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General concepts of vitamins

General concepts of vitamins. VITAMINS. SYNONYMS, VITAMERS STRUCTURE(S) SOURCES PROPERTIES METABOLISM SYNTHETIC COMPOUNDS PRO-VITAMINS BIOSYNTHESIS (HUMAN) STORAGE BIOCHEMICAL FUNCTIONS DEFICIENCY MANIFESTATIONS DIETARY REQUIREMENTS, RDA ANTI VITAMINS

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General concepts of vitamins

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  1. General concepts of vitamins

  2. VITAMINS • SYNONYMS, VITAMERS • STRUCTURE(S) • SOURCES • PROPERTIES • METABOLISM SYNTHETIC COMPOUNDS PRO-VITAMINS BIOSYNTHESIS (HUMAN) STORAGE • BIOCHEMICAL FUNCTIONS • DEFICIENCY MANIFESTATIONS • DIETARY REQUIREMENTS, RDA • ANTI VITAMINS • TOXICITY MANIFESTATIONS • ROLE IN OTHER DISEASES

  3. Definitions of vitamins • Complex organic compounds required in small amounts • Required for essential life processes- to perform specific cellular functions • Consist of a mixed group of compounds unrelated to each other • Generally not synthesized by human • Some vitamins may deviate from the above definition (Vitamin D) • Each vitamin is typically used in multiple reactions and therefore, most have multiple functions Vitamins may be regarded as organic compounds required in small amounts to perform specific biological functions for normal maintenance of optimum growth and health of the organism.

  4. HISTORY • Ancient Egyptians knew that feeding a patient liver would help cure night blindness, now known to be caused by a vitamin A deficiency. • In 1747, the Scottish surgeion James Lind discovered that citrus foods helped prevent scurvy. • In 1905, William Fletcher discovered that eating unpolished rice instead of the polished variety helped to prevent the disease beriberi. • In 1906 Frederick Hopkins postulated that some foods contained "accessory factors"—in addition to proteins, carbohydrates, fats, etc.—that were necessary for the functions of the human body. • In 1912 Kazimierz Funk was the first to isolate the water-soluble complex of micronutrients, whose bioactivity Fletcher had identified, and Funk proposed the complex be named "Vitamine” (vital amine). The name soon became synonymous with Hopkins' "accessory factors“. • In 1920, Jack Cecil Drummond proposed that the final "e" be dropped, to deemphasize the "amine" reference, after the discovery that vitamin C had no amine component. -VITAMIN • Lipid from fish oil was used to cure rickets in rats, and the fat-soluble nutrient was called "antirachitic A". The first "vitamin" bioactivity ever isolated, which cured rickets, was initially called vitamin A

  5. Invention of vitamins • 1919 – Vitamin A • 1922 – Vitamin D • 1923 – Vitamin E • 1926 – Thiamin • 1926 – Riboflavin • 1928 – Bacterial synthesis of B vitamins • 1928 – Vitamin C • 1930 – Pantothenic Acid • 1932 – Choline • 1934 – Vitamin B6 • 1934 – Vitamin K • 1935 – Niacin • 1936 – Biotin • 1943 – Folacin • 1948 – Vitamin B12

  6. CLASSIFICATION VITAMINS Water Soluble Fat Soluble Vit A, Vit D, Vit E, Vit K Non B-complex B-complex e.g. Vitamin C

  7. VITAMIN SYNONYM • Fat Soluble Vitamin A1 Retinol Vitamin A2 Dehydroretinol Vitamin D2 Ergocalciferol Vitamin D3 Cholecalciferol Vitamin E Tocopherol Vitamin K1 Phylloquinone Vitamin K2 Menaquinone Vitamin K3 Menadione • Water Soluble Vitamin B1 Thiamin Vitamin B2 Riboflavin Vitamin B3 Niacin, VitaminPP Vitamin B6 Pyridoxol, Pyridoxal, Pyridoxamine Vitamin B5 Pantothenic Acid Biotin Vitamin H Folacin Vitamin M, Vitamin BC Vitamin B12 Cobalamin Choline Gossypine Vitamin C Ascorbic Acid

  8. Requirements/Occurrence/Sources • Dietary needs differ widely among species. Some vitamins are metabolic essentials, but not dietary essentials • For the most part, vitamins are obtained through food sources. However, a few vitamins are obtained by other means.e.g. microorganisms in the intestine - commonly known as "gut flora" - produce vitamin K and biotin, while one form of vitamin D is synthesized in the skin with the help of natural ultraviolet sunlight. • Some vitamins can be obtained from precursors that are obtained in the diet. Examples include vitamin A, which can be produced from beta carotene and niacin from the amino acid tryptophan. • Vitamins originate primarily in plant tissue • Vitamin B12 – occurs in plant tissue from microbial synthesis • Vitamins A and D occur in plants as a provitamin.

