Abstract
This study was designed to rapidly screen for chemopreventive effects of three natural products, cyanidine-3-glycoside, acetoside and rosemaric acid, against 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP)-induced colonic, pancreatic and prostatic carcinogenesis in rats, using DNA adduct and cell proliferation as end-points. Ten-week-old F344 male rats were maintained for 2 weeks on a powdered basal diet containing 0.03% PhIP alone, PhIP together with 1% or 5% cyanidine-3-glycoside, acetoside or rosemaric acid, 1% or 5% cyanidine-3-glycoside, acetoside or rosemaric acid alone or basal diet. Immunohistochemically, PhIP DNA adduct-positive cells as well as BrdU-positive cells induced by PhIP treatment were significantly (P<0.05) reduced by the combined treatment with 5% cyanidine-3-glycoside in the proximal colon and pancreatic acinar cells as compared to the PhIP alone group values. In addition, combined treatment with 5% cyanidine-3-glycoside significantly (P<0.05) decreased numbers of BrdU-positive cells in the ventral prostate. Combined treatment with 5% rosemaric acid also significantly (P<0.05) reduced PhIP DNA adduct-positive cells in the proximal and distal colon, and ventral prostate as well as BrdU-positive cells in the lateral prostate and exocrine pancreas at 5%, and in the distal colon with 1% or 5%. However, co-treatment with acetoside did not significantly affect these parameters under the present experimental conditions. These results suggest that cyanidine-3-glycoside and rosemaric acid may have the potential to prevent PhIP-induced carcinogenesis in the colon, prostate and/or pancreas.
