Search Results (184)

The Syrian golden hamster (Mesocricetus auratus) is a universally accepted model for visceral leishmaniasis (VL) due to its ability to mimic human disease pathology. Mus musculus (BALB/c) is preferred for evaluating pharmaceutical and immunological responses. This study focuses on the precise role of gene signatures in L. donovani-infected M. auratus and M. musculus, using transcriptomic analysis. Principal component analysis (PCA) revealed distinct clustering among the four groups (uninfected vs. infected spleen samples from M. auratus and M. musculus). After differential expression analysis, 2054 genes in M. auratus and 1108 in M. musculus were found to be differentially expressed, with 153 genes common to both species. Except for 31 genes, most of the commonly dysregulated genes show a similar expression pattern. Although Th1-mediated immune signaling was observed in both cases, the overexpression of LAG3 in both infected groups underscores the important role of T cell exhaustion. Immunological responses against parasite infection in M. auratus appear to be more aggressive, while M. musculus seems more intense. Interestingly, only the M. musculus-infected group shows overexpression of IL-10. Without a definitive role for IL-10, the overexpression of Tgm2, Clec7a, and Adora2b in both species may drive disease outcome. These findings elucidate the immunological mechanisms driving the pathogenesis of VL in rodent models. Full article

Background/Objectives: Many parasitic diseases remain without an effective treatment and cause many deaths worldwide. Leishmaniasis is a complex disease that belongs to the category of Neglected Tropical Diseases, as its treatment relies on outdated drugs that also lead to resistance and negative side-effects. To address this problem, two new chemical families have been tested in vitro against three of the most common parasites from the genus Leishmania. Methods: One family is formed by the polyamine tris(2-aminoethyl)amine functionalised either in one or its three primary amines with different aryl group, and the other is a group of azamacrocyclic cyclophanes containing either one or two aromatic spacers. Results: From the first family, only one compound showed activity against Leishmania donovani, and from the second family, three compounds were selective, two of them for Leishmania braziliensis and a different one against L. donovani, another parasite of the studied genus. Conclusions: The anti-Leishmania activity seems to be related to the compounds’ ability to inhibit the iron superoxide dismutase activity and to alter the parasite metabolism by inhibiting glucose intake in L. braziliensis or by accelerating it in L. donovani and by attacking the parasite defences against ROS, both effects triggering a mitochondrial membrane depolarization that enhances damage, leading to cell death. Full article

Objectives: Visceral leishmaniasis (VL), caused by Leishmania donovani and Leishmania infantum, is a life-threatening neglected tropical disease, particularly in endemic regions such as Djibouti. Current therapies are constrained by toxicity, high cost, and limited availability, highlighting the urgent need for safe, effective, and affordable alternatives. This study aimed to identify novel antileishmanial candidates from Djiboutian medicinal plants using an integrated in silico approach. Methods: A total of 136 phytoconstituents isolated from local medicinal plants were screened via molecular docking against validated protein targets (6UAK and 2JK6). Promising candidates were further analyzed for interaction patterns, drug-likeness according to Lipinski’s Rule of Five, and ADMET properties. Molecular dynamics (MD) simulations over 100 ns were performed to assess the structural stability of selected protein–ligand complexes. Results: Compound C41 emerged as a leading candidate, showing binding affinities of −8.3 kcal/mol and −7.5 kcal/mol toward 6UAK and 2JK6, respectively, comparable to reference drugs. Interaction analysis revealed stable hydrogen bonds and hydrophobic contacts within the catalytic sites. Drug-likeness assessment confirmed compliance with Lipinski’s Rule, while ADMET predictions indicated high intestinal absorption and favorable safety profiles for several candidates. MD simulations corroborated the structural stability of the 2JK6-C41 complex throughout the 100 ns trajectory. Conclusions: These findings underscore Djiboutian medicinal plants as a valuable source of potential antileishmanial leads. Among them, Compound C41 represents a promising candidate for future experimental validation, supporting the development of innovative, safe, and cost-effective therapies against visceral leishmaniasis. Full article

