Chain conformation and anti-tumor activity of derivatives of polysaccharide from Rhizoma Panacis Japonici.

A hyper branched (1→4)-α-d-glucan (RPS3) with degree of branching of 35% extracted from Rhizoma Panacis Japonici adopted a sphere-like conformation and showed little bioactivity. Three derivatives including sulfated (S-), phosphated (P-) and carboxymethylated (CM-) RPS3 were then synthesized and characterized by FTIR, (13)CNMR, and SEC-LLS-Vis-RI. As a result, the molecular weights of CM-RPS3, S-RPS3 and P-RPS3 decreased sharply in contrast to the original one, suggesting that chemical degradation has occurred. Moreover, the sphere-like conformation of RPS3 transferred into the random coil-like conformation according to the increased values of αη, αs and ρ. It was ascribed to the occurrence of the preferential degradation for the branches. In vitro and in vivo tests demonstrated that the negatively charged S-RPS3 and P-RPS3 with properly low molecular mass significantly inhibited H-22 tumor cells growth. This work offered valuable results for broadening the biological applications of α-d-glucans.