Binding of aflatoxin B₁ to DNA inhibited by ajoene and diallyl sulfide

Components of garlic have been shown to inhibit a variety of tumors induced by chemical carcinogens. In this study we determined the effects of ajoene and diallyl sulfide (DAS), two organosulfur compounds of garlic on the metabolism and DNA binding of aflatoxin B₁ (AFB₁) using rat liver 9000xg supernatant as the metabolic activation system. Organosoluble and water-soluble metabolites of[³H]AFB₁ were isolated by reverse-phase high performance liquid chromatography (HPLC). The effects of ajoene and DAS on glutathione-S-transferase (GST) were determined using 1-chloro-2, 4-dinitrobenzene as the substrate. Ajoene and DAS at 100 mg/ml;inhibited [³H]AFB₁ binding to calf thymus DNA and adduct formation. They decreased the formation of both organosoluble and water-soluble metabolites of [³H]AFB₁. Neither compound significantly affected GST activity. These results indicate that ajoene and DAS affected AFB₁ metabolism and DNA binding by inhibiting phase I enzymes and may therefore be considered as potential cancer chemopreventive agents.