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

BACKGROUND: 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. METHODOLOGY/PRINCIPAL FINDINGS: 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. CONCLUSIONS/SIGNIFICANCE: Our data indicates that these new LAPTc inhibitors should be considered for further development as antiparasitic agents for the treatment of Chagas disease.

Correction to "Bespoke Drug Discovery Training for Low-Middle Income Countries".

[This corrects the article DOI: 10.1021/acsmedchemlett.3c00215.].

Bespoke Drug Discovery Training for Low-Middle Income Countries.

Working in drug discovery is difficult for many institutions due to the need for resources, funding, and in-country expertise. The Wellcome Centre for Anti-Infective Research (WCAIR) is responding to the unmet training needs for individuals/institutions working in drug discovery in low-middle income countries. Through their training program, individuals can undertake a practical placement, either online or at the center, with access to a dedicated trainer from their field of research. Practical placements are tailored to the needs of the individual/institute to enable capability building on return to their home institute. In addition to training placements, the center is focused on building partnerships by supporting institutes to work in drug discovery. Here we highlight WCAIR's training program and the partnerships that have developed from this.

Development of Chemical Proteomics for the Folateome and Analysis of the Kinetoplastid Folateome.

The folate pathway has been extensively studied in a number of organisms, with its essentiality exploited by a number of drugs. However, there has been little success in developing drugs that target folate metabolism in the kinetoplastids. Despite compounds being identified which show significant inhibition of the parasite enzymes, this activity does not translate well into cellular and animal models of disease. Understanding to which enzymes antifolates bind under physiological conditions and how this corresponds to the phenotypic response could provide insight on how to target the folate pathway in these organisms. To facilitate this, we have adopted a chemical proteomics approach to study binding of compounds to enzymes of folate metabolism. Clinical and literature antifolate compounds were immobilized onto resins to allow for "pull down" of the proteins in the "folateome". Using competition studies, proteins, which bind the beads specifically and nonspecifically, were identified in parasite lysate ( Trypanosoma brucei and Leishmania major) for each antifolate compound. Proteins were identified through tryptic digest, tandem mass tag (TMT) labeling of peptides followed by LC-MS/MS. This approach was further exploited by creating a combined folate resin (folate beads). The resin could pull down up to 9 proteins from the folateome. This information could be exploited in gaining a better understanding of folate metabolism in kinetoplastids and other organisms.

Automated design of ligands to polypharmacological profiles.

The clinical efficacy and safety of a drug is determined by its activity profile across many proteins in the proteome. However, designing drugs with a specific multi-target profile is both complex and difficult. Therefore methods to design drugs rationally a priori against profiles of several proteins would have immense value in drug discovery. Here we describe a new approach for the automated design of ligands against profiles of multiple drug targets. The method is demonstrated by the evolution of an approved acetylcholinesterase inhibitor drug into brain-penetrable ligands with either specific polypharmacology or exquisite selectivity profiles for G-protein-coupled receptors. Overall, 800 ligand-target predictions of prospectively designed ligands were tested experimentally, of which 75% were confirmed to be correct. We also demonstrate target engagement in vivo. The approach can be a useful source of drug leads when multi-target profiles are required to achieve either selectivity over other drug targets or a desired polypharmacology.