Immunomodulatory activities on macrophage of a polysaccharide from Sipunculus nudus L.

A water-soluble polysaccharide, named as SNP, was extracted and fractioned from the body wall of Sipunculus nudus L. by DEAE-Sepharose anion exchange and Sepharose CL-6B column chromatography. The structural characteristics of SNP investigated by high performance size exclusion chromatography (HP-SEC), Fourier transform infrared spectroscopy (FT-IR) and gas chromatography–mass spectrometry (GC–MS) indicated that SNP was a homogeneous polysaccharide with a molecular mass of 350 kD and the monosaccharide composition was determined to be rhamnose (28%), fucose (16%) and galactose (56%). SNP was able to upregulate the expression of cytokines (IL-6 and TNF-α), but did not affect IL-10 secretion by murine macrophages and human peripheral blood mononuclear cells. RT-PCR analysis demonstrated that the SNP also induced the expression of iNOS and COX-2, responsible for the induction of NO and PGE2 respectively, and SNP suppressed the arginase activity. These results suggest that the polysaccharide isolated from S. nudus activates macrophages and has potent immunostimulating activity.