SIMILARITY OF MONOSACCHARIDE, OLIGOSACCHARIDE AND POLYSACCHARIDE STRUCTURES IN GUM EXUDATE OF ANACARDIUM-OCCIDENTALE

The gum exudate from the Brazilian cashew-nut tree (Anacardium occiden tale) contained traces of the reducing sugars, rhamnose (0.005%), arab inose (0.03%), mannose (0.007%), galactose (0.03%), glucose (0.02%), b eta-D-Galp-(1-->6)-alpha beta-D-Gal (0.05%), alpha-L-Rhap-(1-->4)-alph a beta-D-GlcA (0.008%) and alpha-L-Rhap-(1-->3)-beta-D-GlcpA-(1-->6)-a lpha beta-D-Gal (0.008%). Rhamnose, arabinose, glucose and the three o ligosaccharides are components of the side-chains of tile gum polysacc haride, which has a main chain of (1-->3)-linked beta-D-Galp units. Th e structure of this polysaccharide was determined and found to differ from that previously reported for the gum of a tree growing in India, lacking units of 4-O-methlglucuronic acid. Other new side-chain struct ures were characterized, particularly -alpha-D-Galp-(1-->6)-D-Galp- an d alpha-L-Araf-(1-->6)-D-Galp-. (C) 1998 Elsevier Science Ltd. All rig hts reserved.