CHEMICAL AND SPECTROSCOPIC STUDIES OF THE GUM POLYSACCHARIDE FROM ACACIA-MACRACANTHA

The polysaccharide isolated from Acacia macracantha gum, a Venezuelan Gummiferae spp., contains galactose, arabinose, rhamnose, glucuronic a cid and its 4-O-methyl analogue. C-13-NMR spectroscopy, in combination with chemical methods, was applied in this study. A complex fragment, constituted of galactose, arabinose and glucuronic acid (3:2:1), was obtained from the original polysaccharide and its degradation products . This fragment appears to be an important structural feature of the g um. The backbone of the structure (degraded gum B) is a beta-(1 --> 3) galactan, although glucuronic acid and arabinose residues are still p resent in the core of the structure. Stereochemistry of the molecule m ay work against periodate oxidation of these sugar residues. Arabinose may be present as internal residues and as short side-chains while gl ucuronic acid exists mainly as a terminal residue. Copyright (C) 1996 Published by Elsevier Science Limited.