Isolation and structural characterization of hemicelluloses from palm of Phoenix dactylifera L.

Hemicellulose-type polysaccharides were isolated from the leaflets and the rachis of palm of Phoenix dactylifera L. by alkaline extraction and fractionated by precipitation. The structural investigations were achieved by sugar analysis and NMR spectroscopy. Three fractions were obtained and purified from leaflets as well as from rachis. From leaflets, the water soluble fractions were assumed to be arabinoglucuronoxylans, with 4-O-α-d-glucopyranosyluronic acid groups linked at C-2 and arabifuranosyl at C-3. The water non-soluble fraction from leaflets and all fractions extracted from rachis were assumed to be (1 → 4)-linked β-d-xylan with a 4-O-methyl-α-d-glucopyranosyluronic acid group attached at C-2. The sugar composition and the 1H and 13C NMR spectra showed that their chemical structures were very similar, but with different proportions of 4-O-Me-d-GlcA.