The compounds that simultaneously satisfied the following two criteria were selected for the evaluation of their IC50 values in T. gondii β-gal and the assessment of host cells toxicity after exposure to 2.5 µM: i) when the compound was applied at 1 µM, T. gondii β-gal growth was inhibited by 90% or more compared to control treated with 0.1% DMSO only, and ii) HFF host cell viability was not impaired by more than 50% for a compound applied at 1 µM. Based on the primary screening, seven glucose and galactose dyads 19-24 and 26 were selected. Pyrimethamine, currently used for the treatment of toxoplasmosis, and which inhibited the proliferation of T. gondii β-gal tachyzoites with an IC50 value of 0.326 µM and did not affect HFF viability at 2.5 µM (Table ), was used as reference compound. The selection also included the diruthenium intermediate compounds 2-5 having free OH, NH2 or CO2H groups, along with two diruthenium alkyne ester and amide compounds 6 and 7, and diruthenium azide