In vitro immunostimulating polysaccharide fractions from roots of Glycyrrhiza uralensis fish. et DC

Abstract

AbstractThe water soluble anticomplementary, mitogenic and immune complex (IC) clearance enhancing crude polysaccharide fraction, prepared from the roots of Glycyrrhiza uralensis Fisch. et DC., was fractionated into five polysaccharide fractions by the addition of cetyltrimethylammonium bromide. A strongly acidic polysaccharide fraction (GR‐2), which has the most potent immunostimulating fraction, contained about 60% galacturonic acid with arabinose, galactose and glucose as the major neutral sugars, and a small quantity of protein. Pronase digestion did not alter the anticomplementary and mitogenic activities, however, endo‐α‐(1→4)‐polygalacturonase digestion reduced both activities. The IC clearance activity of GR‐2 was slightly decreased by pronase digestion but not by endo‐polygalacturonase digestion. GR‐2 was further purified by ion exchange chromatography and gave GR‐2IIa, GR‐2IIb and GR‐2IIc. GR‐2IIa and IIb are mainly composed of rhamnose, arabinose, galactose and galacturonic acid and showed only moderate anticomplementary activity. GR‐2IIc consisted of rhamnose, fucose, arabinose, mannose, glucose, galactose, glucuronic acid and galacturonic acid as the component sugars with a small quantity of protein. GR‐2IIc had the most potent anticomplementary, mitogenic and IC clearance activities. From these results it may be concluded that anticomplementary and mitogenic activities are caused by polysaccharides containing a polygalacturonan moiety.