Separation, purification, structural analysis and immune-enhancing activity of sulfated polysaccharide isolated from sea cucumber viscera

A novel sulfated polysaccharide (SCVP-1) was isolated from sea cucumber viscera and purified to elucidate its structure and immune-enhancing ability. SCVP-1 was found to be a homogeneous polysaccharide with a relative molecular weight of 180.8 kDa and composed of total sugars (60.2 ± 2.6%), uronic acid (15.3 ± 1.8%), proteins (6.8 ± 0.8%), and sulfate groups (18.1 ± 0.9%). SCVP-1 consisted of mannose, glucosamine, glucuronic acid, N-acetyl-galactosamine, glucose, galactose and fucose at an approximate molar ratio of 1.00:1.41:0.88:2.14:1.90:1.12:1.24. The fourier transform infrared spectra (FT-IR) and nuclear magnetic resonance (NMR) analyses showed that SCVP-1 was a kind of glycosaminoglycan. And the sulfation patterns of the fucose branches were Fuc2,4S, Fuc3,4S and Fuc0S. The surface morphology of SCVP-1 presented loose and irregular sheet structure formed by aggregation of polysaccharide molecules with spherical structure. Moreover, SCVP-1 promoted the production of nitric oxide (NO) and cytokines (IL-1β, IL-6 and TNF-α) by RAW264.7 cells as well as the expression of related genes (iNOS, IL-1β, IL-6 and TNF-α) and also enhanced their phagocytic activity through TLR4-mediated activation of the MAPKs and NF-κB signaling pathways. This study suggests that sea cucumber viscera are good sources of Polysaccharides and SCVP-1 might be a novel immunomodulator.