Objective: To investigate the effects of Xiancidan(XCD) effective parts on inhibition of lung cancer A549 in vitro

and explore its mechanism. Method: The A549 cells in vitro were treated with the XCD effective parts at different concentrations

the concentrations of the XCD effective parts were 5

10

15

25

50

100

200 mg ·L-1 respectively. The inhibitory rate of the A549 cell proliferation was measured by MTF assay

the IC50 (the 50% inhibitory concentration)was determined. The effects of XCD effective parts on A549 cell cycle and cell apoptosis were determined by Annexin V-FITC/PI double staining assay. Result: MTT assay was used to calculate XCD effective parts in A549 role for 24

48

72 h. the 50% inhibitory concentration(IC50) of the 3 manners above were 136.550

56.671

55.322 mg·L-1 respectively. Flow cytometry was used to measured the XCD effective parts in A549 role for 24

48

72 h. The rates of apoptosis of the above 3 manners were(17.98±0.11)%

(23.34±0.23)%

(29.54±0.78)% respectively. After treated by XCD for 24 h

A549 cells were arrested in S phase

and for 48 h in G0/G1 phase. Conclusion: The XCD effective parts can inhibit the growth of A549 cells remarkably by inducing apoptosis and blocking cell cycle.