  9. Human vitaminsIn humans there are 13, divided into two groups; 4 fat-soluble vitamins (A, D, E and K), and 9 water-soluble vitamins (eight B vitamins and vitamin C).

  10. FACTORS THAT ADVERSELY AFFECT THE STABILITY OF VITAMINSMoistureTemperatureLightPressureFrictionTrace minerals (Cu & Fe)Oxidizing and reducing agentspHChemicalsFeed composition

  11. Vitamers Chemically similar substances that possess qualitatively similar vitamin activity e.g. Retinol, retinal and retinoic acid are vitamers of vitamin A. Pyridoxine, pyridoxal and pyridoxamine are vitamers of vitamin B6. Antivitamins Antagonistic to vitamin activity Admn. of antivitamin causes vit. Deficiency INH – Vit. B6; Avidin – biotin (eating raw eggs-biotin deficiency) Aminopterin, Methotrexate & Trimethoprim – Folic acid

  12. CHEMISTRY of VIT D • Provitamins: • Ergocalciferol (Vit D2) – ergosterol – Plants • Cholecalciferol (Vit D3) – Animals

  13. SYNTHESIS: Plants –Ergosterol Sunlight Ergocalciferol (D2) Animals – 7-Dehydrocholesterol Skin Sunlight Diet Cholecalciferol (D3)

  14. Diet Cholecalciferol (D3) (Liver) 25 hydroxylase 25 hydroxycholecalciferol PTH (+) (Kidney) 1  hydroxylase (-) Low P (+) 1,25 dihydroxycholecalciferol (calcitriol)

  15. ABSORPTION, TRANSPORT & STORAGE: • ABSORPTION:-Small intestine in presence of bile Through lymph – circulation • TRANSPORT:-Bound to -2 globulin • STORE:-Liver and other tissues

  16. BIOCHEMICAL FUNCTIONS: • Calcitriol (1, 25 DHCC) - an active form. • Regulate the plasma levels of calcium and phosphate.

  17. VITAMIN D IS A HORMONE AND NOT A VITAMIN • Vitamin D3 (cholecalciferol) - synthesized in skin. • Active form (calcitriol) - produced in kidney. • Target organs: intestine, bone and kidney. • Calcitriol action - similar to steroid hormone. • Actinomycin D inhibit the action of calcitriol (support calcitriol exert effect on DNA). • Synthesis - self regulated by feedback mechanism. • Calcitriol acts along with PTH and calcitonin. • Halflife in calcitriol is short (10 hours).

  18. RDA • Vit D = 400 IU or 10 g of cholecalciferol • Good sunlight  RDA

  19. DIETARY SOURCES: • Body can obtain Vit D • by consumption of natural food • fortification (milk, butter) irradiation of food (contain precursors of Vit D). • Exposure to sunlight • Good dietary sources are Fatty fish, fish liver oils, egg yolk etc. • Milk is not a good source of vit-D

  20. DEFICIENCY SYMPTOMS: • Less common seen in • strict vegetarians, chronic alcoholics or individual with liver & kidney disease or fat mal-absorption syndrome. • RICKETS in children & OSTEOMALACIA in adults.

  21. Vitamin A • Present in animal product only but provitamin carotenes is found in plants • Chemistry: • Retinol • Retinal • Retinoic acid • β-carotene

  22. Biochemical functions • Help in Vision • Regulate protein synthesis & cell growth • Maintain healthy epithelial tissue • Involved is synthesis of transferrin • Helpful in cholesterol synthesis • Acts as antioxidants

  23. Dietary sources • Best sources: liver, kidney, egg, milk, cheese, butter, fish oil • Plant sources like yellow fruits and green leafy vegetables are good sources of carotenes

  24. RDA • RDA= 1000 retinol equivalents • 1 retinol equivalent=1µg retinol = 6µg β-carotene

  25. Deficiency syndromes • Night blindness • Xeropthalmia • Effect on growth • Effect on reproduction

  26. Hypervitaminosis • Dermatitis • Enlargement of liver • Skeletal decalcification • Loss of hair • Joint pains

  27. VITAMIN E (Tocopherol) VITAMIN E: Anti-sterility vitamin:normal reproduction in many animals. Antioxidant. Tocopherols – derivatives of 6 hydroxy chromane (chromanol) ring with isoprenoid (3 units) side chain. Antioxidant due to chromane ring. Phenolic-OH group on 6th carbon is important for antioxidant activity.