Leishmaniasis is a global health issue, especially in tropical and subtropical areas, with treatment challenges due to the development of resistance to current drugs. This has prompted the search for new antileishmanial compounds. Endoperoxides, due to parasites’ reliance on external iron and susceptibility to oxidative stress, are promising antileishmanial compounds. This study evaluated two sterol endoperoxides—ergosterol endoperoxide (ErgoEP) and dehydrocholesterol endoperoxide (DHCholEP)—for their antileishmanial activity and mechanism in vitro. Cell viability assays with Leishmania donovani and Leishmania tarentolae promastigotes showed IC₅₀ values in the low micromolar range (from 2.0 to 4.5 µM, respectively) with low toxicity to murine and J774A.1 macrophages. Electron paramagnetic resonance spectroscopy confirmed radical generation in the presence of low-molecular-weight iron compounds. However, this did not trigger the antileishmanial effect, as neither N-acetylcysteine nor pyridoxal isonicotinoyl hydrazone altered activity. Mitochondrial function(s) and superoxide production in Leishmania remained unaffected. Both endoperoxides significantly inhibited synthesis of 5-dehydroepisterol, the major sterol in Leishmania tarentolae, suggesting targeting of the sterol biosynthesis pathway. Their limited toxicity to mammalian macrophages makes ergosterol and dehydrocholesterol endoperoxides promising candidates for future antileishmanial drug development. Full article

L. infantum and L. donovani, distinct species in the L. donovani complex, show high phenotypic and genotypic polymorphism and share molecular traits. Therefore, genotyping by a single molecular target can give uncertain results. This study focuses on genotyping a set of L. donovani complex strains, including 18 zymodemes classified according to Montpellier nomenclature (ZMONs) and different clinical forms, by internal transcribed spacer (ITS), heat shock protein 70 (hsp70), and cysteine proteinase b (cpb) sequencing to evaluate their ability in species discrimination. We found an unexpected L. infantum hsp70 variability, with 8 sequence variants. Cpb-PCR could not distinguish L. donovani complex species, due to a L. infantum intraspecific allelic (cpbEF) polymorphism. By combining ITS-hsp70-cpb sequence variants, we obtained different genotypes. ITS(A)-hsp70inf(2)-cpbE identified 69.9% of L. infantum strains representing 12 ZMONs from Mediterranean visceral and cutaneous cases, ITS(A)-hsp70inf(2)-cpbF identified a non-ZMON-1 cluster. Four genotypes represented ZMON-24: ITS(A, B)-hsp70(Y)-cpbF identified a cutaneous cluster from Italy and North Africa, ITS(A, Lombardi)-hsp70(2)-cpbE identified cutaneous and visceral cases from Mediterranean areas. We believe this study contributes to an overview of L. infantum variant populations, and to the discussion on diagnostic targets, in single or multi -target-based approaches, to identify Leishmania populations in the Mediterranean area. Full article

The development of new alternative models is essential to overcome the limitations of traditional two-dimensional (2D) cell cultures and animal models. Three-dimensional (3D) models, such as organoids, better mimic the structural and functional complexity of mammalian organs, thereby reducing the ethical and economic issues related to animal experimentation. These systems provide more physiologically relevant environments, improving the accuracy of disease modeling and drug response prediction. In this context, we have developed mouse hepatic organoids from livers of adult BALB/c mice and characterized them by microscopy and transcriptional analysis. This model was applied to a robust and reproducible high-throughput screening (HTS) platform for testing cytotoxicity at the preclinical stage of drug discovery. In addition, mouse hepatic organoids were co-cultured with amastigotes of Leishmania donovani parasites to establish a model of host–parasite interaction, which was characterized by RNA-seq linked to differential expression analysis and cytokine production by the hepatic organoids. The findings provided in this work establish mouse hepatic organoids as an alternative model for drug discovery and pathogenesis studies. Full article

