Vitamin K.pptx

Vitamin K.pptx

• 1.
  Vitamin D andHealth
• 2.
  • VITAMIN K
• 3.
  • Overview ofVitamin K • Vitamin K, one of the fat-soluble vitamins, was discovered relatively late. In 1929, researcher Henrik Dam observed that chickens fed a diet lacking a specific type of fat experienced bleeding in various tissues and had a prolonged blood clotting time. Initially, it was mistaken for scurvy or a response to a dietary toxin, but neither theory proved correct. Further research revealed that the inclusion of plant sterols prevented the disease, demonstrating it was a nutrient deficiency. Dam named the substance "vitamin K" because it helped with blood clotting (from the German word "koagulation"). Vitamin K's importance in blood clotting and its discovery through animal studies mark significant milestones in our understanding of this vital nutrient
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  • Structure andnomenclature • Vitamin K comes in different forms, including K1 and K2, which were isolated from different sources. Bacteria in the intestines of animals, such as rats and chickens, can produce vitamin K. The K1 family includes compounds with a phytyl moiety at position 3, with phylloquinone being the most important member. K2 compounds, derived from animals, have varying side-chain lengths. K3 compounds, lacking a side chain, can be synthesized in the laboratory. When consumed, K3 compounds are converted to K2 by intestinal bacteria. Vitamin K requires a methyl group at carbon 2, a side chain at carbon 3, and an unsubstituted benzene ring for its activity. Compounds with a 20-carbon side chain have optimal activity. The natural form is all-trans-all-trans-phylloquinone, while synthetic phylloquinone is a mixture of cis and trans forms.
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  • Chemical andPhysical Properties • Phylloquinone (K 120) is a yellow viscous oil. The physical state of menaquinone (K2 20) depends • on its side-chain length. If the side chain is 5 or 10 carbons long it is an oil, if longer it is a solid. • Menadione (K3) is a solid. All three families of compounds are soluble in fat solvents. Menadione can be made water soluble by converting it to a sodium salt. All the vitamin K compounds are • stable to air and moisture but unstable to ultraviolet light. They are also stable in acid solutions but are destroyed by alkali and reducing agents. These compounds possess a distinctive absorption spectra because of the presence of naphthaquinone ring system.
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  • Functions: • VitaminK was initially known for its role in blood clotting. However, we now understand that it serves as a vital cosubstrate for a group of proteins involved in blood coagulation and other functions. These proteins include blood clotting factors II, VII, IX, and X, as well as bone Gla protein, osteocalcin, and plasma proteins C and S.
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  • Blood clottingis a complex process that involves multiple phases. These phases include the formation of thromboplastin, activation of thromboplastin, formation of thrombin, and formation of fibrin. When an injury occurs, fibrinogen, a blood protein, is transformed into fibrin, which forms a network of fibers to create a blood clot. The transformation of fibrinogen to fibrin is catalyzed by thrombin, which is derived from prothrombin. For this transformation to occur, prothrombin and the protease factor Xa need to adhere to damaged cell phospholipids with the help of calcium bridges.
• 9.
  • Carboxylation, aprocess that adds a specific chemical group to proteins, is crucial for the formation of these calcium bridges and the adherence of prothrombin to damaged cell walls. Phospholipids, specifically phosphatidyl choline, play a role in the carboxylase enzyme system required for carboxylation. The synthesis of thrombin from prothrombin relies on prothrombinase, active preaccelerin, and the phospholipid cephalin. These factors are activated by convertins found in blood and tissues, representing the synthesis and activation of the thromboplastin complex.
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  • To avoidconfusion in the understanding of blood coagulation, a numerical system was established to designate various factors involved. Four of these factors (II, VII, IX, and X) are proteins synthesized in the liver and dependent on vitamin K. Calcium ions are necessary for their activation and participation in the coagulation process.
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  • importance ofvitamin K in various biochemical processes and its impact on protein function. • Vitamin K acts as a cosubstrate in the carboxylation of proteins. It undergoes metabolism in the liver. There are two pathways for vitamin K reduction: the epoxi-quinone cycle and DT diaphorase/microsomal dehydrogenase. • Niacin and riboflavin are needed for the metabolism of vitamin K. • Vitamin K is reduced to vitamin KH2 (hydroquinone) using NADH as a coenzyme. • Vitamin K quinone reacts with CO2 and O2 for the carboxylation of glutamyl residues. • Warfarin (coumarin) interferes with vitamin K reduction and epoxide conversion • Vitamin K epoxide can substitute for vitamin K in carboxylation and prothrombin synthesis. • Glutamic acid and aspartic acid residues can be carboxylated. • Proteins require the carboxylation of specific amino acid clusters to function properly. •
• 13.
  • Vitamin Kis not only important for blood clotting but also plays a role in bone health. There is a protein called osteocalcin found in bones, and it relies on vitamin K for its proper functioning. Osteocalcin helps with bone mineralization, which is essential for strong and healthy bones. Vitamin K enables osteocalcin to bind to calcium and other minerals, allowing it to carry out its role in bone formation. So, vitamin K is crucial for both blood clotting and bone health.
• 15.
  • Vitamin Kis involved in regulating calcium levels in bones and kidneys. Two proteins, bone Gla protein (BGP) and a γ-carboxy- glutamic acid-rich protein in the kidneys, depend on vitamin K for their function. BGP helps with bone mineralization, while the kidney protein helps bind and conserve calcium. However, if these proteins become too active, it can lead to the formation of kidney stones. The exact relationship between the carboxylated peptide and stone formation is not yet understood.
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  • Vitamin Kdeficiency • The deficiency of vitamin K is uncommon, since it is present in the diet in sufficient quantity and/or is adequately synthesized by the intestinal • bacteria. However, vitamin K deficiency may occur due to its faulty absorption (lack of bile salts), loss of vitamin into feces (diarrheal diseases) and administration of antibiotics (killing of intestinal flora). • Vitamin K deficiency can occur due to impaired absorption from biliary disease, long-term antibiotic therapy, or the use of anticoagulant medication. The main characteristic of deficiency is a delayed clotting time and increased bruising. A test measuring under-γ-carboxylated prothrombin and decreased urinary excretion of γ-carboxyglutamic acid can detect deficiency. In women, vitamin K deficiency may be linked to osteoporosis and atherosclerosis, as it plays a role in calcium homeostasis. Newborn infants may also experience delayed clotting times, but routine administration of vitamin K to pregnant women is no
• 17.
  • Antagonists ofvitamin K • The compounds—namely heparin, bishydroxy-coumarin— act as anticoagulants and are antagonists to vitamin K. The salicylates and dicumarol are also antagonists to vitamin K. • Dicumarol is structurally related to vitamin K and acts as a competitive inhibitor in the synthesis of active prothrombin.
• 18.
  • Dietary sources •Phylloquinone is the primary form of dietary vitamin K found in humans. It is abundant in alfalfa, which has been known for its high vitamin K content. When studying the vitamin K content of common foods using the chick bioassay method, it has been observed that green leafy vegetables contain significant amounts of vitamin K, meats and dairy products contain moderate amounts, while fruits and cereals contain smaller amounts. • Cabbage, cauliflower, tomatoes, alfa alfa, • spinach and other green vegetables are good sources. It is also present in egg yolk, meat, liver, cheese and dairy products