Effects of dietary Schizandra chinensis, brussels sprouts and Illicium verum extracts on carcinogen metabolism systems in mouse liver

Ethanol extracts of Brussels sprouts (BRX), Schizandra chinensis (SZX) or Illicium verum (IVX) were added to a semi-purified basal diet and fed to adult male and female C57B1/6 mice for 14 and 10 days, respectively. Other groups received the unsupplemented basal diet or a mouse chow. Liver fractions were prepared from these mice to investigate the effects of the diets on the enzyme systems involved in benzo[a]pyrene (BP) and aflatoxin B1 (AFB1) metabolism. The effects of the microsomal or cytosolic liver fractions on the in vitro mutagenicity of BP and AFB1 and on the DNA binding of AFB1 were also studied. There were several apparently sex-related differences in the responses of the monooxygenase system components measured. In males, cytochrome P-450 levels were significantly increased only in the chow group, while significant increases in both 7-ethoxycoumarin O-deethylase (ECD) and aryl hydrocarbon hydroxylase (AHH) activities were seen only in the SZX group. In females, cytochrome P-450 levels were significantly increased in both the BRX and SZX groups, whereas AHH activity was significantly increased only in the chow and BRX groups and ECD activity was increased in the SZX and IVX groups. Microsomal epoxide hydratase (EH) was induced in males in the SZX and IVX groups and in females only in the SZX group, while cytosolic EH was significantly increased only in IVX males. Diet-induced changes in monooxygenase activities were found to be the best indicators of changes in microsome-mediated BP mutagenesis and AFB1 mutagenesis and binding to DNA in vitro, with a direct correlation between high AHH and/or ECD activities and the levels of mutagenic response to BP or AFB1 in the Ames assay and of DNA binding of AFB1.