Methylation and 2D NMR analysis of arabinoxylan from the seeds of Plantago asiatica L.

PLP-3 (Plantago asiatica L polysaccharide 3) was isolated and purified from the seeds of Plantago asiatica L Its structure characters were elucidated by monosaccharide composition analysis, partial acid hydrolysis and methylation analysis, combined with FT-IR, GC/MS, 1D and 2D NMR spectroscopy. PLP-3 was found to be arabinoxylan, containing glucuronic acid. It was consisted of beta-1 4-linked Xylp backbone with short side chains attached to its O-2 (1,2,4-linked Xylp, 17.87%) or O-3 (1,3,4-linked Xylp, 24.24%) positions. The main terminal residues were T-linked Araf (8.13%), T-linked Xylp (15.58%) and T-linked GlcAp (13.22%). Small amounts of other residues were also found in PLP-3, such as 1,2,5-linked Araf, 1.2-linked Rhap, T-linked Glcp and T-linked Galp. A possible molecular structure was proposed. (C) 2012 Elsevier Ltd. All rights reserved.