8-Hydroxyquinolines in medicinal chemistry: A structural perspective

8-Hydroxyquinolines are heterocyclic compounds characterized by a moderate metal-binding affinity. The interest in 8-hydroxyquinolines has grown exponentially in the last two decades as they are privileged structures for the design of new drug candidates that exert a host of biological effects on various targets. The study of biological activities such as neuroprotection, anticancer, antibacterial, antifungal activity has been further promoted by the synthetic versatility of 8-hydroxyquinoline, which allows the generation of a large number of derivatives. These include numerous multifunctional analogues having the metal-binding motif of 8-hydroxyquinoline. In this review, we have summarized 8-hydroxyquinolines, 8-hydroxyquinoline-like compounds, 8-hydroxyquinoline-loaded nanoparticle systems with respect to their biological activities, interaction with metal ions and mechanisms of action.