In continuation of our recent report on the antileishmanial activity of an ethanolic extract from leaves of Ptilostemon chamaepeuce subsp. cyprius (Pcc, Asteraceae), we have now isolated the main sesquiterpene lactone, deacylcynaropicrin, along with a minor derivative, 13-hydroxy-11β,13-dihydro-deacylcynaropicrin. The main constituent was tested for antileishmanial activity against promastigotes and amastigotes of Leishmania infantum (Lin), the causative agent of visceral leishmaniasis. Both STLs were tested against additional protozoan pathogens, including L. donovani, Trypanosoma brucei rhodesiense (Tbr), and Plasmodium falciparum. The STL cynaropicrin from Artichoke (Cynara cardunculus), a congener of deacylcynaropicrin with a hydroxymethacrylate ester group, previously known to possess antiprotozoal activity, was retested against Lin for direct comparison. Cynaropicrin was found to be much more potent than either its deacyl congener or the hydroxylated derivative from Pcc against all tested parasites and also against an isolated parasite enzyme, Tbr pteridine reductase (TbPTR1). The ester moiety of cynaropicrin significantly enhances the antiprotozoal activity of this STL. Since cynaropicrin also displayed significant cytotoxicity against mammalian cells (L6 and J774A.1 cell lines), its utility as candidate for further development appears limited. However, this study provides valuable new insight into the structure–activity relationships of these compounds. Full article

Phytochemical investigation of Radula voluta, a liverwort species collected in the Ecuadorian Amazon, led to the isolation of four known bibenzyl derivatives: 2-prenyl-3,5-dihydroxy-bibenzyl (1), 2-geranyl-3,5-dihydroxybibenzyl (2), 2,2-dimethyl-5-phenethyl-2H-chromen-7-ol (3), and radulanin L (4). Structural elucidation was achieved through extensive NMR and MS analyses, supported by comparison with previously reported data. Compounds 1 and 4 are reported for the first time in R. voluta. The crude extract and isolated compounds were evaluated for their in vitro antiprotozoal activity against Trypanosoma cruzi, Leishmania amazonensis, Leishmania donovani, Naegleria fowleri, and Acanthamoeba castellanii Neff. Among the isolated compounds, bibenzyls 2 and 4 exhibited the most potent activity across multiple protozoan strains. Cytotoxicity was assessed against murine macrophages (J774A.1), obtaining moderate–low toxicities against compounds 1 and 3. These findings highlight the pharmacological value of liverwort-derived bibenzyls and support further research on R. voluta as a promising source of antiparasitic leads. Full article

Visceral leishmaniasis caused by Leishmania donovani is one of the major neglected tropical diseases attributable to parasitic protozoa. In the absence of an effective vaccine, chemotherapy remains the only available therapeutic option. However, current treatments rely on a limited number of drugs that are largely obsolete, highly toxic or require intravenous administration, and their extensive use has led to the emergence of drug resistance. Consequently, the discovery of new antileishmanial agents is an urgent priority. In this study, a commercial library of 449 alkaloids in a high-throughput screening format was evaluated against both axenic bone marrow-derived amastigotes and intramacrophagic amastigotes from mice infected with L. donovani IRFP, a strain engineered to emit infrared fluorescence in its viable form. Six isoquinoline-type alkaloids showed the best antileishmanial efficacy against intramacrophagic amastigotes while exhibiting minimal cytotoxicity toward RAW 264.7 and HepG2 cell lines, with a promising selective index higher than four, and good mouse intestinal tolerance in mouse organoids. Among these compounds, the protoberberine scaffold emerged as the most promising candidate for further drug development. Full article

