phytomenadione brands

Molecular formula: C31H46O2

Vitamin K is a cofactor of gamma-carboxylase. Gamma carboxylase attaches carboxylic acid functional groups to glutamate, allowing precursors of factors II, VII, IX, and X to bind calcium ions. Binding of calcium ions converts these clotting factors to their active form, which are then secreted from hepatocytes into the blood, restoring normal clotting function. Vitamin K may also carboxylate matrix proteins in chondrocytes, inhibiting calcification of joints, and may increase type II collagen. The role of vitamin K in osteroarthritis, bone density, and vascular calcification is currently under investigation. Vit k is necessary for formation of prothrombinogen & other blood clotting factors in liver. During clotting, circulating prothrombin is required for production of thrombin; in turn, thrombin converts fibrinogen to fibrin, network of which constitutes clot. /vit k/ In normal animals and man, phyltonadione ... /is/ virtually devoid of pharmacodynamic activity. In Animals and man deficient in vitamin k, the pharmacological action of vitamin k is identical to its normal physiological function, that is, to promote hepatic biosynthesis of prothrombin (factor ii), proconvertin (factor vii), plasma thromboplastin component (ptc, christmas factor, factor ix), and Stuart factor (factor x). On the basis of studies of microsomal metabolism in vitro and studies in rats and mice in vivo, /it was suggested/ that vitamin K may be mutagenic by affecting the mixed-function oxidase system which metabolizes benzo(a)pyrene. Phylloquinone at a high concentration (200 umol/l) inhibited the conversion of benzo(a)pyrene to its more polar metabolites, ... . Paradoxically, at a lower concentration of phylloquinone (25 umol/l), ... the metabolism of benzo(a)pyrene was increased. In this system, therefore, .... phylloquinone could either potentiate or inhibit it, depending on the concentration. This overall weaker inhibitory effect of phylloquinone could be due to the low solubility of this lipophilic compound, but it is difficult to explain the mechanism of the enhanced metabolism of benzo(a)pyrene at lower concentrations of phylloquinone.

Source: PubChem (NCBI) · compound 5284607