Purification, compositional analysis and antioxidant properties of polysaccharides from black ginseng

Purpose: To extract, purify black ginseng polysaccharides, and study their compositional analysis and antioxidant properties.Methods: Crude polysaccharides from black ginseng were prepared by hot water extraction and subjected to chromatographic purification on Sephadex G-75 and DEAE-cellulose and Sephadex G-75 columns to yield 4 polysaccharide components: BGP-60, BGP-65, BGP-70 and BGP-80. The BGPs were characterized by chemical analysis, gel permeation chromatography (GPC), gas chromatographymass spectrometry (GC-MS), and Fourier transform-infrared spectroscopy (FT-IR). Finally, the in vitro antioxidant activities of the BGPs were determined through their capacities to scavenge superoxide anion, as well as 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals.Results: The four fractions designated BGP-60, BGP-65, BGP-70 and BGP-80 were polysaccharides with glucose as the main component. They were acidic in nature, with estimated molecular weights (MWs) of 28.6, 26.7, 11.4 and 3.05 kDa, respectively. Fractions BGP-60, BGP-65 and BGP-80 had α- type glycosidic linkage, whereas BGP-70 had β-type glycosidic linkage. Compared with vitamin C (vit C), it was found that BGP-60, BGP-65, BGP-70 and BGP-80 had strong potential antioxidant activities; BGP-60 exhibited a stronger antioxidant activity than BGP-65, BGP-70 or BGP-80 against DPPH and superoxide anion radicals, while BGP-65 had the highest antioxidant activity against hydroxyl radical.Conclusion: These results suggest that BGPs may be beneficial in the development and manufacture as potential therapeutic agents and functional foods.Keywords: Black ginseng, Polysaccharides, Purification, Antioxidant activity, Functional foods