Bisamidine Derivatives as Candidates for Tegumentary Leishmaniasis Therapy: Phenotypic Screening in Infection of Macrophages and Mechanistic Insights with Dual RNA-seq

Leishmania braziliensis is the primary causative agent of American tegumentary leishmaniasis (ATL), a critical parasitic tropical neglected disease. The chemotherapeutic arsenal has limited efficacy and significant toxic effects that lead to an urgent need to develop new medicines. Using the "drug repurposing" approach, histone-modifying enzyme inhibitors have been the subject of developing new drugs against neglected parasitic diseases. In this work, furamidine, a known diphenyl furan inhibitor of human Protein Arginine Methyltransferase (PRMT), along with a library of 31 developed analogues, was tested for leishmanicidal activity against L. braziliensis in the in vitro Infection of macrophage assay. The most active and selective leishmanicidal analogue, BSF2 (EC₅₀ of 0.64 μM (95% CI: 0.56-0.72), SI of 17.36), was further investigated by dual RNA-seq at 0.16 μM BSF2. The dual-transcriptome detected only 10 genes with significant differential expression (FDR ≤10%) in L. braziliensis related to ubiquitination, chromatin remodeling, and peroxisomal membrane transport pathways, following BSF2 treatment of infected macrophages. In addition, BSF2 had a significant effect (FDR ≤5%) on the expression of 577 genes in the infected macrophages, including the downregulation of TNF, IL-17, NF-κB, and Toll-like Receptor pathways. This work opens new venues for developing new chemotherapy for leishmaniasis based on BSF2 or derivatives and highlights the dual transcriptome as a valuable phenotypic assay tool to investigate host-parasite interactions for antileishmanial drug discovery.