Antioxidant and immunomodulatory activities of a polysaccharide from Flammulina velutipes

ObjectiveTo evaluate the antioxidant and immunomodulatory activities of a unique polysaccharide from the medicinal fungus Flammulina velutipes in vitro.MethodsUsing water extraction and alcohol precipitation, crude polysaccharides were obtained. After purification by DEAE-cellulose 52 ion exchange chromatography and Sephacryl S-300 HR gel filtration chromatography, High performance liquid chromatography equipped with evaporative light-scattering detector, Infrared radiation and Nuclear magnetic resonance were used to evaluate the structure of the polysaccharide. Its immunomodulatory activity was measured by examining the production of nitric oxide (NO) and cytokine secretion, and via lymphocyte proliferation experiments. Its effects on the scavenging activities of hydroxyl radical, superoxide anion and reducing power were also measured.ResultsA water-soluble polysaccharide, Flammulina velutipes polysaccharide I-A (FVP I-A), was obtained with a molecular mass of 8.14×10⁴ Da determined by high performance gel permeation chromatography. An in vitro antioxidant assay indicated that FVP I-A could scavenge hydroxyl radical, superoxide anion and possessed reducing power and could largely promote NO production and augment the interleukin-1β, interleukin-6, and tumor necrosis factor-α secretion by RAW264.7 macrophages (P<0.05). Moreover, FVP I-A could promote lymphocyte proliferation (P<0.05), and synergistically enhance the augmentation of the proliferation of mouse lymphocytes by concanavalin A and lipopolysaccharides (P<0.01, P<0.05).ConclusionThe FVP I-A obtained from Flammulina velutipes possessed antioxidant activity and could enhance non-specific and specific immune responses in vitro.