Sulfated modification, characterizations, anti-oxidant and immunostimulatory activities of a polysaccharide from Arnebia euchroma (Royle) Johnst. Roots

Chinese Zicao, also known as A. euchroma (Royle) Johnst ., is a valuable agricultural product with roots in traditional Chinese medicine. A polysaccharide was taken from the A. euchroma (Royle) Johnst. Roots, called ARP, produced immunomodulatory effect by activating spleen lymphocyte and RAW264.7 cells. The chemical modification of natural polysaccharide enhanced its physicochemical and functional aspects. The ARP here is modified by sulfation. The total amounts of sugar and protein of the sulfated derivative (S1-ARP and S2-ARP) were decreased, but the molecular weight were increased. The structural analysis illustrated that the conformation of ARP was altered to a triple-helix structure after sulfation. The immunomodulatory and antioxidant activities of S1-ARP with high degree of substitution (DS = 0.24) were evidently enhanced by sulfated modification than unmodified polysaccharide and S2-ARP with low degree of substitution (DS = 0.028), especially the functional activation of macrophage was strengthened. As such, S1-ARP may be developed as an immunomodulatory drug has possible uses in the pharmaceutical and food industries.