Comparison of Antibacterial Activity and Chemical Composition of Essential Oil Extracted from Mentha piperita L. Herb by Microwave and Hydrodistillation Methods

Belonging to the family of Lamiaceae, peppermint (scientifically called as Mentha Piperita L.) is a therapeutic and aromatic herb where the extract has various applications in food, cosmetic, hygienic and pharmaceutical industries. In the present paper, the essential oil of Mentha piperita L. is prepared by SFME method and its chemical and antimicrobial activities have been studied. The essential oil of dry plant was extracted, by hydrodistillation and microwave methods without using a chemical solvent. The chemical composition of the extracts were identified by GC/MS and compared against each other. The antimicrobial activity of each extract was tested on E. coli (PTCC 1330), Bacillus subtilis (PTCC 1254) and Salmonella typhinurium (PTCC 1622). For each essential oil the level of the minimum inhibitory concentration (MIC) was specified. The essential oil of Mentha piperita L. prepared by HD method contained 31 ingredients and the fraction prepared by SFME method contained 33 ingredients successfully identified. The results showed that MIC of both essential oils for the above microorganisms was 1000 ppm. Considering the results of the present research, it might be concluded that SFME method has some advantages namely reduction of extraction time, increase of extraction yield, decrease of energy and water consumption and production of higher percentage of active ingredients.