Fig. 4

Copper chelation generated ROS was responsible for cytotoxicity. a ROS activity generated from different compounds (10 μM) in combination with or without CuCl₂ (10 μM). H2O2 (1:100 diluted) and dye only were positive and negative control respectively. b The cytotoxicity of DS was reversed by NAC. The cells were exposed to DS (1 μM) and CuCl₂ (10 μM) with or without NAC (2 mM) for 6 h and released in drug-free medium. c and d The apoptosis induced by DS was reversed by NAC. The cells were exposed to DS (1 μM) and CuCl₂ (10 μM) with or without NAC (2 mM) for 6 h and subjected Annexin V analysis