Aminoquinoline-based ruthenium(II) and iridium(III) polypyridyl complexes: Investigating potential photosensitisers for cancer treatment via photodynamic therapy

Abstract

Cancer is a devastating noncommunicable disease that remains one of the most pressing health challenges of the twenty-first century. Chemotherapy stands as one of the most common and effective cancer treatment methods. However, severe side effects and acquired drug resistance in many cancers have significantly diminished the efficacy of current chemotherapeutic agents. The urgent demand for novel treatment modalities has led to the development of photodynamic therapy (PDT) for the treatment of various cancer types. In this work, the synthesis of aminoquinoline-based transition metal complexes containing two PGMs (Ir(III) and Ru(II)) as potential photosensitisers is described. Mononuclear N,N-chelated Ru(II) and Ir(III) transition metal complexes were synthesized by reacting 4-aminoquinoline Schiff base ligands, which contain either a pyridyl or a quinolyl entity. The photostable Ru(II) and Ir(III) polypyridyl complexes were investigated for their potential use as PDT agents. In vitro cytotoxicity screenings conducted against a melanoma cell line (501mel) both in the absence and presence of light confirmed that all complexes demonstrated increased biological activity when exposed to visible light at 455 nm. Overall, the Ru(II) complexes are superior phototoxic agents in comparison with their Ir(III) congenors.