| 释义 |
vitamin K
noun
Etymology: Danish koagulation coagulation, from Latin coagulation-, coagulatio
1. : either of two naturally occurring fat-soluble vitamins that are essential for the clotting of blood because of their role in the production of prothrombin in the liver and that are used in preventing and treating hypoprothrombinemia and hemorrhage:
a. or vitamin K1 : a yellow oily disubstituted naphthoquinone CH3(C20H39)C10H4O2 that is obtained especially from alfalfa or made synthetically (as from phytol and methyl-naphthoquinone or their derivatives) and that has a fast, potent, and prolonged biological effect, is effective orally, and is useful especially in treating hypoprothrombinemia induced by anticoagulant drugs; 2-methyl-3-phytyl-1,4-naphthoquinone — called also phylloquinone, phytonadione
b. or vitamin K2 : a pale yellow crystalline disubstituted naphthoquinone CH3(C30H49)C10H4O2 that is obtained especially from putrefied fish meal and is synthesized by various bacteria (as in the intestines of man and higher animals) and that is much more unsaturated than vitamin K1 and slightly less active biologically
2. : any of several synthetic compounds that are closely related chemically to vitamins K1 and K2 but are simpler in structure and that have similar biological activity but except for menadione are less active than the natural vitamins: as
a. or vitamin K3 : menadione
b. or vitamin K4 : a hydroquinone derivative CH3C10H5(OH)2 formed from menadione by hydrogenation and used in the form of its crystalline diacetate or the water-soluble crystalline sodium salt of its diphosphate; 2-methyl-1,4-naphthalene-diol
c. or vitamin K5 : a water-soluble crystalline compound CH3C10H5(OH)NH2.HCl that inhibits the growth of various microorganisms and is useful especially as a food preservative; 4-amino-2-methyl-1-naphthol hydrochloride
d. or vitamin K6 : a toxic water-soluble crystalline compound CH3C10H5(NH2).2HCl; 2-methyl-1,4-naphthalene-diamine dihydrochloride |