Sato Toshiro, Ozaki Rumi, Kamo Shuichi, Hara Yusuke, Konishi Satoru, Isobe Yosuke, Saitoh Sanshiroh, Harada Hiroshi
Nutrition Research Laboratories, Honen Corporation, Asaba-cho, Iwata-gun, Shizuoka 437-1111, Japan.
Biochim Biophys Acta. 2003 Aug 22;1622(3):145-50. doi: 10.1016/s0304-4165(03)00135-1.
2',3'-Dihydrophylloquinone (dihydro-K1) is a hydrogenated form of vitamin K1 (K1), which is produced during the hydrogenation of K1-rich plant oils. In this study, we found that dihydro-K1 counteracts the sodium warfarin-induced prolonged blood coagulation in rats. This indicates that dihydro-K1 functions as a cofactor in the posttranslational gamma-carboxylation of the vitamin K-dependent coagulation factors. It was also found that dihydro-K1 as well as K1 inhibits the decreasing effects of warfarin on the serum total osteocalcin level. In rats, dihydro-K1 is well absorbed and detected in the tissues of the brain, pancreas, kidney, testis, abdominal aorta, liver and femur. K1 is converted to menaquinone-4 (MK-4) in all the above-mentioned tissues, but dihydro-K1 is not. The unique characteristic of dihydro-K1 possessing vitamin K activity and not being converted to MK-4 would be useful in revealing the as yet undetermined physiological function of the conversion of K1 to MK-4.
