Structural investigation of water-hyacinth (Eichhornia crassipes) polysaccharides. Part I. Water-soluble polysaccharides

A galactomannan and a branched (1 → 3)-β- D -glucan were isolated from the water hyacinth plant. The galactomannan, purified from the cold water extract, is composed of D -galactose and D -mannose in a ratio of 1.0:2.8. It has a (1 → 4)-linked D -mannose backbone, one out of three D -mannose residues being substituted with a single α- D -galactosyl unit. The branched (1 → 3)-β- D -glucan isolated from the hot water extract has a main chain composed of β-(1 → 3)-linked D -glucopyranosyl residues, and two single β(1 → 6)- D -glucopyranosyl groups attached as side chains to, on average, every 5 sugar units of the main chain. In addition, the branching of the β-glucan occurs regularly at O-6 of the β-(1 → 3)-linked backbone.