STRUCTURAL STUDIES ON GALACTOMANNANS FROM BRAZILIAN SEEDS

Chemical structures of galactomannans from the native Brazilian specie s, M. scabrella, S. barbatiman and S. parahybum were studied. Their se eds, on aqueous extraction, furnished high yields of viscous galactoma nnans, whose mannose to galactose ratios were 1.1:1, 1.5:1, and 3.0:1, respectively. The polysaccharides were analysed by methylation, perio date oxidation and chromium trioxide oxidation. The results, confirmed by C-13 NMR spectroscopy, indicated expected structures of legume gal actomannans, namely a polymeric main chain of (1-->4)-linked beta-D-ma nnopyranosyl residues substituted at 0-6 by single unit alpha-D-galact opyranosyl side-chains. C-13 NMR spectra showed clear splitting of the 0-substituted resonances of C-4 of the beta-D-mannosyl residues depen ding on the nearest-neighbour probabilities, indicating a random arran gement of the D-galactosyl groups in all of the three galactomannans.