Volatile constituents and antibacterial activity of leaf oil of Thottea ponmudiana Sivar

The essential oil obtained by hydrodistillation of the fresh leaves of Thottea ponmudiana was analyzed by gas chromatography and gas chromatography-mass spectrometry. Twenty-seven components comprising 87.4% of the leaf oil were identified. Among the identified constituents 14.8% were monoterpene hydrocarbons, 32.6% were sesquiterpene hydrocarbons and 40.0% oxygenated sesquiterpenes. The major component, pregeijerene B (E,E,E-1,7-dimethylcylododeca-1,4,7-triene) (25.8%) was isolated and identified by IR, GC/EIMS and 1 H-NMR analyses. The other major components in the leaf oil were 8α-acetoxyelemol (21.6%) followed by terpinolene (10.1%), elemol (8.2%) and bulnesol (4.9%). The antibacterial activity of the oil was tested against both Gram-positive and Gram-negative bacteria. The oil showed significant activity against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, in comparison with the standard, streptomycin.