Sulfated modification and DPPH free radical scavenging ability of polysaccharide from Rhodiola sachalinensis / 中草药

ABSTRACT

Objective: To optimize the sulfated modification conditions of Rhodiola sachalinensis polysaccharide (RSP) and improve the anti-oxidant activity of RSP. Methods: RSP were sulfated by chlorosulfonic acid-pyridine method, and the optimal conditions for the sulfated modification were determined by single factor experiments. The physical and chemical properties of RSP and sulfated RSP (S-RSP) were analyzed by infrared spectroscopy (IR) and scanning electron microscopy (SEM). The relation between substituting degree (DS) of S-RSP and anti-oxidative activity of polysaccharide was investigated by testing the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging ability of RSP and S-RSP. Results: When the volume ratio of chlorosulfonic acid to pyridine was 1∶4, the reaction time was 2 h and the reaction temperature was 60 ℃, the maximum sulfur content of S-RSP was 18.83% and the DS was the highest for 2.38. Moreover, the anti-oxidant activity of RSP was enhanced by the sulfated modification, and there was a certain positive proportional relationship between DS and DPPH free radical scavenging ability of S-RSP. Conclusion: The volume ratio of chlorosulfonic acid to pyridine affects the DS of S-RSP, and the sulfated modification can increase the anti-oxidant capacity of RSP by changing its polarity.