Trypanosoma cruzi nitroreductase: Structural features and interaction with biological membranes

Introducing CRAFT: The Center for Research and Advancement in Fragments and molecular Targets

We introduce the Center for Research and Advancement in Fragments and Molecular Targets (CRAFT), a pioneering research center established in 2021 through a collaboration between the University of São Paulo (USP) and the Federal University of Goiás (UFG). CRAFT integrates fragment-based drug discovery (FBDD), artificial intelligence (AI), and structural biology to develop novel therapeutic strategies. We have created fragment and target libraries and utilize AI models to streamline the drug discovery process. We invite the global scientific community to collaborate with us in addressing neglected diseases, with the goal of enhancing research capabilities and fostering scientific innovation across Latin America.

New 2-nitroimidazole-N-acylhydrazones, analogs of benznidazole, as anti-Trypanosoma cruzi agents

Chagas disease is a neglected tropical parasitic disease caused by the protozoan Trypanosoma cruzi. Worldwide, an estimated 8 million people are infected with T. cruzi, causing more than 10,000 deaths per year. Currently, only two drugs, nifurtimox and benznidazole (BNZ), are approved for its treatment. However, both are ineffective during the chronic phase, show toxicity, and produce serious side effects. This work aimed to obtain and evaluate novel 2-nitroimidazole-N-acylhydrazone derivatives analogous to BNZ. The design of these compounds used the two important pharmacophoric subunits of the BNZ prototype, the 2-nitroimidazole nucleus and the benzene ring, and the bioisosterism among the amide group of BNZ and N-acylhydrazone. The 27 compounds were obtained by a three-step route in 57%-98% yields. The biological results demonstrated the potential of this new class of compounds, since eight compounds were potent and selective in the in vitro assay against T. cruzi amastigotes and trypomastigotes using a drug-susceptible strain of T. cruzi (Tulahuen) (IC50 = 4.3-6.25 µM) and proved to be highly selective with low cytotoxicity on L929 cells. The type I nitroreductase (TcNTR) assay suggests that the new compounds may act as substrates for this enzyme.

Design and Synthesis of Novel 3-Nitro-1H-1,2,4-triazole-1,2,3-triazole-1,4-disubstituted Analogs as Promising Antitrypanosomatid Agents: Evaluation of In Vitro Activity against Chagas Disease and Leishmaniasis

A series of 28 compounds, 3-nitro-1H-1,2,4-triazole, were synthesized by click-chemistry with diverse substitution patterns using medicinal chemistry approaches, such as bioisosterism, Craig-plot, and the Topliss set with excellent yields. Overall, the analogs demonstrated relevant in vitro antitrypanosomatid activity. Analog 15g (R1 = 4-OCF3-Ph, IC50 = 0.09 μM, SI = >555.5) exhibited an outstanding antichagasic activity (Trypanosoma cruzi, Tulahuen LacZ strain) 68-fold more active than benznidazole (BZN, IC50 = 6.15 μM, SI = >8.13) with relevant selectivity index, and suitable LipE = 5.31. 15g was considered an appropriate substrate for the type I nitro reductases (TcNTR I), contributing to a likely potential mechanism of action for antichagasic activity. Finally, 15g showed nonmutagenic potential against Salmonella typhimurium strains (TA98, TA100, and TA102). Therefore, 3-nitro-1H-1,2,4-triazole 15g is a promising antitrypanosomatid candidate for in vivo studies.

Design, synthesis and antitrypanosomatid activity of 2-nitroimidazole-3,5-disubstituted isoxazole compounds based on benznidazole

