Comparative distribution, metabolism, and utilization of phylloquinone and menaquinone-9 in rat liver.

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Reedstrom CK, Suttie JW

Comparative distribution, metabolism, and utilization of phylloquinone and menaquinone-9 in rat liver.

Proc Soc Exp Biol Med. 1995 Sep;209(4):403-9.

PubMed ID

7638250 [ View in PubMed

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Abstract

The liver of most species contains a spectrum of bacterially produced menaquinone homologs as well as the major dietary form of vitamin K, phylloquinone. The relative utilization of phylloquinone and menaquinone-9 (MK-9) as substrates for the microsomal vitamin K-dependent gamma-glutamyl carboxylase was determined in a rat model. Vitamin K 2,3-epoxide, the co-product of the carboxylation reaction, is recycled to the quinone form of the vitamin by a microsomal vitamin K epoxide reductase. This enzyme activity was blocked by warfarin administration, and the appearance of the hepatic epoxides of phylloquinone and MK-9 was determined as a measure of their utilization by the carboxylase. When the liver contained equimolar amounts of phylloquinone and MK-9, four times as much phylloquinone epoxide as MK-9 epoxide was present in the liver 1 hr after warfarin administration. These data suggest that hepatic MK-9 is not as efficiently utilized as phylloquinone. The data obtained have also demonstrated a previously unrecognized difference in phylloquinone and menaquinone metabolism. MK-9 epoxide, and to a lesser extent MK-9, was preferentially localized in the mitochondria, while higher concentrations of phylloquinone were found in the microsomes.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Phylloquinone	Vitamin K-dependent gamma-carboxylase	Protein	Humans	Yes	Substrate Inducer Cofactor	Details