The major pectic arabinogalactan having activity on the reticuloendothelial system from the roots and rhizomes of Saposhnikovia divaricata.

The major acidic polysaccharide, named saposhnikovan A, was isolated from the roots and rhizomes of Saposhnikovia divaricata. It showed remarkable reticuloendothelial system-potentiating activity in a carbon clearance test. It is composed of L-arabinose: D-galactose: D-galacturonic acid in the molar ratio of 6:15:10, and its molecular weight was estimated to be 54000. About 35% of the D-galacturonic acid residues exist as the methyl esters. Methylation analysis, 13C-nuclear magnetic resonance, and controlled Smith degradation studies indicated that the polysaccharide has the alpha-1----4-linked D-galacturonan backbone bearing alpha-1----5-linked L-arabino-beta-3,6-branched D-galactan side chains.