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 β-elemene (25.48%), α-copaene (17.05%), β-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.