Asiatic acid treatment causes mitochondrial dysfunction. (A)–(C) A549 cells were exposed to asiatic acid (80 μmol/L for 3, 6, 12, 24 h or 20, 40, 80 μmol/L for 12 h) and the mitochondrial membrane potential (JC-1 staining, red/green fluorescence ratio) photographed by fluorescence microscopy and quantified by fluorescence spectrometry. (D) and (E) A549 cells were exposed to asiatic acid (20, 40, 80 μmol/L for 12 h) and the level of ROS detected by DCFH-DA staining. (F) A549 cells were exposed to asiatic acid (20, 40 and 80 μmol/L for 12 h) with or without NAC (2.5 mmol/L) for 48 h. The MTT assay was used to evaluate cell viability. Data represent mean±SD of three different experiments. *P<0.05, **P<0.01 vs. control.