ObjectiveTo investigate the effect of tripterine on surface ultrastructure and proliferative activity of Burkitt lymphoma cell line Raji. MethodsRaji cells were treated with different concentrations (0.5,1.0,1.5,and 2.0 μg/ml) of tripterine. Then the proliferation of Raji cells was determined by CCK8 assay, the cell membrane ultrastructure was analyzed by atomic force microscope, the apoptosis of cells was determined by Hoechst 33258 staining and flow cytometric analysis, and the cell cycle was assayed by flow cytometry. ResultsCCK8 assay showed that the survival rate of cells decreased from (80.67±2.08)% to (38.53±2.25)% 24 h after treatment with different concentrations of tripterine. The cell survival rate decreased from (74.17±3.20)% to (33.22±1.64)% 48 h after treatment. Tripterine significantly inhibited the proliferation of Raji cells and the inhibition was in a time- and concentration-dependent manner. Atomic force microscope scan showed that the untreated Raji cells were round, with relatively smooth surface. After Raji cells were treated with 2.0 μg/ml tripterine for 24 h and 48 h, the ultrastructure of the cell membrane was collapsed, and the cell surface was rough and uneven. Hoechst 33258 staining demonstrated apoptotic cells. Apoptotic rate of the Raji cells increased from (3.50±1.73)% to (38.27±6.05)% 24 h after treatment with different concentrations of tripterine. Flow cytometry analysis showed that 24 h after treatment with 1.5 μg/ml tripterine, S phase Raji cells were significantly increased compared with control group (P<0.05). ConclusionOur results demonstrate that tripterine can alter the cell membrane ultrastructure of Raji cells and can inhibit Raji cell proliferation through inducing cell apoptosis.