A particular class of compounds containing this unit are the trithiolato-bridged dinuclear ruthenium(II)-arene complexes (A-C in Figure ), which show not only high antiproliferative activity against cancer cells , but also promising antiparasitic properties . The structure of these complexes is based on a trigonal bipyramidal Ru2S3 framework, with two ruthenium(II)-arene halfsandwich units. Two types of complexes can be distinguished, "mixed" (at least one of the bridge thiols is different, A in Figure ) and "symmetric" (the three bridge thiols are identical, B and C in Figure ) . Former studies of this type of compounds on Toxoplasma gondii , Neospora caninum and Trypanosoma brucei identified high antiparasitic activity for some derivatives. For example, compounds A-C (Figure ) inhibit T. gondii tachyzoites proliferation with IC50 values in nanomolar range (down to 1.2 nM for A) while not affecting the HFF (human foreskins fibroblasts) host cells viability. T. gondii is an obligate intracellular protozoan parasite of the phylum Apicomplexa that causes infections of medical and veterinary significance in humans and animals . Infection is usually asymptomatic in immunocompetent individuals, but it may cause severe complications or even be fatal in immunocompromised patients . Current common treatments for toxoplasmosis are not specific, require prolonged courses and have toxic side effects, and so, new therapeutic solutions are needed . Unlike other pathogens, Toxoplasma has adapted to replicate in all nucleated cells of a wide range of vertebrates, regardless of their cellular metabolism, and thus displays an exceptional metabolic robustness . Accordingly, tackling the parasite auxotrophies and metabolic peculiarities can constitute an interesting therapeutic strategy .