Bioactive Quinone-Based Ru(II) Complexes as Promising Anticancer Agents: Synthesis, Characterization, and Biological Evaluation

Medicinal inorganic chemistry has focused on the development of ruthenium-based compounds as potential anticancer agents. In this work, three Ru(II)-quinone-phosphine complexes with the general formula [Ru(dppb)(tbbipy)(O–O)]PF₆ were synthesized and fully characterized by spectroscopic, electrochemical, and crystallographic techniques. Stability studies demonstrated that the compounds remain stable in DMSO and culture medium for up to 48 h. Cytotoxicity assays against melanoma (A375) and breast cancer (MDA-MB-231 and MCF-7) cells revealed high activity and good selectivity, with enhanced cytotoxicity compared to the free quinone ligands. Notably, [Ru(dppb)(tbbipy)(quinizarin)]PF₆ exhibited potent activity against melanoma cells (IC₅₀ = 0.27 μM; SI = 5.89). The complexes also displayed moderate lipophilicity (log P > 0.5), which may contribute to their biological activity. Overall, these findings highlight Ru(II)-quinone-phosphine complexes as promising scaffolds for anticancer drug development.