Abstract: The structure of an acidic polysaccharide PSM2b-A extracted from the cortex of Paeonia suffruticosa Andr. has been investigated. The result showed that PSM2b-A was composed of L-Rha, L-Ara, D-Xyl, D-Glc, D-Gal and D-Man containing uronic acid and traces of protein. By using chemical techniques such as methylation analysis, partial acidic hydrolysis, periodate oxidation, Smith degradation and IR, ¹³C NMR spectroscopy, the structure of PSM2b-A was deduced characteristic of a low branched heteropolysaccharide with a linkage of (1→6), (1→4) as a main chain which could further form into higher structure by means of intermolecular hydrogen bond.

Key words: Moutan Cortex, polysaccharide, primary structure, microscopic structure