Chemical Composition, Antioxidant, and Antibacterial Activities of the Essential Oil and Methanol Extracts of Eucalyptus largiflorens F. Muell

This study was designed to examine the chemical composition of essential oil and in vitro antioxidant and antimicrobial activity of the essential oil and methanol extracts of Eucalyptus largiflorens F. Muell. The chemical composition of the hydrodistilled essential oil of the leaves of E. largiflorens was analyzed by gas chromatography and gas chromatography/mass spectrometry. The main constituents of the oil were found to be 1,8-cineole (23.1%), cryptone (15.1%), 4-allyloxyimino-2-carene (11.2%), and 4-terpineol (9.6%). The essential oil showed strong antibacterial activity against the studied microorganisms, except for P. aeruginosa, while polar subfraction of methanol extract had moderate antimicrobial activity and the nonpolar subfraction of methanol extract did not show any antimicrobial activity. In contrast, the extract showed better activity than the essential oil in antioxidant activity assays employed, e.g., in a 2,2-diphenyl-1-picryl-hydrazyl system. Also, the polar subfraction of methanol extract (15.1 +/- 0.7 mu g/ml) showed the highest radical-scavenging activity. In the second case, the inhibition capacity (%) of the nonpolar subfraction (92.7% +/- 2.5) was found to be the stronger one. Finally, the total amounts of phenol constituents in the polar subfraction (142.6 +/- 0.9 mu g/mg), nonpolar subfraction (68.6 +/- 0.4 mu g/mg), and the oil (36.0 +/- 0.6 mu g/mg) were determined.