Abstract
BackgroundThe chemical composition and biological activity of Eucalyptus essential oils have been studied extensively (EOs). A few of them were tested for antibacterial effectiveness against otitis strains. The chemical composition and antibacterial activity of the EOs of eight Tunisian Eucalyptus species were assessed in the present study.MethodsHydrodistillation was used to extract EOs from the dried leaves of eight Eucalyptus species: Eucalyptus accedens, Eucalyptus punctata, Eucalyptus robusta, Eucalyptus bosistoana, Eucalyptus cladocalyx, Eucalyptus lesouefii, Eucalyptus melliodora and Eucalyptus wandoo. They are assessed by GC/MS and GC/FID and evaluated for antibacterial activity using agar diffusion and broth microdilution techniques against three bacterial isolates (Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae) and three reference bacteria strains (Pseudomonas aeruginosa, ATTC 9027; Staphylococcus aureus, ATCC 6538; and Escherichia coli, ATCC 8739). Furthermore, the selected twenty-one major compounds and all values of the inhibition zone diameters were subjected to further statistical analysis using PCA and HCA.ResultsThe EO yields of the studied Eucalyptus species range from 1.4 ± 0.4% to 5.2 ± 0.3%. Among all the species studied, E. lesouefii had the greatest mean percentage of EOs. The identification of 128 components by GC (RI) and GC/MS allowed for 93.6% – 97.7% of the total oil to be identified. 1,8-cineole was the most abundant component found, followed by α-pinene, p-cymene, and globulol. The chemical components of the eight EOs, extracted from the leaves of Eucalyptus species, were clustered into seven groups using PCA and HCA analyses, with each group forming a chemotype. The PCA and HCA analyses of antibacterial activity, on the other hand, identified five groups.ConclusionThe oils of E. melliodora, E. bosistoana, and E. robusta show promise as antibiotic alternatives in the treatment of otitis media.
Highlights
The chemical composition and biological activity of Eucalyptus essential oils have been studied extensively (EOs)
EOs derived from numerous Eucalyptus species have been shown to have antibacterial, antiviral, antioxidant, anti-inflammatory, and antiasthmatic activities [28,29,30], Few studies have explored the antibacterial activities of EOs against otitis pathogens
The aim of the present study is to determine the variability of the yield, the chemical composition, and the antibacterial activities of EOs extracted from leaves of 8 Eucalyptus species
Summary
The chemical composition and biological activity of Eucalyptus essential oils have been studied extensively (EOs). The chemical composition and antibacterial activity of the EOs of eight Tunisian Eucalyptus species were assessed in the present study. A variety of respiratory diseases have been associated with these bacterial strains, including acute otitis media (AOM), sinusitis, asthma, and pneumonia [17,18,19,20,21]. Several of these bacterial strains, including P. aeruginosa and S. aureus, as well as K. pneumoniae and other microorganisms, are responsible for otitis externa [22]. The aim of the present study is to determine the variability of the yield, the chemical composition, and the antibacterial activities of EOs extracted from leaves of 8 Eucalyptus species. The antibacterial properties of microbial strains responsible for otitis are of special interest
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