Chemical characterization and preliminary antibacterial screening of essential oils isolated from commerciay available medicinal plants in Armenia

Abstract This study investigated the chemical characterization and preliminary antibacterial activity of essential oils isolated from commercially available dried medicinal plant materials of Thymus vulgaris, Ocimum basilicum, Syzygium aromaticum, Boswellia sacra, and Cinnamomum verum available in Armenia. Essential oils were extracted by hydrodistillation, with yields ranging from 1.85 to 6.10% (v/w). A gas chromatography–flame ionization detection method was developed and validated according to ICH and FDA guidelines for the quantitative determination of selected biologically active marker compounds, including camphene, β-pinene, 3-carene, limonene, menthol, carvone, thymol, eugenol, and cinnamaldehyde. The method demonstrated excellent selectivity, linearity, and precision, confirming its suitability for the quantitative analysis of complex essential oil matrices. Preliminary antibacterial activity was evaluated using the agar disk-diffusion assay against nine clinically relevant bacterial strains, including multidrug-resistant isolates of Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae. Among the investigated samples, Boswellia sacra and Cinnamomum verum essential oils exhibited the strongest antibacterial activity, producing the largest inhibition zones and complete growth inhibition of selected bacterial strains under the experimental conditions. These findings demonstrate the value of combining validated chemical characterization with biological screening and suggest that Boswellia sacra and Cinnamomum verum essential oils are promising candidates for further antimicrobial investigation.