Characterization and anti-tumor activity of a polysaccharide from Hedysarum polybotrys Hand.-Mazz

A water-soluble polysaccharide named as HPS-1 was isolated from the roots of Hedysarum polybotrys Hand.-Mazz by hot water extraction, anion-exchange and gel-permeation chromatography and tested for its anti-tumor activity. Its structural characteristics were investigated by FTIR, HPLC, NMR spectroscopy, GLC–MS, methylation analysis, periodate oxidation and Smith degradation. Based on the data obtained, HPS-1 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 9.4 × 104 Da. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay revealed that HPS-1 significantly inhibited the proliferation of human hepatocellular carcinoma HEP-G2 cells and human gastric cancer MGC-803 cells in vitro, indicating HPS-1 could have a possible cancer therapeutic potential.