Correlation Between Chemical Composition and Antibacterial Activity of Essential Oils from Fifteen Eucalyptus Species Growing in the Korbous and Jbel Abderrahman Arboreta (North East Tunisia)

The essential oils of fifteen Eucalyptus species harvested from the Jbel Abderrahman and Korbous arboreta (North East Tunisia) were screened for their antibacterial activities by the agar disc diffusion method. Eighteen major components as identified by GC/FID and GC/MS were selected for a study of the chemical and biological activity variability. The main one was 1,8-cineole, followed by spathulenol, trans-pinocarveol, α-pinene, p-cymene, globulol, cryptone, β-phellandrene, viridiflorol, borneol, limonene and isospathulenol. The chemical principal component analysis identified five species groups and subgroups, where each group constituted a chemotype, however that of the values of zone diameter of the inhibition (zdi) identified six groups of Eucalyptus oils, characterized by their antibacterial inhibition ability. The strongest activity was shown by E. platypus oil against Enterococcus faecalis and by E. lamannii oil against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. A correlation between the levels of some major components and the antibacterial activities was observed

Chemical composition of essential oils of eight Tunisian Eucalyptus species and their antibacterial activity against strains responsible for otitis

Background The 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. Methods Hydrodistillation 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. Results The 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 alpha-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. Conclusion The oils of E. melliodora, E. bosistoana, and E. robusta show promise as antibiotic alternatives in the treatment of otitis media

Chemical composition of five Tunisian Pinus Species' essential oils and effect of their blends on Otitis infection

Many studies reported the chemical composition and the biological activities of Pinus Essential oils (EOs). A few of them were investigated for their antibacterial activity against strains responsible for otitis. The present paper investigated the variation of the chemical composition and the antibacterial activity of the EOs of five Tunisian Pinus species and of their combinations against six bacterial strains responsible for otitis. The EOs' yields varied from 0.3 +/- 0.1% for P. pinea to 1.8 +/- 0.4% for P. halepensis. Their chromatographic analyses by GC and GC-MS identified 139 components varying according to the species. The main components were beta-pinene followed by trans-caryophyllene, germacrene D, alpha-pinene, beta-myrcene, palustradiene, abieta-7,13-triene, levopimaradiene, thunbergol, and caryophyllene oxide. Four chemical groups were identified basing on the PCA and the HCA of the 25major's components of the studied EOs. However, three subgroups were identified within the antibacterial-based PCA and HCA analyses. The highest antibacterial activity was observed with the blends of oils extracted from P. halepensis and P. canariensis and mixture of oils extracted from P. brutia and P. canariensis. These EOs blends may constitute promising antibiotic alternatives for the treatment of the otitis media

Variation in volatile leaf oils of five eucalyptus species harvested from Jbel Abderrahman Arboreta (Tunisia)

Hydrodistillation of the dried leaves of five species of the genus Eucalyptus L'HER., viz., E. dundasii Maiden, E. globulus LABILL., E. kitsoniana MAIDEN, E. leucoxylon F. MUELL., and E. populifolia HOOK., harvested from Jbel Abderrahman arboreta (region of Nabeul, northeast of Tunisia) in April 2006, afforded essential oils in yields varying from 0.9 +/- 0.3 to 3.8 +/- 0.6%, dependent on the species. E. globulus and E. Kitsoniana provided the highest and the lowest percentage of essential oil amongst the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 127 compounds, representing 93.8 to 98.7% of the total oil composition. The contents of the different samples varied according to the species. The main components were 1,8-cineole (2; 4.7-59.2%), followed by alpha-pinene (1; 1.9-23.6%), trans-pinocarveol (6; 3.5-21.6%), globulol (8; 4.3-12.8%), p-cymene (3; 0.5-6.7%), alpha-terpineol (1.5-4.5%), borneol (0.2-4.4%), pinocarvone (1.1-3.8%), aromadendrene (1.4-3.4%), isospathulenol (0.0-1.9%), fenchol (4; 0.1-2.5%), limonene (1.0-2.4%), epiglobulol (0.6-2.1%), viridiflorol (9; 0.8-1.8%), and spathulenol (0.1-1.6%). E. leucoxylon was the richest species in 2. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) separated the five Eucalyptus leaf essential oils into four groups, each constituting a chemotype

Variation in volatile leaf oils of seven Eucalyptus species harvested from Zerniza Arboreta (Tunisia)

Leaves of seven species of the genus Eucalyptus L'HER., viz., E. cladocalyx F. MUELL., E. citriodora Hook., E. diversicolor F. MUELL., E. fasciculosa F. MUELL., E. grandis W. Hill, E. ovata LABILL., and E. botryoides SM., were harvested from Zerniza arboreta (region of Sejnene, northwest of Tunisia) in June 2007. Of the latter species, leaves were collected from trees having two origins, Morocco and Italy. Hydrodistillation of the dried leaves provided essential oils in yields varying from 0.4 +/- 0.0 to 3.3 +/- 0.1%, according to the species. E. citriodora had the highest mean percentage of essential oil amongst the species examined, whereas the lowest one was obtained for E. botryoides originating from Morocco. Analysis by GC (RI) and GC/MS allowed the identification of 140 compounds, representing 92.5 to 99.4% of the total oil composition. The contents of the different samples varied according to the species. The main components were 1,8-cineole (2), followed by alpha-pinene (1), p-cymene, borneol, alpha-terpineol, cryptone, spathulenol, trans-pinocarveol (4), bicyclogermacrene (5), caryophyllene oxide, and beta-phellandrene. Principal components analysis and hierarchical cluster analysis separated the eight Eucalyptus leaf essential oils into five groups, each constituting a chemotype

