Effects of vitamin antioxidants on hydroxylation of 2-acetylaminofluorene by rat liver microsomes

Abstract

The effects of vitamin A acetate, vitamin A palmitate, ascorbic acid and DL-α-tocopherol in N- and ring-hydroxylation of 2-acetylaminofluorene by rat liver microsomes were examined. Vitamin A acetate at 0.1 mM inhibited both reactions almost completely whereas vitamin A palmitate at that concentration had no detectable inhibitory effects on these reactions. Ascorbic acid and DL-α-tocopherol at 0.1 mM inhibited both hydroxylations by 40-60%. Vitamin A palmitate at 1 mM showed preferential inhibition of N-hydroxylation by 40% without affecting ring-hydroxylation. These results suggest that the antioxidant property of these vitamins may be partly responsible for the inhibitory effects of these vitamins on carcinogenesis by various chemicals.