Effect of allixin, a phytoalexin produced by garlic, on mutagenesis, DNA-binding and metabolism of aflatoxin B₁

Allixin, a phytoalexin isolated from garlic, was examined for its effects on aflatoxin B₁(AFB₁)-induced mutagenesis using Salmonella typhimurium TA100 as the bacterial tester strain and rat liver S9 fraction as the metabolic activation system. The effects of allixin on the binding of [³H]AFB₁ to calf thymus DNA and on the formation of metabolites of [³H]AFB₁ were also determined. Allixin showed a dose-related inhibition of Histidine⁺ revertants induced by AFB₁. Allixin at 75 μg/ml inhibited [³H]AFB₁ binding to calf thymus DNA and reduced formation of AFB₁-DNA adducts. In addition, allixin exhibited a concentration-dependent inhibition of the formation of organosoluble metabolites and the glutathione conjugates of [³H]AFB₁. The data indicate that the effect of allixin on AFB₁-induced mutagenesis and binding of metabolites to DNA may be mediated through an inhibition of microsomal P-450 enzymes. Allixin may thus be useful in the chemoprevention of cancer.