Vitamin K‐antagonistic effect of plastoquinone and ubiquinone derivatives in vitro

Abstract
Decyl‐ubiquinone and decyl‐plastoquinone were used as model compounds to test the potential effect of quinone derivatives on two enzymes of the vitamin K cycle in vitro. Substantial inhibition of γ‐glutamate carboxylase was found, whereas vitamin K‐epoxide reductase was inhibited to a much lesser extent. The inhibitory effect of both decylquinones was eliminated in a time‐dependent way by solubilized microsomes, but not by purified carboxylase. Since a wide variety of prenylquinones occur as micronutrients, these results are of potential relevance for the effects of natural quinones in the human diet.