Antioxidant and immunomodulatory activities of a polysaccharide from Flammulina velutipes

OBJECTIVE: To evaluate the antioxidant and immunomodulatory activities of a unique polysaccharide from the medicinal fungus Flammulina velutipes in vitro.METHODS: Using 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.RESULTS: A water-soluble polysaccharide, Flammulina velutipes polysaccharide I-A(FVP I-A), was obtained with a molecular mass of 8.14×104Da 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).CONCLUSION: The FVP I-A obtained from Flammulina velutipes possessed antioxidant activity and could enhance non-specific and specific immune responses in vitro.

Can nanoparticles and nano-protein interactions bring a bright future for insulin delivery?

Insulin therapy plays an essential role in the treatment of diabetes mellitus.However,frequent injections required to effectively control the glycemic levels lead to substantial inconvenience and low patient compliance.In order to improve insulin delivery,many efforts have been made,such as developing the nanoparticles (NPs)-based release systems and oral insulin.Although some improvements have been achieved,the ultimate results are still unsatisfying and none of insulin-loaded NPs systems have been approved for clinical use so far.Recently,nano?protein interactions and protein corona formation have drawn much attention due to their negative influence on the in vivo fate of NPs systems.As the other side of a coin,such interactions can also be used for constructing advanced drug delivery systems.Herein,we aim to provide an insight into the advance and flaws of various NPs-based insulin delivery systems.Particularly,an interesting discussion on nano?protein interactions and its potentials for developing novel insulin delivery systems is initiated.