Identification of a potent and selective LAPTc inhibitor by RapidFire-Mass Spectrometry, with antichagasic activity

• Published in: PLoS neglected tropical diseases Vol. 18; no. 2; p. e0011956
• Main Authors: Izquierdo, Maikel, Lin, De, O'Neill, Sandra, Webster, Lauren A, Paterson, Christy, Thomas, John, Aguado, Mirtha Elisa, Colina Araújo, Enrique, Alpízar-Pedraza, Daniel, Joji, Halimatu, MacLean, Lorna, Hope, Anthony, Gray, David W, Zoltner, Martin, Field, Mark C, González-Bacerio, Jorge, De Rycker, Manu
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.02.2024; Public Library of Science (PLoS)
• Subjects: Amastigotes; Aminopeptidase; Antineoplastic drugs; Antiparasitic agents; Benznidazole; Binding; Biology and Life Sciences; Cations; Chagas disease; Chemotherapy; Chromatography; Drug dosages; Enzymes; Hemoglobin; Hydrophobicity; Infectious diseases; Inhibitors; Mass spectrometry; Mass spectroscopy; Medicine and Health Sciences; Metal ions; Molecular dynamics; Nifurtimox; Parasites; Parasitic diseases; Peptides; Physical Sciences; Proteins; Protozoa; R&D; Research & development; Research and Analysis Methods; Selectivity; Toxicity; Tropical diseases; Vector-borne diseases; United Kingdom > UK
• ISSN: 1935-2735; 1935-2727; 1935-2735
• DOI: 10.1371/journal.pntd.0011956

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and leads to ~10,000 deaths each year. Nifurtimox and benznidazole are the only two drugs available but have significant adverse effects and limited efficacy. New chemotherapeutic agents are urgently required. Here we identified inhibitors of the acidic M17 leucyl-aminopeptidase from T. cruzi (LAPTc) that show promise as novel starting points for Chagas disease drug discovery. A RapidFire-MS screen with a protease-focused compound library identified novel LAPTc inhibitors. Twenty-eight hits were progressed to the dose-response studies, from which 12 molecules inhibited LAPTc with IC50 < 34 μM. Of these, compound 4 was the most potent hit and mode of inhibition studies indicate that compound 4 is a competitive LAPTc inhibitor, with Ki 0.27 μM. Compound 4 is selective with respect to human LAP3, showing a selectivity index of >500. Compound 4 exhibited sub-micromolar activity against intracellular T. cruzi amastigotes, and while the selectivity-window against the host cells was narrow, no toxicity was observed for un-infected HepG2 cells. In silico modelling of the LAPTc-compound 4 interaction is consistent with the competitive mode of inhibition. Molecular dynamics simulations reproduce the experimental binding strength (-8.95 kcal/mol), and indicate a binding mode based mainly on hydrophobic interactions with active site residues without metal cation coordination. Our data indicates that these new LAPTc inhibitors should be considered for further development as antiparasitic agents for the treatment of Chagas disease.