Inhibitory Effects of Dietary Monoglucosyl-rutin on Azoxymethane-induced Colon Carcinogenesis in Rats.

The dietary effect of monoglucosyl-rutin (M-R), a flavonoid, on azoxymethane (AOM)-induced colon carcinogenesis was investigated in two experiments with 5 week old, F344 male rats. In the first experiment (5 weeks study), effects of MR on AOM (15 mg/kg body weight 3 times weekly)-induced formation of aberrant crypt foci (ACF) in five groups were assessed. In this experiment, group 3 given 500 ppm M-R with AOM had a significantly smaller number of ACF containing 4 or more aberrant crypts than group 1 with AOM alone, and groups 2 and 3 given 100 ppm or 500 ppm M-R respectively had significantly lower BrdU labeling indices in the epithelial cells of large bowel than group 1. For the second experiment, rats were divided into 8 groups. Groups 1-5 were given AOM as in the first experiment. Groups 2-5 were fed diets containing 100ppm or 500ppm M-R for 4 weeks in the initiation phase or 36 weeks in the post-initiation phase. Group 6 was given 500ppm M-R throughout the experiment, and group 7 was kept on the basal diet and served as a control. At the termination of the experiment (40 weeks after the start), groups 2-5 had significantly smaller numbers of positive cells with anti-proliferating cell nuclea antigen (PCNA) antibody than group 1. Furthermore, group 5 treated with 500ppm M-R for 36 weeks demonstrated tendencies for decrease in the incidence and multiplicity of colon tumors. These data suggest that M-R has the potential to inhibit AOM-induced colon carcinogenesis.