Immunomodulatory Activities Of Polysaccharides From Dendrobium Huoshanense On Macrophages And Its Relationships With Structural Characteristics

Dendrobium huoshanense is the traditional Chinese medicine herb. The crude polysaccharides of D.huoshanense (HPS) was fractionated by DEAE-Cellulose anion-exchange column and gel filtration of Sephadex G-100in turn, giving seven fractions including HPS1-A, HPS1-B, HPS1-C, HPS1-D, HPS1-E, HPS1-F and HPS1-G with molecular weights of6743.50,339.69,8.90,6.81,4.97,3.72and2.59kDa, respectively. The physicochemical properties and structural characteristics were revealed by a combination of chemical and instrumental analysis, including congo red method, methylation analysis, UV, GC and GC-MS. The results showed that the seven fractions without proteins and nucleic acids consisted of glucose, galactose and manose with different molar ratio, glycosidic types of which were1,4-linked D-G1cp,1,6-linked D-G1cp,1-linked D-Galp,1,4,6-linked D-Glcp and1,3,6-linked D-Manp.The immunomodulatory activities of seven fractions were examined using murine peritoneal macrophages. The results showed that all the fractions could promot the production of nitric oxide (NO) and TNF-a and the phagocytic function of macrophages. Besides HPS1-B and HPS1-C, other fractions had stimulating effects on IL-1β production of macrophages. The principal component analysis of immunomodulatory activities of seven fractions found that the immune responses of macrophages to HPS were different with different fractions. The immunomodulatory activities of HPS1-B and HPS1-D were the highest while those of HPS1-G were lowest in the seven fractions from HPS.Multiple linear regression was used to identify the relationship between immunomodulatory activities and structural characteristics of polysaccharides from HPS. Four regression equations were obtained with NO, TNF-a and IL-1β production as well as phagocytic activity as dependent variables Y while structural characteristics as independent variables X. Partial regression coefficients of regression equations quantitatively predicted the influence of structural characteristics of polysaccharides from HPS on immunomodulatory activities, which could supply guidance for investigation of immune modulation mechanism of HPS on macrophages.