R-Goitrin- and BHA-induced modulation of aflatoxin B 1 , binding to DNA and biliary excretion of thiol conjugates in rats

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Abstract
Previous studies have shown that dietary R-goitrin is a potent inducer of hepatic glutathione S-transferase (GST) and epoxide hydrolase activities but has no effect on components of the mixed function oxidase system (ethoxycoumarin O -deethylase and cytochrome P-450). In the present work effects of dietary R-goitrin (200 p.p.m.) or butylated hydroxyanisole (BHA) (7500 p.p.m.) on GST activity, binding of aflatoxin B 1 , (AFB]) to DNA, in vivo , and biliary excretion of thiol conjugates of AFB 1 in rats were studied. Increases of GST activities (1.9- and 2.1-fold) were accompanied by reductions in AFB 1 -DNA binding (43% and 85%) and increases (1.7-and 2.2-fold) in biliary excretion of AFB 1 -thiol conjugates in R-goitrin and BHA groups, respectively. Microsomal aflatoxin 8,9-epoxidase activities were not increased in either treatment group. The role of GST induction in the carcinogenesis of AFB 1 and the anticarcinogenic potential of R-goitrin are discussed.