AbstractPachyrhizus erosus (Fabaceae) is a herb commonly known as 'yam bean', which has been cultivated in México since pre-Columbian times for its edible tubers. The seeds are also known for their acaricidal and insecticidal properties due to rotenone and other isoflavonoid contents. Rotenone has exhibited cytotoxic activity against several human tumour cell lines; however, its mechanism of action is still not fully understood. In this study, we determined the cytotoxicity of rotenone isolated from P. erosus seeds on K562 human leukaemia cells. Rotenone exhibited significant cytotoxic activity (IC50 = 13.05 μM), as determined by the MTT assay. Three other isolated isoflavonoids were not cytotoxic. Rotenone genotoxicity was detected using the comet assay. Rotenone induced cell death, and caspase-3 activation as indicated by TUNEL assay, and immunocytofluorescence. Plasmid nicking assay indicated that rotenone does not interact directly with DNA.Keywords:: Pachyrhizus erosus seedsrotenoneK562 leukaemia cellscytotoxicityapoptosiscaspase-3 AcknowledgementsWe are also grateful to María del Rocío Patiño Maya (IR), María de los Ángeles Peña González (RMN), Francisco Javier Pérez Flores (EM) for spectroscopical determination, to Alberto Javier Reyes García and Araceli Zarate Aquino for botanical assistance. The authors have declared no conflict of interest.Additional informationFundingThis research was supported by a grant IG-200513 from PAPIIT-DGAPA-UNAM. E.A. Estrella-Parra is grateful to Posgrado en Ciencias Biológicas de la Universidad Nacional Autonóma de México (PCB-UNAM), and Consejo Nacional de Ciencia y Tecnología (CONACYT; 220355) for providing a scholarship for Ph.D. studies. I. González-Sánchez was supported by a post-doctoral grant (DGAPA-UNAM).