The investigation was designed to determine the chemical composition, antioxidant and cytotoxic effects of the leaf essential oil of Eucalyptus globulus Labill grown in Nigeria. Fresh leaves of E. globulus on steam distillation yielded 0.96 % (v/w) of essential oil. Investigation of the oil on GC/MS resulted in the identification of 16 compounds, the bulk of the oil was constituted by oxygenated monoterpenes (46.5 %) with terpinen-4-ol (23.46 %) as the most abundant constituent. Other notable compounds include γ-terpinene (17.01 %), spathulenol (8.94 %), ρ- cymene (8.10 %) and ρ-cymen-7-ol (6.39 %). Globulol (2.52 %) and α-phellandrene (2.20 %) were also among the constituents identified. The antioxidant features of the essential oil was evaluated using inhibition of 2,2-diphenyl-1-picrylhydrazyl radical, a concentration dependent radical scavenging activity with IC50 value of 136.87 μl/ml was observed. Cytotoxic effect was assayed using the brine shrimp lethality test, Probit’s analysis of the result revealed a LC50 value of 9.59 μl/ml. The absence of 1,8-cineole and presence of α-phellandrene coupled with low antioxidant activity and high cytotoxic effect of the Eucalyptus oil investigated in the study suggest it may not be suitable for medicinal purposes but can be used as insecticidal agents.
