Vitamins Lecture Notes PDF

BBT 302: Molecules of Life Mrs. Mary David, Asst. Professor, SBB, DYPU Unit IV Nucleic acids and Vitamins  Lecture 22 Vitamins - Sources, RDA, and biological role of fat soluble vitamins  Vita...

BBT 302: Molecules of Life Mrs. Mary David, Asst. Professor, SBB, DYPU Unit IV Nucleic acids and Vitamins  Lecture 22 Vitamins - Sources, RDA, and biological role of fat soluble vitamins  Vitamin E Vitamin E was first discovered in vegetable oils and was designated as anti sterility factor as a deficiency of the vitamin causes development of sterility in animals. The active component was first isolated from wheat germ oil and was named tocopherol. Subsequently other tocopherols were also discovered in corn oil, wheat germ oil, rice oil, cottonseed oil, soybean and peanut. It is absent in fish liver oil and olive oil. Structure Vitamin E is the collective term for a group of closely related lipids called tocopherols. They are derivatives of 6-hydroxychroman having an isoprenoid side chain at C- atom 2. The various tocopherols differ w.r.t each other in substituents on carbon 5, 7, and 8. α- tocopherol the most potent form with maximum Vit E activity has 3 methyl groups. 4  Vitamin E structure 5 Forms of DNA http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/113565065/72_1_2.jpg  Role of Vitamin E Tocopherols act as antioxidants and prevent oxidation of easily oxidizable substances. They are commercially added to foods to avoid spoilage. Vitamin A and Vitamin E are also essential for reproduction as it has a beneficial action on the ectoderm and endoderm (Vit A) and mesoderm (Vit E) of developing embryos. Vitamin E also plays a role in preventing destruction of vitamin A. Tocopherol also protects the mitochondrial system by preventing deterioration of unsaturated fatty acids in the mitochondrial membrane 6  Deficiciency diseases due to avitaminoses E and RDA for Vit E Deficiency of Vitamin E may cause sterility due to re-absorption of foetus after conception, degeneration of germinal epithelium of testes and formation of non- motile sperms. Human requirements Vitamin E is ubiquitous in foods and a deficiency rarely occurs. Minimum RDA for humans. RDA Men 30 IU Women 25 IU Pregnant and lactating women 30 IU Infants 1 to 2.5 IU Where 1 IU = 1.1 mg pure compound 7  Vitamin K Vitamin K deficiency was first observed in new born chicks fed on an artificial diet. The chicks developed a fatal hemorrhage characterized by a prolonged blood clotting period. Since the vitamin seemed to aid coagulation (Danish Koagulation), it was designated as vitamin K. It is also called as anti hemorrhagic factor or coagulation vitamin. Occurrence Vit K has two forms Vit K1 and Vit K2. Vit K1 occurs in green vegetables like spinach, alfa alfa, cabbage etc. Vit K2 occurs in putrefied fish meal and intestinal bacteria. Vit K1 is the more potent Vitamin K2. 8  Vitamin K Structure They are derivatives of quinones with a side chain at carbon 3. Vitamin K1 has four isoprene units whereas Vit K2 has 6 isoprene units in its side chains. 9  Role of Vitamin K and deficiency disease associated with avitaminoses K Vitamin K is required for the biosynthesis of prothrombin an essential factor for blood clotting (prothrombin is converted to thrombin which lyses fibrinogen to fibrin. Entrapment of blood corpuscles in the mesh like fibrin fibers is what leads to clotting. Deficiency In infants deficiency of the vitamin causes an inability to clot blood and the slightest cut can cause hemorrhage. This occurs prior to the development of Vitamin K producing bacteria in intestine. The deficiency can be averted by administering Vit K to pregnant mothers prior to child birth. Vitamin K deficiency is rare Human requirement: No such standard requirement has been set. 10 Thank You