Ramon Guerra de Oliveira

Asexual reproduction of malaria parasites requires the basal complex, the equivalent of a eukaryotic contractile ring. Despite its central role, basal complex biogenesis remains largely unknown. Here, we use expansion microscopy and DNA points accumulation for imaging in nanoscale topography to investigate three transmembrane basal complex proteins in Plasmodium falciparum —basal complex transmembrane protein 1 (BTP1), BTP2, and basolateral expansion boundary (BLEB). Parasites lacking BTP2 are still enveloped by membranes but fail to separate from each other, resulting in multiorganellar mutants. We isolate the defect to a specific step during basal complex development and demonstrate that the contractile ability remains intact. By revisiting BLEB, we identify a distinct plasma membrane region that is excluded from daughter cells and associated with the basal complex. Integrating these findings, we propose a three-step model for basal complex biogenesis that highlights the specific role of BTP2 and suggests a role for the BLEB-associated membrane. This study offers a mechanistic framework for how multiple daughter cells are formed simultaneously and highlights the importance of transmembrane proteins for cell division.

Chagas disease (CD), caused by the flagellate protozoan Trypanosoma cruzi, is a neglected tropical disease endemic in 21 countries. The only two antiparasitic drugs approved for its treatment, benznidazole and nifurtimox, have significant drawbacks. We present herein the optimization of a series of substituted indoles that were identified through phenotypic screening against T. cruzi. Early lead compounds with balanced potency and physicochemical properties were advanced to animal studies but showed limited plasma exposure. Medicinal chemistry strategies were used to improve metabolic stability and solubility, but unfortunately, this effort failed to yield compounds with improvements in both exposure and potency. Still, the best compound was progressed for a proof-of-concept efficacy study using acute and chronic mice models of Chagas disease. Despite showing antiparasitic activity in these in vivo studies, the optimization work with this series was stopped due to unfavorable drug metabolism and pharmacokinetic (DMPK) properties and a deprioritized mechanism of action (CYP51 inhibition).

Chagas disease (CD) is a parasitic neglected tropical disease (NTD) caused by the protozoan Trypanosoma cruzi that affects 6 million people worldwide, often resulting in financial burden, morbidity, and mortality in endemic regions. Given a lack of highly efficient and safe treatments, new, affordable, and fit-for-purpose drugs for CD are urgently needed. In this work, we present a hit-to-lead campaign for novel cyanopyridine analogues as antichagasic agents. In a phenotypic screening against intracellular T. cruzi, hits 1 and 2 were identified and displayed promising potency combined with balanced physicochemical properties. As part of the Lead Optimization Latin America consortium, a set of 40 compounds was designed, synthesized, and tested against T. cruzi intracellular amastigotes and relevant human cell lines. The structural modifications were focused on three positions: cyanopyridine core, linker, and right-hand side. The ADME properties of selected compounds, lipophilicity, kinetic solubility, permeability, and liver microsomal stability, were evaluated. Compounds 1-9 displayed good potency (EC₅₀T. cruzi amastigote 50 MRC-5 = 32-64 μM). Despite the good balance between potency and selectivity, the antiparasitic activity of the series appeared to be driven by lipophilicity, making the progression of the series unfeasible due to poor ADME properties and potential promiscuity issues.

In this study, we synthesized a new congener series of N-sulphonylhydrazones designed as candidate ROCK inhibitors using the molecular hybridization of the clinically approved drug fasudil (1) and the IKK-β inhibitor LASSBio-1524 (2). Among the synthesized compounds, the N-methylated derivative 11 (LASSBio-2065) showed the best inhibitory profile for both ROCK isoforms, with IC₅₀ values of 3.1 and 3.8 µM for ROCK1 and ROCK2, respectively. Moreover, these compounds were also active in the scratch assay performed in human breast cancer MDA-MB 231 cells and did not display toxicity in MTT and LDH assays. Molecular modelling studies provided insights into the possible binding modes of these N-sulphonylhydrazones, which present a new molecular architecture capable of being optimized and developed as therapeutically useful ROCK inhibitors.

Tumor aggressiveness is usually associated with metastasis. MDA-MB 231, a triple-negative breast cancer (TNBC), is an aggressive type of breast cancer and associated with early metastasis. The Rho/ROCK pathway is a key regulator of cell motility involving cytoskeleton regulation through stabilization of actin filaments and stress fiber formation. In this study we show that Fasudil, a ROCK inhibitor, inhibited the migration of MDA-MB 231 and A549 cells, without altering the viability of these cells at the concentration of 10 μM, modified tumor cell morphology, with disorganization of stress fibers and promotes activation of the canonical-Wnt/beta-catenin pathway. Therefore, Fasudil present a promising approach to the prevention of breast cancer metastasis through a different mechanism of action from the well-known one.

Leishmaniasis represents a series of severe neglected tropical diseases caused by protozoa of the genus Leishmania and is widely distributed around the world. Here, we present the syntheses of Morita-Baylis-Hillman adducts (MBHAs) prepared from eugenol, thymol and carvacrol, and their bioevaluation against promastigotes of Leishmania amazonensis. The new MBHAs are prepared in two steps from essential oils in moderate to good yields and present IC₅₀ values in the range of 22.30–4.71 μM. Moreover, the selectivity index to the most potent compound is very high (SIrb > 84.92), far better than that of Glucantime^® (SIrb 1.39) and amphotericin B (SIrb = 22.34). Conformational analysis were carried out at the M062X//6-31+G(d,p) level of theory to corroborate a hypothesis about the nitroaromatic bioreduction mechanism.