ISOLATION, H-1 AND C-13 NMR-STUDIES OF (4-O-METHYL-D-GLUCURONO)-D-XYLANS FROM LUFFA FRUIT FIBERS, JUTE BAST FIBERS AND MUCILAGE OF QUINCE TREE SEEDS

The (4-O-methyl-D-glucurono)-D-xylans isolated from luffa fruit fibres (Luffa cylindrica), jute bast fibres (Corchorus capsularis) and mucil age of the seeds of the quince tree (Cydonia oblonga) were studied by H-1 and C-13 NMR spectroscopy. Their NMR spectra were grossly similar, but the molar proportions of D-Xyl and 4-O-Me-D-GlcA varied and were found to be, respectively, 7.5:1, 5:1 and 2:1 for luffa fibres, jute b ast fibres and quince tree seeds mucilage. The mucilage extracted from the seeds of the quince tree contained cellulose microfibrils strongl y associated with a glucuronoxylan possessing a very high proportion o f glucuronic acid residues. In addition to 4-O-methyl-alpha-D-glucopyr anosyluronic residues the presence of alpha-D-glucopyranosyluronic res idues was noticed, respectively, in the molar ratio 4-O-Me-D-GlcA and- D-GlcA 9:1. (C) 1998 Elsevier Science Ltd. All rights reserved.