GC-MS Analysis of the Compositions and Antimicrobial Activities of Essential Oils From Five Species of Lamiaceae in Iran

Essential oils (EOs) separated from Lamiaceae species attract more attention due to their abundant use in the preservation of natural foods and pharmaceutics and have gained considerable interester in research and industrial. The aim of this study was to evaluate composition and antimicrobial activity of EOs obtained from five species Lamiaceae in Iran. After extraction of EOs by Clevenger, their composition was evaluated by gas chromatography-mass spectrometry (GC–MS). Antimicrobial properties were assayed by measuring inhibition zones, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results showed that the effects of species, on yield and predominant compounds amount of EOs of five species were significant with a probability of error of 1 %. The yield of oils were varied from ~ 0.02 to ~ 1.88%. About 66 components were identified by gas chromatography-mass spectrometry (GC-MS), and the dominant compounds were included thymol (67.71%), oleic acid (0.49–62.09%), (-)-caryophyllene oxide (0.41–24.81%), α-pinene (1.09–19.41%), 1,8-cineole (0.22–15.40%), palmitic acid (0.32–13.28%), (+)spathulenol (11.16%), and germacrene D (0.30-10.26%) in different species. The results of analysis of variance showed that there was a significant difference between the mean of the inhibition zone obtained treating the different microorganisms with the essential oil of five species (P ≤ 0.01). The highest inhibition zone belonged to TDEO (39.33 ± 0.58 and 25.00 ± 0.00 mm) against Gram-positive S. aureus and A. brasiliensis. The Gram-negative P. aeruginosa showed the lowest inhibitory resistance to HIEO, SIEO, and ROEO (with a MIC value of 31.25 µg/mL), which was very significant compared to rifampin. Therefore, EOs of five species have potential applications in the control of various bacteria and fungi and can be a natural alternative to some antibiotics.