Key Words： periostrcum cicadae, bioactive component, antibacterial activity, extraction

Abstract：      The antimicrobial components of the traditional Chinese herbal medicine, periostrcum cicadae were extracted and their antibacterial activity examined. Four extraction methods and seven extraction solvents were used. The results show that the highest yield was produced by ultrasonic extraction with 95% ethanol. The antibacterial activity of the obtained extracts against Escherichia coli was determined using different bioassays. The bioassay results indicate that all extracts had an obvious inhibitory effect on E.coli compared to the control (P≤0.05). There was no significant difference in antimicrobial activity between different extracts. The highest antimicrobial activity was from extracts obtained by ultrasonic extraction with 95% ethanol, the minimum inhibitory concentration (MIC) of this extract on E.coli was 0.078 mg/mL.