Anti-tumor activity of the regenerated triple-helical polysaccharide from Dictyophora indusiata

A triple helical polysaccharide (PD3) was isolated from Dictyophora indusiata. After denaturation in dilute NaOH solution (0.3M) and renaturation by sequential dialysis, regenerated polysaccharide (RPD3) was obtained. The physico-chemical properties of RPD3 including intrinsic viscosity [η], molecular weight (Mw) and optical rotation were similar to those of PD3, which suggested that RPD3 also had a triple helical structure after denaturation–renaturation. However, different intrinsic viscosity dependence on the concentration of NaOH solution was noted in PD3 and RPD3, which indicated that RPD3 had lower chain tightness compared with PD3. The anti-tumor activity of this polysaccharide after denaturation–renaturation treatment was further investigated. Both PD3 and RPD3 showed no direct cytotoxicity against S-180 cells in vitro but behaved anti-tumor activity in vivo. Meanwhile, RPD3 in high-dose group showed much higher anti-tumor activity than that of PD3, suggesting that the denaturation–renaturation treatment improved the bioactivity of the polysaccharide from D. indusiata.