Structural characterisation of an anti-
ulcer polysaccharide (GL-BIII), purified from leaves of Panax ginseng C.A. Meyer, was studied. Methylation analysis indicated that
GL-BIII consisted mainly of terminal Arap, 4- or 5-substituted Ara, 2,4-disubstituted Rha, 4- and 6-substituted Gal, and 3,6-disubstituted Gal. Single radial gel diffusion using beta-glucosyl-Yariv
antigen indicated that
GL-BIII contained a small proportion of a beta-(1-->3,6)-
galactan moiety.
GL-BIII also contained terminal, 4-substituted, and 3,4-disubstituted GalA, and terminal and 4-substituted GlcA. Base-catalysed beta-elimination suggested that some 2-substituted Rha in
GL-BIII was attached to position 4 of a 4-substituted
uronic acid. Both mild
acid hydrolysis and endo-alpha-(1-->4)-
polygalacturonase digestion of
GL-BIII did not give fragments consisting mainly of GalA. Methylation analysis and GC-MS analysis of acidic
oligosaccharides liberated by partial
acid hydrolysis indicated that
GL-BIII contained a GalA-(1-->4)-Rha unit in addition to longer acidic units consisting of 2-substituted Rha and 4-substituted GalA.
Lithium-mediated degradation of
GL-BIII followed by
borohydride reduction gave small amounts of fractions containing long and intermediate neutral
oligosaccharide-
alditols and a large amount of a fraction containing short
oligosaccharide-
alditols. The long neutral
oligosaccharide-
alditol fraction mainly comprised 4- or 5-substituted Ara, terminal Galf, 6-substituted Glc, and 2-substituted Man, whereas the intermediate
oligosaccharide-
alditol fraction consisted mainly of terminal and 6-substituted Galp, 6-substituted Glc, and 2-substituted Man. Methylation analysis and GC-MS analysis of the short
oligosaccharide-
alditol fraction suggested that it contained at least 14 kinds of di- to tetra-saccharide-
alditols such as
Gal-(1-->2)-Rha-ol,
Gal-(1-->4)-Rha-ol, Ara-->Ara-ol, and Ara-->Ara-->Ara-ol.