[Vitamin K and Bone Update. In vivo Metabolism of Vitamin K. - In relation to the conve... - 0 views
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Matti Narkia on 07 Dec 09[Vitamin K and Bone Update. In vivo Metabolism of Vitamin K. - In relation to the conversion of vitamin K(1) to MK-4 -] Okano T, Nakagawa K, Kamao M. Clin Calcium. 2009 Dec;19(12):1779-87. Japanese. PMID: 19949269 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