Search Results (156)

The Apolipoprotein L1 (APOL1) innate immunity gene product represents the sole member of the APOL gene family in humans capable of secretion into circulation, thereby mediating the trypanolysis of T. brucei brucei. Gain-of-function variants of the APOL1 gene originated and spread among human population groups to extend APOL1’s protective capacity to include also serum-resistant subspecies, such as T. brucei gambiense (S342G known as APOL1-G1) and T. brucei rhodesiense (N388_Y389del known as APOL1-G2). The biochemical pathways underlying the lytic activity of these evolutionary favored mutations against bloodstream trypanosomes have been elucidated with remarkable precision. However, the intricate molecular mechanisms by which such variants confer an increased susceptibility to renal cellular injury and consequent kidney disease remain incompletely defined. In the absence of a consistent mechanistic explanation for differential kidney injury, we propose pursuing three interrelated avenues of investigation informed by prior epidemiological and mechanistic evidence linking them to APOL1’s cytotoxicity: (1) Molecular evolution of APOL1 haplotypes in human populations, (2) APOL1 splicing and consequent splice isoforms, (3) Interaction of APOL1 with other APOL gene family members, prioritizing APOL3. In the current study, we use reanalysis of population genetics datasets to resolve the haplotype contexts of all protein-altering APOL1 variants, uncovering previously unrecognized variant–haplotype couplings. We further characterize distinct cellular physiological properties among APOL1 splice isoforms, stressing the importance of isoform vB and what can be learned from isoform vC. Finally, a native interaction, and its interface, between APOL1 and APOL3 is reported, and shown to be differentially modulated by G1 and G2. We contend that continuing studies integrating these three interrelated domains will substantially advance mechanistic insights into APOL1 variant-driven renal injury, and leverage the findings to provide a more cohesive framework to guide future research. Full article

The phytochemical screening of extracts of Tacca leontopetaloides tubers has afforded the isolation of two novel chalcones, tarkalynins A and B, along with taccalonolide A and its 12-propanoate. The screening of Zanthoxylum zanthoxyloides stem bark yielded taraxerol acetate, dihydrochelerythrin and fagaramide. These compounds were obtained through column and thin-layer chromatography and identified using NMR and LC-HRMS. The compounds were tested against Trypanosoma brucei brucei s427 and its multi-drug-resistant clone B48, against Trypanosoma evansi, Trypanosoma equiperdum and Trypanosoma congolense, and against Leishmania mexicana. Cytotoxicity was tested against the human HEK293 cell line. The highest activities were observed with dihydrochelerythrin and fagaramide against T. b. brucei s427 and B48, T. evansi, and L. mexicana, with EC₅₀ values of 1.37, 2.559, 1.09, and 5.44 µM and 17.8, 10.9, 10.9, and 13.3 µM, respectively. In addition, tarkalynin A and taraxerol acetate displayed promising activity against T. equiperdum (EC₅₀ = 21.4 and 21.3 µM, respectively). None of these compounds showed significant cross-resistance with existing trypanocides (RF ≈ 1; p > 0.05). The compounds displayed low toxicity to human cells, with most exhibiting no growth inhibition at concentrations of 100, or even 300 µM. This report provides further evidence of the potential use of natural products for combating parasitic diseases. Full article

Background: Human African trypanosomiasis (HAT), caused by Trypanosoma brucei, is a neglected tropical disease with limited treatments, highlighting the pressing need for new drugs. Cell division cycle-2-related kinase 12 (CRK12), a pivotal protein involved in the cell cycle regulation of T. brucei, has emerged as a promising therapeutic target for HAT, yet effective CRK12 inhibitors remain lacking. Methods: An integrated strategy combining computational modeling, virtual screening, molecular dynamics (MD) simulations, and experimental validation was adopted to discover potential inhibitors against CRK12. By using the predicted and refined 3D structure of CRK12 from AlphaFold2 and MD simulation, over 1.5 million compounds were screened based on multiple-scale molecular docking, and 26 compounds were selected for evaluation of biological activity based on anti-T. brucei bioassays. Dose–response curves were generated for the most potent inhibitors, and the interaction mechanism between the top four compounds and CRK12 was explored by MD simulations and MM/GBSA binding free energy analysis. Results: Of the 26 compounds, six compounds demonstrated sub-micromolar to low-micromolar IC₅₀ values (0.85–3.50 µM). The top four hits, F733-0072, F733-0407, L368-0556, and L439-0038, exhibited IC₅₀ values of 1.11, 1.97, 0.85, and 1.66 µM, respectively. Binding free energy and energy decomposition analyses identified ILE335, VAL343, PHE430, ALA433, and LEU482 as hotspot residues for compound binding. Hydrogen bonding analysis demonstrated that these compounds can form stable hydrogen bonds with the hinge residue ALA433, ensuring their stable binding within the active site. Conclusions: This study establishes a robust and cost-effective pipeline for CRK12 inhibitor discovery, identifying several novel inhibitors demonstrating promising anti-HAT activity. The newly discovered scaffolds exhibit structural diversity distinct from known CRK12 inhibitors, providing valuable lead compounds for anti-trypanosomal drug development. Full article

