Objective: To study the effect of Crotonis Fructus alkaloid (CA) on apoptosis and the expression of Bcl-2 and Bax in human hepatoma SMMC-7721 cells. Method: After treatment with CA for 24-48 h

MTT assay was used to determine the cell growth inhibitory rate in vitro

flow cytometry was used to detect the apoptosis of SMMC-7721 cells before and after CA treatment.Western blot was used to detect the expression of Bcl-2 and Bax. Result: CA inhibited the growth of SMMC-7721 cells in a dose-and time-dependent manner.After treatment with 50-200 mg ·L-1 CA for 24 h

the number of apoptosis cells was increased dose-dependently from (0.26±0.14)% in the control group to (5.85±0.47)%

(17.70±1.23)%

(33.25±2.08)% and (49.52±1.85)% in CA groups

respectively.By Western blot analysis

we found the level of Bax was up-regulated

whereas

the level of Bcl-2 down-regulated. Conclusion: CA can efficiently inhibit the proliferation and induce apoptosis in SMMC-7721 cells.Its mechanism is likely related to the down-regulation of Bcl-2 and up-regulation of Bax.