Effect of high sucrose diet on liver enzyme content and activity and aflatoxin B₁-induced mutagenesis

Aflatoxin B₁ (AFB₁) is a fungal toxin and contaminant that has been implicated in human liver carcinogenesis. In this study we evaluated the effect of a 65% of total calories from sucrose diet (HSD) for 90 days on hepatic cytochrome P450 (CYP450) and glutathione-S-transferase (GST) activity compared to rats maintained on standard lab chow (0% sucrose). There was a statistically significant increase in the number of S. typhimurium His⁺ revertants (p < 0.001) gene-rated from the incubation of AFB₁ with hepatic microsomes from rats fed a HSD. The HSD did not affect the total microsomal CYP450 content nor content of CYP450 1A2, 2B1,2 isoforms which activate AFB₁. Alkoxyresorufin O-dealkylase activity (MROD, PROD) of microsomes from animals fed HSD was decreased by 73% and 49%, respectively. MROD activity is linked to CYP 1A2 activity while PROD is linked to CYP 2B1,2 activity. Although the amount of CYP 3A was significantly decreased in rats fed a HSD, its activity, determined by the presence of the fluorometric metabolite 7-hydroxyquinidine, was unchanged. GST activity was significantly lower in the rats fed HSD.