Structural Characterization, Sulfated Derivative, Immunoregulatory Activity Of Exopolysaccharide Isolated From A Coral-associated Fungus

In this paper, the physicochemical and structural properties of GX1-1, GX2-1 from a coral symbiotic fungus Penicillium sp. gxwz406 were investigated. In addition, we also prepared sulfated derivatives-GX1-1S and elucidated the activity of the sulfated polysaccharides. The research results were as follows:1. The crude exopolysaccharides were extracted from the broth of coral symbiotic fungus Penicillium sp.gxwz446 and then was purified by a Q Sepharose Fast Flow column two major fractions contained abundant sugar were eluted with water and 0.25 mol/L Na Cl.The polysaccharides fractions were further purified on a gel permeation chromatography column. By the process, two polysaccharides GX1-1 and GX2-1 were obtained. The yield of GX1-1 and GX2-1 from crude polysaccharideswas 70% and 10%, respectively.Molecular weight of them were 5.0 k Da, 9.5 k Da. GX1-1 contained only glucose, while GX2-1 consisted of mannose, glucose and galactose at the ratio of 1.8:1.0:1.2. Both of the two polysaccharides were neutral polysaccharides. Both of the two polysaccharides were neutral polysaccharides.2. Completely acid hydrolysis, methylation analysis combining with IR, HPLC,GC-MS and NMR were used to determinate the structural properties. The GC-MS data demonstrated that GX1-1 was a kind of glucan which was composed of(1â†'4)-linked glucopyranose,(1â†'2,4)-linked glucopyranose,(1â†'2,4)-linked glucopyranose and terminal glucopyranose residues at the ratio of 8.0:1.7:1.0:3.0. To GX2-1, the linkage styles were more complex. It had three monosaccharides. The linkages of mannose were terminal mannopyranose,(1â†'6)-linked and(1â†'2,6)-linked mannopyranose at the ratio of3.0:4.0:3.4. The glucopyranose mainly contained(1â†'2)-linked glucopyranose and terminal glucopyranose,(1â†'6)-linked glucopyranose at the ratio of 12:2.5:1.4. Not the same as mannopyranose and glucopyranose which had pyran configuration, galactose in GX2-1 had dominant furan configuration with the linkages of Galf(1â†', â†'5)Galf(1â†' andâ†'3,5)Galf(1â†' at the ratio of 4.2:3.7:1.0.3. GX1-1 was the major fraction and had relatively simple composition and structure.Glucan with α configuration also had bioactivity. So GX1-1 was chosed to sulfated modification as an ideal polysaccharide. From IR anaysis, GX1-1 presented typical absorbsof sulfated polysaccharides. which indicated the sulfation of GX1-1 was successful.Through ion chromatography, The sulfate content of GX1-1S was 34.2%. The phagocytic capability of RAW264.7 macrophage was determined by neutral red dye test. The results showed that both GX1-1 and GX1-1S can elevate the phagocytic ability of macrophages.The sulfated derivative exhibited a more significant ability to promote the pinocytic activity of RAW264.7 cells and induce the production of NO.