Abstract: OBJECTIVE: To evaluate the anti-infectious efficacy of essential oil extracted from Caoguo(Fructus Tsaoko).METHODS: Minimum inhibitory concentrations(MICs) against clinical isolates of three extracts andthe essential oil from Caoguo(Fructus Tsaoko) were determined by the agar dilution method. The anti-infectious efficacy of the essential oil was evaluated using a mouse peritonitis model which was infected with Staphylococcus aureus or Escherichia coli. The chemical components of the essential oil were identified.RESULTS: The results showed that the essential oil exhibited strong antibacterial activity in vitro, with MICs ranging from 22.49 to 1438.91 μg/m L. The results of in vivo anti-infectious efficacy showed that the Caoguo(Fructus Tsaoko) essential oil can protect the mice from Staphylococcus aureus or Escherichia coli infection. The compositions of the essential oil and relative component percentages were examined. A total of 32 compounds, were identified. The major compounds of essential oil were 1,8-cineole(25.92%) and geraniol(13.69%).CONCLUSION: Our findings suggest that Caoguo(Fructus Tsaoko) essential oil has broad-spectrum antibacterial properties. It warrants further investigation as an antibacterial agent targeting some bacterium with multi-drug resistance.

Key words: Amomum tsaoko, Oils,volatile, Anti-bacterial agents, Chemistry