Tagetes minuta leaf extracts triggered apoptosis in MCF-7 human breast cancer cell line

•Tagetes minuta (TM) leaves extracts inhibited the growth of MCF-7 human breast cancer cell line.•TM leaf extracts induced caspase-7 activation and apoptosis in MCF-7 cells.•TM leaf extracts altered mitochondria membrane potential and increased ROS generation in MCF-7 cells. Tagetes minuta L. (Family: Asteraceae) has a history of human use as an ingredient in foods, therapeutics, and cosmetics. Although the in vitro cytotoxicity of Tagetes minuta (TM) has been reported in some human cancer cell lines, there is a paucity of information regarding its anticancer mechanisms of actions. In this study, we explored the mechanisms underlying the anticancer potential of TM in breast cancer. The apoptosis-inducing effect of TM leaf extracts was examined by Annexin V/propidium iodide (PI), Hoechst staining, flow cytometry, and fluorescence imaging using the MCF-7 human breast cancer cell line as a model. The activation of Caspase -3/7 was assessed using a luminogenic substrate (DEVD) consisting of a four amino acid peptide sequence conjugated to a fluorogenic compound (7-amino-4-trifluoromethyl coumarin). Also, the 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA) and JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazoylcarbocyanine iodide) stains were used to determine cellular ROS generation and mitochondrial membrane depolarization respectively. The hexane and dichloromethane extracts of TM leaf exhibited moderate cytotoxicity against MCF-7 in a dose-dependent manner. These extracts induced reactive oxygen species (ROS) generation that was accompanied by the disruption of the mitochondrial transmembrane potential, resulting in caspase activation and eventually apoptotic cell death. The study revealed for the first time, that Tagetes minuta leaf extracts induce breast cancer cell death through mitochondrial caspase-dependent apoptosis. The conclusion, therefore, is that the hexane and dichloromethane extracts from Tagetes minuta leaf have the potential to be used as an anticancer agent.