Abstract:To investigate the in vitro antioxidant activity and humoral immunomodulatory function of Cordyceps guangdongensis fruiting body polysaccharides，crude polysaccharides of C. guangdongensis fruiting body（CGFCP） were prepared by hot water extraction and ethanol precipitation in this study. Two purified polysaccharides （CGFPP-W and CGFPP-S） were obtained through subsequent purification with diethylaminoethyl（DEAE） cellulose DE-52 gel. The monosaccharide composition of the polysaccharides was determined by gas chromatography-mass spectrometry （GC-MS），and their in vitro antioxidant activity was assessed. A mouse model was used to evaluate the effects of low，medium，and high doses of CGFCP on antibody-producing cells and serum hemolysin. The results showed that the monosaccharide composition of CGFCP，CGFPP-W，and CGFPP-S was primarily glucose，mannose，arabinose，and galactose. With increasing concentration，all three polysaccharides exhibited strong in vitro antioxidant capacity. Compared to the purified CGFPP-W and CGFPPS，the CGFCP at 10 mg/mL demonstrated stronger antioxidant activity （hydroxyl and DPPH free radical scavenging ability，as well as total reducing power）. Low，medium，and high doses of CGFCP increased the number of hemolytic plaques and titer in mice，with the high-dose group showing a significantly stronger humoral immunomodulatory capacity than the negative control group. In conclusion，C. guangdongensis fruiting body polysac-charides possess certain antioxidant activity and humoral immunomodulatory function.