Chemical Composition and Antibacterial Activity of Essential Oils from L. Species against Methicillin-Resistant .

Essential oils (EOs) were obtained by hydrodistillation of various parts of (Boiss.) Boiss., Krasn. ex. Korovin, and B. Fedtsch. ex Koso-Pol., collected in the flowering/budding and fruiting stages. Eight samples of EOs isolated from and four samples from were analyzed by gas chromatography⁻mass spectrometry (GC-MS). The major constituents of EOs were α-pinene (6.9⁻47.8%), β-pinene (1.5⁻7.1%), sabinene (0.1⁻20.5%), β-phellandrene (0⁻6.5%), -verbenol (0.9⁻7.4%), eremophilene (3.1⁻12%), and 6-2,5,5,10-tetramethyl-undeca-2,6,9-trien-8-one (0⁻13.7%). The major constituents of EOs were α-pinene (0⁻46.2%), β-pinene (0⁻47.9%), sabinene (0⁻28.3%), eremophilene (0⁻10.6), β-caryophyllene (0⁻7.5%), himachalen-7-ol (0⁻28.2%), and an himachalol derivative (0⁻8.3%). Samples of EOs from , , and were evaluated for antibacterial activity against methicillin-resistant (MRSA) pulse-field gel electrophoresis type USA300 (LAC). EOs from exhibited the highest antibacterial activity compared to samples from other spp., with the most potent EOs being isolated from roots at the flowering and fruiting stages and stems at the fruiting stage (IC values of 19.1, 20.9, and 22.9 µg/mL, respectively). Although EOs demonstrated concentration-dependent inhibition of MRSA growth, analysis of the major constituents (α-pinene, β-pinene, and sabinene) showed that they had low activity, suggesting that other components were likely responsible for the observed bioactivity of the unfractionated EOs. Indeed, correlation of the GC-MS data with antibacterial activity suggested that the putative components responsible for antibacterial activity were, either individually or in combination, eremophilene and -verbenol. Overall, these results suggest that the EOs from could have potential for use as alternative remedies for the treatment of infectious diseases caused by MRSA.