Objective: To study the chemical compositions and biological activity of the essential oil from the leaves of Mentha piperita

and lay foundation for further development and utilization of M. piperita. Method: The essential oil was obtained by supercritical carbon dioxide extraction assay; its chemical compositions were analyzed with gas chromatography-mass spectrometry (GC-MS) method; then their antioxidant activity and biological toxicity were evaluated by DPPH method and artemia respectively. In addition

disk-diffusion method and Artemia aegypti larval poisoning method were used to evaluate their antimicrobial activity and insecticidal activity. Result: the essential oil yield was 0.089% in the supercritical carbon dioxide extraction assay

and 11 chemical compositions were identified

accounting for 93.0% of the total essential oil amount. Linalool content accounted for 49.9% of the total essential oil amount

so it was considered as the main composition. The IC50 was 0.45 g·L-1 for DPPH

526.0 mg·L-1 for Artemia. When the concentration of essential oil was 10 g·L-1

its inhibition zone was (9±1)mm against E. Coli

but had no significant effect on Staphylococcus aureus; its LC50 was 339.6 mg·L-1 for A. aegypti. Conclusion: Essential oil from leaves of M. piperita showed certain inhibition effect on Escherichia coli.

with weak antioxidant and insecticidal activities

so it was not suitable for development as insecticides; in addition

the essential oil from the leaves of M. piperita showed weak biotoxicity

providing scientific basis for development and utilization of M. piperita in this study.