CHEMICAL PROFILE AND ANTIMICROBIAL ACTIVITIES OF ESSENTIAL OILS OF EUCALYPTUS GLOBULUS LEAVES

Abstract

Eucalyptus globulus is one of the abundant tree species in Ethiopia known for medicinal values of its essential oils. The essential oil composition of a given species may vary with environmental factors. In this study, leaf of essential oil compositions and their antimicrobial activities were analyzed from E. globulus sampled from Haramaya University (HU) and Entoto Park (EP). Essential oils were extracted by steam distillation method and their compositions were analyzed using GC. Antimicrobial activities of the essential oils at different concentration levels were assessed with streptomycin and dimethyl sulfoxide used as positive and negative controls, respectively. The results showed that the essential oils from HU and EP samples contained 20 and 17 terpene compounds, respectively. Chemical profile of essential oils contained Terpene, Oxygenated monoterpene,, Hydrocarbon monoterpene, Oxygenated sesquiterpene and Hydrocarbon sesquiterpene ranging from 86.67-87.01%, 8.01- 8.32%, 1.57-1.97%, and 1.04 -2.64%, respectively. The extracted essential oils were also evaluated for their antibacterial activities by papering disc diffusion method against four bacterial species of Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, and Proteus mirabilis. EPEO extracts of the plant were shown to have higher antibacterial activities with maximum zone of inhibition (14.43±0.15mm) against S. aureus and minimum zone of inhibition (7.77±029 mm) against P. aeruginosa than HUEO extract with the maximum zone of inhibition (14.23±0.11mm) against S.aurous while minimum zone of inhibition (6.47±0.21 mm) against P. aeruginosa compared with that of Streptomycin against bacteria as references antibiotics