Clawing back: broadening the notion of metal chelators in medicine

[Display omitted] ► Not all chelators are the same: more than metal sequestration and elimination. ► Metal chelates can redistribute metals across biological membranes. ► Metal-chelating fragments provide leads for metalloenzyme inhibition. ► Metal chelation can enhance metal reactivity and thus cytotoxicity. ► Prochelators provide site-activated metal chelation and passivation. The traditional notion of chelation therapy is the administration of a chemical agent to remove metals from the body. But formation of a metal-chelate can have biological ramifications that are much broader than metal elimination. Exploring these other possibilities could lead to pharmacological interventions that alter the concentration, distribution, or reactivity of metals in targeted ways for therapeutic benefit. This review highlights recent examples that showcase four general strategies of using principles of metal chelation in medicinal contexts beyond the traditional notion of chelation therapy. These strategies include altering metal biodistribution, inhibiting specific metalloenzymes associated with disease, enhancing the reactivity of a metal complex to promote cytotoxicity, and conversely, passivating the reactivity of metals by site-activated chelation to prevent cytotoxicity.