Effects of black tea, green tea and wine extracts on intestinal carcinogenesis induced by azoxymethane in F344 rats

We investigated whether polyphenolic extracts from black tea, green tea or red wine affect azoxymethane (AOM)induced intestinal carcinogenesis. Male F 344 rats were treated 10 times (1 week apart) with AOM (7.4 mg/kg, s.c.) an d then allocated into groups receiving black tea, green tea or red wine ext racts mixed in the diet at a dose of 50 mg/kg body weight for 16 weeks. In the rats treated with black tea or wine extracts, there were significantly fewer colorectal tumours than in controls (the mean +/- SE number of tumour s/rat was 2.54 +/- 1.6 in controls, 1.54 +/- 1.4 in the black tea group, 3. 2 +/- 1.9 in the green tea group and 1.63 +/- 1.6 in the wine extract group ). Significantly fewer rats in the black tea and wine extract groups had ad enomas than in controls (86%, 59%, 90% and 50% of rats in the control, blac k tea, green tea and wine extract groups, respectively, had adenomas), The tumours from the black tea group and, to a lesser extent, those from the wi ne group, had a significantly greater apoptotic index than tumours In contr ols (mean +/- SE apoptotic index: 2.92 +/- 0.25, 4.13 +/- 0.46, 2.88 +/- 0. 30 and 3.72 +/- 0.46 in controls, black tea, green tea or wine extract grou ps, respectively). Tn contrast, the apoptotic index of the normal mucosa di d not vary among groups. These data indicate that black tea and wine extrac ts, but not green tea extracts, can protect against AOM-induced colon carci nogenesis by a mechanism probably involving increased apoptosis in tumours.