Separation Of Antioxidants From Natural Products Via High Speed Countercurrent Chromatography

Separation and purification of bioactive natural products is important in organic analytical chemistry and drug discovery. As a liquid-liquid chromatography, Countercurrent chromatography (CCC) has widely been used in the separation of natural products. Therefore, methodology study for separation of bioactive natural products via countercurrent chromatography is not only meaningful in science but also valuable in economy. The specific research works were listed as follows:In the first part, the bioassay guided separation of antioxidants from Ampelopsis heterophylla was carried out via CCC. The antioxidant activity of the crude extract was initially evaluated by on-line HPLC method. Five compounds in the crude extract, namely hyperoside (1), isoquercitrin (2), rutin (3), kaempferol-3-rutinoside (4) and quercetin (5), exhibited good antioxidant activities. These compounds were further separated by countercurrent chromatography using biphasic solvent systems. Their structures were then identified by mass spectrometry and NMR. All the compounds exhibited significant DPPH radical scavenging activities with the IC50values at18.2±1.3,17.0±1.4,24.2±1.2,38.1±1.7and9.0±1.2/M, respectively. The scavenging ratios of the compounds against hydroxyl radicals were65±5%,68±4%,96±2%,70±4%and98±2%, respectively. This strategy could improve the separation efficiency and may have promising application.In the second part, two target bioactive compounds, namely apigenin-7-O-glucoside and acacia-7-O-glucoside, were separated from Chrysanthemum morifolium via countercurrent chromatography with the solvent system MtBE/n-Butanol/ACN/H2O(1.5/2/1/5, v/v).Moreover, the recent progress of countercurrent chromatography, including the elution modes, is also reviewed in this paper.