Effects of different extraction methods on composition and antibacterial activity of volatile oil from Forsythiae Fructus, Schinzonepetae Herba, and Menthae Haplocalycis Herba / 中草药

ABSTRACT

Objective To compare the chemical composition and antibacterial activity of the volatile oils from Forsythiae Fructus (FF), Schizonepetae Herba (SH), Menthae Haplocalycis Herba (MH), and their compatibility, and to explore the influence of different extraction methods on components and antibacterial activity of volatile oil. Methods GC-MS was employed to analyze the composition of the volatile oil from FF, SH, and MH extracted separately, and their mixture extracted, as well as physical mixing volatile oil of FF, SH, and MH extracted separately. The diameter of the inhibition zone and the minimum inhibitory concentration (MIC) were measured using the paper agar diffusion method and micro dilution method. The antibacterial activities of volatile oil on four common pathogens of respiratory tract were evaluated. Results When FF, SH, and MH were mixed and extracted, the main obtained components and contents of volatile oil changed. Compared to separately extracted volatile oil, eight new components emerged, seven components from FF and seven components from SH disappeared in FF and SH mixture extracted volatile oil. In FF and MH mixture extracted volatile oil, compared with separately extracted, six components from FF and eight components from MH disappeared, and eight new components emerged. As to SH and MH mixture extracted volatile oil, four components from SH and seven components from MH disappeared, and seven new components emerged. In the three herbs mixture extracted volatile oil, six components from FF, four components from SH, and two components from MH disappeared, one commom component of FF and MH, two common components of SH and MH disappeared, however, nine new components emerged. The content of pulegone significantly decreased in the three herbs mixture extracted volatile oil compared with that in separately extracted. The antibacterial experiments showed that the antibacterial effects of the volatile oils obtained by different extraction methods were different. The antibacterial effects of volatile oil extracted separately and their physical mixing volatile oil on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans were better than that from mixture extracted. Conclusion Volatile oil is an important effective component of Chinese patent medicines with relieving exterior syndrome function. Different extraction methods have a certain influence on the yield and composition of volatile oil, which ultimately affects the efficacy of drugs. Therefore, we should pay more attention to extraction method and process of volatile oil in these prescriptions.