The inhibition and selectivity indices (SI) of pyrimidine nucleoside analogues against intracellular <i>T</i>. <i>cruzi</i> following 48 hours incubation.

SI is in relation to HEK293 cells. 1) IC50 value, or if IC50 value could not be determined, the percentage inhibition at the highest test concentration of 183 μM (or for HEK293 cells this was 87 μM). NA = ≤50% activity at the highest concentration tested and an IC50 value could not be determined. EdU and EdC showed <20% activity against 3T3 cells in the image-based assay. 2) EdU resulted in a plateau of activity (Emax) of 57% against HEK293 cells, therefore the IC50 value was estimated and based on a sub-optimal effect against these cells. 3) F-ara-EdU inhibited 50% of parasite growth at 183 μM, with <50% inhibition observed at 73 μM. Selectivity index (SI) to T. cruzi intracellular amastigotes was in relation to HEK293 cells. * As residual host cells were not completely inhibited, and although they were smaller and fibrous, they could not be excluded from the script, thus the IC50 value against host cells following wash off could not be determined. NFX = nifurtimox. PURO = puromycin.