Search Results (25)

This work reports the synthesis and characterization of a new molecular hybrid 4, created by combining 1,4-naphthoquinone with the drug zidovudine (AZT) through an azide-alkyne cycloaddition reaction catalyzed by Cu¹⁺. In vitro studies assessed the anti-trypanosomatid activity of hybrid 4, along with its precursors and synthetic intermediates (1, 2, and 3), against Trypanosoma cruzi (T. cruzi Tulahuen C2C4 LacZ), Trypanosoma brucei (T. b. brucei 427), and Leishmania infantum, as well as cytotoxicity in RAW 264.7 macrophages and LLC-MK2 cells. The biological results confirm the molecular design, showing that the new hybrid is effective against both epimastigotes and amastigotes of T. cruzi (IC₅₀ = 22.26 ± 5.78 μM and 143.10 ± 5.79 μM, respectively), with approximately 4.5-fold better capacity than AZT to inhibit the epimastigote form. Additionally, the hybrid was also active against bloodstream T. b. brucei (IC₅₀ = 54.47 ± 6.70 μM), with approximately 2.2-fold better capacity than AZT to inhibit this parasite. It also shows low toxicity in RAW 264.7 macrophages (CC₅₀ > 200 μM) and LLC-MK2 cells (CC₅₀ > 200 μM). For example, hybrid 4 exhibited approximately a 6.6-fold higher SI than 1,4-naphthoquinone 1 against T. cruzi amastigotes. In this context, the work contributes to the broader knowledge base guiding the design of hybrid molecules for antiparasitic chemotherapy. It provides a rational foundation for preparing subsequent, more potent analogues. Full article

Background: Chagas disease and leishmaniasis remain public health concerns. Despite the existence of approved medications for the treatment of these diseases, most patients discontinue treatment due to long drug regimens and/or the severe side effects of these drugs. This leads to treatment failure and potential future drug resistance. Therefore, the search for new molecules with trypanocidal activity, low cytotoxicity, and high selectivity is essential to address this challenge. Methods: In this work, three series (a, b, and c) of pyridine-2,5-dicarboxylate esters were synthesized using different β-keto-esters bearing naturally occurring fragments and 1,2,3-triazine-1-oxides via the inverse electron demand Diels–Alder (IEDDA) reaction. The structural elucidation of the compounds was performed using NMR (¹H and ¹³C) and HRMS, and the crystal structure of compound 6a was also obtained. Furthermore, a biological assay was performed for all synthesized and characterized compounds to determine their cytotoxicity against Trypanosoma cruzi, Leishmania mexicana, and the J774.2 macrophage cell line. Finally, the in silico determination of their pharmacokinetic and toxicological properties was performed using the SwissADME and ProTox 3.0 platforms. Results: Compounds 3a, 4a, 5a, 4b, and 8c had the highest anti-Trypanosoma cruzi activity against both strains (IC₅₀ ≤ 56.68 µM). Compounds 8b, 10a, 9b, and 12b had considerable leishmanicidal activity against Leishmania mexicana against both strains (IC₅₀ ≤ 161.53 µM). Furthermore, in silico prediction of ADMET properties suggest that these pyridine compounds possess good pharmacokinetic profile. The results are also consistent with low in vitro cytotoxicity and high selectivity. Conclusions: The synthesized pyridine-2,5-dicarboxylate esters have promising activity against Trypanosoma cruzi and Leishmania mexicana, with low cytotoxicity and good drug-like properties, suggesting that these compounds are potential candidates for further evaluation as new treatments for Chagas disease and leishmaniasis. Full article

Sterol biosynthesis is crucial for the function of biological membranes and an important target for anti-protozoan/anti-fungal drugs. In the trypanosomatid parasite Leishmania major, the deletion of sterol C14-demethylase (C14DM) results in hypersensitivity to heat, increased plasma membrane fluidity, profound mitochondrial dysfunctions, and reduced virulence in mice. In this study, we show that C14DM-null mutants are defective in their tolerance to membrane-disrupting agents and osmotic stress and their ability to form autophagosomes. In addition, C14DM-null mutants exhibit a heightened sensitivity to anti-trypanosomatid drugs including antimony, ethidium bromide, and pentamidine. The combination of itraconazole (a C14DM antagonist) and pentamidine synergistically inhibits the growth of Leishmania parasites. These findings reveal new insight into the roles of sterol synthesis in protozoan pathogens and highlight the potential of using drug combinations to achieve better treatment outcomes. Full article

