Aim: To study the immunosuppressive activity of SM735 {[3-(12-β-artemisininoxy)] phenoxyl succinic acid}, a synthetic artemisinin derivative with nonsteroidal antiinflammatory drug structure, with the aim of finding potential immunosuppressive agents. Methods: Concanavalin A (ConA), lipopolysaccharide (LPS), and mixed lymphocyte reaction (MLR), were used to induce the proliferation of splenocytes, and [~3H]-thymidine incorporation was used to evaluate the proliferation of splenocytes. Cytokine production was promoted with ConA, LPS, or PMA plus ionomycin, and was detected with the enzyme-linked immunosorbent assay. Dinitrofluorobenzene (DNFB) and sheep red blood cells (SRBC) were used to induce delayed-type hypersensitivity and quantitative hemolysis of SRBC (QHS) mouse models, as criteria for the evaluation of in vivo immune activity. Results: SM735 strongly inhibited the proliferation of splenocytes induced by ConA, LPS, or MLR, withIC_(50)) values of 0.33 μmol/L, 0.27 μmol/L, and 0.51 μmol/L, respectively. When compared with a CC_(50) value of 53.1 μmol/L, SM735 had a favorable safety range. SM735 dose-dependently inhibited proinflammatory cytokine production [including interleukins (IL)-12, interferon (IFN)-γ and IL-6] induced by LPS or PMA plus ionomycin. Upon ConA stimulation, SM735 suppressed IFN-γ in a dose-dependent manner, but did not affect IL-2 secretion. SM735 also strongly suppressed both T-cell-mediated delayed-type hypersensitivity (DTH) and B-cell-mediated QHS reactions. Conclusion: SM735 had strong immunosuppressive activity in vitro and in vivo, suggesting a potential role for SM735 as an immunosuppressive agent, and established the groundwork for further research on SM735. Aim: To study the immunosuppressive activity of SM735 {[3- (12-β-artemisininoxy)] phenoxyl succinic acid}, a synthetic artemisinin derivative with nonsteroidal antiinflammatory drug structure, with the aim of finding potential immunosuppressive agents. Methods: Concanavalin A ( ConA), lipopolysaccharide (LPS), and mixed lymphocyte reaction (MLR), were used to induce the proliferation of splenocytes, and [~ 3H] -thymidine incorporation was used to evaluate the proliferation of splenocytes. Cytokine production was promoted with ConA, LPS , or PMA plus ionomycin, and was detected with the enzyme-linked immunosorbent assay. Dinitrofluorobenzene (DNFB) and sheep red blood cells (SRBC) were used to induce delayed-type hypersensitivity and quantitative hemolysis of SRBC (QHS) mouse models, as criteria for the evaluation of in vivo immune activity. Results: SM735 strongly inhibited the proliferation of splenocytes induced by ConA, LPS, or MLR, with IC 50 values) 0.33 μmol / L, 0.27 μmol / L, and 0.57 μmol / L, respectively. When compared with CC_ (50) value of 53.1 μmol / L, SM735 had a favorable safety range. SM735 dose- dependently inhibited proinflammatory cytokine production [including interleukins (IL) Upon gamma stimulation, SM735 suppressed IFN-γ in a dose-dependent manner, but did not affect IL-2 secretion. SM735 also strongly suppressed both T-cell-mediated delayed-type hypersensitivity (DTH) and B-cell-mediated QHS reactions. Conclusion: SM735 had strong immunosuppressive activity in vitro and in vivo, suggesting a potential role for SM735 as an immunosuppressive agent, and established the groundwork for further research on SM735.