NMR structural elucidation of the arabinan from Prunus dulcis immunobiological active pectic polysaccharides

Abstract

The structure of the arabinan moiety of a purified arabinan-rich pectic polysaccharide from the cell walls of Prunus dulcis seeds was investigated by NMR spectroscopy. This polymer, which is able to induce a lymphocyte stimulatory effect, had an arabinan glycosidiclinkage composed of T-Araf: (1 fi 5)-Araf: (1 fi 3,5)-Araf: (1 fi 2,3,5)-Araf in the relative proportions of approximately 3:2:1:1. Based on the 1 H, 13 C, COSYPR, gHSQC and gHMBC spectra of analysed arabinan, a tentative structure is presented, showing that it is composed by a very branched and, possibly, repetitive structure of seven residues. The observed (1 fi 5) direct linkage between (1 fi 2,3,5)-Araf and (1 fi 3,5)-Araf residues support the occurrence of these contiguous branched residues in the arabinan backbone.

Characterization of nonderivatized plant cell walls using high‐resolution solution‐state NMR spectroscopy

“…[49] Thus, the α-L-Araf anomeric correlations for pine, aspen, and kenaf are depicted at 4.83/108.4 ppm. [31,32,50] Reducing ends of the polysaccharides can also be seen in the spectra and are tentatively assigned here. The reducing α and β ends of D-Glcp residues are shown at 4.94/92.7 ppm and 4.40/96.9 ppm.…”

Structural analysis of an acidic polysaccharide isolated from white tea

“…Strong signals at 4.22 and 4.21 ppm were assigned to the anomeric proton of 1, 4 linked β-D-mannose residues. Signals at 4.22 and 3.69-3.63 ppm probably arose from D-mannopyranose and D-arabinopyranose configurations (28)(29)(30)(31). This assignment was supported by the 1 H NMR spectrum of WTPS in which signals from glucose were weaker, while signals for mannose and arabinose were stronger.…”

Fractionation of sugar beet pulp by introducing ion-exchange groups

“…5)-glycosidically linked polysaccharide (Keenan, Belton, Matthew, & Howson, 1985). In addition, there are several anomeric signals at 110.47/5.12, 110.47/5.10, 110.01/5.16 and 109.40/5.25 ppm, which are typical for arabinan (Cardoso et al, 2007;Dourado, Cardoso, Silva, Gama, & Coimbra, 2006), and the peaks at 106.80/4.63, 102.80/4.97 and 102.20/ 5.14 ppm were assigned to Galp and GalA units (Mukhiddinov, Khalikov, Abdusamiev, & Avloev, 2000).…”