Structure-Based Design, Synthesis, and Biological Evaluation of Novel Inhibitors of Human Cyclophilin A

Cyclophilin A is involved in many cellular processes, including protein folding and intracellular transports. Because cyclophilin A has been shown to interact with HIV-1 gag proteins and to enhance the viral infectivity, nonimmunosuppressive cyclophilin A ligands may represent a new class of therapeutic agents against HIV. Here, we report a virtual screening using structure- and pharmacophore-based design to identify original nonpeptidic cyclophilin ligands. Following a lead identification of compounds 1 [1-(3-benzyloxypyridin-2-yl)-3-(3-chlorophenyl)urea] and 2 [1-(3-benzyloxypyridin-2-yl)-3-(3-trifluoromethylphenyl)urea] (IC(50) = 0.3 microM), a series of molecules were synthesized from a diarylurea scaffold and evaluated for their in vitro ability to inhibit the cis-trans isomerase activity of cyclophilin A. Molecular modifications provided several more potent compounds, in particular analogues 4d and 4i with IC(50) of 14 and 20 nM, respectively. Then, we evaluated the effect of analogues 1 and 2 on HIV virion infectivity in both immortalized and primary cells. Both 1 and 2 reduced virion infectivity in the replication-defective one-round infection assay, but only 1 impaired wild-type HIV infection in human peripheral blood mononuclear cells.