Screening and comparison of the immunosuppressive activities of polysaccharides from the stems of Ephedra sinica Stapf

Three polysaccharide fractions A, B and C (PA, PB and PC) were acquired from the stems of Ephedra sinica Stapf by sequential extraction with cold water, hot water, and 1.0 M NaOH, respectively. Immunosuppressive activities of PA, PB and PC were investigated by carbon clearance test, delayed-type hypersensitivity reaction and humoral immune response in vivo. Then PB was further isolated to afford four purified polysaccharides (ESP-B1, ESP-B2, ESP-B3 and ESP-B4) by various ion exchange and gel-filtration chromatography. Meanwhile, the purified polysaccharides were subjected to composition analysis and valuated for mice splenocyte proliferation activity in vitro. Among four purified polysaccharides, ESP-B4 has the highest inhibitory effect on splenocyte proliferation and its branches are extremely important for the expression of the inhibitory effect. The results in our study indicate that PB and ESP-B4 have therapeutic potential for the treatment of autoimmune and atopic diseases due to their immunosuppressive effects.