Structural features of a polysaccharide from the mucin of water hyacinth

The mucin found in the nodal region of the weed, water hyacinth (Eichhornia crassipes), is a heteropolysaccharide composed of d-xylose, l-galactose and l-arabinose in the mol ratio of 1.3:1.2:1.0. Partial hydrolysis with acid gave four oligosaccharides which were characterized as: d-Xylp-(1 → 3)-l-Ara, l-Galp-(1 -→ 2)-l-Ara, d-Xylp-(1 → 3)-l-Galp-(1 → 2)-l-Ara, and d-Xylp-(1 → 2)-d-Xylp-(1 → 3)-l-Galp-(1 → 2)-l-Ara. These, together with the results of methylation analysis using GC and GC/MS and periodate oxidation, indicated that the trisaccharide repeating unit, → 4)-d-Xylp-(1 → 3)-l-Galp-(1 → 2)-l-Araf-(1 →, constitutes the backbone of the polysaccharide. Further, all the d-xylopyranosyl residues of the backbone are substituted at O-2 and, in addition, one out of seven such residues is also substituted at O-3; the substituents being l-Araf-(1 →, d-Xylp-(1 →, l-Galp-(1 →, d-Xylp-(1 → 3)-l-Araf-(1 →, residues.