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

Elaissi A, Rouis Z, Salem NA, Mabrouk S, ben Salem Y, Salah KB, Aouni M, Farhat F, Chemli R, Harzallah-Skhiri F, Khouja ML - BMC Complement Altern Med (2012)

Bottom Line: The cytotoxic effect and the antiviral activity varied significantly within Eucalyptus species oils.In addition, E. odorata oil showed the most cytotoxic effect.However, the best antiviral activity appeared with E. bicostata.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Pharmacognosy, Faculty of Pharmacy, University of Monastir, Avenue Avicenne, Monastir 5019, Tunisia. aelaissi@yahoo.fr

ABSTRACT

Background: In 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.

Methods: The 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.

Results: 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 Eucalyptus oils. The cytotoxic effect and the antiviral activity varied significantly within Eucalyptus species oils.

Conclusions: E. 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 (IC(50) = 0.7 mg/ml, SI = 22.8) than cell-pretreatment (IC(50) = 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.

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ACP of the 26 major components of eight eucalyptus essential oils. For the abbreviation of Eucalyptus species (▴) and components (●) see Table 1.
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Figure 1: ACP of the 26 major components of eight eucalyptus essential oils. For the abbreviation of Eucalyptus species (▴) and components (●) see Table 1.

Mentions: The yield content of the 25 selected component was significantly different (p < 0.05) among species (Table 1). These 25 components were used for the PCA and the HCA analysis. The PCA horizontal axis explained 47.2% of the total variance while the vertical axis a further 23.80% (Figure 1). The HCA based on the Euclidean distance between groups indicated three specie groups (A, B and C) (with a dissimilarity of 11.0) (Figure 2), identified by their essential oil chemotypes. Group A clearly stood out forming a separate group in the PCA (Figure 1) and a deep dichotomy in the HCA (Figure 2). It was correlated positively with the axes 1 and 2. Groups A and B were negatively correlated, their separation was mainly due to axis 2. Group A species reduced to E. odorata, the essential oil of which was characterized by the highest mean percentage of cryptone (20.9 ± 1.3%), cuminal (6.6 ± 0.6%), phellandral (6.6 ± 0.4%), verbenone (0.9 ± 0.2%), p-cymen-8-ol (2.9 ± 0.6%), sapthulenol (3.2 ± 0.9%), carvacrol (1.7 ± 0.3%), p-cymene (16.7 ± 5.2%), terpinene-4-ol (3.0 ± 0.8%), caryophyllene oxyde (1.7 ± 0.2%), viridiflorol (4.5 ± 1.6%) and by the lowest level of 1,8-cineole (4.5 ± 1.6%). Group B, made up of E. maidenii, E. lehmannii, E. sideroxylon and E. cinerea, has essential oils characterized by the highest amount of limonene (3.1 ± 0.2 to 4.4 ± 0.2%), α-terpineol (2.2 ± 0.3% for E. maidenii to 10.3 ± 1.1% for E. cinerea). The PCA showed that the variation between these species is mainly due to the variation of 1,8-cineole content (57.8 ± 1.9% for E. maidenii to 70.4 ± 2.5 for E. cinerea) and of α-pinene (4.5 ± 0.7% for E. cinerea to 17.6 ± 7.5% for E. lehmannii). Group C, consisting of E. astringens, E. leucoxylon and E. bicostata, has essential oils distinguished by their highest mean percentage of epiglobulol (1.0 ± 0.2 - 1.2 ± 0.3%), globulol (5.4 ± 1.2 - 6.2 ± 0.9%), trans-pinocarveol (4.3 ± 1.0 to 7.0 ± 2.5%), aromadendrene (2.0 ± 0.8 - 3.6 ± 1.2%) and pinocarvone (1.2 ± 0.2 - 2.2 ± 0.5%). The E. bicostata and E. leucoxylon oils differed from E. astringens oil by their richness in 1,8-cineole (68.0 ± 5.3, 59.2 ± 10.1%, respectively) and their poverty in α-pinene (3.7 ± 1.2, 7.8 ± 2.3%, respectively) against 42.0 ± 5.9% and 22.0 ± 6.0%, respectively for the latter species.


