The biological activity of the carbohydrate azides and alkyne derivatives 14-16 and, respectively, 17 and 18 was not measured as these compounds were not isolated pure. Glucose and galactose conjugates 19-26, glucose azide derivative 10 and diruthenium alkyne intermediate 6 were assessed for their in vitro biological activity in inhibiting proliferation of T. gondii β-gal, a transgenic strain that constitutively expresses β-galactosidase and for toxicity to HFFs (human foreskin fibroblast) used as host cells. The compounds were applied to infected or non-infected HFFs cultures for 72 h and at concentrations of 0.1 and 0.1 µM, the results being summarized in Table and Figure . The trithiolato diruthenium complexes 2-5 and 9, and alkyne intermediates 7 and 8 were evaluated previously against T. gondii β-gal under similar conditions , and the corresponding values are shown in Table and Figure for comparison. The viability of treated HFFs was measured by the alamarBlue metabolic assay, and the proliferation of T. gondii β-gal was quantified by the β-galactosidase colorimetric test. In both cases, results are expressed as percentage (%) compared to control parasitic and host cells treated with 0.1% DMSO for which proliferation and viability were set to 100% (Table ). Table . Results of the primary efficacy/cytotoxicity screening of the azide derivative 10 and of trithiolato diruthenium compounds 2-9 and 19-26 in non-infected HFF cultures and T. gondii β-gal tachyzoites cultured in HFFs. Non-infected HFF monolayers treated only with 0.1% DMSO exhibited 100% viability and 100% proliferation was attributed to T. gondii β-gal tachyzoites treated with 0.1% DMSO only. The compounds selected for determination of IC50 values against T. gondii β-gal are tagged with * . For each assay, standard deviations were calculated from triplicates. For each assay, standard deviations were calculated from triplicates and are displayed on the graph. Data for compounds 2-5 and 7-9 were previously reported .