Structural analysis of immunostimulating sulfated polysaccharides from Ulva pertusa

► The glycosidic linkage of the sulfated polysaccharide from U. pertusa was investigated. ► The optimal desulfation method was the reaction at 120 °C for 40 min with methanol. ► The backbone was linked by (1→4)-rhamnopyranosyl or (1→4)-glucopyranosyl residues. ► Branches were at the O-2 position of the (1→4)-rhamnopyranosyl residues. ► The sulfate groups were found mostly on glucuronic acid residues at O-3 position.