Effect of vitamin e on rat hepatic cytochrome p‐450 activity

Abstract

Hepatic cytochrome P‐450 activity has been shown to be affected by various dietary factors including vitamin E. However, reports of the effect of dietary vitamin E on cytochrome P‐450 activity have been inconsistent. The aim of the present study was to investigate the influence of dietary vitamin E on rat hepatic cytochrome P‐450 activity. Three groups of six male weanling Sprague‐Dawley rats were fed semipurified diets containing 0, 100, or 1,500 ppm vitamin E for eight weeks. Vitamin E was given in the form of a‐tocopheryl acetate. Dietary vitamin E significantly affected liver vitamin E content (p < 0.05) but had no effect on rat hepatic total P‐450 content, N‐nitrosodimethylamine demethylase, and NADPH‐cytochrome‐P‐450 reductase activities. Hepatic pentoxyresorufin O‐dealkylase and glu‐tathione S‐transferase activities were significantly greater in rats fed 100 and 1,500 ppm vitamin E than in rats fed no vitamin E (p < 0.05). Dietary vitamin E induced changes in hepatic phospholipid fatty acid composition. Hepatic phos‐pholipid linoleate was significantly greater in rats fed 0 and 1,500 ppm vitamin E than in rats fed 100 ppm vitamin E (p < 0.05). Hepatic phospholipid eicosapentaenoate was increased significantly by dietary vitamin E (p< 0.05). Hepatic thiobarbituric acid‐reactive substance was significantly greater in rats fed no vitamin E than in rats fed 100 and 1,500 ppm vitamin E (p < 0.05). The results suggest that vitamin E may influence cytochrome P‐450 IIB1 enzyme activity and may affect hepatic phospholipid fatty acid composition.