Chemical Profiling and Evaluation of Antioxidant and Anti-Microbial Properties of Selected Commercial Essential Oils: A Comparative Study

Background: The last decades have seen an increased awareness by the scientific community of the extent of resistance to conventional antibiotics, particularly with respect to the emerging multidrug-resistant pathogenic microbes. Additionally, natural antioxidants have received significant attention among food professionals and consumers because of their assumed safety and potential therapeutic value. The aim of this work was to assess the antioxidant activities of eight selected commercial essential oils (EOs), together with the evaluation of their antibacterial and anti-quorum sensing properties. Methods: The chemical profiling of the EOs was performed using gas chromatography-mass spectrometry (GC-MS) analysis. The antioxidant properties of the EOs were evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and by β-carotene bleaching test. Disc diffusion assays were employed to evaluate the anti-bacterial and anti-quorum sensing activities of the EOs. Results: It was observed that EOs from three Eucalyptus species are rich in eucalyptol. Generally, linalool is abundant in EOs from four Lavandula species. The oil of Cymbopogon citratus is the one with the best capacity to scavenge the DPPH free radicals and presented great antibacterial activity. Conclusions: The geographical origins of the plant species are determinant factors in the EO composition and in the corresponding biological activities.