In vivo effect of dietary factors on the molecular action of aflatoxin B1: role of non-nutrient phenolic compounds on the catalytic activity of liver fractions.

Young adult rats were kept on a synthetic diet containing various food associated phenolic compounds each at 0.5% level. The ability of liver microsomes to catalyze reactions of aflatoxin B1 leading to its activation and DNA adduct formation was measured after an experimental feeding period of 3 weeks. A decrease in both activities was observed with several flavonoids (fisetin, kaempferol, morin, naringin and (+/-)catechin), phenolic acids (caffeic acid and chlorogenic acid), other phenolics (eugenol, vanillin) and synthetic phenolic antioxidants butylated hydroxyanisole and butylated hydroxytoluene. Certain phenolics notably naringin, (+/-) catechin, eugenol, vanillin and butylated hydroxyanisole were also found to induce cytosolic glutathione S-transferase activity that stimulated the formation of specific aflatoxin B1-glutathione conjugate. The results emphasize the role of phenolic compounds in the activation and detoxification processes, and hence in modulating the carcinogenicity of aflatoxin B1.