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Fractionation of green tea extracts: correlation of antimutagenic effect with flavanol content
Author(s) -
BuAbbas Ali,
Copeland Emma,
Clifford Michael N,
Walker Ron,
Ioannides Costas
Publication year - 1997
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/(sici)1097-0010(199712)75:4<453::aid-jsfa897>3.0.co;2-3
Subject(s) - chemistry , epigallocatechin gallate , gallic acid , ames test , polyphenol , epicatechin gallate , antimutagen , food science , green tea , fractionation , catechin , antioxidant , biochemistry , mutagen , chromatography , dna , bacteria , biology , salmonella , genetics
Abstract The present study was undertaken to evaluate the role of individual flavanols in the antimutagenic potential of green tea. Aqueous extracts of green tea were fractionated into four fractions, each of which was fully defined with respect to its content of (‐)‐epigallocatechin gallate, (‐)‐epicatechin gallate, (‐)‐epigallocatechin, (‐)‐epicatechin and gallic acid. The ability of each fraction to antagonize the mutagenicity of four model mutagens, namely N ‐nitrosopyrrolidine, benzo( a )pyrene, 2‐aminoanthracene and Glu‐P‐1 (2‐amino‐6‐methyldipyrido[1,2‐ a : 3,2‐ d ]imidazole), was investigated in the Ames test. No correlation could be established between any of the flavanols and antimutagenic potential. Similarly, no correlation was evident between the flavanol content of each fraction and its ability to inhibit CYP1A, as exemplified by the O ‐dealkylations of methoxy‐ and ethoxy‐resorufin. Furthermore, no relationship could be established between CYP2B activity, as exemplified by the O ‐depentylation of pentoxyresorufin and the antimutagenic potential of green tea. Using a modified Ames test procedure, the ability of each tea fraction to scavenge the metabolically generated reactive intermediates of the model mutagens was investigated, this being an additional mechanism of the antimutagenic potential of green tea. Generally, fractions with high flavanol content were more effective scavengers. It is concluded that the contribution of flavanols to the antimutagenic activity of green tea is, at best, limited. ©1997 SCI