Extraction And Separation Of Antioxidant Components In The Flower Of Mucuna Sempervirens

Mucuna sempervirens belongs to Leguminosae Mucuna family. Its rattan, flower and seed have been used as Chinese traditional medicine for hundreds of years. But less research involve the chemical constituents in the flower of Mucuna sempervirens. In order to investigate the active components in the flower of Mucuna sempervirens, the antioxidants constituents were investigated in the present study.The flower of Mucuna sempervirens was extracted with 95% ethanol, partitioned with petroleum ether, ethyl acetate, chloroform and n-butanol after the extraction solution was concentrated to yield petroleum ether extract, ethyl acetate extract, chloroform extract and n-butanol extract which were used for the assay of antioxidant activity. The experiments of scavenging DPPH free radical and O2- free radical of the four extracts showed only ethyl acetate extract and n-butanol extract possessed antioxidant activity. Therefore, ethyl acetate extract and n-butanol extract were subjected to separate to find the compounds.Ethyl acetate extract was separated by high-speed countercurrent chromatography (HSCCC) with a biphasic solvent system composed of TBME-mathanol-water (2:1:1, V/V). The HSCCC separation yielded components A-H possessing antioxidant activity. Then the components were subjected to preparative HPLC separation, which resulted in quercetin-3-O-β-D-glucopyranoside (Ⅰ), dihydroquercetin (II), 4-hydroxybenzoic acid (III), E-P-methoxycinnamic acid (IV) and kaempferol (V), in which componentsⅠ,II and V possessing higher antioxidant activity.N-butanol extract was separated by HSCCC with a biphasic solvent system composed of n-butanol-TBME-water (4:1:5, V/V). The HSCCC separation yielded components I-O possessing hantioxidant activity. Then the components were subjected to preparative HPLC separation, which resulted in isoschaftoside (VI), kaempferol-3-O-[α-L-rhamnopyranosyl-(1-6)-β-D-galactopyranoside] (VII), kaempferol-3-O-[β-D-glucopyranoside-(1-4)-α-L-rhamnopyranosyl] (VIII) and 1-(4-hydroxybenzoyl)-glucose (IX). They all have some antioxidant activity.The above studies demonstrate that antioxidant compounds occur in the flower of Mucuna sempervirens. Quercetin-3-O-β-D-glucopyranoside, dihydroquercetin and kaempferol are the main functional compounds.