Variation in chemical composition and antibacterial activity of the essential oil of wild populations of Phlomis olivieri

Various species of the genus Phlomis have been reported to produce metabolites demonstrating significant pharmacological efficiency. In this study, the essential oils from 12 populations of Phlomis olivieri collected from natural habitats were investigated for their chemical components. The hydrodistillated essential oil analyzed by GC-FID and GC-MS. Analyses revealed 27 compounds, constituting 90.52-98.51% of the essential oils. Results indicated that the major components of the essential oils from various populations of P. olivieri were germacrene D (26.54 to 56.41%), bicyclogermacrene (6.38 to 30.55%), β-caryophyllene (5.32 to 24.52%) and α-pinene (1.29 to 15.53%). Principal component analyses (PCA) was used to identify any geographical variations in essential oil composition. Notably, three groups of Iranian P. olivieri populations were determined according to the major compounds. Results of the in vitro antibacterial activity indicated that P. olivieri essential oils showed good inhibitory activities against bacteria, especially Bacillus subtilis. The results of this study gave new insights for cultivation and industrial uses of P. olivieri in Iran.