Effect of plant flavonoids on microsome catalyzed reactions of aflatoxin B1 leading to activation and DNA adduct formation

Twenty-six plant phenolic flavonoids were tested for their ability to modulate microsome mediated activation of aflatoxin B1 (AFB1) and covalent adduct formation of activated metabolites with DNA. Some of the flavonoids were observed to inhibit both the reactions very significantly. A few of these showed inhibition of these reactions at varying degrees while others were inactive. Structurally, polyhydroxy flavonols such as robinetin, quercetin, fisetin and morin were found to be very active. Methylation and glycosylation usually rendered the flavonoid less active or inactive. With active flavonoids DNA adduct formation appeared to be modulated through their action on microsomal enzymes, and this could form a basis to counteract the carcinogenic action of aflatoxin B1.