Purification, characterization and antioxidant activity of polysaccharides from Flammulina velutipes residue

In this study, we isolated polysaccharides from Flammulina velutipes residue (FVRP) using microwave-assisted extraction and then purified the polysaccharides by column chromatography to yield FVRP-1, FVRP-2 and FVRP-3. The structural characteristics of FVRP-1, FVRP-2 and FVRP-3 were investigated, and their antioxidant activities against ABTS+, DPPH and hydroxyl radicals were also analyzed in vitro. FVRP-1 was found to be neutral and rich in galactose. However, FVRP-2 and FVRP-3 were acidic polysaccharides and were rich in glucose. The average molecular weight of FVRP-1, FVRP-2 and FVRP-3 were 29,930, 62,290, and 36,310 Da, respectively. The glycosyl residue of FVRP-1 was an α-type glycosidic linkage, whereas FVRP-2 and FVRP-3 were β-type glycosidic linkages. We found FVRP-1, FVRP-2 and FVRP-3 had strong potential antioxidant activities in the order of FVRP-1 < FVRP-3 < FVRP-2. Our results thus suggested that FVRPs might be suitable for use as functional foods and as potential therapeutic agents.