Three sulphated polysaccharides isolated from the mucilage of mud snail, Bullacta exarata philippi: Characterization and antitumour activity

► Polysaccharides from the mucilage of mud snail were studied for the first time. ► They were sulphated polysaccharides. ► Chemical composition and structure feature were remarkably distinct. ► BEMPA showed significant inhibitory effects on the growth of cancer cells. Three sulphated polysaccharides, coded as BEMPA, BEMPB1, BEMPB2, were extracted from the mucilage of mud snail of Bullacta exarata and purified by DEAE-cellulose ion-exchange and size-exclusion chromatography. Structural analysis of purified polysaccharides by chemical and biochemical methods revealed BEMPA was a high (1→3,4)-linked mannose-containing polysaccharide with molecular weight of 22,977Da. BEMPB1, with molecular weight of 64,117Da, was a high (1→3)-linked arabinose-containing polysaccharide. BEMPB2 was mainly composed of (1→3,4)-linked mannose with molecular weight of 47,507Da. The comparison between sulphated polysaccharides and their desulphated products showed that sulphate substitutions of BEMPB1 were deduced to be at the C-3 of (1→4)-linked mannose, while sulphate substitutions of BEMPA and BEMPB2 were at C-4 of (1→3)-linked mannose. Furthermore, BEMPA exhibited highest inhibitory effects on growth of B-16 melanoma cells, and IC50 were 31.1μg/mL.