chemistry Chick anti dermatitis factor Contains β- alaninePantoicacid Carrier of acyl groups Involved in metabolism of fat, proteins & carbohydrates

  42. PANTOTHENIC ACID: active form • Used in synthesizing two important acyl carriers • Coenzyme A ( CoASH) • Acyl carrier protein( ACP of fatty acid synthase complex)

  43. PANTOTHENIC ACID: functions Coenzyme A (CoA / CoA-SH) Coenzyme (CoA) participates in several enzymatic reactions of carbohydrate, lipid and amino acid metabolism. Important CoA derivatives: Acetyl CoA, Succinyl CoA, HMG CoA, Malonyl CoA, Palmityol CoA, Propionyl CoA Acyl carrier protein - Pantothenic acid is required for the synthesis of phosphopantotheine of fatty acid synthases complex - carry acyl groups in fatty acid synthesis

  44. PANTOTHENIC ACID: Sources • Whole cereals • Legumes • Egg yolk • Liver • yeast • Also synthesized by bacterial flora in the intestine • RDA: 10mg/day

  45. PANTOTHENIC ACID: DEFICIENCY • It is rare in humans ( due to widespread distribution of the vitamin) • Burning feet syndromeseen in prisoners of war and during famine manifested as: -Painful burning sensations(Paraesthesia) in feet -Staggering gait -impaired coordination & sleep disturbance .

  46. VITAMIN B6: PYRIDOXINE Chemistry • Three compounds derived from pyridine show vitamin B6 activity.

  47. VITAMIN B6: PYRIDOXINE Active form of vitamin B6 Pyridoxal kinase PyridoxalPyridoxalphosphate(PLP) ATP ADP Pyridoxal phosphate

  48. PLP FUNCTIONS • Proteinmetabolism: transamination decarboxylation transulfuration deamination • Lipid metabolism sphingomyelin synthesis • Carbohydrate metabolism glycogenolysis gluconeogenesis • Hemesynthesis

  49. PLP DEPENDANT REACTIONS • Transamination Amino acid1+ Ketoacid2 Amino acid2 + Ketoacid1 Example: PLP Alanine + α- KetoglutaratePyruvate + Glutamate Alanine transaminase

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