| Genus Mentha L. accessions are perennial or far-between annual herbage, widely spread over the temperate zones of the world. The genus Mentha L. includes about 30 species worldwide, and about 12 species in our country. Among them, Mentha haplocalyx Briq. and Mentha spicata L. are two commom and widely used species. Both of them are used in food and medicine, meanwhile, they are also use as important industrial materials.The purpose of this paper is to characterize the essential oil composi-tion and variations of M. haplocalyx and M. spicata from different areas (mainly from Sichuan province, China) and check whether there are specific chemotypes and materials in these areas, and reveal antimicrobial activity differences of essential oils with different composition, and also the antioxidant activity of mentha extracts, so as to provide reference for the future application of genus Mentha. This study used M. haplocalyx and M. spicata from different areas (mainly from Sichuan province, China) as the research materials. The composition and antimicrobial ac-tivity of the essential oils, and the antioxidant activity of extracts of M. haplocalyx and M. spicata were studied, and the main results were as follows:1. To study the essential oils components of 24 M. haplocalyx and M. spicata collected in different areas, maily from Sichuan province, China, we extracted the volatile componentts by traditional hydro-distillation, and analyzed the components by GC-MS. The results showed that the constituents and conents of volatile oils in different Mentha resources were various. Totally,37 chemical components were identified from the volatile oils of 24 Mentha accessions. Menthone, menthol, pulegone, carvone, piperitone oxide etc. were found the main components.2. Based on the percentage of the chemical components of the essen-tial oils of M. haplocalyx and M. spicata accessions,24 accessions were analyzed by cluster analysis. It was found that all the acces-sions were classified into 4 groups, namely 4 chemotypes, includ-ing menthone- menthol- pulegone, carvone, menthol, menthone. All the M.spicata accessions were chemotype carvone, the plant morphological characteristics of M25 and M26 were close to M. haplocalyx, but essential oils constituents, main components were in accordance with M. spicata, so its chemotype was carvone. The other M. haplocalyx accessions were divided into 4 different chemotypes. It was devoted to mention that the phenotype of M25 and M26 is similar to M. haplocalyx, but their chemotypes were the same as M. spicata, which belonged to chemotype carvone. Chemotype menthone was first report of M. haplocalyx collected in Sichuan province, China.3. In this study,the antimicrobial activities of essential oils of 14 Mentha L. against Staphylococcus aureus ATCC29213, Staphylo-coccus epidermidis ATCC12228, Escherichia coli ATCC25922, Candida albicans ATCC 10231 were tested by the method of disc diffusion method and micro broth dilution. The results showed that M31 had strong inhibitory effects on all tested microorganisms, and its main components were menthone, menthol and pulegone. There are some relationships between antimicrobial activities and the major constituents of essential oils, but the antimicrobial ac-tivities were not completely depend on the main chemical compo-sitions of essential oils. It suggested there were some other com-pounds in the essential oils of Mentha L., which could display a series of physiological activities and multi-ingredient might have the synergistic effects.4. The antioxidant activity of ethanol extracts of M. haplocalyx and M. spicata collected in different areas (maily from Sichuan province, China) was measured by three analytical methods:2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-di-(3-ethylbenzothialozine-sulphonic acid) (ABTS);β-carotene bleaching test.The results of DPPH·seavenging were consistent with ABTS+ scavenging. It has been shown by experi-mentation that the antioxidant activity of M21 and M26 was close to BHT. The results ofβ-carotene bleaching test were not consis-tent with the free radical scavenging activity, and the inhibitingβ-carotene bleaching activities of all the tested samples were rela-tively lower.5. Total phenols, total flavonoids of ethanol extracts of M. haplocalyx and M. spicata were determined by spectrophotometry. As ex-pected, the phenolie content of M21 and M26 was much higher than other samples.The results of correlation analysis showed that there were significant relationships between the contents of total phenols, total flavonoids and the free radical scavenging activ-ity, while the contents of total phenols, total flavonoids exhibited no correlation with the inhibitingβ-carotene bleaching activities. |
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