Résumé
Background : Total polyphenolic extracts from red wine protect against azoxymethane (AOM)–induced colon carcinogenesis in rats. Since red wine contains more than 200 different polyphenolic compounds, it is still unclear which substances are responsible for this effect. Aim of the study : We investigated the effect of high molecular weight polyphenols (HMWP), low molecular weight polyphenols (LMWP) and total polyphenolic extracts from red wine (WE) on colon carcinogenesis. We also tested the effect of 4–OH–coumaric acid, a potent phenolic antioxidant present in wine and fruit. Methods : F344 rats were treated weekly with 1,2–dimethylhydrazine (DMH) (30 mg/kg b.w. subcutaneously x 10 times). One week after the final DMH injection rats were divided into five groups and fed: a) a high fat (HF) diet containing 23% corn oil (w/w), as control or the same basal diet supplemented with b) 0.11 % (w/w) WE; c) 0.027% (w/w) HMWP d) 0.083% (w/w) LMWP or e) 0.1 % (w/w) 4–OH–coumaric acid. The dietary treatments continued until sacrifice, 16 weeks after the last DMH injection. Results : WE treated rats had significantly fewer (p < 0.05) colorectal adenomas than controls, while rats in other treatment groups did not differ significantly from controls (colorectal adenomas/rat were: 2.2 ± 0.3; 1.4 ± 0.2; 2.9 ± 0.5; 2.6 ± 0.4; 2.3 ± 0.3; in controls, WE, HMWP, LMWP and 4–OH–coumaric acid groups, respectively; means ± SE). The mean number of colorectal carcinomas per rat was similar among all experimental groups. Proliferative activity in the normal colon mucosa did not vary among experimental groups. Conclusions : Total polyphenolic extracts (WE) from red wine, but neither the HMWP nor the LMWP, have some inhibitory effect on the process of colon carcinogenesis by DMH reducing the number of adenomas.