Studies on Chemical Constituents, Antioxidant and Antimicrobial Activity of Essential Oil from Leaves of Combretum albidum G. Don

The chemical composition, antioxidant and antibacterial activities of essential oil isolated by hydrodistillation from the leaves part of Combretum albidum was evaluated. The chemical composition was analyzed by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC/MS). Forty four substances were identified, consisting of a complex mixture of sesquiterpenes (92.5 %) and monoterpenes (1.5 %). The main components in the oil were germacrene-D (20.6), caryophyllene (17.9), alpha-copaene (5.2), bicyclogermacrene (4.7), E-nerolidol (4.5), alpha-cadinol (3.6), d-cadinene (3.5), delta-cadinol (2.8), spathulenol (2.7),gamma-muurolene (2.5), alpha-muurolene (2.4), trans-beta-farnesene (2.1),. tau.-muurolol (2.0), caryophyllene oxide (1.8) and globulol (1.8 %) along with alpha-pinene, beta-copaene, cis-alpha-bisabolene, cubebol, phytol, beta-elemene,gamma-cadinene, epicubenol,gamma-muurolene, beta-bourbonene, cubenol, beta-ylangene as minor constituents. The separation of oil into fractions led to identification of other components such as limonene and logifolene in the fraction eluted with low polar solvent and compounds such as geranyl acetate in fraction eluted with high polar solvent. The antioxidant property of the oil was assessed by free radical scavenging (DPPH) assay. The essential oil presented interesting radical scavenging activity (IC50 = 29.4 +/- 0.1 mu g/mL). The antimicrobial property of the oil was also tested by zone of inhibition method and was found effective against S. aureus, E. coli, C. albicans and S. typhii. To our knowledge, this will be the first detailed study of the essential oil composition, antioxidant and antimicrobial activities from the C. albidum leaves collected from Southern India.