Ruthenium(II) complexes of curcumin and β-diketone derivatives: effect of structural modifications on their cytotoxicity.

Ruthenium(II) complexes (Ru1-Ru3) with the general formula [Ru(O-O)(PPh₃)₂(bipy)]PF_6, bearing two triphenylphosphine (PPh₃), bipyridine (bipy) and a series of natural and synthetic β-diketones (O,O) ligands were synthesized and characterized using various analytical techniques. The interaction between the complexes and calf thymus DNA (CT-DNA) was investigated and demonstrated a weak interaction. The cytotoxicity of the complexes was investigated against breast cancer cells (MDA-MB-231 and MCF-7), lung cancer cells (A549), cisplatin-resistant ovarian cancer cells (A2780cis), as well as non-tumour lung (MRC-5) and non-tumour breast (MCF-10A) cell lines. All complexes exhibited cytotoxic activity against all the cell lines studied, with half maximal inhibitory concentration (IC₅₀) values ranging from 0.39 to 13 µM. Notably, the three complexes demonstrated selectivity against the A2780cis cell line, with IC₅₀ ranging from 0.39 to 0.82 µM. Among them, Ru2 exhibited the highest cytotoxicity, with an IC₅₀ value of 0.39 µM. Consequently, this new class of complexes shows good selectivity towards cisplatin-resistant ovarian cancer cells and it is promising for further investigation as anti-cancer agents.