Trypanosoma cruzi GenBank^® M21331 encodes for Antigen 36 (Ag 36), which is a tandemly repeated T. cruzi antigen. GenBank M21331 has a gene sequence similarity to human immune genes IFN-α, IFN-β, and IFN-γ, as well as to human TRIM genes. A BLAST-p search revealed that T. cruzi GenBank M21331 had seven gene sequences homologous to microtubule-associated protein (MAP) genes with a 100% amino acid sequence identity. There are 36 genes in the T. cruzi genome with >94% identity to GenBank M21331, and these genes encode proteins ranging in size from 38 to 2011 amino acids in length, the largest containing 20, 25, and 30 repeats of the Ag 36 thirty-eight-amino-acid-sequence motif. The purpose of this study was to perform a genetic and molecular comparative analysis of T. cruzi GenBank M21331 to determine if this gene sequence is unique to the T. cruzi clade, present in the T. brucei clade, and/or exists in other trypanosomatids. There are seven homologous genes to GenBank M21331 in T. cruzi, but only one homolog found of this gene in T. brucei. The MAP genes in T. cruzi appear to have expanded at least eleven-fold in number compared to similar MAP genes in T. brucei. The DNA sequences and functions of these MAP genes in their respective species and clades will be discussed and are a fascinating area for further scientific study. Full article

The serendipitous discovery of antiparasitic drugs, such as quinine and artemisinin, of plant origin reveals that searching new chemical pharmacophores from medicinal plants is valuable. The present study sought to explore the antiplasmodial, antileishmanial, and antitrypanosomal activities of Lippia adoensis extracts. Crude extracts of L. adoensis leaves and twigs, which were obtained by extraction using 70% ethanol in water, were assayed for antiplasmodial activity against P. falciparum 3D7 and Dd2 through the SYBR green I-based fluorescence assay; and for antileishmanial, antitrypanosomal, and cytotoxic effects on Leishmania donovani, Trypanosoma brucei brucei, and Vero cells, respectively, using resazurin colorimetric assays. In vitro phytochemical analysis of L. adoensis extracts was performed using standard methods. Moreover, liquid chromatography–mass spectrometry (LC-MS) feature-based detection and molecular networking flow on Global Natural Product Social (GNPS) were also used for the phytochemical screening of L. adoensis extracts. Crude extracts from L. adoensis inhibited the growth of P. falciparum (3D7 and Dd2) (IC₅₀s; (3D7): 10.00 and 97.46 μg/mL; (Dd2): 29.48 and 26.96 μg/mL), L. donovani (IC₅₀s: 22.87–10.52 μg/mL), and T. brucei brucei (IC₅₀s: 2.30–55.06 μg/mL). The extracts were found to be non-cytotoxic to Vero cells, thus yielding median cytotoxic concentrations (CC₅₀s) above 100 μg/mL. In vitro phytochemical analysis of the crude extracts revealed the presence of alkaloids, terpenoids, phenolic compounds, and carbohydrates. The LC-MS tandem molecular networking flow predicted that the extracts contained valsafungin A and bacillamidin in the first cluster, and fatty acids, ketone, and aldehyde derivatives in the second cluster. Overall, the present study demonstrated the antiparasitic effects of L. adoensis extracts, thus justifying the use of this plant in the traditional treatment of fever and malaria conditions. Nevertheless, detailed metabolomic studies and antiparasitic mechanisms of action of the extracts are expected to unveil the potential antiparasitic hit compounds. Full article

The present study investigates the prevalence and diversity of Plasmodium and Trypanosoma infections in Allochrocebus solatus, a vulnerable primate species native to Gabon. Using molecular techniques like nested PCR and phylogenetic analysis, we found 34.0% infection rate for malaria parasites infection, 21.3% for Trypanosoma spp., and 12.8% co-infections. Additionally, Hepatocystis was exclusively detected among malaria parasites, while Trypanosoma brucei brucei, T. vivax, and T. congolense were identified. These results underscore the complex host–parasite interactions influenced by captivity and the ecological and immunological consequences of such infections, particularly the increased susceptibility associated with captivity-induced stress. This preliminary study highlights the need for ongoing surveillance to mitigate health risks in primates and prevent potential zoonotic spillovers, providing critical data for conservation efforts. Full article

