Investigations into the interaction between tumor-inhibiting ruthenium(III) complexes and nucleotides by capillary electrophoresis

Ruthenium(III) complexes of the general formula HL[RuCl4L2], with two trans-standing heterocyclic ligands L bound to ruthenium via nitrogen, show remarkable activity in different tumor models. To obtain a deeper insight into the mode of action of this class of anticancer compounds, we investigated the interaction of HIm trans-[RuCl4(im)2] (im, imidazole) and HInd trans-[RuCl4(ind)2] (ind, indazole) with all four nucleoside monophosphates in buffered solution by means of capillary electrophoresis. A preference for GMP- and AMP-coordination was found. A decrease of the pH resulted in a significantly increased amount of bound nucleotide. This feature seems to be interesting with regard to the lower pH values in solid tumors.