Mazaki Masanori, Kataoka Keiko, Kinouchi Takemi, Vinitketkumnuen Usanee, Yamada Masami, Nohmi Takehiko, Kuwahara Tomomi, Akimoto Shigeru, Ohnishi Yoshinari
Department of Molecular Bacteriology, Institute of Health Biosciences, The University of Tokushima Graduate School, Japan.
J Med Invest. 2006 Feb;53(1-2):123-33. doi: 10.2152/jmi.53.123.
To elucidate the mechanism of antimutagenicity of caraway, we examined the effects of caraway seed extract on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced mutagenesis in DNA methyltransferase-deficient Salmonella typhimurium strains, O6-methylguanine DNA adduct formation, and thiol content in S. typhimurium cells. MNNG was highly mutagenic for ogt- strains YG7104 (ogt- ada+) and YG7108 (ogt- ada-), and it showed slightly higher mutagenicity in strain YG7100 (ogt+ ada-) than in strains TA100 and TA1535. Hot water extract of caraway seeds inhibited MNNG-induced mutation only in the ogt+ strains. In the presence of caraway extract, O6-methylguanine DNA adducts in strain YG7100 were decreased in proportion to the decrease of MNNG-induced mutagenesis. Although MNNG is known to degrade in the presence of thiols to produce methyl cation which can react with DNA, caraway had no effect on cellular concentrations of acid-soluble thiols. These results indicate that caraway does not directly inactivate MNNG and that Ogt-O6-methylguanine-DNA methyltransferase may be involved in the antimutagenic activity of caraway.
为阐明香菜抗诱变的机制，我们研究了香菜籽提取物对DNA甲基转移酶缺陷型鼠伤寒沙门氏菌菌株中N-甲基-N'-硝基-N-亚硝基胍（MNNG）诱导的诱变作用、O6-甲基鸟嘌呤DNA加合物的形成以及鼠伤寒沙门氏菌细胞中的巯基含量。MNNG对ogt-菌株YG7104（ogt- ada+）和YG7108（ogt- ada-）具有高度诱变作用，并且在菌株YG7100（ogt+ ada-）中显示出比在菌株TA100和TA1535中略高的诱变活性。香菜籽热水提取物仅在ogt+菌株中抑制MNNG诱导的突变。在存在香菜提取物的情况下，菌株YG7100中的O6-甲基鸟嘌呤DNA加合物随着MNNG诱导的诱变作用降低而相应减少。虽然已知MNNG在巯基存在下会降解产生可与DNA反应的甲基阳离子，但香菜对酸溶性巯基的细胞浓度没有影响。这些结果表明，香菜不会直接使MNNG失活，并且Ogt-O6-甲基鸟嘌呤-DNA甲基转移酶可能参与了香菜的抗诱变活性。
