Imidazole-based Ru(III) complexes: synthesis, characterisation and anticancer activity

In this work, we prepared a series of substituted imidazole-derived Ru(III) complexes, ImRu1-ImRu5, analogous to the clinically evaluated NAMI-A. These Ru(III) complexes, with different functional groups on the imidazole ring, were characterised by ¹H NMR and UV-Vis spectroscopy, elemental analysis, low- and high-resolution mass spectrometry, and single crystal X-ray diffraction. The cytotoxicity of the Ru(III) complexes was evaluated in vitro against different cancer and non-cancer cell lines, exhibiting low cytotoxicity activity and antimigratory characteristics comparable to those of the NAMI-A complex, except for the Ru(III) complex bearing an alkyne substituent on the imidazole ring (ImRu3). ImRu3 exhibited selective cytotoxicity against A549, MeWo and T24 cells, while retaining antimigratory activity against T24 cells, indicating that modifications at the imidazole ligand can modulate biological behaviour. Computational and fluorescence studies suggest that functional variations of the imidazole ligand enhance albumin-binding affinity, potentially facilitating transport and contributing to the observed anticancer activity.