HHQ induced loss in mitochondrial membrane potential (MMP) in human breast cancer cells (MDA-MB-231 and MCF-7). The breast cancer cells were treated with 12.5 μM and 25 μM of HHQ for 48 h at 37 °C and then immunostained for JC1. HHQ treated cells showed loss of MMP comparable to that of the control cells. Data are representative of three independent experiments done in triplicates and expressed as mean ± S.E.M. *p < 0.005 represents statistical significant difference between control and HHQ test groups.