Chemical investigation of the butanolic fraction of the leaves of Blighia unijugata Baker (Sapindaceae)

Abstract

In this work, we report the isolation and characterization of a phenolic acid and a triterpenoid saponin from the butanolic fraction of the leaves of Blighia unijugata a plant of the Sapindaceae family. B. unijugata is widely used in folk medicine for the treatment of various ailments. Chemical investigations were carried out on the leaves powder extract obtained at room temperature using MeOH-H2O (8:2) solvents mixture. The resulting extract was then dissolved in small amount of distilled water, then partition with hexane, ethylacetate (EtOAc) and n-butanol (n-BuOH) saturated with water. The n-butanolic fraction was evaporated and subjected to a HP-20SS Diaion type adsorbent resin column chromatography with a varying solvent gradient of H2O-MeOH. From the resulting fractions, fraction B was further subjected to a vacuum liquid chromatography (VLC) with silica gel (40-63 μm). Two fractions (B1 and B4) of interest were then purified using successive CC over silica and Sephadex LH-20 gels yielding three pure compounds, indexed BU1, BU2 and BU3. The structural elucidations of two of them were performed using spectroscopic methods (1D and 2D NMR), mass spectrometry along with comparison to literature data. These compounds were elucidated and identified as 4-hydroxybenzoic acid (BU1) and 3-O-β-D-xylopyranosyl-(1→4)-β-D-glucopyranosyl-(1→3)-α-L- rhamnopyranosyl-(1→2)-α-L-arabinopyranosylhederagenin (BU2).