Transition metal complexes with tetradentate Schiff bases (N₂O₂) obtained from salicylaldehyde: A review of their possible anticancer properties

Despite multiple advances in prevention and treatment, cancer remains a deadly disease globally. From 1942 to the present day, chemotherapy has been recognized as one of the main alternatives in the treatment of cancer. Nevertheless, the use of anticancer metallodrugs was investigated until 1965, when the therapeutic application of cisplatin was discovered circumstantially. Currently, other metallodrugs based on platinum and ruthenium have reached intermediate and advanced clinical research phases, some even reaching the market (carboplatin, heptaplatin, lobaplatin, miriplatin, nedaplatin, oxaliplatin, etc.). During the last decades, scientists have developed new metallodrugs that are more effective and selective, but with fewer side effects. Metal complexes based on transition metals have demonstrated very good anticancer activity, mainly when coordinated with organic ligands containing nitrogen or oxygen. In this sense, various reports have confirmed that Schiff bases derived from salicylaldehyde form ideal N2O2 ligands (salphen, salen, salpn) to design coordination complexes with dblock metals potentially useful in chemotherapy. Therefore, this document could pave the way for the scientific community focused on the design of new metallodrugs based on tetradentate Schiff bases and transition metals.