  28. DIETARY SOURCES: • Vegetable & seed oils: Sunflower oil, corn oil, soybean oil, wheat germ oil safflower seed oil, Cottonseed oil etc. • Also – meat, milk, butter & egg. RDA :  = PUFA (0.4 mg/gm PUFA) Adult man 10mg = 15 IU of  tocopherol woman 8 mg = 12 IU of  tocopherol ABSORPTION, TRANSPORT & STORAGE ABSORPTION: Require bile salt & get absorbed along with chylomicron. TRANSPORT: Lipoproteins chylomicrons. Liver : LDL, VLDL STORED: Liver, Adipose tissue & muscle

  29. BIOCHEMICAL FUNCTIONS As ANTIOXIDANT: Vit E is the most important Natural Antioxidant • Prevent non-enzymatic oxidation of cell components (PUFA) by (O2.-) & H2O2. First line of defense against peroxidation of PUFA contained in cellular and subcellular phospholipids. • Membrane structure & integrity of cell: also k/a membrane antioxidant. • Prevent peroxidation of PUFA of various tissue memb. • Protect RBC from hemolysis. •  synthesis of heme by δ ALA synthase. • Prevent oxidation of Vitamin A & carotene. • Protect liver from toxic substance • Along with Vitamin A, C &  carotene delay cataract formation. • Prevention of Cancer and heart disease (prevention of oxidation of LDL).

  30. Other biochemical functions of Vitamin E ROLE IN REPRODUCTION IN RATS Maintain germinal epithelium of gonads. Prevent sterility in male rats. Ovary is unaffected in Vitamin E deficiency. Fetus malformation seen. OTHERS Storage of creatine in skeletal muscle. Optimum absorption of AA from GIT. Synthesis of nucleic acid. Involved in oxidative phosphorylation (by coenzyme Q synthesis).

  31. Deficiency Manifestation: Animal male sterility. Human being : • Anemia of newborn - haemolytic anaemia ( RBC fragility and  heme synthesis). • mild neurological symptoms. Vit E: destroyed by commercial cooking, food processing, deep freezing TOXICITY: LEAST TOXIC

  32. VITAMIN K Fat Soluble Vitamin with coenzyme function. Required for the production of blood clotting factors. CHEMISTRY: Vitamin K exists in different forms - Side chain of isoprenoid in K1 & K2. • Vitamin K1 (Phylloquinone) – Plants • Vitamin K2 (Menaquinone) – Animal tissue (bacteria of GIT) • Vitamin K3 (Menadione) –synthetic All Heat stable

  33. DIETARY SOURCES: Vitamin K1: Green leafy vegetables, alfa alfa, spinach, cauliflower, cabbage, soyabeans, tomatoes, etc. Vitamin K2: synthesized by GIT bacteria, egg yolk, meat, liver, cheese & dairy products. RDA : No RDA: half of body requirement – diet 70-140 g/day. ABSORPTION, TRANSPORT & STORAGE Diet/ synthesized by intestinal bacteria ABSORPTION: Small intestine in the presence of bile salt along with chylomicrons. TRANSPORT: Along with LDL STORE: Liver & other tissue in small amount EXCRETION: Faeces

  34. BIOCHEMICAL FUNCTIONS BLOOD COAGULATION: Promotion of blood coagulation by post translational modifications of blood clotting factors II, VII, IX & X. Clotting Factors: synthesized in inactive form (zymogens) in liver. Vit K – coenzyme for carboxylation of glutamic acid by carboxylase (microsomal). Glutamate (Glu) → γ-carboxyglutamate (Gla) INHIBITOR: Dicumarol an anticoagulant found in sweet clover. Warfarin is synthetic analogue.

  35. CALCIUM BINDING PROTEIN OF BONE: Required for carboxylation of glutamic acid residue of osteocalcin. ROLE IN OXIDATIVE PHOSPHORYLATION: Cofactor in oxidative phosphorylation associated with mitochondrial lipids. Role of Gla in clotting: γ carboxyglutamic acid (Gla) is negative charge. Combine with Ca2+ (positive)  form complex. Clotting factor - Ca complex binds to phospholipid on memb of Platelets. Activation of conversion of Prothrombin to thrombin

  36. DEFICIENCY SYMPTOMS: Uncommon. Seen in: • fat malabsorption (stetorrhoea due to pancreatic, liver or intestinal disease). • Diarrheal disease [loss in feaces]. • Administration of antibiotics/ sulfa drugs [intestinal flora]. • Malnourished individual. • Haemorrhagic disease of newborn [gut is sterile; insufficient from placenta] Deficiency of Vit K  active prothrombin  blood clotting time HYPERVITAMINOSIS K Large dose  hemolytic anaemia & jaundice mainly in infants due to  breakdown of RBC. ANTAGONISTS: • Heparin, bishydroxy coumarin (anticoagulants) • Dicumarol (structural analogue)  competitive inhibitor in synthesis of active prothrombin. • Salicylates

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