A Study on Essential Oil Chemical Compositions, Antioxidant, and Antimicrobial Activities of Native and Endemic Satureja Species Growing in Iran

In this study, chemical compositions of the essential oil and antioxidant activities of four Satureja species, namely S. hortensis (SH), S. bachtiarica (SB), S. laxiflora (SL), and S. intermedia (SI) were evaluated. GC and GC/MS were employed to analyze the essential oil samples extracted via hydrodistillation. DPPH and FRAP assays were used to evaluate the radical scavenging and antioxidant properties as well as antimicrobial activities. The GC and GC/MS analysis revealed and identified a total of 25 compounds. The most abundant chemical constituents were rho-cymene (13.07 - 17.50%) in all four species, gamma-terpinene in SL, SH, and SI (11.35 - 37.60%), thymol in SL, SB, and SI (24.54 - 38.75%), and carvacrol in SB and SH (32.07 - 42.51%). The FRAP assay showed that none of the methanol and dichloromethane extracts possessed significant antioxidant activity as compared to quercetin. In addition, the radical scavenging activity of SB and SI methanol extracts were higher than that of SL and SH (DPPH assay). However, all extracts did not show potent radical scavenging activities. It should be noted that this study was the first to evaluate the possible antioxidant or radical scavenging properties of SI and SL. The antimicrobial assay demonstrated a potent activity of all samples against Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus fumigatus, and Epidermophyton floccosum (minimum inhibitory concentrations, MIC = 0.06 - 8 mu g/mL). Due to rich content of thymol and carvacrol isomers in Satureja species, they can be suggested for use in various pharmacological applications.