Pifithrin-alpha is a small molecule p53 functional inhibitor reported to behave like an antiapoptotic agent in neurodegenerative models. Pifithrin-alpha is a prodrug that under physiological conditions spontaneously undergoes ring closure to yield pifithrin-beta. Pifithrin-beta demonstrated antiproliferative and neuroprotective effects in vitro. Pifithrin-beta is able to activate the aryl hydrocarbon receptor (AhR) in a complete independent way of the p53 inhibition.