Background: Collectively, leishmaniasis and Chagas disease cause approximately 8 million cases and more than 40,000 deaths annually, mostly in tropical and subtropical regions. The current drugs used to treat these diseases have limitations and many undesirable side effects; hence, new drugs with better clinical profiles are needed. Fungal endophytes associated with plants are known to produce a wide array of bioactive secondary metabolites, including antiprotozoal compounds. In this study, we analyzed endophytic fungal isolates associated with Theobroma cacao and Coffea arabica crop plants, which yielded extracts with antitrypanosomatid activity. Methods: Crude extracts were subjected to bioassay-guided isolation by HPLC, followed by spectrometric and spectroscopic analyses via mass spectrometry (MS) and nuclear magnetic resonance (NMR), Results: Compounds 1–9 were isolated and displayed novel antitrypanosomal and antileishmanial activities ranging from 0.92 to 32 μM. Tandem liquid chromatography–mass spectrometry (LC–MS) analysis of the organic extracts from different strains via the feature-based Global Natural Products Social (GNPS) molecular networking platform allowed us to dereplicate a series of metabolites (10–23) in the extracts. Molecular docking simulations of the active compounds, using the 3-mercaptopyruvate sulfurtransferase protein from L. donovani (Ld3MST) and the cruzipain enzyme from T. cruzi as putative molecular targets, allowed us to suggest possible mechanisms for the action of these compounds. Conclusions: The isolation of these antiprotozoal compounds confirms that crop plants like coffee and cacao harbor populations of endophytes with biomedical potential that confer added value to these crops. Full article

Leishmania infantum is the vector-borne trypanosomatid parasite causing visceral leishmaniasis in the Mediterranean basin. This neglected tropical disease is treated with a limited number of obsolete drugs that are not exempt from adverse effects and whose overuse has promoted the emergence of resistant pathogens. In the search for novel antitrypanosomatid molecules that help overcome these drawbacks, drug repurposing has emerged as a good strategy. Nitroaromatic compounds have been found in drug discovery campaigns as promising antileishmanial molecules. Fexinidazole (recently introduced for the treatment of stages 1 and 2 of African trypanosomiasis), and pretomanid, which share the nitroimidazole nitroaromatic structure, have provided antileishmanial activity in different studies. In this work, we have tested the in vitro efficacy of these two nitroimidazoles to validate our 384-well high-throughput screening (HTS) platform consisting of L. infantum parasites emitting the near-infrared fluorescent protein (iRFP) as a biomarker of cell viability. These molecules showed good efficacy in both axenic and intramacrophage amastigotes and were poorly cytotoxic in RAW 264.7 and HepG2 cultures. Fexinidazole and pretomanid induced the production of ROS in axenic amastigotes but were not able to inhibit trypanothione reductase (TryR), thus suggesting that these compounds may target thiol metabolism through a different mechanism of action. Full article

The development of new treatments for neglected tropical diseases (NTDs) remains a major challenge in the 21st century. In most cases, the available drugs are obsolete and have limitations in terms of efficacy and safety. The situation becomes even more complex when considering the low number of new chemical entities (NCEs) currently in use in advanced clinical trials for most of these diseases. Natural products (NPs) are valuable sources of hits and lead compounds with privileged scaffolds for the discovery of new bioactive molecules. Considering the relevance of biodiversity for drug discovery, a chemoinformatics analysis was conducted on a compound dataset of NPs with anti-trypanosomatid activity reported in 497 research articles from 2019 to 2024. Structures corresponding to different metabolic classes were identified, including terpenoids, benzoic acids, benzenoids, steroids, alkaloids, phenylpropanoids, peptides, flavonoids, polyketides, lignans, cytochalasins, and naphthoquinones. This unique collection of NPs occupies regions of the chemical space with drug-like properties that are relevant to anti-trypanosomatid drug discovery. The gathered information greatly enhanced our understanding of biologically relevant chemical classes, structural features, and physicochemical properties. These results can be useful in guiding future medicinal chemistry efforts for the development of NP-inspired NCEs to treat NTDs caused by trypanosomatid parasites. Full article

