Isolation and characterization of a novel polysaccharide from the mucus of the loach, Misgurnus anguillicaudatus

A method for the isolation of polysaccharides from the mucus of the loach, Misgurnus anguillicaudatus, has been devised. It involves the extraction of the skin mucus with tap-water (pH 7) at room temperature, followed by centrifugation, vacuum vaporization, Sevag extraction, precipitation with ethanol, vacuum filtration and lyophilization. The sediment preparation was identified to be a carbohydrate compound by several qualitative tests. Using Sephadex G-100 column (1×50 cm) gel filtration to treat the sediment preparation, two major constituents, P and O, were yielded. P was identified to be a novel polysaccharide and named M. anguillicaudatus polysaccharide (MAP) or misgurnan. Its average molecular weight (Mw=1.30×105, Mn=1.23×105) was determined by gel permeation chromatography (GPC). It was characterized by UV, IR and NMR spectroscopy. The major structural monomers of MAP were identified to be d-galactose, l-fucose and d-mannose by paper chromatography (PC) and gas chromatography (GC). Smith degradation test showed that the monoses link each other by α-1,3 bonds. This is the first report on the chemical structure of a free neutral hetero-polysaccharide in loach mucus.