Antibacterial activity of the essential oils from the leaves of Eucalyptus globulus against Escherichia coli and Staphylococcus aureus

Objective:To examine the in vitro antimicrobial activities of essential oil of the leaves of Eucalyptus globulus(E.globulus).Methods:The essential oils of this plant were obtained by the hydrodistillation method.The inhibitory effects of this essential oil were tested against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)by using agar disc diffusion and dilution broth methods.Results:The results obtained showed that essential oil of the leaves of E.globulus has antimicrobial activity against gram negative bacteria(E.coli)as well as gram positive bacteria(S.aureus).Conclusion:The encouraging results indicate the essential oil of E.globulus leaves might be exploited as natural antibiotic for the treatment of several infectious diseases caused by these two germs,and could be useful in understanding the relations between traditional cures and current medicines.

Transcript Level Analysis of Lignin and Flavonoid Biosynthesis Related Genes in <i>Eucalyptus globulus</i>

We have investigated a correlation of transcript abundances of key genes that influence the quality of wood and flavonoid biosynthesis, such as the two p-hydroxycinnamoyl-CoA:quinate shikimate p-hydroxycinnamoyl transferase (HCT) and the two chalcone synthases (CHS) from Eucalyptus globulus grown in a greenhouse. The EglHCT1 and EglHCT2 transcripts accumulated in stems of all ages, but to a lesser extent in leaves. On the other hand, EglCHS3 and EglCHS4 exhibited high transcript levels in leaves, roots and shoots, but low levels in the stem. A positive correlation (R2 > 0.70) was observed between the transcript levels of the EglHCT1, EglHCT2 genes and Klason lignin (KL) content. In addition, the sum of transcript levels of EglHCT1 and EglHCT2 genes were highly correlated to KL contents (R2 > 0.85). However, there is no relationship between transcript levels of two CHS genes and, KL or flavonoid contents. This may imply that lignin biosynthesis and flavonoid biosynthesis are independently regulated in E. globulus.

Antibacterial Activity of <i>Bougainvillea Glabra, Eucalyptus Globulus, Gnaphalium Attenuatum</i>, and Propolis Collected in Mexico

Bougainvillea glabra C., Eucalyptus globules Labill., and Gnaphalium attenuatum DC., as well as propolis, have been used in Mexican traditional medicine as a remedy to treat respiratory illnesses. There are few biological reports of such material collected in Mexico, despite the high demand for them as raw material for popular and industrial uses. The antibacterial activity of the plants and propolis studied here were evaluated against a panel of bacteria using three different methodologies: agar disc diffusion, macro and micro dilution methods. E. globules and G. attenuatum extracts showed the strongest active values (P > 0.05) in the agar disc diffusion method with a range of 8 - 22 mm inhibition zone, MIC values ranging from 25 - 250g/mL, and MBC values of 25 - 500g/mL obtained by macro and micro dilution methods. B. glabra extracts were active against E. coli, S. typhi, K. pneumoniae, S. aureus and S. agalactiae, with 8 - 13 mm inhibition zone, MICs ranging from 500 - 3000g/mL, and MBCs of 1000 - 3000g/mL. The propolis extract turned out to be active against E. coli, K. pneumoniae, S. aureus and S. agalactiae, with values of 7 - 12 mm, MICs of 1000 - 2000g/mL, and MBCs of 2000 - 2500g/mL. E. globules and G. attenuatum extracts were the most active in the three methodologies assayed. This is also the first time that the antibacterial activity of G. attenuatum has been experimentally demonstrated. The microdilution method showed to be more sensitive, less expensive and minor time-consuming technique compared with the other two.

