Structure characterization of high molecular weight heteropolysaccharide isolated from Artemisia sphaerocephala Krasch seed

The structure of a high molecular weight heteropolysaccharide (60P) isolated from Artemisia sphaerocephala Krasch was elucidated using methylation analysis and 20 NMR spectroscopy. 60P (Mw: 551 kDa) was isolated from A. sphaerocephala Krasch (ASK) seeds, using hot water extraction and ammonium sulphate salt precipitation. Methylation and GC-MS analysis indicated that 60P was mainly composed of three types of sugar residues: 4-Xylp (27.8%), 2,4-Xylp (26.0%) and T-GlcpA (22.5%); small amount of 4-GalpA, 4-Glcp, T-Araf, T-Arap and 4, 6-GalpA were also detected with comparable molar ratio. Based on the results of monosaccharide composition, methylation analysis and NMR spectroscopy, a proposed structure is shown below: -> 4)-beta-D-xylp-(1 -> 4)-beta-D-xylp-(1 -> 4)-beta-D-xylp-(1 -> 4)-beta-D-xylp-(1 -> 4)-beta-D-xylp-(1 -> 4)-beta-D-xylp-(1 R represents one of the following groups: T-Araf, T-Arap, T-Araf -> 3-Araf (1 -> and T-Arap -> 3-Araf (1 ->. (C) 2011 Published by Elsevier Ltd.