Structural characteristics of water-soluble polysaccharides from Heracleum sosnowskyi Manden

Fractions containing arabinogalactan proteins (AGPs) and pectic polysaccharides were isolated from above-ground parts of Heracleum sosnowskyi. Major units of their structure were elucidated using ion-exchange chromatography, gel chromatography, and NMR spectroscopy. The carbohydrate backbone of the polysaccharides consisted of 1,3-beta-D-galactopyranosyl residues, whereas side chains of the branched region consisted of the residues of 1,6-beta-galactopyranose, 1,5-alpha-L-arabinofuranose, 1,4-beta-D-glucuronic acid, and 1,6-beta-D-glucopyranose. The branching points were identified as 1,3,6-beta-D-galactopyranose residues. Side chains were terminated with beta-D-galactopyranose, alpha-L-arabinofuranose and alpha-L-rhamnopyranose. A significant part of the side-chain beta-1,6-galactan was substituted at C6 by 4-OMe-beta-D-glucuronic acid. A minor part of glucuronic acid was included in the alpha-Rhap-(1 -> 4)-beta-GlcA-(-> fragment. All the studied fractions contained 1,4-beta-D-galacturonic acid as well. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.