Structural characterization of a highly branched polysaccharide from the seeds of Plantago asiatica L.

In this paper, polysaccharides were extracted from the seeds of Plantago asiatica L with hot water and separated into three fractions PLP-1 (18.9%), PLP-2 (52.6%) and PLP-3 (28.5%) by Sephacryl (TM) S-400 HR column chomatography. The main fraction PLP-2's structure was elucidated using oxalic acid hydrolysis, partial acid hydrolysis, methylation, GC, GC-MS, 1D and 20 NMR. PLP-2 was composed of Rha, Ara, Xyl, Man, Glc and Gal, in a molar ratio of 0.05:1.00:1.90:0.05:0.06:0.10. Its uronic acid was GlcA. PLP-2 was highly branched heteroxylan which consisted of a beta-1,4-linked Xylp backbone with side chains attached to O-2 or O-3. The side chains consisted of beta-T-linked Xylp, alpha-T-linked Araf, alpha-T-linked GlcAp, beta-Xylp-(1 -> 3)-alpha-Araf and alpha-Araf-(1 -> 3)-beta-Xylp, etc. Based on these results, the structure of PLP-2 was proposed. (C) 2011 Elsevier Ltd. All rights reserved.