Abstract: Objective To explore the effect of esculin on proliferation and apoptosis of A549 lung cancer cells.Methods The A549 lung cancer cells were assigned into a negative control group,a positive control group(0.77 mmol/L of 5-fluorouracil),and three esculin groups(0.4,0.8,and 1.6 mmol/L esculin).Methyl thiazolyl tetrazolium(MTT) method was used to observe the growth of A549 cells.Cell cycle,cell apoptosis and mitochondrial membrane potential of the A549 lung cancer cells were detected with flow cytometry,and the expressions of Bax,Bcl-2,and caspase-3 protein were detected with Western blot.Results Esculin could inhibit the growth of A549 lung cancer cells,with a 50% inhibitory concentration(IC₅₀) of 0.4 mmol/l,and reduce mitochondrial membrane potential of the cells.Compared with the control group,the proportion of cells in S phase(20.35±0.26%) and cell apoptosis rate(29.15%) increased,and the ratio of cells in G2/M phase decreased(25.46±0.17%) for the A549 lung cancer cells treated with 1.6 mmol/L esculin.In addition,esculin could enhance the expressions of Bax and caspase-3 protein and inhibit the expression of Bcl-2 protein in dose-dependent manner.Conclusion Esculin can induce apoptosis of A549 lung cancer cells through mitochondrial pathway.