Investigation of Composition and Antimicrobial Properties of Lavandula stoechas Essential Oil Using Disk Diffusion and Broth Microdilution

Background and Objective: Lavandula stoechas is a species of native and permanent plants in Golestan province that belongs to the family Lamiaceae. L. stoechas has been used in traditional medicine for treatment of various diseases. The aim of this study was to extract essential oil using steam distillation method from the flowers of L. stoechas collected from Jahan-nama region in the Golestan province, and evaluate its antibacterial activity. Methods: Steam distillation (Clevenger) and GC-MS system were used to separate volatile oils and identify the essential oil components, respectively. Two methods of disk diffusion and broth micro dilution were used to evaluate the antimicrobial effect of L. stoechas essential oil. Six bacterial species including Staphylococcus aureus, Bacillus sp., Enterococcus faecalis, Salmonella enteritidis, Escherichia coli and Pseudomonas aeruginosa were tested. Results: The essential oil yield was 0.28%. The main components were camphor (71.86%), 1, 8-cineole (4.08%), linalool (3.77%) and borneol (3.19%). The essential oil showed no inhibitory effect on P. aeruginosa and E. faecalis, while it had different inhibitory effects on other bacteria. S. aureus and Bacillus sp. showed the highest sensitivity with inhibition zone diameter of 32 and 29 mm, respectively. Conclusion: The results of this study showed that the essential oil of L. stoechas has high inhibitory and antimicrobial activity particularly against Gram-positive bacteria, which may be due to the presence of 71.86% camphor in its composition.