Relevant structural features of the polysaccharide from Pithecellobium mangense gum exudate

Pithecellobium mangense (Leguminosae), disseminated in north-cast of Venezuela, produces a clear gum very soluble in water. The polysaccharide, isolated from this gum, contains galactose, arabinose and glucuronic acid and its 4-o-methyl derivative. Smith degradation analysis indicated that the backbone structure is that of a beta-(1-->3) galactan. Methylation analysis revealed the presence of 3,6-di-o-substituted galactosyl units, indicating a branched structure. Arabinosyl side chains, up to four units long, were present as (x-L-arabinofuranosyl (terminal and 3-o-linked) and beta -L-arabinopyranosyl (3-o-linked) residues. Two aldobiouronic acids, 6-o-beta -D-glucopyranosyluronic acid-D-galactose and 4-o-(4-o-methyl-alpha -D-glucuronopyranosyl)-D-galactose, were isolated and characterized. (C) 2001 Elsevier Science Ltd. All rights reserved.