An unusual (4- O-methyl- d-glucurono)- d-xylan isolated from the mucilage of seeds of the quince tree ( Cydonia oblonga)

Abstract

The major water-soluble polysaccharide in the mucilage of the seeds of the quince tree, Cydonia oblonga, is a partially O-acetylated(4- O-methyl- d-glucurono)- d-xylan having an exceptionally high proportion of glycuronic acid residues. The 4- O-methyl-α- d-glucopyranosyluronic and α- d-glucopyranosyluronic acid groups are linked to positions 2 of a (1 → 4)-β- d-xylan that is somewhat branched through the 2-positions. The O-acetyl groups are linked to the β- d-xylopyranosyl residues. The molar proportions of d-Xyl, 4- O-Me- d-GlcA, d-GlcA, and O-Ac are ∼ 2:0.8:0.2:1.