Structural characterisation of a water-soluble polysaccharide from tissue-cultured Dendrobium huoshanense C.Z. Tang et S.J. Cheng.

ABSTRACT

A water-soluble polysaccharide TC-DHPA4 with a molecular weight of 8.0 × 105 Da was isolated from tissue-cultured Dendrobium huoshanense by anion exchange and gel permeation chromatography. Monosaccharide analysis revealed that the homogeneous polysaccharide was made up of rhamnose, arabinose, mannose, glucose, galactose and glucuronic acid with a molar ratio of 1.2811.674.7110.431.42. The sugar residue sequence analysis based on the GC-MS files and NMR spectra indicated that the backbone of TC-DHPA4 consisted of the repeated units→6)-ß-Galp-(1→6)-ß-Galp-(1→4)-ß-GlcpA-(1→6)-ß-Glcp-(1→6)-ß-Glcp-(→. The sugar residue sequences ß-Glcp-(1→)-α-Rhap-(1→3)-ß-Galp-(1→, ß-Glcp-(1→4)-α-Rhap-(1→3)-ß-Galp-(1→, ß-Galp-(1→6)-ß-Manp-(1→3)-ß-Galp-(1→, and α-l-Araf-(1→2)-ß-Manp-(1→3)-ß-Galp-(1→ were identified as the branches attached to the C-3 position of (1→6)-linked galactose in the backbone.