CHARACTERIZATION OF 2 NOVEL POLYSACCHARIDES HAVING IMMUNOLOGICAL ACTIVITIES FROM THE ROOT OF PANAX-GINSENG

Two acidic polysaccharides, called ginsenan S-IA and ginsenan S-IIA, w ere isolated from the root of Panax ginseng C. A. MEYER. They were hom ogeneous on electrophoresis and gel chromatography, and their molecula r masses were estimated to be 5.6 x 10(4) and 1.0 x 10(5), respectivel y. Ginsenan S-IA is composed of L-arabinose: D-galactose: D-galacturon ic acid in the molar ratio of 8:8:1, and ginsenan S-IIA is composed of L-arabinose: D-galactose: D-glucose: D-galacturonic acid in the molar ratio of 15:10:2:5, in addition to small amounts of O-acetyl groups. About a half (ginsenan S-IA) and about a quarter (ginsenan S-IIA) of t he hexuronic acid residues exist as methyl esters. Reduction of carbox yl groups, methylation analysis, nuclear magnetic resonance and period ate oxidation studies indicated that their structural features include mainly alpha-1,5-linked L-arabino-beta-3,6-branched D-galactan type s tructural units. Both polysaccharides showed remarkable reticuloendoth elial system-potentiating activity in a carbon clearance test and pron ounced anti-complementary activity. These substances are the first exa mples having a relatively high content of both alpha-3,5-branched L-ar abinose and beta-1,4-linked D-galactose units among the acidic arabino galactans with activities on phagocytosis and anti-complement.