Preparation, characterization, antioxidant activity and protective effect against cellular oxidative stress of phosphorylated polysaccharide from Cyclocarya paliurus

In this study, a phosphorylated derivative of Cyclocarya paliurus polysaccharide (CP) was synthesized using sodium tripolyphosphate and sodium trimetaphosphate. Antioxidant activities and cytoprotective effects of unmodified polysaccharide and phosphorylated derivatives were investigated employing various in vitro systems. Results showed that phosphorylated modification caused a significant change in chemical composition and the apparent structure of CP. Phosphorylated Cyclocarya paliurus polysaccharide (P-CP) showed excellent scavenging capacities against DPPH and hydroxyl radical in a dose-dependent manner. P-CP provided a more significant protective effect against hydrogen peroxide-induced oxidative stress in RAW264.7 cells by a compositive oxidation defense mechanism than CP. P-CP could reduce oxidative stress by significantly enhancing the contents of antioxidant enzyme superoxide dismutase (SOD) and decreasing malondialdehyde (MDA) content in oxidative damaged cells, in addition to scavenging ROS directly and regulating cell cycle distribution, reducing apoptosis capacity and improving cell viability, consequently achieving the intracellular antioxidant activity. This study suggested that phosphorylated modification is an effective method to improve the antioxidant activities of CP, so as to expand the development and application of CP.