Effect of melatonin on the induction of foci of aberrant crypts in the colon by azoxymethane in rats

<p><b>OBJECTIVE</b>A program of research was established on the question whether melatonin played a chemopreventive role in the development of foci of aberrant crypts in the intestinal tract of male rats. Male F344 rats were injected i.p. with an aqueous solution of 15 mg/kg azoxymethane (AOM) on day 50 and day 57, and a group was also injected i.p with 0.5 mg melatonin in 0.5 ml of 10% ethanol solution 5 times per week beginning at age 47 days. Foci and multiplicity of aberrant crypts were determined after 8 weeks. These groups of animals were kept in light daily from 4∶30 to 16∶30.</p><p><b>RESULTS</b>In the group receiving AOM and the melatonin injections, there were fewer foci of aberrant crypts in the colon and the average number of crypts was lower after 8 weeks, compared to the group on AOM alone.</p><p><b>CONCLUSIONS</b>Melatonin inhibited the formation of foci of aberrant crypts in the descending colon of rats. Also, it reduced the number of aberrant crypts per focus from foci with 3 and more aberrant crypts.</p>

Prevention of coronary heart disease and cancer by tea, a review

Biomedical research has uncovered the mechanisms whereby tea promotes good health and lowers the risk of major chronic diseases, such as heart disease and many types of cancer. The active components in tea are polyphenols, epigallocatechin gallate in green tea, theaflavins and thearubigins in black tea. Green and black tea and the polyphenols have similar beneficial effects. The mechanisms are categorized into 5 groups. 1) Tea polyphenols are powerful antioxidants. They decrease the oxidation of LDL cholesterol and lower the risk of heart disease, and also inhibit action of reactive oxygen species mediating the oxidation of DNA associated with carcinogenesis 2) Tea polyphenols induce detoxifying enzymes, glucuronosyl transferases, eliminating active forms of carcinogens and other toxicants, accounting for the lower cancer risk. 3) Tea polyphenols lower duplication rates of cancer cells and inhibit the growth of cancer, increase apoptosis and lower angiogenesis. 4) Tea polyphenols alter the intestinal bacterial flora, suppressing undesirable bacteria and favoring growth of beneficial bacteria. 5) Aging phenomena, and diseases associated with the formation of reactive oxygen species (ROS) are inhibited.