Biological activities of thymus serpyllum and pinus nigra essential oil combinations

In this study, phytochemical analysis of commercial Thymus serpyllum and Pinus nigra essential oils and the biological activities of their combinations were investigated. GC-GC/MS analyzes were carried out to reveal the chemical profiles of essential oils. The main components of T. serpyllum essential oil were found as geraniol (19.3%) and p-cymene (12.9%), the main components of P. nigra essential oil were found as α-pinene (73.8%) and trans-verbenol (4.4%). Then, in vitro antimicrobial activities of T. serpyllum and P. nigra essential oils and the activities of their combinations were examined. Studies Bacillus cereus NRRLB-3711, Bacillus subtilis NRRLB-4378, Enterococcus faecalis ATCC 29212, Escherichia coli NRLLB-3008, Klebsiella pneumoniae ATCC 4352, Moraxella catarrhalis ATCC 23245, Salmonella typhimurium ATCC 13311, Staphylococcus aureus ATCC 6538, Staphylococcus aureus ATCC BAA44, Staphylococcus epidermidis ATCC 12228, Streptococcus mitis NCIMB 13770, Streptococcus mutans ATCC 2512 microorganisms and MIC values were determined in the range of 250-1000 μg/mL. T. serpyllum and P. nigra essential oils were evaluated with each other and the combinations of each essential oil with ciprofloxacin, amoxicillin and tetracycline were evaluated by the checkerboard method. It was determined that T. serpyllum-P. nigra combination against Enterococcus faecalis (FICI:0.1875) and Staphylococcus epidermidis (FICI:0.375) combinations showed a synergistic effect. The combination of P. nigra and amoxicillin showed a synergistic effect against the Streptococcus mitis (FICI:0.187) strain. In addition, the activities of geraniol and α- pinene combinations, which were identified as the main components of the two essential oils, were evaluated, and independent effects were observed against all microorganisms used in the study. The cytotoxicity of concentrations that have a synergistic effect in essential oil and antibiotic combinations was examined by the MTT method on the HEK93 cell line and it was determined with no toxicity. As a result of all biological activity studies, it was revealed for the first time within the scope of this thesis that T. serpyllum-P. nigra and P. nigra-Amoxicillin combinations could be considered as potential antimicrobial agents at low concentrations.