Water-soluble polysaccharides from Ulva intestinalis: Molecular properties, structural elucidation and immunomodulatory activities

Water-soluble sulfated polysaccharides extracted from Ulva intestinalis and fractionated using DEAE Sepharose fast flow column to identify their molecular properties and macrophage cells stimulating activities. Crude and fractions (F-1 and F-2) were formed of neutral sugars (58.7-74.7%), sulfates (6.2-24.5%), uronic acids (4.9-5.9%) and proteins (3.2-10.4%). Different levels of sugar constituents including rhamnose (30.1-39.1%), glucose (39.0-48.4%), galactose (0.0-15.8%), xylose (8.5-11.3) and arabinose (0.0-5.1%). The molecular weight (M-w) of crude a nd fractionated polysaccharides ranged from 87.1 x 10(3) to 194.1 x 10(3) (g/ mol). Crude polysaccharides were not toxic to RAW264.7 cells and fractions induced cell proliferation. Fraction F1 stimulated RAW264.7 cells to release considerable amounts of nitric oxide, IL-1b, TNF-alpha, IL-6, IL-10 and IL-12 cytokines. The main backbone of the most immunostimulating polysaccharide (F-1) was consisted of mixed linkages of (1 -> 2)-linked rhamnose and (1 -> 2)-linked glucose residues. Copyright (C) 2017, Food and Drug Administration, Taiwan. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license.