Infectious diseases caused by trypanosomatids, including African trypanosomiasis (sleeping sickness), Chagas disease, and different forms of leishmaniasis, are Neglected Tropical Diseases affecting millions of people worldwide, mainly in vulnerable territories of tropical and subtropical areas. In general, current treatments against these diseases are old-fashioned, showing adverse effects and loss of efficacy due to misuse or overuse, thus leading to the emergence of resistance. For these reasons, searching for new antitrypanosomatid drugs has become an urgent necessity, and different metabolic pathways have been studied as potential drug targets against these parasites. Considering that trypanosomatids possess a unique redox pathway based on the trypanothione molecule absent in the mammalian host, the key enzymes involved in trypanothione metabolism, trypanothione reductase and trypanothione synthetase, have been studied in detail as druggable targets. In this review, we summarize some of the recent findings on the molecules inhibiting these two essential enzymes for Trypanosoma and Leishmania viability. Full article

Neglected tropical diseases transmitted by trypanosomatids include three major human scourges that globally affect the world’s poorest people: African trypanosomiasis or sleeping sickness, American trypanosomiasis or Chagas disease and different types of leishmaniasis. Different metabolic pathways have been targeted to find antitrypanosomatid drugs, including polyamine metabolism. Since their discovery, the naturally occurring polyamines, putrescine, spermidine and spermine, have been considered important metabolites involved in cell growth. With a complex metabolism involving biosynthesis, catabolism and interconversion, the synthesis of putrescine and spermidine was targeted by thousands of compounds in an effort to produce cell growth blockade in tumor and infectious processes with limited success. However, the discovery of eflornithine (DFMO) as a curative drug against sleeping sickness encouraged researchers to develop new molecules against these diseases. Polyamine synthesis inhibitors have also provided insight into the peculiarities of this pathway between the host and the parasite, and also among different trypanosomatid species, thus allowing the search for new specific chemical entities aimed to treat these diseases and leading to the investigation of target-based scaffolds. The main molecular targets include the enzymes involved in polyamine biosynthesis (ornithine decarboxylase, S-adenosylmethionine decarboxylase and spermidine synthase), enzymes participating in their uptake from the environment, and the enzymes involved in the redox balance of the parasite. In this review, we summarize the research behind polyamine-based treatments, the current trends, and the main challenges in this field. Full article

Trypanosomatids are mainly responsible for leishmaniasis, sleeping sickness, and Chagas disease, which are the most challenging among the neglected tropical diseases due to the problem of drug resistance. Although problems of target deconvolution and polypharmacology are encountered, a target-based approach is a rational method for screening drug candidates targeting a biomolecule that causes infections. The present study aims to summarize the latest information regarding potential inhibitors of squalene synthase and farnesyl phosphate synthase with anti-Trypanosomatidae activity. The information was obtained by referencing textbooks and major scientific databases from their inception until April 2023. Based on in vitro experiments, more than seventy compounds were reported to inhibit squalene synthase and farnesyl diphosphate synthase. Among these compounds, more than 30 were found to be active in vitro against Trypanosomatidae, inferring that these compounds can be used as scaffolds to develop new drugs against trypanosomatid-related infections. Overall, natural and synthetic products can inhibit enzymes that are crucial for the survival and virulence of trypanosomatids. Moreover, in vitro experiments have confirmed the activity of more than half of these inhibitors using cell-based assays. Nevertheless, additional studies on the cytotoxicity, pharmacokinetics, and lead optimization of potent anti-Trypanosomatid compounds should be investigated. Full article

