Inhibition of Cell Proliferation and Induction of Apoptosis During Azoxymethane Induced Colon Carcinogenesis by Black Tea

Tea (Camellia sinensis) is one of the most popular beverages, consumed worldwide. The health promotingproperties of tea have been attributed to its antioxidative polyphenolic constituents and their oxidative products.The aim of the present study was to evaluate the chemopreventive efficacy of a black tea infusion on azoxymethaneinduced colonic preneoplastic lesions, the aberrant crypt foci in Sprague-Dawley rats. Rats were injected withazoxymethane (15mg/kg.b.w.) and received oral administration of 1% and 2% (w/v) tea infusions from the 1st day ofcarcinogen application. The treatment was continued for 12 weeks. The colons were then assessed for aberrant cryptfoci and compared with the untreated carcinogen control group. In situ cell proliferation and in situ apoptosis werealso estimated using Brdu incorporation and the TUNEL method, respectively. Aberrant crypt foci were reducedsignificantly (by 44% in the 1% tea-treated and by about 40% in 2% tea-treated group). Significant decrease inproliferation and increase in apoptosis suggest a possible interplay between the two processes resulting in inhibitionof colon carcinogenesis by black tea.