CHARACTERIZATION OF ANACARDIUM-OCCIDENTALE EXUDATE POLYSACCHARIDE

The composition, structure and molar mass distribution of Anacardium o ccidentale exudate polysaccharide of Brazilian origin was investigated . The composition from gas-liquid chromatography (GLC) and C-13 NMR wa s 72% beta-D-galactopyranose, 14% alpha-D-glucopyranose, 4.6% alpha-L- arabinofuranose, 3.2% alpha-L-rhamnopyranose and 4.5% beta-D-glucuroni c acid. A thorough analysis of high resolution C-13 NMR spectra from i ntact, partially hydrolysed and Smith-degraded polysaccharide enabled reliable chemical shift assignments to be made, and indicated the pres ence of three types of unit within the branched galactan core: linked at C-1 and C-3, at C-1 and C-6, and at C-1, C-3 and C-6. The polysacch aride was fractionated with respect to molar mass using water/ethanol as a solvent/non-solvent system. The polysaccharide and fractions were characterized by gel permeation chromatography (GPC), intensity light scattering, dilute solution viscometry and sedimentation velocity. Th e intrinsic viscosity in 0.1 M aqueous NaCl at 25 degrees C was found to depend on molar mass according to: [eta]/(cm(3) g(-1))=0.052 M-0.42 . The molar mass distribution for the whole polysaccharide, determined by GPC using a universal calibration, exhibited two main peaks at 28 000 and 67 000 gmol(-1), together with traces of much higher molar mas s material. (C) 1998 SCI.