Extraction, purification and characterization of polysaccharides from clam (Ruditapes philippinarum)

Polysaccharides were extracted from clam (Ruditapes philippinarum) (RPPS) by enzymatic method, and the crude polysaccharides were purified by filtration DEAE-Sepharose Fast Flow chromatography and Sephacryl S-400 size-exclusion chromatography. Two main fractions of RPPS-1a and RPPS-1b were separated. Furthermore, characterizations, such as polysaccharides composition and thermal properties, were analyzed. The results showed that polysaccharides extraction rate was 0.89%, and polysaccharides content was 62.5%. The polysaccharides were comprised of aminosu-gars, uronic acid, fucose and sulfate, which accounted for 0.27%, 59.30%, 0.75% and 1.33%, respectively. According to the infrared spectra, both RPPS-1a and RPPS-1b were polysaccharides containing -CHO and-COOH, and RPPS-1a had an additional sulfate groups. DSC analysis revealed that RPPS-1a might have straight-chain crystals, and RPPS-1b might contain more branch-chain crystals.