Plant mucilages. XXIV. The structural features of althaea-mucilage O, a representative mucous polysaccharide from the roots of Althaea officinalis.

Abstract

Partial acid hydrolysis of Althaea-mucilage O, a representative mucous polysaccharide isolated from the roots of Althaea officinalis L., led to the isolation of five oligosaccharides. Analysis of their components, as well as reduction and methylation, and partial degradation studies showed that these oligosaccharides are O-α-(D-galactopyranosyluronic acid)-(1→2)-L-rhamnopyranose, O-β-(D-glucopyranosyluronic acid)-(1→3)-O-α-(D-galactopyranosyluronic acid)-(1→2)-L-rhamnopyranose, and the hexasaccharide, the nonasaccharide, and the dodecasaccharide composed of a repeating unit having the structure of the trisaccharide through position 4 of the D-galacturonic acid residue. The polysaccharide was also subjected to chromium trioxide oxidation, and to controlled Smith degradation. The configuration and the mode of branching were determined. The structural features of the mucilage are discussed.