Abstract: In this study, a polysaccharide named AAP-10 was isolated from Auricularia auricula-judge from Longquan region of Zhejiang province by hot water extraction and stepwise ethanol precipitation. Physicochemical analyses were used to characterize the polysaccharide. Furthermore, this study evaluated the immunomodulatory effect of polysaccharide AAP-10 in a mouse model of immunosuppression induced by cyclophosphamide (CPA). Results indicated that AAP-10 had high purity and was a homogeneous polysaccharide. Monosaccharide composition analysis showed that AAP-10 was mainly composed of glucose and mannose at a molar ratio of 6:1 as determined by high performance liquid chromatography with precolumn derivatization with 1-phenyl-3-methyl-5-pyrazolone. High-performance gel-permeation chromatography analysis showed that the average molecular mass of AAP-10 was 6.56 × 105 Da. Moreover, the negative effect of CPA on body mass and spleen of immunosuppressed mice was improved by AAP-10 administration at a certain dose. In addition, AAP-10 enhanced the proliferation of splenic lymphocytes and natural killer cell activity, as well as mononuclear macrophage phagocytosis, especially at low and intermediate doses (2.5 and 5.0 mg/(kg·d)). These results showed that AAP-10 had good immunoregulatory effect in immunosuppressed mice.

Key words: Auricularia auricula-judae, polysaccharide, immunoregulation, cyclophosphamide