Electron Paramagnetic Resonance as a Tool for Studying the Mechanisms of Paramagnetic Anticancer Metallodrugs

Electron paramagnetic resonance spectroscopy (EPR) is an invaluable method for characterizing ligand environments and oxidation states of paramagnetic metal complexes. In this review we describe applications of this technique to understanding the often complicated mechanisms of metal-based anticancer compounds. EPR has been instrumental in unravelling this in many instances, providing insight into conformations upon dissolution, aqueous ligand exchange, pH effects, and redox processes. EPR studies have also characterized the protein and DNA interactions of metal-based chemotherapeutics, enabling discrimination of different binding modes. EPR can also be used to probe the behaviour of metallodrugs with whole cells, revealing interactions with cellular components and redox stability. Together, these studies provide important information on aspects of anticancer activity and demonstrate the scope and potential of EPR to contribute to the ongoing development of metal-based anticancer complexes.