Abstract
Volatile constituents of the essential oil obtained from Pakistani Eucalyptus camaldulensis var. brevirostris leaves by hydro-distillation were analyzed by gas chromatography and gas chromatography-mass spectrometry. The yield of essential oil from fresh leaves was 1.5±0.1 g/g. The 80 components identified in the essential oil were all terpenes and related compounds, which comprised of 11 monoterpenes (tota1 60 μg/g of oil), 8 oxygenated monoterpenes (277 μg/ g), 25 sesquiterpenes (1,940 μg/g), 29 oxygenated sesquiternpenes (9,420 μg/g), and 7 esters (175 μ/g). The major chemical compounds in the oil were spathulenol (1,900 μg/g), α-14-oxymuurolene (1,830 μg/g), β-bisabolene (1,190 μg/g), caryophyllene oxide (1,010 μg/g), γ-patchoulene (848 μg/g), aristolone (797 μg/g), α-atlantone (561 μg/g), β-piotol (332 μg/g), (E)-caryophyllene (328 μg/g), and β-copaen-4α-ol (313 μg/g). The essential oil obtained in the present study contained considerably higher concentrations of oxygenated sesquiterpenes than oils from other classes of Eucalyptus leaves. This oil exhibited clear antioxidant activity with a dose-response in DPPH radical scavenging and β-carotene bleaching assays. These essential oil-rich Eucalyptus leaves could be a useful source of ingredients for flavor and fragrance enhancement as well as natural antioxidants.