Abstract:Mesona chinensis polysaccharides MCP-A and MCP-B were obtained by different treatments，and the physicochemical properties and in vitro antioxidant activities of the two polysaccharides were studied.The structure of polysaccharides was characterized by synchronous thermal analyzer，ultraviolet ray，infrared ray，X-ray diffraction，scanning electron microscope，etc.The antioxidant activities of polysaccharides were investigated from the aspects of DPPH，ABTS+free radical scavenging rate and reducing power.The results showed that MCP-A solution was more viscous than MCP-B solution on the dynamic rotational hydration radius.MCP-A had stronger heat resistance than MCP-B.Both of the two polysaccharides had absorption peaks with polysaccharide characteristics，MCP-A was the pyranoside ring skeleton of α-glycosidic bond and β-glycosidic bond，and MCP-B was the pyranoside ring skeleton of β-glycosidic bond.The X-ray diffraction pattern showed that the main forms of the two polysaccharides were amorphous.The scanning electron microscopy（SEM）showed that MCP-B had a larger specific surface area than MCP-A.The in vitro antioxidant results showed that MCP-A was stronger than MCP-B in scavenging DPPH and ABTS+free radicals，and both had stronger reducing power.The study indicated that the physicochemical properties and antioxidant activities of polysaccharides treated by two methods are significantly different.Compared with MCP-B，MCP-A had higher thermal stability and antioxidant capacity，which can be used as a potential antioxidant ingredient in food.