Structural Studies on Galactomannans From Brazilian Seeds |
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Authors: | Joana L M S Ganter Selma F Zawadzki-Baggio Sirlei C S Leitner Maria-Rita Sierakowski Fany Reicher |
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Institution: | Departments of Biochemistry and Chemistry , P.O. Box 19046, Universidade Federal do Paraná, 81531-970, Curitibac, PR, Brazil |
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Abstract: | Abstract Chemical structures of galactomannans from the native Brazilian species, M. scabrella, S. barbatiman and S. parahy-bum were studied. Their seeds, on aqueous extraction, furnished high yields of viscous galactomannans, whose mannose to galactose ratios were 1.1:1, 1.5:1, and 3.0:1, respectively. The polysaccharides were analysed by methylation, periodate oxidation and chromium trioxide oxidation. The results, confirmed by 13C NMR spectroscopy, indicated expected structures of legume galactomannans, namely a polymeric main chain of (l→4) -linked β-D-mannopyranosyl residues substituted at 0–6 by single unit α-D-galactopyranosyl side-chains. 13C NMR spectra showed clear splitting of the O-substituted resonances of C-4 of the β-D-mannosyl residues depending on the nearest-neighbour probabilities, indicating a random arrangement of the D-galactosyl groups in all of the three galactomannans. |
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