Essential oils of four Phlomis species growing in Iran: chemical composition, antimicrobial and antifungal activity

Abstract

The essential oils of four Phlomis species (Phlomis olivieri, Phlomis bruguieri, Phlomis rigida and Phlomis kurdica), collected from kordestan province of Iran during the flowering stage, were hydrodistillated and analyzed by gas chromatography/mass spectrometry (GC/MS). Totally, 20 compounds in the oil of P. olivieri (representing 86.3%), 17 compounds in the oil of P. bruguieri (representing 80.5%), 17 compounds in the oil of P. rigida (representing 93.6%) and 26 compounds in the oil of P. kurdica (representing 92.1%) were identified. The major components of all examined oils were germacrene D, trans-caryophyllene and caryophyllene oxide except for P. rigida which was rich in tetradecanoic acid (29.6%). The antimicrobial activities of the oils were tested against a gram-positive, two gram-negative bacteria and a pathogenic fungus. The essential oils of P. kurdica and P. oliveri showed moderate antifungal activity (MICs: 20 and 25 mg/ml, respectively) against C. albicans. The essential oil of P. rigida was found to be the most active oil against Staphylococcus aureus and Candida albicans comparing to other oils (MICs: 6 and 3 mg/ml, respectively) that possibly attributed to the high amount of tetradecanoic acid.