ANTIOXIDATIVE ACTIVITIES AND CHEMICAL CONSTITUENTS OF THE ETHYL ACETATE EXTRACT FROM JASMINUM UNDULATUM KER-GAWL

Abstract

From the total crude ethanol extract of Jasminum undulatum Ker Gawl.’s leaves and stems, five fractionss were obtained by partitioning with petroleum ether, chloroform, ethyl acetate and n-butanol solvents. These five fractions were investigated for antioxidative activity using the DPPH radical scavenging and nitric oxide-inhibitory assay. All the fractions showed antioxidative activity except the petroleum ether fraction. Among the fractionss, the ethyl acetate fraction was the most potent fraction in both assays with the SC50 values of 5.30 μg/ml and 80.90 μg/ml, respectively. Further investigation on the eight sub-fractions isolated and extracted from the ethyl acetate fraction showed that one of these sub-fractions, the TE6 sub-fraction, showed the most significant antioxidative activity with the SC50 values of 3.15 μg/ml and 61.83 μg/ml respectively in the DPPH radical scavenging and nitric oxide-inhibitory assay. From the TE4 and TE6 sub-fractions, three compounds were isolated, including p-tyrosol (1), protocatechuic acid (2) and hydroxytyrosol (3). The structure of those compounds were elucidated by spectrometric methods IR, MS, 1D-NMR, and 2D-NMR.