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-met hyl-alpha -D-glucurono)-D-xylan was isolated by alkaline extraction and fra ctionation of the crude hemicellulose, employing ion-exchange chromatograph y and gel filtration. The results of compositional and linkage analysis, su pported by NMR spectral data of the polysaccharide, showed the (1 --> 4)-li nked beta -D-xylopyranosyl backbone with about 15% of 4-O-methyl-D-glucuron ic 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 polysacc haride. The results evidenced that the branching of the xylan molecule is n ot regular. When tested for antitussive activity on mechanically induced co ughing in cats, the glucuronoxylan exhibited a much greater effect in compa rison to the drugs used in clinical practice to treat coughing. (C) 2002 El sevier Science Ltd. All rights reserved.