Chemical Characterization and Biological Potential of the Essential Oil of Eucalyptus globulus Labill

Oxidation of lipids in various products,along with the growth of medically important pathogens,has led to a search for medicinal plants with antioxidant and antimicrobial activities.As a result,the aim of this study was to evaluate the antioxidant and antibacterial activity of the essential oil of Eucalyptus globulus(EO-Eg).Antioxidant activity was assessed by using the 2,2-diphenyl-1-picrylhydrazyl hydrate(DPPH)assay method.Existing components were identified through gas chromatography-mass spectrometry(GC-MS)analysis.Antibacterial activity and minimum inhibitory concentration(MIC)were assessed by using the broth microdilution method with standard multidrug-resistant bacterial strains.The main EO-Eg compounds identified by GC-MS were isopulegol,citronellal,and citronellol,which are primarily used in the industrial sectors.EO-Eg demonstrated excellent antioxidant activity with an effective concentration(EC50)of 4.48μL/mL owing to the presence of phenolic compounds.Regarding antibacterial activity,the EO-Eg displayed a broad antimicrobial spectrum of antimicrobial activity across the different resistance phenotypes analyzed.The most notable antibacterial activity was observed against Staphylococcus aureus 169 MRSA(MIC=0.0625%).As a result,our findings suggest that EO-Eg has antioxidant and antibacterial potential against hospital-acquired multidrug-resistant pathogens,which may be correlated with its major components.

Eucaglobulin, A New Complex of Gallotannin and Monoterpene from Eucalyptus globulus

Eucaglobulin 1, a new complex of gallotannin and monoterpene, was isolated from the leaves of Eucalyptus globulus. Its structure was determined by spectral methods.

Factors determining the occupancy of nest-boxes by Great Tits(Parus major)in eucalypt plantations

Providing nest-boxes as surrogate tree cavities can be of great importance to increase the breeding populations of cavity-nesting birds in managed forests.However,the exact placement of nest-boxes should be taken into consideration to enhance their occupancy according to species-specific preferences.In this study,we investigated which factors can better predict nest-box occupancy by the Great Tit(Parus major)in eucalypt plantations.We used generalised linear mixed-effects models to analyse the influence of topography,nest-box positioning,vegetation cover and landscape variables on three-year occupancy records from 80 newly provided nest-boxes.Non-random patterns of nest-box occupancy were found with respect to all categories except topography.Results suggest that Great Tits prefer to occupy high-placed nest-boxes,close to areas that can provide them with supplementary resources either within or in the vicinity of the stand(i.e.,trees other than eucalypts,riparian vegetation,and large patches of adjacent habitats).Overall,this study provides important recommendations for nest-box placement and spatial distribution in managed forests and enhances the potential of nest-box interventions as a biodiversity offset and management tool.

Response of soil respiration to a severe drought in Chinese Eucalyptus plantations

Extreme droughts can adversely affect the dynamics of soil respiration in tree plantations. We used a severe drought in southwestern China as a case study to estimate the effects of drought on temporal variations in soil respiration in a plantation of Eucalyptus globulus. We documented a clear seasonal pattern in soil respiration with the highest values (100.9 mg C-CO2 m(-2) h(-1)) recorded in June and the lowest values (28.7 mg C-CO2 m(-2) h(-1)) in January. The variation in soil respiration was closely associated with the dynamics of soil water driven by the drought. Soil respiration was nearly twice as great in the wet seasons as in the dry seasons. Soil water content accounted for 83-91% of variation in soil respiration, while a combined soil water and soil temperature model explained 90-99% of the variation in soil respiration. Soil water had pronounced effects on soil respiration at the moisture threshold of 6-10%. Soil water was strongly related to changes in soil parameters (i.e., bulk density, pH, soil organic carbon, and available nitrogen). These strongly influenced seasonal variation in soil respiration. We found that soil respiration was strongly suppressed by severe drought. Drought resulted in a shortage of soil water which reduced formation of soil organic carbon, impacted soil acid-base properties and soil texture, and affected soil nutrient availability.