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

Elaissi A, Rouis Z, Salem NA, Mabrouk S, ben Salem Y, Salah KB, Aouni M, Farhat F, Chemli R, Harzallah-Skhiri F, Khouja ML - BMC Complement Altern Med (2012)

ACP of the 26 major components of eight eucalyptus essential oils. For the abbreviation of Eucalyptus species (▴) and components (●) see Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475086&req=5

Figure 1: ACP of the 26 major components of eight eucalyptus essential oils. For the abbreviation of Eucalyptus species (▴) and components (●) see Table 1.
Mentions: The yield content of the 25 selected component was significantly different (p < 0.05) among species (Table 1). These 25 components were used for the PCA and the HCA analysis. The PCA horizontal axis explained 47.2% of the total variance while the vertical axis a further 23.80% (Figure 1). The HCA based on the Euclidean distance between groups indicated three specie groups (A, B and C) (with a dissimilarity of 11.0) (Figure 2), identified by their essential oil chemotypes. Group A clearly stood out forming a separate group in the PCA (Figure 1) and a deep dichotomy in the HCA (Figure 2). It was correlated positively with the axes 1 and 2. Groups A and B were negatively correlated, their separation was mainly due to axis 2. Group A species reduced to E. odorata, the essential oil of which was characterized by the highest mean percentage of cryptone (20.9 ± 1.3%), cuminal (6.6 ± 0.6%), phellandral (6.6 ± 0.4%), verbenone (0.9 ± 0.2%), p-cymen-8-ol (2.9 ± 0.6%), sapthulenol (3.2 ± 0.9%), carvacrol (1.7 ± 0.3%), p-cymene (16.7 ± 5.2%), terpinene-4-ol (3.0 ± 0.8%), caryophyllene oxyde (1.7 ± 0.2%), viridiflorol (4.5 ± 1.6%) and by the lowest level of 1,8-cineole (4.5 ± 1.6%). Group B, made up of E. maidenii, E. lehmannii, E. sideroxylon and E. cinerea, has essential oils characterized by the highest amount of limonene (3.1 ± 0.2 to 4.4 ± 0.2%), α-terpineol (2.2 ± 0.3% for E. maidenii to 10.3 ± 1.1% for E. cinerea). The PCA showed that the variation between these species is mainly due to the variation of 1,8-cineole content (57.8 ± 1.9% for E. maidenii to 70.4 ± 2.5 for E. cinerea) and of α-pinene (4.5 ± 0.7% for E. cinerea to 17.6 ± 7.5% for E. lehmannii). Group C, consisting of E. astringens, E. leucoxylon and E. bicostata, has essential oils distinguished by their highest mean percentage of epiglobulol (1.0 ± 0.2 - 1.2 ± 0.3%), globulol (5.4 ± 1.2 - 6.2 ± 0.9%), trans-pinocarveol (4.3 ± 1.0 to 7.0 ± 2.5%), aromadendrene (2.0 ± 0.8 - 3.6 ± 1.2%) and pinocarvone (1.2 ± 0.2 - 2.2 ± 0.5%). The E. bicostata and E. leucoxylon oils differed from E. astringens oil by their richness in 1,8-cineole (68.0 ± 5.3, 59.2 ± 10.1%, respectively) and their poverty in α-pinene (3.7 ± 1.2, 7.8 ± 2.3%, respectively) against 42.0 ± 5.9% and 22.0 ± 6.0%, respectively for the latter species.

Bottom Line: The cytotoxic effect and the antiviral activity varied significantly within Eucalyptus species oils.In addition, E. odorata oil showed the most cytotoxic effect.However, the best antiviral activity appeared with E. bicostata.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Pharmacognosy, Faculty of Pharmacy, University of Monastir, Avenue Avicenne, Monastir 5019, Tunisia. aelaissi@yahoo.fr

ABSTRACT

Background: In 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.

Methods: The 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.

Results: 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 Eucalyptus oils. The cytotoxic effect and the antiviral activity varied significantly within Eucalyptus species oils.

Conclusions: E. 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 (IC(50) = 0.7 mg/ml, SI = 22.8) than cell-pretreatment (IC(50) = 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.

Show MeSH
Related in: MedlinePlus