Abstract

A novel acidic polysaccharide named SSPA50–1 was isolated from Scapharca subcrenata using a simulated gastric fluid extraction method. SSPA50–1 is a heteropolysaccharide with an average molecular weight of 44.7 kDa that is composed of galacturonic acid, glucose, galactose, mannose, ribose, rhamnose, fucose, xylose and arabinose at a molar ratio of 1.00:5.40:9.04:3.10:1.59:4.01:2.10:2.21:2.28. The structural characterization based on the methylation and 1D/2D NMR analyses indicated that SSPA50–1 is composed of →3)- β -L-Rha p -(1→, →3)- β -L-2-O-Me-Fuc p -(1→, →2)- α -D-Xyl p -(1→, →5)- α -L-Ara f -(1→, →3)- β -D-Gal p -(1→, →6)- α -D-Glc p -(1→, →3,4)- β -D-Man p -(1→, →3,4)- β -D-Gal p -(1→, β -D-Rib f -(1→, α -D-Glc p -(1→, and α -D-GalA p 6Me-(1→. Furthermore, SSPA50–1 possessed potent immunoregulatory activity by enhancing the phagocytosis and NO, iNOS, TNF- α and IL-6 secretion capacity of RAW264.7 cells. Otherwise, SSPA50–1 significantly promoted the proliferation of splenic lymphocytes and RAW264.7 macrophages. These results indicated that SSPA50–1 could be developed as a potential ingredient for immunostimulatory agents.