Relevant structural features of the polysaccharide from Pithecellobium mangense gum exudate

Pithecellobium mangense (Leguminosae), disseminated in north-cast of Venezu ela, produces a clear gum very soluble in water. The polysaccharide, isolat ed from this gum, contains galactose, arabinose and glucuronic acid and its 4-o-methyl derivative. Smith degradation analysis indicated that the backb one structure is that of a beta-(1-->3) galactan. Methylation analysis reve aled the presence of 3,6-di-o-substituted galactosyl units, indicating a br anched structure. Arabinosyl side chains, up to four units long, were prese nt as (x-L-arabinofuranosyl (terminal and 3-o-linked) and beta -L-arabinopy ranosyl (3-o-linked) residues. Two aldobiouronic acids, 6-o-beta -D-glucopy ranosyluronic acid-D-galactose and 4-o-(4-o-methyl-alpha -D-glucuronopyrano syl)-D-galactose, were isolated and characterized. (C) 2001 Elsevier Scienc e Ltd. All rights reserved.