Variation in volatile leaf oils of 13 Eucalyptus species harvested from Souinet Arboreta (Tunisia)

Hydrodistillation of the dried leaves of 13 species of the genus Eucalyptus L' HER., viz., E. bicostata MAIDEN, BLAKELY & SIMMONDS, E. cinerca F. WELL. ex BENT U., E. exertra F. MUELL., E. gigantea HOOK. F. E. gunnii HOOK. F., E. macarthurii DEANE & MAIDEN., E. macrorrhyuclut F. MUELL., E. maidenii F. WELL., E. odorala BEHR. E. pauciflora SIEBER ex SPRENGEL. E. stderoxylon A. CUNN. ex WOOLLS, E. tercticornis SM., and E. viminalis LA BILL., harvested from Souinet arboreta (region of Ain Draaham, north of Tunisia) in June 2006, afforded essential oils in yields varying from 0.5+/-0.2 to 3.9+/-0.4%, dependent on the species. E. cinerea and E. exertra provided the highest and the lowest percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 142 components, representing 81.5 to 98.9% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8-cineole followed by cryptone, spathulenol (4), p-cymene (2), viridiflorol (6), globulol (7), beta-eudesmol, alpha-terpineol (5), limonene (8), D-piperitone, alpha-pinene (3), cuminal, and gamma-eudesmol. The principal component and the hierarchical cluster analyses separated the 13 Eucalyptus leaf essential oils into three groups, each constituting a chemotype

Chemical composition of 8 <it>eucalyptus</it> species' essential oils and the evaluation of their antibacterial, antifungal and antiviral activities

<p>Abstract</p> <p>Background</p> <p>In 1957, Tunisia introduced 117 species of <it>Eucalyptus</it>; they have been used as fire wood, for the production of mine wood and to fight erosion. Actually, <it>Eucalyptus</it> essential oil is traditionally used to treat respiratory tract disorders such as pharyngitis, bronchitis, and sinusitis. A few investigations were reported on the biological activities of <it>Eucalyptus</it> oils worldwide. In Tunisia, our previous works conducted in 2010 and 2011 had been the first reports to study the antibacterial activities against reference strains. At that time it was not possible to evaluate their antimicrobial activities against clinical bacterial strains and other pathogens such as virus and fungi.</p> <p>Methods</p> <p>The essential oils of eight <it>Eucalyptus</it> species harvested from the Jbel Abderrahman, Korbous (North East Tunisia) and Souinet arboreta (North of Tunisia) were evaluated for their antimicrobial activities by disc diffusion and microbroth dilution methods against seven bacterial isolates: <it>Haemophilus influenzae</it>, <it>Klebsiella pneumoniae</it>, <it>Pseudomonas aeruginosa</it>, <it>Staphylococcus aureus</it>, <it>Streptococcus agalactiae</it>, <it>Streptococcus pneumoniae</it> and <it>Streptococcus pyogenes</it>. In addition, the bactericidal, fungicidal and the antiviral activities of the tested oils were carried out.</p> <p>Results</p> <p>Twenty five components were identified by GC/FID and GC/MS. These components were used to correlate with the biological activities of the tested oils. The chemical principal component analysis identified three groups, each of them constituted a chemotype. According to the values of zone diameter and percentage of the inhibition (zdi, % I, respectively), four groups and subgroups of bacterial strains and three groups of fungal strains were characterized by their sensitivity levels to <it>Eucalyptus</it> oils. The cytotoxic effect and the antiviral activity varied significantly within <it>Eucalyptus</it> species oils.</p> <p>Conclusions</p> <p><it>E. odorata</it> showed the strongest activity against <it>S. aureus</it>, <it>H. influenzae</it>, <it>S. agalactiae</it>, <it>S. pyogenes</it>, <it>S. pneumoniae</it> and against all the tested fungal strains. In addition, <it>E. odorata</it> oil showed the most cytotoxic effect. However, the best antiviral activity appeared with <it>E. bicostata</it>. Virus pretreatment with <it>E. bicostata</it> essential oil showed better antiviral activity (IC₅₀ = 0.7 mg/ml, SI = 22.8) than cell-pretreatment (IC₅₀ = 4.8 mg/ml, SI = 3.33). The essential oil of <it>E. astringens</it> showed antiviral activity only when incubated with virus prior to cell infection. This activity was dose-dependent and the antiviral activity diminished with the decreasing essential oil concentration.</p