Abstract: Objective To investigate the effects of acetoacetate extractive of celastrus orbiculatus thunb on HepG2 cells. Methods The proliferation of cells were tested with CCK-8；The cell cycles and the apoptosis of HepG2 cells intervened by acetoacetate extractive of celastrus orbiculatus thunb were detected by flow cytometry； The change of caspase-3 activity in HepG2 cells were detected by spectrophotometer. Results Acetoacetate extractive of celastrus orbiculatus thunb induced apoptosis of HepG2 cells in an obvious dose-and time-dependent manner，and the IC50 at 24h，48h，72h was 111.8μg/ml，99.7μg/ml and 43.0μg/ml；The cell cycle stopped at G0-G1 phase after 24 hours of action at 240μg/ml of acetoacetate extractive of celastrus orbiculatus thunb treatment （P=0.01）；Compared with control，the apoptosis rate of HepG2 cells obviously increased by intervention of acetoacetate extractive of celastrus orbiculatus thunb（F=5.449，P<0．05）；the caspase-3 activity increased when HepG2 cells were treated at 30μg/ ml，60μg/ml and 120 μg/ml of the extracts of celastrus for 24h and 48h，respectively. Conclusions The acetoacetate extractive of celastrus orbiculatus thunb could inhibit the proliferation and induce the apoptosis of HepG2 cells，which might be related to the increased caspase 3 activity.

Key words: Celastrus orbiculatus thunb, HepG2 cell line, Proliferation, Apoptosis, Caspase-3