Chemical Composition, Antibacterial and Antifungal Activities of Four Essential Oils Collected in the North-East of Tunisia

This work aimed to determine the essential oil composition and their biological activities of four local medicinal plant species (Pinus halepensis, Tetraclinis articulata, Juniperus phoenicea and Juniperus oxycedrus) widely planted in the same geographical site. Essential oil isolation was isolated using hydrodistillation and the chemical composition was based on GC/MS analysis. The antibacterial and antifungal activities of essential oils were assessed against 8 pathogenic bacteria and 4 yeast, and 3 different tests were used. GC/MS results showed that essential oil chemical composition is highly affected by plant species (P<0.001). GC/MS identification revealed that beta-phellandrene (21.8%), beta-caryophyllene (37.2%), alpha-pinene (24.7%) and camphor (22.4%) were identified as the major compounds of J. phoenicea, P. halepensis, J. oxycedrus and T. articulata essential oils, respectively. Interestingly, two volatile compounds: beta-pinene and p-cymen-8-ol were present in all isolated essential oils with similar concentrations: 0.8 and 0.5% of the total identified componenents. Antibacterial results suggested that essential oils were efficient in arresting the growth of most tested bacteria with different extent depending on the studied plant and bacterial strains. Interestingly, Pseudomonas aeruginosa was the most resistant bacterium and Shigella sonnei was the most sensible to tested essential oils. Indeed, the lowest and the highest inhibition diameters were recorded for latter bacterial strains, respectively. Concerning the antifungal activity, results showed interesting efficiency against tested Candida strains. The most susceptible yeast was Candida glabrata, and the most resistant strain was Candida krusei, as the inhibition zone diameter generated by tested essential oils were the lowest and were limited to 13 mm (J. oxycedrus).