Preliminary Evaluation of the Synergistic Antibacterial Effects of Selected Commercial Essential Oil Compounds...

Background/Objectives: Growing antibiotic resistance is one of the most significant problems of current medicine. Various research efforts are focused on the search for new substances and their combinations as potential solutions to this problem. Essential oil compounds (EOCs) are considered promising candidates in this regard. However, the interactions between these natural compounds remain understudied. This study conducted a preliminary evaluation of the antimicrobial action of various commercial EOCs (1,8-cineole, eugenol, linalyl acetate, (-)-α-pinene, limonene, α-terpineol, DL-menthol, geraniol, farnesol, carvacrol, and myrcene) alone and in combination (n = 56) against methicillin-resistant Staphylococcus aureus strain (ATCC 43300). Methods: The following parameters were studied: antibacterial activity of EOCs alone and in combination using microdilution and checkerboard assays. Results: After the initial screening, geraniol, farnesol, linalyl acetate, carvacrol, (-)-α-pinene, α-terpineol, 1,8-cineole, and eugenol exhibited antibacterial activity against the tested strain and were, therefore, selected for further evaluation in the checkerboard assay. The checkerboard assay revealed 10 synergistic interactions, with farnesol demonstrating the highest number of synergistic combinations among the tested compounds. The results highlighted its high synergistic potential in combination with eugenol, linalyl acetate, (-)-α-pinene, α-terpineol, geraniol, and carvacrol. Conclusions: In conclusion, the results help elucidate the different interactions between EOCs and may be helpful in further applications of natural compounds as antimicrobial agents in wound dressings. Overall, the most promising compound was found to be farnesol.