This study was conducted to evaluate the in vitro antimicrobial properties of essential oil, its major component, 1,8-cineole, and extracts of two Eucalyptus species, Eucalyptus intertexta and Eucalyptus largiflorens. Minimum inhibitory concentration (MIC) of the extracts was calculated by broth dilution method and the zone of inhibition was studied by agar disk diffusion method. Gentamicin (10 µg/disk) and rifampin (5 µg/disk) were used as reference controls for antibacterial studies and nystatin (100 µg/disk) for antifungal studies. The results of MIC study revealed that the essential oil has a stronger activity and broader spectrum than those of methanol extracts. It is interesting to point out that the oils had even greater potential of antimicrobial activities than those of 1,8-cineole as their main component.
Keywords: Antimicrobial activity; Eucalyptus intertexta; Eucalyptus largiflorens; minimum inhibitory concentration; zone of inhibition.