The Study Of Structure Characterization And Immunological Activities Of Longan Polysaccharide

In order to define the compositions and structures of longan polysaccharide and reveal the differences of compositions and immunomodulatory activity between dried and fresh longan polysaccharide, six homogeneous polysaccharide fractions were obtained from dried and fresh longan in this study The structures of these polysaccharide were characterized by infrared spectroscopy (IR),SEC-LLS、 gas chromatography (GC) and nuclear magnetic resonance (NMR). Then the influences of dried and fresh longan polysaccharide against phagocytic activity of macrophages,cytokine secretion and spleen lymphocyte proliferation were analyzed. Then the differences of immunomodulatory activity between dried and fresh longan polysaccharide were investigated. The main findings are as follows:1. Determine the discoloring and removal of protein process of longan polysaccharidesEffects of the seven kinds of resin on deproteination and decolorization in purifying longan polysaccharide were compared the D301-R resin is the best one. The optimal conditions of D301-R has been confirmed as fellow:liquid ratio 0.61 g:1 mL, temperature 48℃, time 2.0h, pH5.0. Under the optimal conditions, decolorization rate and retention rate of is 75.32% and 93.37%, respectively. The deproteination rate is 91.83%%.2. Six kinds of homogeneous polysaccharide were obtained in arillus longan.The conditions for ion exchange separation were determined through comparing the separationeffect between DEAE-FF and Q-FF. Using G4000PWxl series G3000PWx1,, the the neutral polysaccharide LPgl (16.41 min) and the acidic polysaccharide LPg2 (25.23 min) were separated from dried longan flesh. Four kindsof polysaccharides, LPx1 (16.08min), LPx2 (17.75min) and acidic polysaccharides LPx3 (20.83min), LPx4 (27.10min) were purified from fresh longan flesh.3. The structural analysis of longan polysaccharidesThe structures of five kinds of homogeneous polysaccharide were characterized by IR、SEC-LLS、GC and NMR. LPg1 was a-polysaccharide composed of rhamnose, mannose, glucose and galactose (relative molar ratio 0.2:0.21:1:0.2, Mw=1.06× 107Da; Rz=51.7nm) with acetyl structure. LPx1 was a-polysaccharide composed of mannose and glucose (relative molar ratio 0.59:1, Mw=1.31×107Da; Rz=50.3nm). LPx3 was β-polysaccharide composed of arabinose,xylose,mannose,glucose and galactose (relative molar ratio 0.09:0.18:1.15:1:0.51, Mw=1.85×106Da, Rz=53.1nm) with acetyl structure. LPg2 was β-polysaccharide composed of arabinose,mannose,glucose and galactose (relative molar ratio 0.25:0.49:1:0.5, Mw=9.64×106Da; Rz=54.0nm). LPx4 was a-furanose composed of rhamnose, fucose, arabinose, xylose, mannose, glucose, galactose, glucuronide and galacturonic acid (relative molar ratio 0.05:0.07:0.12:0.14:1.16:1:0.22:0.32:0.1, Mw=6.31×104Da;Rz=100.6nm).4. The immunomodulatory activities of polysaccharide from dried and fresh longan were compared.The results showed that in 12.5～100μg/mL concentration range, polysaccharides from dried and fresh longan are able to increase the phagocytic activity of macrophages. Relative to polysaccharide from fresh longan, The polysaccharides from dried longan have a better effect in low concentration range((12.5-25μg/mL)), and it has a stronger role in promoting macrophages to secrete NO, IL-1β, IL-6and IFN-γ. In 12.5～50μg/mL concentration range,polysaccharides from dried and fresh longan have the effect that promote the spleen lymphocyte proliferation and show dose-dependent manne,and the polysaccharide which comes from dried longan have a powerful influence. In 25-100μg/mL concentration range, they showed inhibition on multiplication of spleen lymphocyte that had been induced with LPS and the dried longan polysaccharides have a more marked effect. Comprehensive the above results show that polysaccharides from dried longan may play a better activity role in in regulation of macrophages and spleen lymphocyte proliferation.Base on the difference among monosaccharide composition,structure and activity,this paper can reveal the material foundation of healthy function of polysaccharides from dried longan.Clear and definite the relationship between structures and immunomodulatory activity of longan polysaccharides, to provide the foundation for process deeply industry of longan.