中药对大肠杆菌SOS反应的抑制及其作用机制

Inhibitory Effects of Chinese Medicines on SOS Responses in E. coli and Their Mechanism

用SOS测试方法筛选了60种中药对大肠杆菌SOS反应的抑制作用。结果表明,11种中药可以抑制原噬菌体的诱导释放。其中黄精、党参和枸杞子的抑制作用较强。用SOS显色法进一步证实了这3种中药对SOS反应的抑制作用。这3种中药同时还可抑制羟基脲诱发的酵母细胞的基因转变。经Sephadex G-25分离,薄层层析鉴定,黄精抑制SOS反应的有效成分为分子量不大于3000道尔顿的还原糖。此成分可抑制GW1060(recA441)细胞42℃诱发的SOS反应,而对GW1107(lex A51)细胞SOS网络的基因表达没有影响,从而推断它是recA蛋白酶的抑制剂。

Sixty kinds of commonly used Chinese medicines have been examined for their ability to depress the release of Lambda phage from lysogenic strain in the inductest. 11 Chinese medicines showed an inhibitory effects. Among them, Codonopsu radix, Polygonatum radix and fractus Lycium were strong depressors. They also showed an inhibitory effect on SOS response in SOS chromotest with a dose-effect response. These medicines were also found to decrease the frequency of gene conversion in S. cerevisiae in the presence of hydroxyurea. The effective compound (s) of Polygonatum radix partially purified from the extract with Sepha-dex G-25 chromatography was a reductive carbohydrate with molecular weight less than 3,000. The compound was shown to exert an inhibitory effect on SOS response occured at 42℃ in E. coli GW1060 (recA441), but has no effect on SOS network gene expression in E. colt GW 1107 (lexA51), suggesting that Polygonatum radix may contain an inhibitor of RecA protease-