ANTIBACTERIAL ACTIVITY OF ESSENTIAL OILS FROM Myrtus communis L. ORGANS (LEAVES, BERRIES, FLOWERS AND BUDS) HARVESTED AT THREE DEVELOPMENT STAGES.

The seasonal variability of yield, chemical composition and antibacterial activity of Myrtus communis L. essential oils was investigated. The essential oils were extracted by hydro-distillation technique from leaves, berries, flowers and floral buds collected at three stages of development from northeast Algeria. The essential oil yield values ranged from 0.09 to 0.94 % (w/w). They depend significantly on the phenological stage and the plant part used for the extraction of essential oils. Myrtle leaf is the valuable organ for the essential oil production with a yield varied from 0.44 to 0.94 % (w/w); the highest yield was obtained at the flowering stage. The GC-MS analysis indicated that all essential oils of myrtle were dominated by monoterpenes, a-pinene (37.16-49.39 %) and 1,8-cineole (25.87-49.11 %), which were the main compounds found in essential oils at each harvest period. The antibacterial activity was evaluated using the disk-diffusion method against Escherichia coli, Extended-Spectrum-ß-Lactamase, Carbapenem-Sensitive Klebsiella pneumoniae, Staphylococcus aureus, Enterococcus faecalis, and Salmonella spp. The essential oil of Myrtle berries and leaves extracted before flowering stage showed the best inhibitory effect against all tested bacterial strains, with inhibition zones diameter ranging from 11.24-26.52 mm and 12.84-29.84 mm, respectively. Myrtus communis L. essential oils displayed however a variable degree of antimicrobial activity with an absolute action against Klebsiella pneumonia. [ABSTRACT FROM AUTHOR]