Saikosaponins induce intracellular ROS accumulation in HeLa cells. HeLa cells were treated with cisplatin (8 μM) or saikosaponin-a (10 μM) or saikosaponin-d (2 μM) individually or combination of saikosaponin and cisplatin for 30 min. 5 μM of DHE (A) or 5 μM of CM-H2DCFDA (B) was added 30 min before collecting cells. The fluorescent intensities of 10,000 cells were analyzed with a flow cytometer. Untreated cells with DHE or CM-H2DCDA staining were used as a negative control. The histogram overlays show the results of treated cells (red lines) compared with untreated cells (green lines). x-axis, fluorescent intensity showing the extent of DHE or CM-H2DCFDA oxidation; y-axis, cell number. The data (mean fluorescence for each group) was also presented as bar charts below the profiles (error bars indicate SD of triplicate experiments).