Effect of tea extracts, polyphenols, and epigallocatechin gallate on azoxymethane-induced colon cancer
| Autor: | Douglas A. Balentine, Joel Reinhardt, Cesar Aliaga, Edith Zang, John H. Weisburger, Brian Pittman, Charles W. Boone, Vernon E. Steele, Abraham Rivenson, Gary J. Kelloff |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Male
Colorectal cancer Polymers Azoxymethane Pharmacology Epigallocatechin gallate General Biochemistry Genetics and Molecular Biology Catechin law.invention chemistry.chemical_compound Phenols law medicine Carcinoma Animals Anticarcinogenic Agents Flavonoids Tea Plant Extracts food and beverages CYP2E1 medicine.disease Small intestine Rats Inbred F344 Rats medicine.anatomical_structure Biochemistry chemistry Toxicity Colonic Neoplasms Phytotherapy |
| Zdroj: | Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.). 217(1) |
| ISSN: | 0037-9727 |
| Popis: | Studies were conducted to determine the chemopreventive efficacy of several types of tea extracts on azoxymethane-induced colon cancer in male F344 rats. After determining the maximally tolerated dosage of the tea products, their effect in a colon cancer model was investigated. Groups of 36 male F344 rats received 2 subcutaneous doses of 15 mg/kg azoxymethane (AOM) at Weeks 6 and 7. Experimental groups also received as drinking fluids 3600 ppm of black or green tea extracts, 1800 ppm of EGCG, or 1800 ppm of black or green tea polyphenols beginning at 5 weeks of age. Additional groups drank a lower dose of 360 ppm of the five tea products. The experiments were terminated 43 weeks after the first tea exposure. No evidence of toxicity was observed since the body weight gain of all groups was similar. The rats given AOM had carcinoma of the small intestine and of the colon, classified histologically as in situ carcinoma, exophytic, invasive, and Peyer's patch carcinoma. In the small intestine, most of the neoplasms were classified as invasive, but in the colon, most were exophytic. The various tea products failed to produce a significant difference in the incidence of the several types of colon and small intestine carcinoma. The multiplicity of colon cancers ranged from 1.2-2.8 in all groups. The group on 3600 ppm of green tea had a significantly higher tumor multiplicity than the control group on AOM and water. Also, the group on 3600 ppm of green tea had a significantly higher tumor multiplicity than the group on 360 ppm. The tea products did not affect the development aspects of the tumors in most groups. The mechanisms underlying these findings rest on the fact that azoxymethane is metabolized mainly by cytochrome P450 2E1, and this enzyme system is not affected by tea. |
| Databáze: | OpenAIRE |
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