Isolation and structure elucidation of novel glucan from Astragalus mongholicus / 中草药

ABSTRACT

Object To isolate the immunoactive polysaccharide from Astragalus mongholicus Bunge and elucidate its chemical structure Methods The polysaccharide was purified from water extracts of A mongholicus by ethanol precipitation, deproteination, selective precipitation with hexadecyltri methylammonium bromide, ion exchange and gel filtration chromatography Its homogeneity and molecular weight were estimated by gel filtration chromatography, the structure was deduced from sugar analysis, methylation analysis, Smith degradation, IR and 13 CNMR spectrophotometry Results A homogeneous polysaccharide A2Nb was obtained with a molecular mass of 360 000 , and composed of D glucose with a major linkage form of ? D (1→4) glucose Side chains were found at 6 O positions once in every 25 glucose residues Conclusion A high molecular weight glucan A2Nb was obtained from A mongholicus for the first time It showed the ability of promoting the proliferation of the splenocytes of mice