The effects of Chinese tea on the methylation of DNA by the esophageal carcinogen N-nitrosomethylbenzylamine.
In order to investigate the mechanisms of the anticarcinogenic effect of Chinese tea on the development of esophageal tumors in rats induced by N-nitrosomethylbenzylamine, the alkylation of DNA in various organs was studied in rats treated with 2 varieties of Chinese tea, i.e. Fujian Oolong tea and Jasmine tea. Male Wistar rats were given a single i.v. injection of N-nitroso-[methyl-14C]-benzylamine (2.5 mg/kg body wt) after having been provided tea in drinking water and by gavage for 2-3 weeks. Control rats were provided with tap water. Three to four hours after administration of the N-nitroso compound, the methylation of purine bases in the DNA isolated from various organs was measured by high performance liquid chromatography and liquid scintillation counting. In the tea-drinking rats, there was an appreciable reduction of O6-methylguanine formation in the esophageal DNA as well as the ratio of O6-methylguanine to N7-methylguanine, as compared to the control rats. No O6-methylguanine was detected in lung or liver DNA.[1]References
- The effects of Chinese tea on the methylation of DNA by the esophageal carcinogen N-nitrosomethylbenzylamine. Zhu, J.Q., Xiao, Y., Liu, Z.Q., Chen, J.S., Guo, Z.L. Biomed. Environ. Sci. (1991) [Pubmed]
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