Structural characterization and antitussive activity of a glucuronoxylan from Mahonia aquifolium (Pursh) Nutt.

From the stems of Mahonia aquifolium (Pursh) Nutt. a water-soluble (4-O-methyl-α-d-glucurono)-d-xylan was isolated by alkaline extraction and fractionation of the crude hemicellulose, employing ion-exchange chromatography and gel filtration. The results of compositional and linkage analysis, supported by NMR spectral data of the polysaccharide, showed the (1→4)-linked β-d-xylopyranosyl backbone with about 15% of 4-O-methyl-d-glucuronic acid attached to O-2 of the xylose residues. The distribution pattern of uronic acid units along the xylan chain was determined by the method based on interpretation of the activity coefficient of the calcium counter-ions, estimated in a molecular-disperse solution of calcium salt of the polysaccharide. The results evidenced that the branching of the xylan molecule is not regular. When tested for antitussive activity on mechanically induced coughing in cats, the glucuronoxylan exhibited a much greater effect in comparison to the drugs used in clinical practice to treat coughing.