Evaluation of antibacterial and antifungal activities of olive (Olea europaea) essential oil

Abstract

Context: Essential oil Olea europaea was investigated for its antibacterial and antifungal activities. Aim: To evaluate antimicrobial activity of O. europaea essential oil against infectious microbial pathogens. Settings and Design: Seeds of O. europaea were grounded by using domestic mixer and powdered material was hydro‑distilled in Clevenger apparatus continuously for 5 hrs to yield essential oil. Essential oil was analysed on Gas‑Chromatography‑Mass spectrometry (GC‑MS) from which 24 components were identified, representing total 99.98% of the oil. Extracted oil was evaluated for their antibacterial and antifungal activities. Materials and Methods: Paper disc diffusion and serial micro‑dilution assays were performed for the determination of inhibition zone diameters and minimal inhibitory concentration, respectively. Results: The O. europaea essential oil showed the diameter of inhibition zone (DIZ) ranging from 19.4 ± 0.07‑26.4 ± 0.09 mm at a concentration level of 28 μg/disc (W/V) separately in all the ten strains tested. The minimum inhibitory concentration of essential oil against bacterial strains was obtained in a range of 7.0-56.0 μg/ml while in and fungal strains it was in a range of 7.0‑28 μg/ml. Statistical analysis: All statistical calculations are expressed as mean ± SE of three replicates. Data were analyzed by one‑way Analysis of Variance (ANOVA) to locate significant variations in oil activity in various bacterial and fungal strains followed by the Duncan’s multiple range tests. Conclusions: Antibacterial and antifungal activities of O. europaea essential oil are due to the presence of certain secondary plant metabolites such as terpenoids, steroids and flavonoids, esters, and acids, which were identified in the essential oil. The oil components can be further investigated for their biological activities and study to overcome the problem of drug resistance in microbes. Key words: Antimicrobial activity, essential oil, gas-chromatography-mass spectrometry analysis, inhibition zone diameters, minimum bacterial concentration, minimum fungicidal concentration, minimum inhibitory concentration, Olea europaea