Double ester prodrugs of FR900098 display enhanced in-vitro antimalarial activity.

Fosmidomycin and FR900098 are inhibitors of the 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR; IspC), a key enzyme of the mevalonate-independent isoprenoid biosynthesis pathway. We have determined the in-vitro antimalarial activity of two double ester prodrugs 2, 3 in direct comparison with the unmodified FR900098 1 against intraerythrocytic forms of Plasmodium falciparum. Temporarily masking the polar properties of the phosphonate moiety of the DXR inhibitor FR900098 1 enhanced not only its oral bioavailability but also the intrinsic activity of this series against the parasites.