Effects of capsaicin on rat liver S9-mediated metabolism and DNA binding of aflatoxin.

At concentrations of 25, 50, and 100 microM, capsaicin, which is the major component in various aspects of Capsicum hot peppers, decreased the binding of aflatoxin (AFB1) to calf thymus DNA by 19%, 44%, and 71%, respectively, in incubations with rat liver S9. At concentrations of 50 and 100 microM, capsaicin decreased the formation of AFB-DNA adducts (AFB1-N7-Gua) by 53% and 75% as determined by high-pressure liquid chromatography (HPLC). HPLC analysis of organo-soluble fractions showed that these effects correlated with a concentration-dependent decrease in S9-mediated metabolism of AFB1 by capsaicin. Capsaicin also altered the formation of water-soluble conjugates of AFB1. This was indicated by a decrease in radioactivity in water-soluble fractions and in glutathione conjugates of AFB1 analyzed by HPLC. These results suggest that capsaicin inhibited the biotransformation of AFB1 by modifying Phase I hepatic enzyme activity.