Effects of dietary broccoli and butylated hydroxyanisole on liver-mediated metabolism of benzo[a]pyrene.
Groups of male Wistar rats were given either a basal diet or diets supplemented with 10 or 25% broccoli or 0.8% BHA. Liver fractions were assayed for cytochrome P-450, for aryl hydrocarbon hydroxylase (AHH), glutathione-S-transferase and epoxide hydrolase activities and for benzo[a]pyrene (BaP) metabolism. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of liver microsomes was also performed. Mean relative liver weight in the BHA group was significantly higher than that of the control and 10% broccoli groups but not significantly higher than that of the 25% broccoli group. Gel electrophoresis of liver microsomes indicated a diet-dependent variation in intensity in a band that corresponded in mol wt to those of certain cytochrome P-450s. Diet-dependent increases (20-90% over control) in cytochrome P-450 and in the activities of AHH, glutathione-S-transferase and epoxide hydrolase were observed in livers from rats given broccoli-supplemented diets. Except for AHH activity, such increases also occurred in the group fed BHA. Analysis of BaP metabolites revealed that the proportion of 4,5-diol formed relative to the major diols identified was unchanged in the broccoli- or BHA-treated groups relative to the control group. The proportion of 9,10-diol formed was unchanged in the broccoli-fed groups but was significantly higher in the BHA group than in the control group. The proportion of cis and trans-7,8-diol formed was unchanged in both broccoli-fed groups but was significantly lower in the BHA group. In comparison with the control group, the ratio of phenol I (comprising primarily 9-OH-BaP) to total phenols (primarily 9-OH and 3-OH) was significantly decreased by about 30% in the 25%-broccoli group and by about 70% in the BHA group. Qualitative differences in the phenol-II peak (comprising 3-OH and 7-OH phenols) were also observed between samples from the controls and those of 25%-broccoli- and BHA-fed rats. The implications of these findings are discussed with respect to the effects of broccoli and BHA on benzo[a]pyrene toxicity.
D000818:Animals; D000840:Anisoles / Q000494:pharmacology*; D001564:Benzo(a)pyrene; D001580:Benzopyrenes / Q000378:metabolism*; D001835:Body Weight / Q000187:drug effects; D002083:Butylated Hydroxyanisole / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D008099:Liver / Q000187:drug effects; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D014675:Vegetables
D000840:Anisoles; D001580:Benzopyrenes; D002083:Butylated Hydroxyanisole; D001564:Benzo(a)pyrene