Structural characterization and antitumor activity of a polysaccharide from ramulus mori

This study investigated the chemical characterization and antitumor effects of a polysaccharide from ramulus mori. A water-soluble polysaccharide, RMP1 with the estimated molecular weight of 137 kDa, was isolated and purified from ramulus mori through gel permeation chromatography. RMP1 is mainly composed of arabinose, xylose, glucose, galactose and rhamnose in a ratio of 0.56: 0.37: 0.17: 1.00: 0.08. Methylation and NMR analysis revealed that RMP1 had a backbone composed of 1,6-beta-D-Galp, 1,3,6-beta-D-Galp and 1,3-beta-D-Galp residues, two main branches of 1,2-alpha-L-Araf, 1,3,6-beta-D-Galp and 1,4-beta-D-Xylp; it also had alpha-L-Araf and beta-D-Glcp as terminals. In the MTT assay, RMP1 showed significant anticancer effects against the SGC-7901 and HeLa cells. In addition, no cytotoxicity was observed on the HEK-293 and RAW 264.7 cells. Flow cytometry showed that RMP1 exerted a stimulatory effect on the SGC-7901 cells apoptosis and induced the cell cycle arrest at the S phases. These findings suggest that RMP1 may serve as a potential novel antitumor agent.