Ruthenium-based compounds and tumour growth control (review)

Heavy metals have often been represented, as an uncertain entity related to renal and other risks of toxicity. In favour of this thought there are several lines of evidence, first of all traffic pollution, other evidence that metals such as arsenite, mercury, cadmium or even iron or radioactive heavy metals, that may be introduced into the body by accident, have been responsible of well known pathologies (for example saturnism with lead) or acute toxicity. Therefore, the biological and medical literature have debated on this subject, mainly from the toxicological point of view, rather than studying possible advantages that might come from compounds based on these metals. Exceptions are represented by studies on the role of metal ions in the biochemistry of enzymes and energy production and, although with less emphasis, on their possible use for correcting metabolic malfunctions. Ruthenium, as a metal, has received an even poorer interest and besides the use in histology, neither ruthenium ions nor ruthenium compounds have a clear place in medicine and biology. Nevertheless, since the middle seventies, many studies have been published, showing in a convincible and repetitive manner, the possible advantages of ruthenium as a base for new competitive drugs. The aim of this review is therefore that of critically examining the past and the actual work on ruthenium compounds with emphasis on their proposed role in cancer therapy.