Mono- and binuclear Ru(II) arene complexes with (fluoro substituted) picolinic acid: Synthesis, characterization and cytotoxicity

Four mono- (1–4) and four binuclear Ru(II) arene (5–8) complexes have been isolated from the reaction of [Ru(η6-benzene)Cl(μ-Cl)]2 or [Ru(η6-toluene)Cl(μ-Cl)]2 with 2-pyridinecarboxylic acid and 6-fluoro-2-pyridinecarboxylic acid. Their structural characterization included IR and NMR spectroscopy and MS spectrometry. The cytotoxic potential of the compounds has been tested by MTT assay in seven human cancer cell lines: alveolar basal adenocarcinoma (A549), large cell lung carcinoma (HTB177), colorectal carcinoma (HCT116), malignant melanoma (A375), prostate adenocarcinoma (PC3), breast carcinoma (MDA-MB-453), cervix adenocarcinoma (HeLa), and one human non-malignant lung fibroblast cell line (MRC-5). Mononuclear complexes 1 and 3 carrying 2-pyridinecarboxylic acid have displayed moderate antiproliferative effect toward HCT116 and HeLa, slightly better in comparison to their binuclear analogues, 5 and 7. The highest activity and cytoselectivity has been observed 1 as it has reduced viability of HCT116 cells 1.5 times more efficiently (IC50 = 27.5 μM), than of the MRC-5 cells (IC50 = 41.3 μM). In contrast to 1 and 3, compounds 2, 4–8 have been found to exhibit lack of cytotoxicity or mild cytotoxicity with IC50 values ranging from 100 to 300 μM.