Characterization of an Acidic Polysaccharide with Immunological Activities from the Tuber of Pinellia ternata

An acidic polysaccharide, called pinellian PA, was isolated from the tuber of Pinellia ternata Breit. It was homogeneous on electrophoresis and gel chromatography, and its molecular mass was estimated to be 11.8 x 10⁴. Pinellian PA is composed of L-arabinose: n-galactose: L-rhamnose: D-galacturonic acid: D-glucuronic acid in the molar ratio of 5:15:1:3:3, in addition to small amounts of O-acetyl groups and peptide moieties. Reduction of carboxyl groups, methylation analysis and nuclear magnetic resonance studies show that the core structural features include a backbone chain composed of β-1,3-linked D-galactose units. Some of the galactose units in the backbone carry β-1,6-linked D-galactosyl side-chains at position 6. Pinellian PA produces significant potentiation of the reticuloendothelial system, as shown by a carbon clearance test, and also exhibits potent anti-complementary activity.