In this paper we report a review of the results obtained in the last few years by our
group in the development of ruthenium(III) complexes characterized by the presence of
sulfoxide ligands and endowed with antitumor properties. In particular, we will focus on
ruthenates of general formula Na[trans-RuCl4(R1R2SO)(L)], where R1R2SO =
dimethylsulfoxide (DMSO) or tetramethylenesulfoxide (TMSO) and L = nitrogen donor
ligand. The chemical behavior of these complexes has been studied by means of
spectroscopic techniques both in slightly acidic distilled water and in phosphate buffered
solution at physiological pH. The influence of biological reductants on the chemical
behavior is also described. The antitumor properties have been investigated on a number
of experimental tumors. Out of the effects observed, notheworthy appears the capability
of the tested ruthenates to control the metastatic dissemination of solid metastasizing
tumors. The analysis of the antimetastatic action, made in particular on the MCa
mammary carcinoma of CBA mouse, has demonstrated a therapeutic value for these
complexes which are able to significantly prolong the survival time of the treated
animals. The antimetastatic effect is not attributable to a specific cytotoxicity for
metastatic tumor cells although in vitro experiments on pBR322 double stranded DNA
has shown that the test ruthenates bind to the macromolecule, causing breaks
corresponding to almost all bases, except than thymine, and are able to cause interstrand
bonds, depending on the nature of the complex being tested, some of which results active
as cisplatin itself.
