Abstract: Eucalyptus species are well reputed for their
traditional use in Asia as well as in other parts of the world; therefore,
the present study was designed to investigate the antimicrobial and
antioxidant activities associated with essential oils from different
Eucalyptus species. Essential oils from the leaves of six Eucalyptus
species, including: Eucalyptus woodwardi, Eucalyptus stricklandii,
Eucalyptus salubris, Eucalyptus sargentii, Eucalyptus torquata and
Eucalyptus wandoo were separated by hydrodistillation and dried
over anhydrous sodium sulphate. DPPH, ferric reducing antioxidant
power, and hydroxyl radical scavenging activity assays were carried
out to evaluate the antioxidant potential of the oils. The results
indicate that examined oils exhibit substantial antioxidant activities
relative to ascorbic acid. Previously, these oils were evaluated for
their antimicrobial activities, against wide range of bacterial and
fungal strains, and they were shown to possess significant
antimicrobial activities. In this study, further investigation into the
growth kinetics of oil-treated microbial cultures was conducted. The
results clearly demonstrate that the microbial growth was markedly
inhibited when treated with sub-MIC concentrations of the oils.
Taken together, the results obtained indicate a high potential of the
examined essential oils as bioactive oils, for nutraceutical and
medical applications, possessing significant antioxidant and anti
microbial activities.