Effects of extraction methods on the antioxidant activities of polysaccharides obtained from Flammulina velutipes

Four polysaccharides (CFP, UFP, MFP and EFP) were extracted from Flammulina velutipes using hot water, ultrasonic, microwave or enzymatic methods optimized by orthogonal test. Preliminary structural characterizations were conducted using physicochemical properties. Polysaccharides extracted by all four methods showed similar physicochemical characteristics and FT-IR spectra. However, SEM images of tissues of F. velutipes were significantly different. EFP demonstrated better antioxidant activities against hydroxyl radical as well as improved metal chelating activity. UFP showed higher DPPH scavenging activity, but CFP exhibited higher antioxidant activity in reducing power. Hence, these polysaccharides can be used as natural antioxidants in functional foods or medicine. Further experiments on the biological activities of these four polysaccharides are currently in progress.