Fractionation, preliminary structural characterization and bioactivities of polysaccharides from Sargassum pallidum

•Sargassum pallidum polysaccharides were fractioned to obtain four fractions.•Preliminary structural features of four polysaccharide fractions were determined.•The bioactivities of four polysaccharide fractions were compared.

Sargassum pallidum polysaccharides were fractioned using a DEAE-Sepharose fast-flow column and four polysaccharide fractions (SP-P1, SP-P2, PV-P3 and SP-P4) were obtained. Structural analyses indicated that SP-P2 and SP-P4 had higher molecular weights than SP-P1 and SP-P3. SP-P2, SP-P3 and SP-P4 comprised of fucose, rhamnose, arabinose, galactose, glucose, xylose, and mannose in a similar molar ratio, while SP-P1 did not contain arabinose. SP-P2 and SP-P4 had a similar number of (1 → 6) or (1→) glycosidic linkages (1 → 2) or (1 → 4) glycosidic linkages and (1 → 3) glycosidic linkages, while SP-P1 and SP-P3 contained a small number of (1 → 3) glycosidic linkages. SP-P2 exhibited better bioactivities than SP-P1, SP-P3 and SP-P4, including antioxidant, anti-hemolysis inhibitory, α-amylase and α-glucosidase inhibitory and antiproliferative activities. These data suggest that S. pallidum has four polysaccharide fractions with different structural features and bioactivities and SP-P2 has potential to be explored as a functional food or complementary medicine.