Vitamin K (K from "Koagulations-Vitamin" in
German and
Scandinavian languages[1]) denotes a group of
lipophilic,
hydrophobic vitamins that are needed for the
posttranslational modification of certain proteins, mostly required for
blood coagulation. Chemically they are 2-
methyl-
1,4-naphthoquinone derivatives.
Vitamin K1 is also known as phylloquinone or phytomenadione (also called phytonadione). Vitamin K2 (menaquinone, menatetrenone) is normally produced by bacteria in the Large Intestine[2], and dietary deficiency is extremely rare unless the intestines are heavily damaged, are unable to absorb the molecule, or due to decreased production by normal flora, as seen in broad spectrum antibiotic use[3].
There are three synthetic forms of vitamin K, vitamins K3, K4, and K5, which are used in many areas including the pet food industry (vitamin K3) and to inhibit fungal growth (vitamin K5) [4]
All members of the vitamin K group of vitamins share a methylated naphthoquinone ring structure, and vary in the aliphatic side chain attached at the 3-position (see figure 1). Phylloquinone (also known as vitamin K1) invariably contains in its side chain four isoprenoid residues, one of which is unsaturated.
