Piperazine designer drugs induce toxicity in cardiomyoblast h9c2 cells through mitochondrial impairment

•Piperazine derivatives presented cytotoxicity, being TFMPP the most cytotoxic.•Piperazine designer drugs significantly increased Ca2+ intracellular levels.•All drugs caused decreased intracellular ATP and mitochondrial membrane potential.•Mitochondrial permeability transition pore seems to play a role in cytoxicity.•There were found early apoptotic cells and cells undergoing secondary necrosis. Abuse of synthetic drugs is widespread among young people worldwide. In this context, piperazine derived drugs recently appeared in the recreational drug market. Clinical studies and case-reports describe sympathomimetic effects including hypertension, tachycardia, and increased heart rate. Our aim was to investigate the cytotoxicity of N-benzylpiperazine (BZP), 1-(3-trifluoromethylphenyl) piperazine (TFMPP), 1-(4-methoxyphenyl) piperazine (MeOPP), and 1-(3,4-methylenedioxybenzyl) piperazine (MDBP) in the H9c2 rat cardiac cell line. Complete cytotoxicity curves were obtained at a 0–20mM concentration range after 24h incubations with each drug. The EC50 values (μM) were 343.9, 59.6, 570.1, and 702.5 for BZP, TFMPP, MeOPP, and MDBP, respectively. There was no change in oxidative stress markers. However, a decrease in total GSH content was noted for MDBP, probably due to metabolic conjugation reactions. All drugs caused significant decreases in intracellular ATP, accompanied by increased intracellular calcium levels and a decrease in mitochondrial membrane potential that seems to involve the mitochondrial permeability transition pore. The cell death mode revealed early apoptotic cells and high number of cells undergoing secondary necrosis. Among the tested drugs, TFMPP seems to be the most potent cytotoxic compound. Overall, piperazine designer drugs are potentially cardiotoxic and support concerns on risks associated with the intake of these drugs.