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

Abstract

BackgroundIn 1957, Tunisia introduced 117 species of Eucalyptus; they have been used as fire wood, for the production of mine wood and to fight erosion. Actually, Eucalyptus 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 Eucalyptus 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.MethodsThe essential oils of eight Eucalyptus 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: Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pneumoniae and Streptococcus pyogenes. In addition, the bactericidal, fungicidal and the antiviral activities of the tested oils were carried out.ResultsTwenty 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 Eucalyptus oils. The cytotoxic effect and the antiviral activity varied significantly within Eucalyptus species oils.ConclusionsE. odorata showed the strongest activity against S. aureus, H. influenzae, S. agalactiae, S. pyogenes, S. pneumoniae and against all the tested fungal strains. In addition, E. odorata oil showed the most cytotoxic effect. However, the best antiviral activity appeared with E. bicostata. Virus pretreatment with E. bicostata 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 E. astringens 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.

Chemical profile, nutraceutical and anti-phytobacterial properties of the essential oil from Dalea foliolosa (Fabaceae)

“…These yields were higher than those reported for some Eucalyptus species and to those of D. formosa and D. strobilacea (Lucero et al, 2005;Elaissi et al, 2012;Benites et al, 2016). The number of replicates revealed the infra-specific variation of volatiles in D. folioliosa and the general changes in the chemical profile during the three consecutive years studied.…”

CHEMICAL COMPOSITION, ANTIMICROBIAL, ANTIOXIDANT AND CYTOTOXIC ACTIVITIES OF <i>EUCALYPTUS CHAPMANIANA</i> GROWN IN IRAQ

“…The activity of this chemical compound may be increased by other minor components. However, based on the chemical composition of essential oils in the samples, the antimicrobial activity was not related to a high content of a single chemical compound, but rather to synergic effects of major and minor components (Elaissi et al, 2012).…”

Impact of geographic’s variation on the essential oil yield and chemical composition of three Eucalyptus species acclimated in Tunisia

“…To evaluate the identified essential oil constituents useful for chemical reaction between selected species, 16 compounds were identified from the oil samples with contents in the essential oils of 0.9% in at last one species, were subjected to PCA and HCA using SPSS 12.0 software (SPSS Inc. Chicago, IL, USA) (Elaissi et al, 2012).…”

“…The relative concentration was calculated using the software HP Chemstation, which allows assimilating the percentages of the peak areas to the percentages of the various constituents. Retention indices were obtained by running a series of aliphatic hydrocarbons (C9 -C28) by increasing the number of carbon atoms in the Carbowax column (Elaissi et al, 2012) GC column).…”

“…The mass spectrometer operating conditions were: 70 eV ionization voltage, 70 eV; 230°C ion source. The GC analysis conditions were as described above (see GC Analysis) (Elaissi et al, 2012).…”