Essential oil composition, phenolic content, antioxidant, and antimicrobial activity of cultivated Satureja rechingeri Jamzad at different phenological stages

Abstract

Satureja rechingeri is a rare endemic and endangered species found in Iran. Its propagation, variations in essential oil and phenolic content, as well as antioxidant and antimicrobial activities at different phenological stages are reported in this study. The chemical composition of essential oils obtained by hydro-distillation from the aerial parts were determined by GC and GC-MS. A total of 47 compounds were identified in the essential oils of S. rechingeri at different phenological stages. The major components of all oils were carvacrol (83.6%-90.4%), p-cymene (0.8%-2.9%) and γ-terpinene (0.6%-2.4%). The total phenolic content and the antioxidant activity of methanolic extracts were determined with the Folin-Ciocalteau reagent and by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing antioxidant power (FRAP) assay, respectively. Total phenols varied from 35.5 to 37.5 mg gallic acid equivalents/g dry weight (dw), and IC50 values in the radical scavenging assay ranged from 46.2 to 50.2 mg/mL, while those in the FRAP assay were between 49.6 and 52.5 μM quercetin equivalents/g dw. By the disc diffusion method and by determination of the minimum inhibitory concentrations (MIC), the essentials oils of the various phenological stages were found to have high activities against four medically important pathogens.