Compositional and structural characteristics of sulfated polysaccharide from Enteromorpha prolifera

Polysaccharide from Enteromorpha prolifera (PE) has been reported to have biological activities such as anticancer, antioxidant and immunomodulatory activities, but the structural characteristics of PE remain unclear. In this study, the composition of PE was characterized using chemical methods, IR spectroscopy and HPLC. PE was identified as a sulfated polysaccharide mainly composed of rhamnose (Rha), glucuronic (GlcUA), xylose (Xyl) at a molar ratio of 3.2: 1.1: 1, and the average molecular weight was 620.3 kDa. An enzymatic hydrolysis method was used to obtain three carbohydrate products. The MS and NMR results of these residues revealed that the backbone of PE consisted of D-GlcUAp-α-(1 → 4)-3-sulfate-l-Rha p-β-(1 → 4)-d-Xyl p-β-(1 → 4)-3-sulfate-l-Rha p units. In this study, specific carbohydrate residues rich in sulfated rhamnose were prepared from E. prolifera. The structural determination of these sulfated carbohydrates may contribute to future studies on the relationship between structure and bioactivities.