Chemical composition of essential oil and antioxidant activity of the essential oil and methanol extracts of Knema globularia (Lam.) Warb. from Vietnam.

This study is the first to investigate the chemical composition of essential oil and antioxidant activity of the essential oil and methanol extracts from the leaves of Knema globularia (Lam.) Warb. from Vietnam. According to gas chromatography and gas chromatography-mass spectrometry analysis, the major constituents of K. globularia essential oil were ß-elemene (25.48%), α-copaene (17.05%), ß-caryophyllene (9.37%), and α-humulene (8.42%). The antioxidant activity of the samples was determined using DPPH and ABTS methods. In both assays, the polar subfraction of the methanolic extract showed better antioxidative capacity than the nonpolar subfraction and the essential oil. In addition, the amounts of total phenol value in the polar subfraction and the nonpolar subfraction were determined to be 113.84 µg/mg and 47.52 µg/mg, respectively. The findings demonstrate that the essential oil and methanol extracts of K. globularia possess significant antioxidant activities and may be a new potential source of natural antioxidants.

Chemical composition of the leaf oil of Actephila excelsa from Vietnam..

Fresh leaves of Actephila excelsa (Dazl.) Muell. from Vietnam were steam distilled to produce an oil in a yield of 0.15% (v/w). The essential oil was analyzed by a combination of capillary gas chromatography-flame ionization detection (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). The main constituents of the oil were the sesquiterpenes γ-elemene (25.7%) and ß-caryophyllene (11.2%). Other significant compounds were methyl salicylate (5.8%), benzyl benzoate (5.2%), (E,E)-farnesylacetone (4.9%), anisole (4.7%), sabinene (4.1%) and menthone (4.0%). This is the first report on the volatile constituents of this plant.