Abstract
Vitamin K is a fat-soluble vitamin and a well-known cofactor for γ-glutamyl carboxylase (GGCX), an enzyme that converts specific glutamic acid residues in several proteins to γ-carboxyglutamic acid (Gla) residues related to blood coagulation and bone formation in the vitamin K cycle. It has two major homologues, the plant-derived vitamin K_1 (phylloquinone: PK)and the bacterium-derived vitamin K_2 (menaquinone-n: MK-n). Among these homologues, MK-4 has attracted attention because of its interesting biological activities. For example, MK-4 showed additional biological actions related to gene transcription through the steroid and xenobiotic receptor (SXR), suppression of cancer cell proliferation, and so on. Therefore, we evaluated the biological action of vitamin K homologues with chemical techniques using heavy oxygen labeled, fluorescent labeled, and deuterated labeled analogues. Furthermore, we also elucidated new analogues with high rates of conversion to MK-4. Those analogues can be expected to lead to new drugs once the biological importance of MK-4 is clarified.
