GALACTOMANNANS FROM BRAZILIAN SEEDS - CHARACTERIZATION OF THE OLIGOSACCHARIDES PRODUCED BY MILD ACID-HYDROLYSIS

Galactomannans with Man:Gal ratios ranging from 1.1:1 to 3:1, obtained from the seeds of Mimosa scabrella, Stryphnodendron barbatiman, Schiz olobium parahybum and Schizolobium amazonicum, were submitted to mild acid hydrolysis. The products were fractionated by gel permeation chro matography on BioGel P2 yielding fractions with degrees of polymerizat ion (DP) of 1 to 6. Those with DP 2 to 6 from each species were analys ed by ion-exchange high-performance liquid chromatography and characte rized by C-13- and H-1-nuclear magnetic resonance (NMR) spectroscopy. The distribution of the oligosaccharides of each degree of polymerizat ion was very similar for the products from S. parahybum and S. amazoni cum, indicating the same D-galactosyl distribution on the D-mannan bac kbone, in agreement with the C-13-NMR splitting in the C4 region of th e D-mannosyl units in the original polymers. The hydrolytic conditions adopted allowed characterization of compounds that are not generally produced by enzymatic treatments. The results show that the structures of the oligosaccharides, even if there is a preferential hydrolysis o f Gal-Man linkages, reflect the composition of the parent polymer.