Microsome Mediated Aflatoxin B₁-8,9-Epoxide Conjugation to Glutathione in Presence of Purified Hepatic Glutathione S-Transferases from Control and Butylated Hydroxyanisole Pretreated Rats

Abstract

The effect of 2(3)-tert-butyl-4-hydroxyanisole (BHA) pretreatment of rats on aflatoxin B₁ (AFB₁) binding to glutathione has been studied in vitro. Young male F344 rats were fed AIN-76A diet with or without 0.75% BHA for 2 weeks. The isozymes of glutathione S-transferase in the liver cytosol were resolved using S-hexylglutathione affinity chromatography and chromatofocusing procedures. Although the yield of various isozymes from BHA-treated rats was much higher than in controls, there was no significant difference in the apparent catalytic activity of the enzymes for AFB₁-glutathione conjugate formation. The mμ group of enzymes (3-3, 3-4 and 4-4) from both groups of animals show 2-5 fold higher activity compared to the alpha set of enzymes (1-1, 1-2, 2-2). These results indicate the involvement of mμ set of enzymes in detoxication of AFB₁ and the increased amount of these proteins induced in BHA treated rats might be primarily responsible for its ability to inhibit hepatic AFB₁-DNA binding.