茶水提取物和茶多酚抑制诱变的类型及其机制

目的 :研究茶水提取物和茶多酚的去突变特征和机制 ,鉴别茶和茶多酚去突变的量效关系和抑菌关系 ,了解去突变剂与直接诱变剂(1_NP)、间接(Trp_P_1)诱变剂的抗突变作用方式和抑制效果。 方法 :用细胞外抑制诱变试验和改进型两次活化的Ames试验方法。 结果 :茶水提取物和与其相关的儿茶素等都存在非抑菌性的去突变效果 ,其中表没食子儿茶素没食子酸酯(EGCG)和茶黄素(TF)的效果最好。抗突变试验结果表明 ,茶水提取物对Trp_P_1( +S9)有显著的抗突变性 ,与Trp_P_1的混合液在非代谢活性条件时无诱变性 ;茶水提取物对1_NP( -S9)也有抑制活性 ,但比对Trp_P_1的抑制活性低(P<0.01) ,与1_NP混合物经代谢活化后有诱变性 ,且与非代谢活化的抗突变结果呈较高的相关性(r= -0.9694)。 结论 :茶多酚能抑制间接诱变剂的前体形成 ,也有对直接诱变剂构成阻断剂的作用 ,但是在阻断具有强氧化性的诱变剂时可能形成不稳定的结合物或不安全的结构物。

ANTIMUTAGENIC TYPE AND MECHANISM OF TEA EXTRACT AND RELATED COMPONENTS

Purpose: To study the antimutagenic effect and mecha ni sm of water extract of tea and related components; to distin guish between desmutagenic dose effect relationship and bactericid al action; in order to discern their similarities or differenc es in antimutagenesis against direct mutagen(1_NP) and indirect mutagen(Trp_P_1). Methods: Desmutagenic assay and modified Ames te st with Salmonella typhimurim TA 98 were applied. Results: Both tea extract and polyphenols were desmutagenic active without b actericidal action, EGCG and TF were far better than the oth ers; Tea extract was more powerful in antimutagenicity on indi rect mutagen(Trp_P_1) +S 9 than on direct mutagen(1_NP)-S 9(P<0.01 ). The mixture of tea extract and Trp_P_1 was not mutagenize d(without S 9), but was mutagenized with S 9 pre_incubation, and the mutagenic activity was highly related to tea extract in hibiting rate against 1_NP-S 9(r=-0.969 4). Conclusion: Tea poly phenols can inhibit the formation of indirect mutagen precursors . As a suppressive agent it can also inhibit direct mutagens . Tea polyphenols can form unstable combinations or unsafe str uctures as they block some strong oxidative mutagens.