Physicochemical Properties, Antioxidant And Immunomodulatory Activities Of Polysaccharides From The Stem, Leaf And Flower Of Dendrobium Candidum

In this study, the physicochemical properties such as chemical composition, monosaccharide, molecular weight, fluorescence spectrum, IR spectrum and scanning electron microscopy analysis of three Dendrobium candidum polysaccharides (SDPS, LDPS, FDPS) isolated from the stem, leaf and flower of Dendrobium candidum were analyzed; In vitro antioxidant activities were investigated in six different methods; And the effects of Immunomodulatory Activities on Macrophages RAW264.7.The chemical composition and physicochemical properties of Polysaccharides from the Stem, Leaf and Flower of Dendrobium candidum were different. It can be observed that the yields (34.64% for SDPS,10.85% for LDPS,6.25% for FDPS). Analysis of the chemical compositions (phenols, uronic acid, and protein) revealed that they may belong to acid polysaccharides bound with protein. The neutral sugar contents in SDPS significantly higher than that in FDPS and LDPS. The uronic acid contents in FDPS significantly higher than that in SDPS and LDPS. According to the results of gas chromatography analysis, SDPS, LDPS and FDPS were composed of six mobosaccharides with L-rhamnose, D-mannose, D-glucose, D-galactose, L-arabinose, and D-xylose. These Dendrobium candidum polysaccharides had large molecular weight ranging from 104 to 106. IR and SEM were applied to measure the structures of these three Dendrobium candidum polysaccharides (SDPS, LDPS and FDPS). The results indicate that the protein and uronic acid in polysaccharides may play a key role in their bioactivity.Assays of DPPH, ABTS, FRAP, OH, H2O2 and FIC in vitro to measure the antioxidant activities showed that SDPS showed the best OH radical scavenging ability(IC50=292.20μg/mL) and the best FIC assay (IC50=633.27μg/mL); FDPS showed the best DPPH radical scavenging ability(IC50=1998μg/mL), the best ABTS radical scavenging activities (IC50=1998μg/mL) and the best FRAP scavenging effects(under concentration of 2000μg/mL, the value of FRAP was 1796.60μmol/L);While LDPS showed the best H2O2 scavenging ability (under concentration of 500μg/mL, the scavenging rate was 40.94%). It may be related to the different chemical composition, monosaccharide composition and molecular weight.The study and the immunomodulatory activities of these three Dendrobium candidum showed that these three Dendrobium candidum polysaccharides significantly enhanced mouse peritoneal macrophages proliferation, the secretory activity of NO, TNF-α, IL-1β. There was a significant difference between the control group and the control group. FDPS showed the best activity to enhance the secretory of IL-1β (the value of IL-1β was 89.48μmol/L, under concentration of 800μg/mL). FDPS showed the best activity to enhanced mouse peritoneal macrophages proliferation (the Proliferation rate was168.07%, under concentration of 100μg/mL). LDPS showed the best activity to enhance the secretory of IL-1 β (the value of IL-1βwas 89.48μmol/L, under concentration of 800μg/mL) and the best activity to enhance the phagocytic activity (the value of OD was 0.40, under concentration of 400μg/mL). FDPS showed the best activity to enhance the secretory of NO (the value of NO was 54.9μmol/L, under concentration of 50μg/mL). The difference in the activity of Immunomodulatory may be related to the different components of SDPS, LDPS and FDPS.