Okano Toshio, Nakagawa Kimie, Kamao Maya
Department of Hygienic Sciences, Kobe Pharmaceutical University, Japan.
Clin Calcium. 2009 Dec;19(12):1779-87.
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.
叶绿醌是膳食维生素K的主要形式（>90%），但在动物和人类组织中以最高浓度存在的维生素K形式是甲基萘醌-4（MK-4）。尽管存在这种巨大差异，但直到最近组织MK-4的来源仍未阐明。我们证明，氘标记的叶绿醌在小鼠体内可转化为氘标记的MK-4，这种转化在口服或肠内给药后发生，但非肠道外给药后不发生。通过口服途径，带有氘标记侧链（叶绿基侧链）的叶绿醌可明显转化为带有非氘标记侧链（香叶基香叶基侧链）的甲基萘醌-4，这意味着叶绿醌通过完整侧链去除转化为甲基萘醌-4。我们的结果表明，脑内甲基萘醌-4起源于叶绿醌的摄入，以及叶绿醌在肠道中释放甲萘醌，随后甲萘醌在肠道或组织中异戊烯基化成为甲基萘醌-4。
