Isolation, 1H and 13C NMR studies of (4-O-methyl-d-glucurono)-d-xylans from luffa fruit fibres, jute bast fibres 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 mucilage of the seeds of the quince tree (Cydonia oblonga) were studied by 1H and 13C 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 bast fibres and quince tree seeds mucilage. The mucilage extracted from the seeds of the quince tree contained cellulose microfibrils strongly associated with a glucuronoxylan possessing a very high proportion of glucuronic acid residues. In addition to 4-O-methyl-α-d-glucopyranosyluronic residues the presence of α-d-glucopyranosyluronic residues was noticed, respectively, in the molar ratio 4-O-Me-d-GlcA and-d-GlcA 9:1.