Chemical properties and immunostimulatory activity of a water-soluble polysaccharide from the clam of Hyriopsis cumingii Lea

A water-soluble polysaccharide HCLPS-1 was isolated from clam of Hyriopsis cumingii Lea by hot water, DEAE-cellulose and Sephadex-G200, gel-permeation chromatography and tested for its immunostimulatory activities. Its structural characteristics were investigated by UV, IR, HPLC, NMR spectroscopy, methylation analysis and GLC–MS. HCLPS-1 consisted of glucose and xylose with the molar ratio of 35:1. Based on the data obtained, HCLPS-1 was determined to has a main chain of (1 → 4)-linked β-d-glucopyranosyl residues, with a weight-average molecular weight of about 1.56 × 105 Da. HCLPS-1 not only could significantly promote concanavalin A (Con A), lipopolysaccharide (LPS)-stimulated splenocytes proliferation in concentration-dependent manner in vitro, but also increase Con A- and LPS-induced splenocytes proliferation in mice immunized with the sheep red blood cell (SRBC). Meanwhile, HCLPS-1 remarkably promoted 2, 4-dinitrofluorobenzene (DNFB)-induced delayed-type hypersensitivity (DTH) reactions. These results suggested that HCLPS-1 could improve both specific and non-specific cellular immune response and might be explored as a potential natural immunomodulator.