An acidic polysaccharide having immunological activities from the rhizome of Cnidium officinale.

An acidic polysaccharide, designated as cnidirhan AG, was isolated from the rhizomes of Cnidium officinale Makino. It was homogeneous on electrophoresis and gel chromatography, and its molecular mass was estimated to be 5.1 x 10(4). It showed pronounced reticuloendothelial system-potentiating activity in a carbon clearance test, and had a remarkable effect on both anti-complementary and alkaline phosphatase-inducing activities. It is composed of L-arabinose: D-galactose: D-glucuronic acid in the molar ratio of 2:6:1, in addition to small amounts of O-acetyl groups. Methylation analysis, carbon-13 nuclear magnetic resonance, controlled Smith degradation and limited acid hydrolysis indicated that the core structural features of cnidirhan AG include a backbone chain composed of beta-1,3-linked D-galactose residues. Some of the galactose units in the backbone carry beta-D-galactosyl side chains at position 6. Both alpha-L-arabinosyl arabinose side chains and terminal beta-D-glucuronic acid residues are linked to the core galactan units.