Identification of chemical composition, antioxidant and antimicrobial activities of summer savory (Satureja hortensis L.) essential oil

Summer savory (Satureja hortensis L.) is an aromatic plant, belonging to Lamiaceae family. The essential oil of this plant is used in medicinal and food industries. The essential oil of summer savory has antioxidant, anti-inflammatory and analgesic properties. The main objective of this study was to identify the chemical composition of aerial parts and evaluate the antioxidant and antimicrobial activities of summer savory essential oil against a few microorganisms including gram positive, gram negative bacteria, filamentous fungi and yeast.

In this experimental study, shoot essential oil was extracted by hydro-distillation technique using clevenger apparatus. The oil was analyzed by capillary GC and GC/MS. Antioxidant activity of essential oil was assessed by diphenyl picrylhydrazyl radical-scavenging activity and compared with synthetic antioxidant Butylated Hydroxyl Toluene (BHT). Antimicrobial properties of the plant essential oil were determined using micro broth dilution and well disk diffusion methods.

The major components of essential oil were carvacrol (42.10%), thymol (19.74%) and P-cymene (8.19%), respectively. The half maximal inhibitory concentration (IC50) of summer savory essential oil was 10.63±0.15 μg/ml, while this parameter for BHT 9.45±0.09 μg/ml. Bioassay of essential oil showed that summer savory had strong antimicrobial effects. So that, aerial part essential oil showed the best antifungal activity and this effect is more than the antibacterial activity. The mean diameter of inhibitory growth zone in well disk diffusion method at 15 µl concentration was equal to 31.05±0.57 mm in the case of gram positive bacteria, 21.68±0.40 mm for gram negative ones and 42.76±0.33 mm in the case of filamentous fungi and yeast. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of summer savory essential oil ranged from 0.5 to 16 µl/ml in the case of all microorganisms.

It can be stated that summer savory essential oil on all of yeast and filamentous fungi, gram positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) and gram negative bacteria (Shigella flexneri, Serratia marcescens, Escherichia coli and Klebsiella pneumonia) showed more antimicrobial activity than amphotericin B, vancomycin and gentamicin, respectively. Although more research is needed in this field, summer savory essential oil can be used as a new antimicrobial agent in the pharmaceutical and food industries.