CHEMICAL PROFILING AND ANTIBACTERIAL EFFICACY OF LAVANDULA PINNATA L. ESSENTIAL OIL WITH CONVENTIONAL ANTIBIOTICS: SYNERGISTIC INTERACTIONS

The study evaluates the phytochemical composition of Lavandula pinnata essential oil (LPEO) and its interactions with three common antibiotics against various bacterial strains. The strains include Gram-negative species (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and Gram-positive species (Staphylococcus aureus, Micrococcus luteus, Bacillus subtilis). The study aims to find innovative solutions in the field of antimicrobial agents, by combining LPEO with antibiotics to optimize their efficacy. LPEO was extracted by hydrodistillation, followed by qualitative and semi-quantitative GC-MS analysis. The modified medium dilution method was used to determine the minimum inhibitory concentrations (MICs) of LPEO and the antibiotics, with interaction analysis using the fractional inhibitory concentration index (FICI). The results show that LPEO, composed of 24 main compounds including beta-linalol, eucalyptol, camphor and borneol, has MICs of 100 to 1000 µg/mL, with variable sensitivity depending on the strain. Synergistic effects were observed between LPEO and ampicillin on three strains, and partially synergistic effects with amoxicillin and erythromycin. No antagonistic effects were observed. Combinations of LPEO and antibiotics could be effective antimicrobial agents against certain bacterial strains. This promising approach merits further investigation to improve antibacterial therapies and explore potential therapeutic applications.