Effects of tea and chlorophyllin on the mutagenicity of N-hydroxy-IQ: Studies of enzyme inhibition, molecular complex formation, and degradation/scavenging of the active metabolites
✍ Scribed by Judith Hernaez; Meirong Xu; Roderick Dashwood
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 89 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0893-6692
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✦ Synopsis
Green tea and black tea inhibit the formation of and several tea constituents was detected in spectrocarcinogen-DNA adducts and colonic aberrant photometric studies, but the binding constants were crypts in rats given 2-amino-3-methylimidazo[4, only on the order of 1 1 10 3 M 01 , suggesting that 5-f]quinoline (IQ), a mutagen from cooked meat. mechanisms other than complex formation might The Salmonella mutagenicity assay was used in the prevail under the conditions of the Salmonella present study to test individual constituents of tea as assay. Comparison of the results in two different inhibitors of 2-hydroxyamino-3-methylimidazo[4, strains of Salmonella typhimurium, TA98 and 5-f]quinoline (N-hydroxy-IQ), a direct-acting metabo-TA98/1,8-DNP 6 , indicated that the antimutagenic lite of IQ. Testing of pure compounds at doses rele-activity of EGCG was dependent, at least in part, vant to their levels in tea identified epigallocatechin on a functional O-acetyltransferase activity in the (EGC) and epigallocatechin-3-gallate (EGCG) as bacteria. These studies suggest that tea constituents the primary antimutagens. Studies of the inhibitory inhibit the enzyme(s) which generate the aryl nimechanisms established that the rate of degrada-trenium ion and directly scavenge the reactive election of N-hydroxy-IQ under aqueous conditions was trophile, whereas CHL complexes with heterocyclic not increased significantly in the presence of tea, in amines and facilitates the degradation of active mecontrast to the results obtained with the complexing tabolites.