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

Three sulphated polysaccharides, coded as BEMPA, BEMPB(1), BEMPB(2), 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 22,977 Da. BEMPB(1), with molecular weight of 64,117 Da, was a high (1→3)-linked arabinose-containing polysaccharide. BEMPB(2) 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 BEMPB(1) were deduced to be at the C-3 of (1→4)-linked mannose, while sulphate substitutions of BEMPA and BEMPB(2) were at C-4 of (1→3)-linked mannose. Furthermore, BEMPA exhibited highest inhibitory effects on growth of B-16 melanoma cells, and IC(50) were 31.1 μg/mL.