title: The gel-forming polysaccharide of psyllium husk (Plantago ovata Forsk).
abstract: The physiologically active, gel-forming fraction of the alkali-extractable polysaccharides of Plantago ovata Forsk seed husk (psyllium seed) and some derived partial hydrolysis products were studied by compositional and methylation analysis and NMR spectroscopy. Resolving the conflicting claims of previous investigators, the material was found to be a neutral arabinoxylan (arabinose 22.6%, xylose 74.6%, molar basis; only traces of other sugars). With about 35% of nonreducing terminal residues, the polysaccharide is highly branched. The data are compatible with a structure consisting of a densely substituted main chain of beta-(1-->4)-linked D-xylopyranosyl residues, some carrying single xylopyranosyl side chains at position 2, others bearing, at position 3, trisaccharide branches having the sequence L-Araf-alpha-(1-->3)-D-Xylp-beta-(1-->3)-l-Araf. The presence of this sequence is supported by methylation and NMR data, and by the isolation of the disaccharide 3-O-beta-D-xylopyranosyl-L-arabinose as a product of partial acid hydrolysis of the polysaccharide.
authors.affiliation: Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Milton H
authors.initials: MH
authors.lastname: Fischer
authors.forename: Nanxiong
authors.initials: N
authors.lastname: Yu
authors.forename: Gary R
authors.initials: GR
authors.lastname: Gray
authors.forename: John
authors.initials: J
authors.lastname: Ralph
authors.forename: Laurens
authors.initials: L
authors.lastname: Anderson
authors.forename: Judith A
authors.initials: JA
authors.lastname: Marlett
mesh_terms: D001089:Arabinose / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D010084:Oxidation-Reduction; D010943:Plantago / Q000737:chemistry*; D011134:Polysaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D014994:Xylose / Q000737:chemistry
chemical_list: D005782:Gels; D011134:Polysaccharides; D014994:Xylose; D001089:Arabinose