Abstract: In order to optimize extraction of ursolic acid (UA) from Ilex kudingcha C.J.Tseng and investigate its antibacterial activity.Based on the results of single-factor tests,the ratio of liquid to solid,extractiontemperatureand ethanol concentration were optimized by response surface analysis.Staphylococcus aureus,Bacillus subtilis,Clostridium sporogenes,Pseudomonas aeruginosa,Escherichia coli,Candida albicans,Aspergillus niger were used as tested bacterial strains in this experiment to explore antibacterial activity of UAfrom Ilex kudingcha C.J.Tseng and its MIC.The results demonstrated that the process of optimum extraction were the ratio of liquid to solid of 17∶1 (mL/g),ethanol concentration of 83%,extraction temperature of 83 ℃.The antibacterial experiments showed that UA had a certain inhibition on 7 strains.The MIC was as following:6.25 mg/mL to Escherichia coli and Pseudomonas aeruginosa,12.5 mg/mL to Staphylococcus aureus,Bacillus subtilis,Clostridium sporogenes,25 mg/mL to Candida albicans and Aspergillus niger.

Key words: Ilex kudingcha C.J.Tseng, response surface methodology, ursolic acid, antibacterial activity