Characterization and renal protective effect of a polysaccharide from Astragalus membranaceus

A water-soluble polysaccharide named as APS was isolated from the roots of Astragalus membranaceus by hot water extraction, anion-exchange and gel-permeation chromatography and tested for its renal protective effect. Its structural characteristics were investigated by FTIR, AMLC, NMR spectroscopy, GLC–MS, methylation analysis, periodate oxidation and Smith degradation. Based on the data obtained, APS was found to be an α-(1→4)-d-glucan, with a single α-d-glucose at the C-6 position every nine residue, on average, along the main chain. The glucan has a weight-average molecular weight of about 3.6 × 104 Da. 24 h Urine protein quantification and morphological observation revealed that APS significantly decreased the proteinuria and morphological changes on glomerulonephritis rats induced by cationic Bovine Serum Albumin (C-BSA), indicating APS could have a possible glomerulonephritis therapeutic potential.