Characterization, sulfated modification and bioactivity of a novel polysaccharide from Millettia dielsiana

Millettia dielsiana is a traditional herb medicine to treat rheumatic arthritis and gynecological diseases. In this study, a novel polysaccharide (MDP1) with a molecular weight of 139.54 kDa was isolated from Millettia dielsiana by DEAE-52 cellulose chromatography. Its sulfated derivative (S-MDP1) was prepared by the chlorosulfonic acid-pyridine method. Structural analysis indicated that MDP1 was a pectic polysaccharide and did not exhibit a triple helical conformation. In vitro, MDP1 and S-MDP1 had protective effect on H₂O₂-induced PC12 cells death. Immunological assay showed that MDP1 and S-MDP1 significantly stimulated NO production and phagocytic activity in RAW264.7 cells, and promoted lymphocyte proliferation. Anticoagulant assay indicated that S-MDP1 effectively prolonged activated partial thromboplastin time (APTT) and thrombin time (TT), but not prothrombin time (PT), and MDP1 prolonged APTT and TT weakly. These results implied that MDP1 and S-MDP1 had the potential to be used as antioxidant, immunomodulatory and anticoagulant agents.