Structure of Silenan, a Pectic Polysaccharide from Campion Silene vulgaris (Moench) Garcke

Abstract

A pectic polysaccharide named silenan, [α]_D ²⁰ +148.6° (c 0.1; H₂O), was isolated earlier from the aerial part of campion, Silene vulgaris (Moench) Garcke. Silenan has been shown to contain homogalacturonan segments as “smooth regions” and rhamnogalacturonan fragments as “hairy regions”. The present study reveals a generalization of structural features of silenan. Silenan was subjected to enzymic digestion with pectinase, to Smith degradation, and to lithium-degradation to determine the conforming poly- and oligosaccharide fragments of “hairy regions” of silenan. The NMR-spectral data and massspectrometry confirmed that the core of the ramified region of silenan consisted of residues of α-rhamnopyranose 2-O-glycosylated with the residues of α-1,4-D-galactopyranosyl uronic acid. The part of the α-rhamnopyranose residues of the backbone are branched at O-4. On the basis of the data, the hairy regions of silenan proved to contain mainly linear chains of β-1,3-, β-1,4-, and β-1,6-galactopyranan and α-1,5-arabinofuranan. The side chains of the ramified region were shown to have branching points represented 2,3-, 3,6-, 4,6-di-O-substituted β-galactopyranose residues.