Two Acidic Polysaccharides Having Reticuloendothelial System Potentiating Activity from the Raw Root of Rehmannia glutinosa

Two acidic polysaccharides, called rehmannan FS-I and rehmannan FS-II, were isolated from the raw root of Rehmannia glutinosa Liboschitz. They were homogeneous on electrophoresis and gel chromatography, and their molecular masses were estimated to be 5.8 x 10⁴ and 6.6 x 10⁴, respectively. Rehmannan FS-I is composed of L-arabinose: D-galactose: L-rhamnose: D-galacturonic acid: D-glucuronic acid in the molar ratio of 68:40:4:84:3; rehmannan FS-II is composed of L-arabinose: D-galactose: L-rhamnose: D-galacturonic acid in the molar ratio of 18:15:4:33, in addition to small amounts of 0-acetyl groups. About two-thirds (rehmannan FS-I) and about one half (rehmannan FS-II) of the hexuronic acid residues exist as methyl esters. Methylation analysis of the carboxyl-reduced derivatives and nuclear magnetic resonance studies indicated that their structural features include mainly both arabino-3, 6-galactan and rhamno-galacturonan type structural units. Both polysaccharides showed remarkable reticuloendothelial system-potentiating activity in a carbon clearance test.