| Abstract
| - The methanol extract from Uncaria sinensis showed a suppressive effect on umu gene expressionof the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 3-amino-1,4-dimethyl-5H-pyrido[4,3b]indole (Trp-P-1), which requires liver metabolizing enzymes. The methanolextract from U. sinensis was re-extracted with hexane, CH2Cl2, BuOH, and water, respectively. CH2Cl2 extract showed a suppressive effect. A suppressive compound 1 in CH2Cl2 extract was isolatedby SiO2 column chromatography. Compound 1 was identified as ursolic acid by IR, electron ionizationEI-MS, and NMR spectroscopy. Suppressive effects of ursolic acid (1) and its derivatives, methylursolate (1M), acetylursolic acid (1A), and methyl acetylursolate (1MA), were determined in the umutest. These compounds suppressed 61.3, 37.7, 71.5, and 37.8% of the Trp-P-1-induced SOS responseat a concentration of 0.4 μmol/mL, respectively. The ID50 values of compounds 1 and 1A were 0.17and 0.20 μmol/mL. In addition, these compounds were assayed with the activated Trp-P-1.Suppressive effects on activated Trp-P-1 were decreased as compared with those of Trp-P-1. Keywords: Uncaria sinensis; Rubiaceae; ursolic acid; SOS response; umu test
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