Ortho-dihydroxychalcones as cupric ion-dependent prooxidants: Activity and mechanisms

•Activity and mechanisms of o-dihydroxychalcones as Cu(II)-dependent prooxidants were studied.•They can induce DNA damage and apoptosis of HepG2 cells under low concentrations.•Sequential proton loss electron transfer steers the oxidation process.•Relative sensitivity and role of catechol moieties on A and B rings for the oxidation were explored.•This work should be helpful for understanding ROS or prooxidant-based cancer treatment.