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Vitamin K

Vitamin K is the group of chemical compounds known as quinones. The naturally-occurring fat-soluble vitamins are K1 (phylloquinone), K2 menaquinone, and K3 (menadione). Phylloquinone contains a C20 phytyl chain, in which only the first isoprene unit contains a double bond. GGPP is transformed into phytyl pyrophosphate (PPP), the starting material for the further formation of tocopherols, by geranylgeranyl pyrophosphate oxidoreductase (GGPPOR). Vitamin K is one of the fat-soluble vitamins and also called "antihemorrhagic vitamin" since the deficiency in vitamin K causes reduced coagulability of blood. It has been recently suggested that the reduced coagulability of blood may be caused by the deficiency of vitamin K since vitamin K is essential for the biosynthesis of several blood clotting factors including prothrombin. Vitamin K has activity on blood coagulation and electron transport systems and has been widely employed clinically. Clinical uses of Vitamin K in the past have been directly linked with its ability to influence coagulation rather than any deficiency disease process, primarily in anticoagulant-induced prothrombin deficiency caused by coumarin or indanedione derivatives, hypoprothrombinemia due to antibacterial therapy, factors limiting absorption, or salicylism. Vitamin K is necessary for the production via the liver of active prothrombin (Factor II), proconvertin (Factor VII), plasma thromboplastin component (Factor IX) and Stuart Factor X. Vitamin K deficiency usualy results in poor clotting of the blood, among other symptons. Since the deficiency of this vitamin brings deterioration of the ability to coagulate blood, vitamin K is held to constitute itself one species of fat-soluble vitamin otherwise called an antihemorrhagic vitamin. The amount of the vitamin K which is found necessary for the purpose of preventing the deterioration of the blood-coagulating ability is extremely small. The synthetic vitamins K1 and K2 are used as medicines for the therapy of the disease of the vitamin K deficiency hemorrhage.

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