Chagas disease and leishmaniasis are neglected diseases of high priority as a public health problem. Pharmacotherapy is based on the administration of a few drugs, which exhibit hazardous adverse effects and toxicity to the patients. Thus, the search for new antitrypanosomatid drugs is imperative to overcome the limitations of the treatments. In this work, 46 2-nitroimidazole 3,5-disubstituted isoxazole compounds were synthesized in good yields by [3 + 2] cycloaddition reaction between terminal acetylene (propargyl-2-nitroimidazole) and chloro-oximes. The compounds were non-toxic to LLC-MK2 cells. Compounds 30, 35, and 44 showed in vitro antichagasic activity, 15-fold, 12-fold, and 10-fold, respectively, more active than benznidazole (BZN). Compounds 30, 35, 44, 45, 53, and 61 acted as substrates for the TcNTR enzyme, indicating that this might be one of the mechanisms of action involved in their antiparasitic activity. Piperazine series and 4-monosubstituted compounds were potent against T. cruzi parasites. Besides the in vitro activity observed in compound 45, the in vivo assay showed that the compound only reduced the parasitemia levels by the seventh-day post-infection (77%, p > 0.001) compared to the control group. However, 45 significantly reduced the parasite load in cardiac tissue (p < 0.01) 11 days post-infection. Compounds 49, 52, and 54 showed antileishmanial activity against intracellular amastigotes of Leishmania (L.) amazonensis at the same range as amphotericin B. These findings highlight the antitrypanosomatid properties of 2-nitroimidazole 3,5-disubstituted isoxazole compounds and the possibility in using them as antitrypanosomatid agents in further studies.

Anti-Trypanosoma cruzi Activity, Mutagenicity, Hepatocytotoxicity and Nitroreductase Enzyme Evaluation of 3-Nitrotriazole, 2-Nitroimidazole and Triazole Derivatives

Chagas disease (CD), which is caused by Trypanosoma cruzi and was discovered more than 100 years ago, remains the leading cause of death from parasitic diseases in the Americas. As a curative treatment is only available for the acute phase of CD, the search for new therapeutic options is urgent. In this study, nitroazole and azole compounds were synthesized and underwent molecular modeling, anti-T. cruzi evaluations and nitroreductase enzymatic assays. The compounds were designed as possible inhibitors of ergosterol biosynthesis and/or as substrates of nitroreductase enzymes. The in vitro evaluation against T. cruzi clearly showed that nitrotriazole compounds are significantly more potent than nitroimidazoles and triazoles. When their carbonyls were reduced to hydroxyl groups, the compounds showed a significant increase in activity. In addition, these substances showed potential for action via nitroreductase activation, as the substances were metabolized at higher rates than benznidazole (BZN), a reference drug against CD. Among the compounds, 1-(2,4-difluorophenyl)-2-(3-nitro-1H-1,2,4-triazol-1-yl)ethanol (8) is the most potent and selective of the series, with an IC50 of 0.39 µM and selectivity index of 3077; compared to BZN, 8 is 4-fold more potent and 2-fold more selective. Moreover, this compound was not mutagenic at any of the concentrations evaluated, exhibited a favorable in silico ADMET profile and showed a low potential for hepatotoxicity, as evidenced by the high values of CC50 in HepG2 cells. Furthermore, compared to BZN, derivative 8 showed a higher rate of conversion by nitroreductase and was metabolized three times more quickly when both compounds were tested at a concentration of 50 µM. The results obtained by the enzymatic evaluation and molecular docking studies suggest that, as planned, nitroazole derivatives may utilize the nitroreductase metabolism pathway as their main mechanism of action against Trypanosoma cruzi. In summary, we have successfully identified and characterized new nitrotriazole analogs, demonstrating their potential as promising candidates for the development of Chagas disease drug candidates that function via nitroreductase activation, are considerably selective and show no mutagenic potential.

Repurposing of 5‐nitrofuran‐3,5‐disubstituted isoxazoles: A thriving scaffold to antitrypanosomal agents

Chagas disease (CD) is a neglected disease caused by the protozoan Trypanosoma cruzi. The two drugs used in the treatment schedules exhibit adverse effects and severe toxicity. Thus, searching for new antitrypanosomal agents is urgent to provide improved treatments to those affected by this disease. 5-Nitrofuran-isoxazole analogs were synthesized by cycloaddition reactions [3+2] between chloro-oximes and acetylenes in satisfactory yields. We analyzed the structure-activity relationship of the analogs based on Hammett's and Hansch's parameters. The 5-nitrofuran-isoxazole analogs exhibited relevant in vitro antitrypanosomal activity against the amastigote forms of T. cruzi. Analog 7s was the trending hit of the series, showing an IC₅₀ value of 40 nM and a selectivity index of 132.50. A possible explanation for this result may be the presence of an electrophile near the isoxazole core. Moreover, the most active analogs proved to act as an in vitro substrate of type I nitroreductase rather than the cruzain, enzymes commonly investigated in molecular target studies of CD drug discovery. These findings suggest that 5-nitrofuran-isoxazole analogs are promising in the studies of agents for CD treatment.