As unicellular parasites are highly dependent on NADPH as a source for reducing equivalents, the main NADPH-producing enzymes glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) of the pentose phosphate pathway are considered promising antitrypanosomatid drug targets. Here we present the biochemical characterization and crystal structure of Leishmania donovani 6PGD (Ld6PGD) in complex with NADP(H). Most interestingly, a previously unknown conformation of NADPH is visible in this structure. In addition, we identified auranofin and other gold(I)-containing compounds as efficient Ld6PGD inhibitors, although it has so far been assumed that trypanothione reductase is the sole target of auranofin in Kinetoplastida. Interestingly, 6PGD from Plasmodium falciparum is also inhibited at lower micromolar concentrations, whereas human 6PGD is not. Mode-of-inhibition studies indicate that auranofin competes with 6PG for its binding site followed by a rapid irreversible inhibition. By analogy with other enzymes, this suggests that the gold moiety is responsible for the observed inhibition. Taken together, we identified gold(I)-containing compounds as an interesting class of inhibitors against 6PGDs from Leishmania and possibly from other protozoan parasites. Together with the three-dimensional crystal structure, this provides a valid basis for further drug discovery approaches. Full article

The interactions between cell and cellular matrix confers plasticity to each body tissue, influencing the cellular migratory capacity. Macrophages rely on motility to promote their physiological function. These phagocytes are determinant for the control of invasive infections, and their immunological role largely depends on their ability to migrate and adhere to tissue. Therefore, they interact with the components of the extracellular matrix through their adhesion receptors, conferring morphological modifications that change their shape during migration. Nevertheless, the need to use in vitro cell growth models with the conditioning of three-dimensional synthetic matrices to mimic the dynamics of cell-matrix interaction has been increasingly studied. This becomes more important to effectively understand the changes occurring in phagocyte morphology in the context of infection progression, such as in Chagas disease. This disease is caused by the intracellular pathogen Trypanosoma cruzi, capable of infecting macrophages, determinant cells in the anti-trypanosomatid immunity. In the present study, we sought to understand how an in vitro extracellular matrix model interferes with T. cruzi infection in macrophages. Using different time intervals and parasite ratios, we evaluated the cell morphology and parasite replication rate in the presence of 3D collagen I matrix. Nevertheless, microscopy techniques such as scanning electron microscopy were crucial to trace macrophage-matrix interactions. In the present work, we demonstrated for the first time that the macrophage-matrix interaction favors T. cruzi in vitro replication and the release of anti-inflammatory cytokines during macrophage infection, in addition to drastically altering the morphology of the macrophages and promoting the formation of migratory macrophages. Full article

The bifunctional enzyme Dihydrofolate reductase-thymidylate synthase (DHFR-TS) plays a crucial role in the survival of the Leishmania parasite, as folates are essential cofactors for purine and pyrimidine nucleotide biosynthesis. However, DHFR inhibitors are largely ineffective in controlling trypanosomatid infections, largely due to the presence of Pteridine reductase 1 (PTR1). Therefore, the search for structures with dual inhibitory activity against PTR1/DHFR-TS is crucial in the development of new anti-Leishmania chemotherapies. In this research, using the Leishmania major DHFR-TS recombinant protein, enzymatic inhibitory assays were performed on four kauranes and two derivatives that had been previously tested against LmPTR1. The structure 302 (6.3 µM) and its derivative 302a (4.5 µM) showed the lowest IC₅₀ values among the evaluated molecules. To evaluate the mechanism of action of these structures, molecular docking calculations and molecular dynamics simulations were performed using a DHFR-TS hybrid model. Results showed that hydrogen bond interactions are critical for the inhibitory activity against LmDHFR-TS, as well as the presence of the p-hydroxyl group of the phenylpropanoid moiety of 302a. Finally, additional computational studies were performed on DHFR-TS structures from Leishmania species that cause cutaneous and mucocutaneous leishmaniasis in the New World (L. braziliensis, L. panamensis, and L. amazonensis) to explore the targeting potential of these kauranes in these species. It was demonstrated that structures 302 and 302a are multi-Leishmania species compounds with dual DHFR-TS/PTR1 inhibitory activity. Full article

