In vivo effect of dietary factors on the molecular action of aflatoxin B1: role of copper on the catalytic activity of liver microsome.

Wealing rats were kept on a synthetic copper-free diet for 9-13 weeks and subsequently on the same diet but supplemented with copper at different levels for 2 weeks. The ability of liver microsomes to catalyze reactions of aflatoxin B1 leading to its activation and DNA adduct formation was measured after each period of experimental feeding. An increased molecular reactivity of aflatoxin B1 was evident during deficiency such that the degree of its conversion to its reactive metabolite and subsequent DNA adduct formation was higher with microsomes from copper deficient rats as compared to rats maintained on a normal supply of copper. These activities of microsomes returned to normal after supplementation of the diet with a small level of copper. The results emphasize the role of copper in the activation, and hence in modulating the carcinogenicity of aflatoxin B1.