Structure identification of a new immunostimulating polysaccharide from the stems of Dendrobium huoshanense

The water-soluble polysaccharide HPS, obtained from the stems of Dendrobium huoshanense by hot-water (50-60 degrees C) extraction and ethanol precipitation, was fractionated by DEAE-Cellulose anion-exchange and gel filtration chromatography including Sephacryl S-200 and Sephadex G-75/G-100, giving one polysaccharide fraction of HPS-IB23 which was investigated by chemical techniques and NMR spectroscopy. This polysaccharide fraction consists of glucose, mannose and galactose in the ratio of 31:10:8. On the basis of periodate oxidation-smith degradation, methylation analysis and partial acid hydrolysis, the repeating unit of HPS-IB23 was established: OAc down arrow 3 -> 1)-alpha -D-Glup-(6 -> 1)- alpha -D-Glup-(6 -> 1)- alpha -D-Glup-(6 -> 1)- alpha -D-Glup (6 -> 1)- alpha -D-Glup-(6 -> 1)- alpha -D-Manp-(6 -> 1)- alpha -D-Manp-(6 -> 1)-alpha -D- Glup-(4 -> 1)- a -DGlup-(4 -> 3 3 down arrow down arrow 1 1 alpha -D-Gal alpha -DGal Pharmaceutical experiments showed that the polysaccharide of HPS-1B23 possessed potent stimulating functions on IFN-gamma and TNF-alpha production in the culture medium of splenocytes and macrophages, respectively. (c) 2006 Elsevier Ltd. All rights reserved.