Bu-Abbas A, Nunez X, Clifford M N, Walker R, Ioannides C
Molecular Toxicology Group, School of Biological Sciences, University of Surrey, Guildford, UK.
Mutagenesis. 1996 Nov;11(6):597-603. doi: 10.1093/mutage/11.6.597.
The present study was undertaken to compare the antimutagenic activity of aqueous extracts, at the concentrations used for human consumption, from green, black and decaffeinated black tea. Antimutagenic potential was evaluated against three indirect-acting dietary carcinogens, Glu-P-1, benzo(a)pyrene and nitrosopyrrolidine. All three types of tea gave rise to strong and concentration-dependent suppression of the mutagenicity of the three premutagens in the presence of an activation system. No major difference in the antimutagenic potential of the three types of tea could be discerned. Black tea, decaffeinated black tea and, to a lesser extent, green tea also antagonized the mutagenicity of the direct-acting mutagen 9-aminoacridine. All three types of tea inhibited markedly the NADPH-dependent reduction of cytochrome c and the O-dealkylations of ethoxy-, methoxy- and, to a much lesser extent, pentoxy-resorufin. When the microsomal metabolism was terminated, after the metabolic activation of the premutagens, incorporation of the aqueous tea extracts into the activation system caused a concentration-dependent suppression of mutagenic response. No significant difference in the antimutagenic activity of the three types of tea in this system was evident. Bearing in mind the much higher concentration of flavanols in green tea compared with the black teas, it may be concluded either that these compounds are unlikely to be the major tea components responsible for the antimutagenic, and possibly anticarcinogenic, properties of tea or that their fermentation products are similarly active.
本研究旨在比较绿茶、红茶和脱咖啡因红茶水提取物在人类消费所用浓度下的抗诱变活性。针对三种间接作用的膳食致癌物Glu-P-1、苯并(a)芘和亚硝基吡咯烷评估了抗诱变潜力。在有活化系统存在的情况下，所有三种茶都对这三种前诱变剂的诱变性产生了强烈且浓度依赖性的抑制作用。三种茶的抗诱变潜力没有明显差异。红茶、脱咖啡因红茶以及在较小程度上的绿茶也拮抗了直接作用诱变剂9-氨基吖啶的诱变性。所有三种茶都显著抑制了细胞色素c的NADPH依赖性还原以及乙氧基、甲氧基和在更小程度上的戊氧基试卤灵的O-脱烷基作用。在前诱变剂代谢活化后，当微粒体代谢终止时，将茶水提取物加入活化系统会导致诱变性反应的浓度依赖性抑制。在该系统中，三种茶的抗诱变活性没有明显差异。鉴于绿茶中黄烷醇的浓度比红茶高得多，因此可以得出结论，要么这些化合物不太可能是茶叶中负责抗诱变以及可能抗癌特性的主要成分，要么它们的发酵产物具有类似的活性。
