[Inhibitory effects of Chinese medicines on SOS responses in E. coli and their mechanism].

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, Codonopsis 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 Sephadex 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 occurred at 42 degrees C in E. coli GW1060 (recA441), but has no effect on SOS network gene expression in E. coli GW 1107 (lexA51), suggesting that Polygonatum radix may contain an inhibitor of RecA protease.