Parasites of the Leishmania genus are globally distributed and cause various clinical presentations in animals and humans, collectively known as leishmaniasis. The genomes of Leishmania and other trypanosomatids exhibit remarkable plasticity, shaped by several distinctive genetic features. Although these features can hinder the application of next-generation DNA sequencing (NGS) technologies, NGS data have been successfully used to characterize the whole-genome diversity of circulating Leishmania strains. The results complement and are broadly aligned with previous findings obtained with more traditional methods, offering greater resolution when working with geographically closer strains. In this review, we summarize advances over the past two decades in characterizing the genome diversity of Leishmania parasites using NGS strategies. We also discuss the application of these strategies to elucidate other aspects relevant to the epidemiology of these parasites, including their population structure and mode of reproduction. The vast majority of the studies to date have focused on species within the L. donovani/infantum complex or the L. (Viannia) subgenus, highlighting the need to incorporate other relevant underrepresented species and regions from both the Old and New World. Full article

Neglected tropical diseases (NTDs) constitute a group of infectious diseases that severely affect the health of impoverished populations, and the health, economies, and health systems of affected countries. Leishmaniasis and human African trypanosomiasis (HAT) are particularly notable, and malaria, despite not being neglected, is part of the “big three” (HIV, tuberculosis, and malaria) with high incidence, increasing the probability of infection by NTDs. Therefore, efforts are ongoing in the search for new drugs targeting the enzyme N-myristoyltransferase (NMT), a potential drug target that has been explored. Thus, we provide a review here that highlights the epidemiological data for these diseases and the importance of discovering new drugs against these agents. Here, the importance of NMT and its inhibitors is clear, with this study highlighting thiochromene, pyrazole, thienopyridine, oxadiazole, benzothiophene, and quinoline scaffolds, identified by computational methods followed by biological assays to validate the findings; for example, this study shows the action of the aminoacylpyrrolidine derivative 13 against Leishmania donovani NMT (IC₅₀ of 1.6 nM) and the pyrazole analog 23 against Plasmodium vivax NMT (IC₅₀ of 9.48 nM), providing several insights that can be used in drug design in further work. Furthermore, the selectivity and improvement in activity are related to interactions with the residues Val⁸¹, Phe⁹⁰, Tyr²¹⁷, Tyr³²⁶, Tyr³⁴⁵, and Met⁴²⁰ for leishmaniasis (LmNMT); Tyr²¹¹, Leu⁴¹⁰, and Ser³¹⁹ for malaria (PvNMT); and Lys²⁵ and Lys³⁸⁹ for HAT (TbNMT). We hope our work provides valuable insights that research groups worldwide can use to search for innovative drugs to combat these diseases. Full article

Background: Drug development for leishmaniases treatment follows a very selective process in order to propose drug candidates that possess all the qualities that meet the strict specifications of the pharmaceutical industry. Drug resistance is a limiting factor that can impact the lifespan of a marketed drug. It is now essential that the risk of drug resistance be evaluated at the early stage of in vitro studies to discard a lead compound that could quickly generate drug resistance once available on the market. Objectives: This article aims to estimate the risk of drug resistance emergence for a promising drug candidate at the in vitro early stage of drug development. Methods: A sequential method is proposed to study some of the phenotypic characteristics and parameters of resistant parasites such as time to achieve maximal resistance during stepwise drug pressure, resistance amplitude, stability, fitness, and infectivity both in vitro and in vivo. Results: Some examples with drugs in clinical use and former drug candidates are given. Conclusions: This method providing an evaluation of the risk of drug resistance from an in vitro model of Leishmania donovani be extrapolated to other Leishmania species. Full article