Synthesis of Green Adhesive with Tannin Extracted from Eucalyptus Bark for Potential Use in Wood Composites

Recently,the exploitation of renewable plant resources in the formulation of adhesives is very promising for their availability at low coast,as well as their richness in biomolecules such as polyphenols.In this way,many research studies tannins extracted from different sources such as mimosa,quebracho,and pine have been the subject of very satisfactory recent studies.In this paper,a new complete characterization of the tannins extracted from the bark of eucalyptus globulus harvested from two regions in Algeria was achieved.The structural characterization enabled us to confirm the richness in condensed tannins,particularly in procyanidin and prodelphinidin units.The most reactive tannins obtained during extraction at 70℃(yield:27.1%)have a Stiasny number of 75.92%.This extract was used for the formulation of adhesives(tannin/hexamine).The thermal characterizaction of the adhesives showed higher stability for the tannin formulation of eucalyptus/hexamine as well as an excellent mechanical performance with a MOE of 2807 MPa at 180℃and shear strength of 689.4 N/mm^(2).

Note on Glycaspis brimblecombei Moore (Hemiptera Psyllidae): A new pest of Eucalyptus in Greece

Leaves of eucalyptus infested by Glycaspis brim-blecombei Moore were found on river red gum (E. camaldulensis) and blue gum (E. globulus) trees in Attiki and Chania region, Greece. The psyllid is recorded for the first time in Greece. Brief information about this psyllid is provided.

Lignocellulosic Micro and Nanofibrillated Cellulose Produced by Steam Explosion for Wood Adhesive Formulations

The reinforcing impact of Lignocellulosic micro and nanofibrillated cellulose(L-MNFCs)obtained from Eucalyp-tus Globulus bark in Urea-Formaldehyde UF adhesive was tested.L-MNFCs were prepared by an environmentally friendly,low-cost process using a combination process involving steam explosion followed by refining and ultra-fine grinding.Obtained L-MNFCs showed a web-like morphology with some aggregates and lignin nanodroplets.They present a mixture of residual fibers and fine elements with a width varying between 5 nm to 20μm,respec-tively.The effects of the addition of low amounts of L-MNFCs(1%wt.)on the properties of three different adhe-sives(Urea-Formaldehyde UF,Phenol-Formaldehyde PF,and Tannin-Hexamine TH)were studied by the evolution of the pH,the viscosity,and the mechanical properties.Results showed that the viscosity of PF and UF adhesives increased with the addition of L-MNFCs,unlike TH.Meanwhile,the addition led to better mechan-ical behavior for the three adhesives.Particleboards were then prepared using modified UF with L-MNFCs and tested.Results showed that an amount of 1%wt.of L-MNFCs was sufficient to increase the internal bonding by≈67%,the modulus of elasticity by≈43%,and the modulus of rupture by≈29%.

埃塞俄比亚首都亚的斯亚贝巴Entoto自然公园和Bole Sub-City黑翅牡丹鹦鹉的种群和受胁状况(英文)

2008年9月至2009 年2月,我们采用样点法调查了埃塞俄比亚首都亚的斯亚贝巴Entoto自然公园和BoleSub-City两地黑翅牡丹鹦鹉(Agapornis taranta)的种群和受胁状况。两地平均共记录到58只黑翅牡丹鹦鹉,其中Bole Sub-city平均记录到46只,Entoto自然公园则平均记录到12只。在Bole Sub-City记录最多的是其干季,最多记录到57只鹦鹉,而在Entoto自然公园记录最多的是其湿季,最多记录到 15 只。在湿季和干季,Entoto自然公园的成年鹦鹉雌雄性比分别为1:0.71和1:0.60,而在Bole Sub-City该比例则分别为1:0.76和1:0.78。对同一地点而言,干湿季之间的成年鹦鹉雌雄性比差异均不显著(p > 0.05)。Entoto 自然公园中影响黑翅牡丹鹦鹉以及其他鸟类现状的主要因素是自然栖息地的破碎化以及因公园内优势树种蓝桉(Eucalyptus globulus)导致的食物资源减少。当地居民的放牧、过度的农业生产以及森林采伐活动造成了土地退化,进而破坏了自然公园的栖息地环境。建议对Entoto自然公园及其他市区公园的植被加以有效地管理,为该地区的鸟类提供合适的生存环境。