Constituents of the seed of Malva verticillata. III. Characterization of the major pectic peptidoglycan and oligosaccharides.

Abstract

The major pectic peptidoglycan, designated as MVS-V, was isolated from the seeds of Malva verticillata L. It was homogeneous on electrophoresis and gel chromatography. It was composed of about 43% polysaccharide and 57% protein moieties, and its molecular weight was estimated to be 22000. The polysaccharide moiety was isolated, and found to be composed of L-arabinose : D-xylose : D-galactose : L-rhamnose : D-galacturonic acid in the molar ratio of 6 : 5 : 3 : 8 : 24. One-sixth of the D-galacturonic acid residues exist as the methyl esters. O-Acetyl groups were identified, and the content amounted to 3.3% of the polysaccharide moiety. Methylation analysis of the carboxyl-reduced derivative, nuclear magnetic resonance, periodate oxidation, and partial hydrolysis studies enabled elucidation of the structural features of the polysaccharide moiety. It is a pectic substance having a rhamnogalacturonan backbone with arabinoxylogalactan side chains. Several oligosaccharides belonging to the raffinose family were also isolated and identified from the seeds.