Phytochemical composition of the essential oil, total phenolic content, antioxidant and antimicrobial activity in Iranian Satureja sahendica Bornm. at different ontogenesis conditions

Abstract

The effects of different ontogenesis conditions (pre-flowering, full-flowering and post flowering) on the yield, essential oil composition, total phenolic content, antioxidant and antimicrobial activity of Satureja sahendica Bornm. was investigated. The essential oil was obtained from the aerial parts of the plant by hydro distillation and analyzed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). In total, 33 components were identified in the essential oil of S. sahendica under different harvesting times, that represented 98.54 to 98.72% of the oils. The major components were thymol (28.76 to 42.24%), P-cymene (23.89 to 34.33%), γ-terpinene (13.78 to 19.37%) and myrcene (1.87 to 2.28). The highest essential oil yield was obtained in flowering stage. The highest thymol content was observed in the pre-flowering and the highest p-cymene and γ-terpinene contents as precursors of thymol and carvacrol were observed in flowering and post-flowering stages. Total phenolics and antioxidant activity of plant extracts were measured by the Folin-Ciocalteu and DPPH free radical scavenging assays, respectively. The total phenolic content under different ontogenesis conditions varied from 24.78 to 25.56 (mg gallic acid equivalent/g dw). IC50 values in the DPPH assay ranged from 7.85 to 8.34 μg/ml and the highest activity was observed in pre-flowering stage. Antimicrobial activity of the essential oil of S. sahendica was evaluated using the disc diffusion method; and minimum inhibitory concentrations (MIC) and minimum fungicidal/bactericidal concentrations (MFC/MBC) were recorded using the micro dilution method. This study confirms that the essential oil of S. sahendica possesses high antimicrobial activities in in vitro against Candida albicans and Staphylococcus aureus, two medically important pathogens. The maximum activity of S. sahendica oil was observed in the oil obtained at pre-flowering stage, against Gram-positive bacteria (S. aureus) and the yeast (C. albicans).