Synthesis, biochemical evaluation and molecular modeling studies of nonpeptidic nitrile-based fluorinated compounds.

Aim: Compounds that block enzyme activity can kill pathogens and help develop effective and safe drugs for Chagas disease and leishmaniasis. Materials & methods: A library of nonpeptidic nitrile-based compounds was synthesized and had their inhibitory affinity tested against cruzain, Leishmania mexicana cysteine protease B and cathepsin L. Isothermal titration calorimetry experiments and molecular simulations were performed for selected compounds to obtain thermodynamic fingerprints and identify main interactions and putative modes of binding with cruzain. Results: The derivatives provided increased affinity against all enzymes compared with the lead, and thermodynamic and computational studies showed improved thermodynamic properties and a possible different mode of binding. Conclusion: Our studies culminated in 1b, a compound 60-fold more potent in cruzain than its lead that also showed entropic and enthalpic contributions favorable to Gibbs binding energy.