Phytomonas serpens is a trypanosomatid phytoparasite, found in a great variety of species, including tomato plants. It is a significant problem for agriculture, causing high economic loss. In order to reduce the vegetal infections, different strategies have been used. The biological activity of molecules obtained from natural sources has been widely investigated to treat trypanosomatids infections. Among these compounds, chalcones have been shown to have anti-parasitic and anti-inflammatory effects, being described as having a remarkable activity on trypanosomatids, especially in Leishmania species. Here, we evaluated the antiprotozoal activity of the chalcone derivative (NaF) on P. serpens promastigotes, while also assessing its mechanism of action. The results showed that treatment with the derivative NaF for 24 h promotes an important reduction in the parasite proliferation (IC₅₀/24 h = 23.6 ± 4.6 µM). At IC₅₀/24 h concentration, the compound induced an increase in reactive oxygen species (ROS) production and a shortening of the unique flagellum of the parasites. Electron microscopy evaluation reinforced the flagellar phenotype in treated promastigotes, and a dilated flagellar pocket was frequently observed. The treatment also promoted a prominent autophagic phenotype. An increased number of autophagosomes were detected, presenting different levels of cargo degradation, endoplasmic reticulum profiles surrounding different cellular structures, and the presence of concentric membranar structures inside the mitochondrion. Chalcone derivatives may present an opportunity to develop a treatment for the P. serpens infection, as they are easy to synthesize and are low in cost. In order to develop a new product, further studies are still necessary. Full article

Hydroxymethylnitrofurazone (NFOH) is a prodrug of nitrofurazone devoid of mutagenic toxicity, with in vitro and in vivo activity against Trypanosoma cruzi (T. cruzi) and in vitro activity against Leishmania. In this study, we aimed to increase the solubility of NFOH to improve its efficacy against T. cruzi (Chagas disease) and Leishmania species (Leishmaniasis) highly. Two formulations of NFOH nanocrystals (NFOH-F1 and NFOH-F2) were prepared and characterized by determining their particle sizes, size distribution, morphologies, crystal properties, and anti-trypanosomatid activities. Furthermore, cytotoxicity assays were performed. The results showed that the optimized particle size of 108.2 ± 0.8 nm (NFOH-F1) and 132.4 ± 2.3 nm (NFOH-F2) increased the saturation solubility and dissolution rate of the nanocrystals. These formulations exhibited moderate anti-Leishmania effects (Leishmania amazonensis) in vitro and potent in vitro activity against T. cruzi parasites (Y strain). Moreover, both formulations could reduce parasitemia (around 89–95% during the parasitemic peak) in a short animal model trial (Y strain from T. cruzi). These results suggested that the increased water solubility of the NFOH nanocrystals improved their activity against Chagas disease in both in vitro and in vivo assays. Full article

Trypanosomiasis and leishmaniasis are neglected infections caused by trypanosomatid parasites. The first-line treatments have many adverse effects, high costs, and are prone to resistance development, hence the necessity for new chemotherapeutic options. In line with this, twenty five 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) derivatives were synthesized and evaluated in vitro for their anti-trypanosomatid activity. Ten and five compounds from this series showed IC₅₀ ≤ 10 µM against the promastigote and the bloodstream stage of Leishmania mexicana and Trypanosoma brucei brucei, respectively. Overall, derivatives with pyrazole rings substituted with electron-withdrawing groups proved more active than those with electron-donating groups. The hits proved moderately selective towards L. mexicana and T. brucei (selectivity index, SI, compared to murine macrophages = 5–26). The exception was one derivative displaying an SI (>111–189) against T. brucei that surpassed, by >6-fold, the selectivity of the clinical drug nifurtimox (SI = 13–28.5). Despite sharing a common scaffold, the hits differed in their mechanism of action, with halogenated derivatives inducing a rapid and marked intracellular oxidative milieu in infective T. brucei. Notably, most of the hits presented better absorption, distribution, metabolism, and excretion (ADME) properties than the reference drugs. Several of the bioactive molecules herein identified represent a promising starting point for further improvement of their trypanosomatid potency and selectivity. Full article