Partial structure of an anti-ulcer pectic polysaccharide from the roots of Bupleurum falcatum L.

Methylation analysis of a pectic polysaccharide (Bupleuran 2IIc) with anti-ulcer activity, isolated from the roots of Bupleurum falcatum L., revealed (1----4)-linked alpha-GalA together with small proportions of 2,4- and 3,4-linked GalA, and variously linked neutral sugars. Digestion of Bupleuran 2IIc with endo-alpha-(1----4)-polygalacturonase gave mainly galacturono-oligosaccharides (PG-4) and small proportions of enzyme-resistant regions (PG-1-3). PG-1 contained the sequence----4)GalA- (1----2)-Rha-(1----4)-GalA-(1----, and partial acid hydrolysis gave GalA-(1----4)-Rha, GlcA-(1----4)-Rha, and several di- and oligosaccharides consisting variously of Xyl, Glc, Gal, and Man. PG-2 and PG-3 each contained Rha, Fuc, Ara, Xyl, Man, Gal, Glc, GalA, GlcA, 2-Me-Fuc, 2-Me-Xyl, apiose (Api), aceric acid (AceA), and 3-deoxy-D-manno-2-octulosonic acid (Kdo). PG-4 contained (1----4)-linked alpha-galacturono-di-to-penta- saccharides and GalA. The galacturono-tetra- and -penta-saccharides had one and three methyl-esterified GalA units, respectively, and some of the galacturono-oligosaccharides contained 2,4- or 2,3-linked GalA.