[In vivo metabolism of vitamin K: in relation to the conversion of vitamin K1 to MK-4].
Phylloquinone is a major form (>90%) of dietary vitamin K, but the form of vitamin K that exists at the highest concentrations in tissues of animals and humans is menaquinone-4 (MK-4) . Despite this great difference, the origin of tissue MK-4 had not been clarified until recently. We demonstrated that deuterium-labeled phylloquinone was converted into deuterium-labeled MK-4 in mice and this conversion occurred following an oral or enteral administration, but not parenteral administration. By the oral route, the phylloquinone with the deuterium-labeled side chain (phytyl side-chain) was clearly converted into menaquinone-4 with a non-deuterium-labeled side chain (geranylgeranyl side-chain), implying that phylloquinone was converted into menaquinone-4 via integral side-chain removal. Our results suggest that cerebral menaquinone-4 originates from phylloquinone intake and the release of menadione from phylloquinone in the intestine followed by the prenylation of menadione into menaquinone-4 in the intestine or tissues.
Okano
Toshio
T
Department of Hygienic Sciences, Kobe Pharmaceutical University, Japan.
Nakagawa
Kimie
K
Kamao
Maya
M
D000284:Administration, Oral; D000818:Animals; D001921:Brain / Q000378:metabolism; D006801:Humans; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D051379:Mice; D009474:Neurons / Q000378:metabolism; D014018:Tissue Distribution; D010837:Vitamin K 1 / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism*; D024482:Vitamin K 2 / Q000031:analogs & derivatives* / Q000378:metabolism
D024482:Vitamin K 2; C030814:menatetrenone; D010837:Vitamin K 1