Efficacy of sulfonamides targeting malic enzyme in an animal model of Chagas disease

Thaís Cristina Ferreira dos Santos^1*Ramon Borges da Silva¹Irene Layane de Souza¹Fabrício Fredo Naciuk¹Letícia Marchese¹Amanda Gonçalves Eufrásio¹Angel Eduardo Lobo-Rojas¹Renan Marcel Giampauli¹Valéria Barbosa de Souza²André Almeida Schenka²Marjorie Bruder¹Silvana A. Rocco¹Artur Torres Cordeiro^1*

• ¹Centro Nacional de Pesquisa em Energia e Materiais, Campinas, Brazil
• ²Universidade Estadual de Campinas, Campinas, Brazil

Introduction: Even after a century since its discovery, Chagas disease remains a major public health concern. Benznidazole and nifurtimox are the only approved treatments, but their limited efficacy and adverse effects highlight the urgent need for new therapies. In the last decade, several phenotypic screenings performed by pharmaceuticals and academic groups revealed new promising compounds. In a previous study, we identified the T. cruzi malic enzyme (TcME) as the molecular target for the sulfonamide TCMDC-143108, a phenotypic hit made public available through the Chagas Box collection. Indeed, we determined crystallographic structures for TcME-inhibitor complexes and synthesized new molecules with improved activity against intracellular T. cruzi forms. Aim: The present study aims to evaluate the efficacy of new sulfonamides derived from TCMDC-143108 in an animal model for acute Chagas disease. Methods: The new sulfonamides were evaluated for TcME inhibition and activity against T. cruzi Dm28c strain, infecting h9c2 cardiomyoblast. Active compounds progressed to ADME in vitro assays. Promising hits were assessed for oral bioavailability. In vivo efficacy was evaluated in infected balb/c mice by direct parasitemia, parasite tissue burden (heart, colon, and spleen), and histopathological examination. Results: Compounds AC-R008, AC-M109, and AC-M110 inhibited TcME and T. cruzi intracellular growth. AC-R008 and AC-M110 exhibited good solubility at basic pH and favorable LogD7.4 values. AC-M110 exhibited high permeability with pH-dependent behavior in the PAMPA assay and intermediate values in the Caco-2 assay, while AC-R008 showed high permeability in both assays. However, both compounds presented short half-lives and high clearance in liver microsomal assays, consistent with extensive phase I metabolism. In vivo, oral administration resulted in plasma concentrations up to 1 µM after 1 hour. In the Chagas disease animal model, AC-R008 and AC-M110 reduced parasitemia by 50% but did not reduce tissue parasite load. Conclusion: These findings demonstrate the potential of this sulfonamide scaffold while also underscoring metabolic instability and limited systemic exposure as major challenges. Future optimization efforts will focus on structural modifications and formulation strategies to enhance pharmacokinetics and therapeutic efficacy.