Objective: Visceral leishmaniasis (VL), a Neglected Tropical Disease caused by Leishmania donovani, remains insufficiently addressed by current therapies due to high toxicity, poor efficacy, and immunosuppressive complications. This study aimed to identify and characterize repurposed drugs that simultaneously target parasite-encoded and host-associated mechanisms essential for VL pathogenesis. Methods: Two complementary in silico drug repurposing strategies were employed. The first method utilized electron–ion interaction potential (EIIP) screening followed by molecular docking and molecular dynamics (MD) simulations targeting two L. donovani proteins: Rab5a and pteridine reductase 1 (PTR1). The second approach employed network-based drug repurposing using the Drugst.One platform, prioritizing candidates via STAT3-associated gene networks. Predicted drug–target complexes were validated by 100 ns MD simulations, and pharmacokinetic parameters were assessed via ADMET profiling using QikProp v7.0 and SwissADME web server. Results: Entecavir and valganciclovir showed strong binding to Rab5a and PTR1, respectively, with Glide Scores of −9.36 and −9.10 kcal/mol, and corresponding MM-GBSA ΔG_bind values of −14.00 and −13.25 kcal/mol, confirming their stable interactions and repurposing potential. Network-based analysis identified nifuroxazide as the top candidate targeting the host JAK2/TYK2–STAT3 axis, with high stability confirmed in MD simulations. Nifuroxazide also displayed the most favorable ADMET profile, including oral bioavailability, membrane permeability, and absence of PAINS alerts. Conclusions: This study highlights the potential of guanine analogs such as entecavir and valganciclovir, and the nitrofuran derivative nifuroxazide, as promising multi-target drug repurposing candidates for VL. Their mechanisms support a dual strategy targeting both parasite biology and host immunoregulation, warranting further preclinical investigation. Full article

Phlebotomine sandflies are the primary vectors of Leishmania parasites, the causative agents of leishmaniasis. In India, Phlebotomus argentipes is the confirmed vector of Leishmania donovani. The sandfly gut microbiota plays a crucial role in Leishmania development and transmission, yet it remains largely understudied. This study used a metagenomic approach targeting the V3–V4 region of the 16S rRNA gene to compare the gut bacterial communities of P. argentipes and Sergentomyia babu prevalent in Kerala. A total of 18 distinct bacterial phyla were identified in P. argentipes, and 14 in S. babu, both dominated by Proteobacteria, Actinobacteria, and Firmicutes. A total of 315 genera were identified in P. argentipes, with a high relative abundance of Pseudomonas (6.3%), whereas S. babu harbored 327 genera, with Pseudomonas showing a higher relative abundance of 11%. Unique to P. argentipes, bacterial phyla such as Fusobacteria, Armatimonadetes, Elusimicrobia, Chlamydiae, and Crenarchaeota were identified, whereas Chlorobi was specific to S. babu. Additionally, 145 species were identified in P. argentipes, compared to 164 species in S. babu. These findings provide a comparative baseline of gut microbial diversity between vector and non-vector sandfly species, offering a foundation for future functional investigations into vector competence. Full article

Background/Objectives: Currently there are very few effective oral antileishmanial treatments. In this study we evaluated a new bis(pyridine-2-carboxamidine) antileishmanial drug (JNII40_base) and its hydrochloride salt (JNII40_HCl). Methods: The characterization studies performed allowed us to determine the crystallinity, hydration water, and presence of hydrogen bonds in these drugs. Different dissolution methods were employed to predict intestinal absorption. A high-performance liquid chromatography–mass spectrophotometry (HPLC-MS/MS) method was developed for the determination of JNII40 in plasma. Results: Pharmacokinetic studies in rats of JNII40_base at 100 and 20 mg/kg, and JNII40_HCl at 20 mg/kg, showed a non-linear pharmacokinetic at high doses. An innovative biorelevant medium of phosphate buffer pH 6.8 with polysorbate 80 at 0.6% (w/v) showed high concentration values for JNII40_base at 30 min, which predicts good intestinal absorption. These results were consistent with the bioavailability data, which exhibited a significant (p < 0.05) increase in maximum plasma concentration (C_max) and a slight delay in time to maximum (T_max) compared to JNII40_HCl. Furthermore, the sustained release of JNII40_base in this biorelevant media was related to high plasma concentration values at 24 h (C_24h) observed in bioavailability studies. These plasma concentrations of JNII40_base were above the half-maximal inhibitory concentration (IC₅₀) against promastigote and amastigote forms of Leishmania donovani, which is indicative of effectiveness and should reduce the occurrence of drug resistance during treatments. Conclusions: The bioavailability and pharmacokinetic data support the consideration of this drug for further in vivo studies as an oral antileishmanial treatment. Full article