Alpha-tocopherol and phylloquinone as non-competitive inhibitors of retinyl ester hydrolysis

Inhibition of rat intestinal retinyl ester hydrolase by alpha-tocopherol (vitamin E) and phylloquinone (vitamin K1) was non-competitive. Maximum inhibition occurred within 10 min, and, particularly with alpha-tocopherol, was substantially reversible. Consequently, increasing tissue concentrations of retinyl esters, which might occur with advancing age or changes in diet, would not diminish the effects of the inhibitors. These data further support the notion that alpha-tocopherol may, at physiological concentrations, influence the concentration of vitamin A and its ester in tissues.