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-1was 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, Nacetyl-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-1 beta, IL-6 and TNF-alpha) by RAW264.7 cells aswell as the expression of related genes (iNOS, IL-1 beta, IL-6 and TNF-alpha) and also enhanced their phagocytic activity through TLR4-mediated activation of the MAPKs and NF-kappa B signaling pathways. This study suggests that sea cucumber viscera are good sources of polysaccharides and SCVP-1 might be a novel immunomodulator. (C) 2019 Published by Elsevier B.V.