Structural characterization and antioxidant activity of oligosaccharides from Panax ginseng C. A. Meyer.

The purpose of present work was to investigate the antioxidant activity of oligosaccharides from mountain-cultivated ginseng (MCG) and cultivated ginseng (CG). The antioxidant activity of total oligosaccharides from MCG and CG were compared preliminary. And then, the total oligosaccharides of MCG, which displayed stronger activity than that of CG, were separated by Carbon-Celite column and eluted with water and ethanol of different concentrations (30%, 50%, 70%, 95%, v/v). Five fractions, MCGOS-H2O, MCGOS-30, MCGOS-50, MCGOS-70, MCGOS-95, were obtained. Seven oligosaccharides were purified from MCGOS-30-MCGOS-95. The structure features of oligosaccharides (MCGO-1-MCGO-7) were characterized using high performance liquid chromatography (HPLC), methylation and gas chromatography-mass (GC-MS), as well as nuclear magnetic resonance spectroscopy. ABTS radical scavenging assay, DPPH radical scavenging assay as well as ferric reducing antioxidant power assay were adopted for antioxidant activity of all the different oligosaccharides sub-fraction. The result showed that the fractions of MCGOS-70 and MCGOS-95 exhibited significant radical scavenging activity with DPPH and ABTS. In conclusion, the oligosaccharides from MCG possessed the significant antioxidant activity. Therefore, we propose that the oligosaccharides from Panax ginseng can be developed as natural antioxidants in food and pharmaceutical fields.