Abstract: Objective： To study the protective effects of arctigenin and verify the synergistic effect of combined arctigenin and positive drug （bromocriptine mesylate and
benzhexol hydrochloride） on rotenone-treated PC12 cells. Methods： Rotenone-treated PC12 cells were employed for the in vitro experiments. The cells were exposed to rotenone with or without arctigenin and different positive drug solutions with different concentration. The optical density （OD） value was determined by microplate reade r， and the cell survival rate of each group was calculated. The cell viability was assessed using MTT to estimate the protective effect of arctigenin， positive drug only or combination of arctigenin and positive drug on the growth of PC12 cells of different concentration， and the median-effect principle was used to analyze union of medication. Results： Compared to the model group， the cell viability of groups （arctigenin， bromocriptine mesylate and benzhexol hydrochloride） was significantly increased. According to the Chou-Talalay method， the combination index （CI） of arctigenin and bromocriptine mesylate （ratio：1∶4 and 1∶2 ） was beyond 1， and the CI of arctigenin and benzhexol hydrochloride （ratio：1∶1 and 2∶1 ） was also greater than 1， show that combination effect both were antagonistic action. Conclusion：Combination of arctigenin and bromocriptine mesylate or benzhexol hydrochloride have not synergistic protective effect on PC12 cells treated with rotenone， but have antagonistic action.

Key words: arctigenin, bromocriptine mesylate, benzhexol hydrochloride, combination, antagonistic action