Structure characterization, chemical and enzymatic degradation, and chain conformation of an acidic polysaccharide from Lycium barbarum L.

An acidic polysaccharide, named as p-LBP, was isolated from Lycium barbarum L. by water extraction and purified by decoloration, ion exchange chromatography, dialysis and gel chromatography, successively. The primary structure analysis was determined by HPAEC-PAD, HPSEC, FT-IR, GC -MS, and NMR. The results showed p-LBP was a homogeneous heteropolysaccharide as a pectin molecule with an average molecular weight of 64 kDa p-LBP was an approximately 87 nm hollow sphere in 0.05 mol/L sodium sulfate solution determined by HPSEC-MALLS, DLS and TEM. A discussion of degradation patterns gave the detailed structural information of p-LBP. Therefore, the results from degraded fragments elucidated that the backbone of p-LBP was formed by -> 4-alpha-GalpA-(1 ->, repeatedly. Partial region was connected by -> 4-alpha-GalpA-(1 -> and -> 2-alpha-Rhap-(1 ->, alternatively. On the C-4 of partial -> 2-alpha-Rhap-(1 -> residues existed branches forming by -> 4-beta-Galp-(1 -> 3-beta-Galp-(1 -> or -> 5-alpha-Araf-(1 -> while on the C-6 of partial -> 3-beta-Galp-(1 -> residues existed secondary branches forming by terminal-alpha-Araf, terminal-beta-Galp or -> 3-alpha-Araf-(1 ->. (C) 2016 Elsevier Ltd. All rights reserved.