A new glucomannan from Bletilla striata: structural and anti-fibrosis effects.

A novel water-soluble polysaccharide, designated Bletilla striata polysaccharide b (BSPb), was isolated from a traditional Chinese medicinal herb, Bletilla striata. The crude polysaccharide was obtained by hot water extraction and purified by ion-exchange chromatography. The molecular weight was 260 kDa as determined by HPGPC (high performance gel permeation chromatography). Monosaccharide analysis showed that BSPb contained glucose and mannose with a molar ratio of 3:1. Methylation and spectroscopic analyses with 1D and 2D NMR spectroscopy showed that the backbone of BSPb is mainly composed of (1 → 2)-linked α-D-mannopyranose and (1 → 4)-linked β-D-glucopyranose residues. In this study, BSPb plays an important role in protection against the renal fibrosis effect, which is probably mediated by down-regulated TGF-β RI, TGF-β RII, and α-SMA in vitro.