TABLE 2.

IC₅₀ values for inhibitors of putative apicoplast enzymes^a

Inhibitor	Mean IC50 ± SD (μM)	Presumed target
Ciprofloxacin	123 ± 38	Topoisomerase II
Clindamycin	>400	Large-subunit rRNA
Rifampin	96 ± 2	RNA polymerase B
Triclosan	20 ± 2	Missing
Fenoxaprop	262 ± 13	Missing
Fosmidomycin	No inhibition	DOXP reductoisomerase

^aInhibition of tritiated thymidine uptake by T. parva-infected B-lymphocyte culture. Cells were treated with drugs over 48 h and allowed to incorporate tritiated thymidine over the final 12 h of this treatment. IC₅₀s are the averages for three replicate samples from a representative experiment.