Molecular characterization and biological activities of watersoluble sulfated polysaccharides from Enteromorpha prolifera

Sulfated polysaccharides isolated from Enteromorpha prolifera and fractionated using ion exchange and gel permeation chromatography were investigated to determine their molecular characteristics and biological activities. The crude and fractionated polysaccharides (F1, F2, and F3) consisted mostly of carbohydrates (50.8–62.5%), sulfates (14.5–18.8%), and uronic acid (13.8–16.6%) with different levels of monosaccharides, including rhamnose (57.1–87.6%), glucose (3.6-39.1%), and xylose (2.4–8.8%). The protein content ranged from 1.0 to 13.9%, and after the fractionation, most proteins were included in the F2 fraction (11.3%). The crude, F1, F2, and F3 exhibited the molecular weights (Mw) of 37–1,281×103 g/mol. The polysaccharides had no significant direct cytotoxicity to cancer cells AGS or DLD- 1. On the other hand, the F1 and F2 stimulated Raw 264.7 cells to produce a considerable amount of nitric oxide (NO). The investigation of F2 subfractions failed to reveal a specific subfraction more significantly affecting the NO production, thus requiring further systematic elucidation of their structural characteristics.