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.