Barbituric Acid Derivatives as Covalent Inhibitors of Leishmania braziliensis Dihydroorotate Dehydrogenase

  • J Med Chem. 2025 Jul 14. doi: 10.1021/acs.jmedchem.5c00462.
Thamires Quadros Froes  1  2 ,  Temitayo Omowumi Alegbejo Price  1 ,  Bruna Fleck Godoi  1 ,  Miguel Menezes Vaidergorn  1  2 ,  Thiago Dos Santos  1 ,  Pedro Ivo Palacio Leite  1 ,  Daniel Gedder Silva  1 ,  Aline Dias da Purificação  1  2 ,  Leonardo Loch  3 ,  Sergio Schenkman  3 ,  Jadel M Kratz  4 ,  Flavio da Silva Emery  1 ,  Maria Cristina Nonato  1  2
Affiliations
  • 1. Center for the Research and Advancement in Fragments and molecular Targets (CRAFT), School of Pharmaceutical Sciences at Ribeirao Preto, University of São Paulo, Ribeirão Preto, SP 14040-903, Brazil.
  • 2. Protein Crystallography Laboratory, Department of Biomolecular Sciences, School of Pharmaceutical Sciences of Ribeirao Preto, University of São Paulo, Ribeirão Preto, SP 14040-903, Brazil.
  • 3. Departamento de Microbiologia Imunobiologia e Parasitologia, Disciplina de Biologia Celular, Universidade Federal de São Paulo, R. Pedro de Toledo 669 6A, Vila Clementino, São Paulo, SP 04039032, Brasil.
  • 4. Drugs for Neglected Diseases initiative (DNDi) Latin America, Rio de Janeiro, SP 20010-020, Brazil.
PMID: 40658390 DOI: 10.1021/acs.jmedchem.5c00462
Abstract

Covalent drug design applied to Parasite proteins enables selective therapies by targeting nucleophilic residues of macromolecules. We present the first covalent inhibitors of Leishmania braziliensis Dihydroorotate Dehydrogenase (LbDHODH), a key enzyme in pyrimidine biosynthesis with a reactive cysteine (Cys131) in its active site. From barbituric acid derivatives, we discovered 2i as a LbDHODH inhibitor with leishmanicidal activity, exhibiting an IC50 of 0.5 ± 0.1 μM, a Kinact/KI of 767 M-1s-1, no inhibition of the human ortholog, and an EC50 of 11 ± 5 μM in L. braziliensis promastigotes, with no cytotoxicity in THP-1 cells and good passive permeability. X-ray crystallography confirms covalent bond formation with Cys131 and reveals active-site rearrangements. These findings support the proposed covalent inhibition mechanism and provide structural insights for further optimization. Our study validates LbDHODH as a promising target for leishmaniasis therapy and highlights the potential of covalent inhibition in antiparasitic drug discovery.

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