LAUSR

This study was performed to optimize ultrasound-assisted extraction (UAE) of polysaccharides from Flammulina velutipes using response surface methodology (RSM). The optimum extraction conditions producing a maximum F. velutipes polysaccharide (FVP) yield of 20.52% were as follows: material granularity (X1), 400-mesh; ultrasonic power (X2), 380 W; and extraction time (X3), 25 min. The in vitro antioxidant activity of FVP prepared using UAE (FVP-UE) under optimum conditions and hot water extraction (FVP-HE) were compared using three free radical (hydroxyl radical, superoxide anion radical and 2,2-di[4-tert-octylphenyl]-1-picrylhydrazyl [DPPH]) scavenging activity and the ferric-reducing antioxidant power (FRAP) assays. The results showed that FVPS exhibited weaker (p < 0.5) reducing power and hydroxyl radical scavenging ability than vitamin C (VC) did. Superoxide anion radical scavenging rate of FVPS was dose-dependent, the scavenging rate was higher than that of VC (p < 0.5) within the range of 0.5–1.0 mg/mL. The DPPH scavenging ability was lower than that of VC (p < 0.5) at concentration <1.0 mg/mL. Both FVPS exhibited no significant difference (p > 0.5) in reducing power as well as hydroxyl radical, superoxide anion radical and DPPH scavenging activities. These findings suggest that UAE had a negligible effect on antioxidant activity under the optimal condition, FVP-UE could be used as a natural antioxidant.