Mechanism of action of the curcumincis-diammineplatinum(ii) complex as a photocytotoxic agent

In the search for new and more active anticancer drugs, light-activated compounds are emerging as effective drugs to be used in photodynamic therapy (PDT) and photoactivated chemotherapy (PACT). These clinical treatments are able to overcome severe side effects caused by the conventional Pt(ii) complexes in chemotherapy, since the cytotoxic species are released directly into the target regions, reducing toxicity in healthy tissues. The curcumincis-diammineplatinum(ii) complex has been proposed for PACT as it allows the controlled release of aquated diammine-platinum(ii) species as a DNA cross-linking agent and curcumin as a potential photosensitizer, thus working as a dual action anticancer agent. The curcumin ligand dissociation upon irradiation with visible light was examined by means of DFT and TD-DFT calculations. The outcomes clearly unraveled the metal-centered triplet states(3)MC as active species involved in the photocleavage of curcumin that lead to the formation of aquated platinum species and ruled out the potential activity of such a complex in the dark.