Modifying effects of fungal and herb metabolites on azoxymethane-induced intestinal carcinogenesis in rats

Modifying effects of a fungal product, flavoglaucin, and four plant-derived chemicals, shikonin, gingerol, oleanolic acid and paeoniflorin, on intestinal carcinogenesis were examined in a rat model using azoxymethane (AOM). A total of 280 male F344 rats, 6 weeks old, were divided into 12 groups. Group 1 (30 rats) was given two subcutaneous injections of 15 mg/kg of AOM at the start of the experiment. Groups 2 (30 rats), 3 (20 rats), 4 (20 rats), 5 (30 rats) and 6 (30 rats) received a test chemical (flavoglaucin, shikonin, gingerol, oleanolic acid or paeoniflorin, respectively) in the diet at a concentration of 0.02% for 3 weeks, during which time AOM was applied, and then kept on basal diet until the end of experiment (one year). Groups 7-11 (each 20 rats) were given a test chemical corresponding to Groups 2-6, respectively. Group 12 (20 rats) served as a control. The incidence and average number of intestinal tumors in Group 2 (47%, 0.57 +/- 0.68) were significantly less than in Group 1 (74%, 1.07 +/- 0.87) (P < 0.05, respectively). Multiplicity of intestinal neoplasms of Group 3 (0.55 +/- 0.60) or 4 (0.47 +/- 0.51) was also significantly smaller than that of Group 1 (P < 0.05 and P < 0.01, respectively). These results suggest that flavoglaucin, shikonin and gingerol might be promising chemopreventive agents for intestinal neoplasia.