Abstract:In this study，in order to further explore the antioxidant and immune activities of millet bran polysaccharide，millet polysaccharide（MP）was prepared by water extraction and alcohol precipitation method.MP-1 and MP-2 were separated and purified by DEAE -52 cellulose chromatography.The chemical composition，molecular weight，antioxidant capacity and immune activity of MP before and after separation were evaluated.The results showed that the polysaccharide content of MP，MP-1 and MP-2 was 59.78%，78.58% and 45.78%，respectively.The molecular weights were 16.4，14.1 kDa and 13.9 kDa.In vitro antioxidant experiments showed that millet bran polysaccharide had significant antioxidant activity and free radical scavenging ability.Cell experiments showed that MP-1 had more significant immunomodulatory ability，and it could promote the production of NO and the proliferation of RAW264.7 cells，thus showing immunomodulatory activity.Reverse transcription-polymerase chain reaction（RT-PCR）results indicated that millet bran polysaccharide could promote the activation of macrophages and secretion of inflammatory factors by specifically binding to TLR4 receptor.Millet bran polysaccharide MP-1 could not only be used as an antioxidant，but also as a potential functional dietary/nutritional supplement and natural source.