Synthesis, spectroscopic characterization and anticancer potential studies of organoruthenium(II) arene dithiocarbamate complexes

Four organoruthenium(II) arene dithiocarbamate complexes: RuCl(piperidine dithiocarbamate)(p-cymene), C1; RuCl(1-phenylpiperazine dithiocarbamate)(p-cymene), C2, RuCl(ethylphenyl dithiocarbamate)(p-cymene), C3; RuCl(4-benzylpiperidine dithiocarbamate)(p-cymene), C4 were synthesized and characterized by elemental analysis, UV-Vis, FTIR, NMR and mass spectroscopic techniques. Spectroscopic data indicate that the complexes are four coordinate tetrahedral geometry consisting of one dithiocarbamato anion, p-cymene and a chlorido ligand around the ruthenium(II) ion. The dithiocarbamato anions coordinate the ruthenium(II) ions isobidentately. The cytotoxic effects of the compounds were assessed against human cervical cancer (HeLa) and human lung fibroblast (MRC5-SV2) cell lines using the 3-(4,5-dimethylthiazol-2-yl)−2,5-diphenyl tetrazolium bromide (MTT) assay. Only two compounds, C1 and C3 showed potent cytotoxicity after 48 h treatment. C1 was the most potent, with IC₅₀ values of 6.7 ± 2.3 µM and 8.1 ± 0.8 µM against the HeLa and MRC5-SV2 cells, respectively, while C3 had IC₅₀ values of 11.5 ± 3.1 µM and 10.3 ± 1.3 µM, respectively. Remarkably, compared to cisplatin (used as the reference anticancer drug), C1 was twice more potent against HeLa cells and more than five times more potent against MRC5-SV2 cells, while C3 was nearly equipotent with cisplatin against HeLa cells but five times more potent against MRC5-SV2 cells. These two compounds exhibited good potential as anticancer agents, thus warranting further studies.