Structural studies of arabinogalactan and pectin from Silene vulgaris (M.) G. callus

Arabinogalactan and pectin (named silenan) were isolated from Silene vulgaris (M.) G. callus. Fractionation by ion-exchange chromatography on DEAE-cellulose and digestion with pectinase demonstrated that silenan from S. vulgaris callus (80% of D-galacturonic acid) and silenan from the aerial part of the campion S. vulgaris are similar: both pectins contain a high quantity of homogalacturonan segments. The NMR spectral data and mass spectrometry of the purified polysaccharide and its fragment obtained by Smith degradation confirmed that the core of the arabinogalactan consisted of the different segments of beta-1,3-D-galactopyranan. Some of the beta-galactopyranose residues of the backbone are branched at O-6. The side chains of the arabinogalactan were shown to contain residues of terminal and 3-O-substituted beta-galactopyranose, terminal alpha-arabinofuranose and alpha-rhamnopyranose, and 2-O-substituted alpha-rhamnopyranose. The alpha-rhamnopyranose residues in the sugar chain appeared to be 2-O-glycosylated by the beta-1,4-D-galactopyranosyl uronic acid residues.