Non-platinum complexes containing releasable biologically active ligands

Since the discovery of anticancer activity of cisplatin and other transition metal complexes, a lot of compounds have been reported as containing ligand(s) bearing its(their) own biological activity. Nowadays, the complexes containing releasable bioactive ligand(s), for which several terms (e.g., multi-targeted, multi-action or multi-modal) have been introduced, represent one of the hottest topics for the bioinorganic chemists. Herein we focused on rationally designed cytotoxic complexes of platinum-group metals, namely ruthenium, rhodium, palladium, osmium and iridium, which contain releasable bioactive ligand(s). Because a concept of multi-targeted complexes is based on a release and subsequent joint biological effect of multiple species, we concentrate especially on complexes whose fate under the (pseudo)physiological conditions is provably or most likely connected with a release of bioactive ligand(s)/substituent(s) and cytotoxic metal-containing species. Thus, the simultaneous action of the released species ensures various biological profits, such as higher cytotoxic activity, cytotoxicity at different cells (connected with the ability to overcome resistance) or modified processes connected with the mode of action, as compared with the initial complexes without bioactive ligand(s). (C) 2019 Elsevier B.V. All rights reserved.