The aim of this study was to evaluate bioactive properties of Basidiomycota fungi, mainly Suillus sp. Wide spectrum of activities were revealed for S. variegatus, S. luteus, S. bovinus and S. granulatus; and obtained results were compared with other common fungi. Total Phenolic Content (TPC) varied from 245.32 ± 5.45 to 580.77 ± 13.10 (mg (GAE) per 100 g of dry weight) in methanolic extracts of S. bovinus and S. granulatus fruiting bodies, respectively. In ethyl acetate extracts, the highest TPC were obtained for S. variegatus (310 ± 9.68, mg (GAE)/100 g, dry matter), and the lowest means for S. luteus (105 ± 3.55, mg (GAE)/100 g dry weight). The ethyl acetate extracts of the tested Suillus species exhibited a stronger antioxidant activity (AA) to scavenge DPPH^● and ABTS^•+ than the methanolic ones, and the highest effects were determined for S. luteus (EC₅₀, 0.15 ± 0.05 and 0.23 ± 0.05%, respectively). In the case of methanolic extracts, the highest AA were evaluated for S. granulatus. (EC₅₀ for DPPH^● and ABTS^•+, 0.81 ± 0.30 and 0.95 ± 0.22%, respectively). The ABTS^•+ scavenging potential varied from 0.25 ± 0.05 to 0.74 ± 0.10 (mmol/L, TROLOX equivalent, for S. granulatus and S. variegatus fruiting body extracts, respectively) in the ethyl acetate extracts. S. granulatus extracts demonstrated the widest range of antimicrobial effects against both gram-positive and gram-negative bacteria (from 11.7 ± 1.3 to 28.5 ± 3.3 mm against Pseudomonas aeruginosa and Bacillus mycoides, respectively); and against two fungal strains (up to 13.6 ± 0.4 mm on Meyerozyma guilliermondii) in agar disc diffusion tests. Our study revealed that methanolic extracts of the most tested Suillus sp. were not active enough against the tested parasites: Trypanosoma cruzi, Trypanosoma brucei, Leishmania infantum and Plasmodium falciparum. Only S. variegatus extracts showed good antiprotozoal effects against P. falciparum (12.70 µg/mL). Cytotoxic activity was observed on human diploid lung cells MRC-5 SV2 by S. granulatus extracts (64.45 µg/mL). For comparative purposes, extracts of other common Lithuanian fungi, such as Xerocomus sp. (X. badius, X. chrysenteron and X. subtomentosus), Tylopilus felleus, Phallus impudicus and Pycnoporus cinnabarinus were investigated for their activity. The P. cinnabarinus extracts demonstrated the highest and broadest overall effects: 1.32 µg/mL against T. brucei, 1.46 µg/mL against P. falciparum, 3.93 µg/mL against T. cruzi and 21.53 µg/mL against L. infantum. Additionally, this extract exhibited strong cytotoxicity on MRC-5 cells (13.05 µg/mL). The investigation of bioactive fungal metabolites is important for the development of a new generation of antioxidants, antimicrobials, antiparasitic and anticancer agents. Full article

Trypanosomes are parasitic protozoa that cause severe diseases in humans and animals. The most important species of Trypanosmes include Trypanosoma evansi and Trypanosoma brucei gambiense. The most well-known human diseases are sleeping sickness in Africa and Chagas disease in South America. The most identified animal diseases include Nagana in the African tsetse fly belt and Surra in South Asia, North Africa, and the Middle East. Surra is caused by Trypanosoma evansi. Diminazene resistance is an emerging threat caused by T. evansi infecting animals. The underlying mechanism of diminazene resistance is poorly understood. Trypanosoma brucei gambiense causes African sleeping sickness. The development of diminazene resistance in Trypanosoma brucei gambiense is associated with the alterations in the corresponding P2 adenosine transporter-1 (AT-1) gene. In the present study, by extrapolating the findings from Trypanosoma brucei gambiense, we analyzed genetic diversity in the P2 adenosine transporter-1 gene (AT-1) from T. evansi to explore a potential link between the presence of mutations in this locus and diminazene treatment in ruminants. We examined T. evansi-infected blood samples collected from goats, sheep, camels, buffalo, and cattle in seven known endemic regions of the Punjab province of Pakistan. Heterozygosity (H_e) indices indicated a high level of genetic diversity between seven T. evansi field isolates that had resistance-type mutations at codons 178E/S, 239Y/A/E, and 286S/H/I/D/T of the P2 adenosine transporter-1 (AT-1) locus. A low level of genetic diversity was observed in 19 T. evansi field isolates with susceptible-type mutations at codons A178, G181, D239, and N286 of the P2 adenosine transporter-1 (AT-1) locus. Our results on T. evansi warrant further functional studies to explore the relationship between diminazene resistance and the mutations in AT-1. Full article

G-quadruplexes (G4s) are non-canonical secondary structures that play a crucial role in the regulation of genetic expression. This study explores the interaction between G4s and a small family of oligostyrylbenzene (OSB) derivatives, characterized by tris(styryl)benzene and tetrastyrylbenzene backbones, functionalized with either trimethylammonium or 1-methylpyridinium groups. Initially identified as DNA ligands, these OSB derivatives have now been recognized as potent G4 binders, surpassing in binding affinity commercially available ligands such as pyridostatin and displaying good selectivity for G4s over duplex DNA. Furthermore, OSB derivatives 1 and 2 demonstrated significant antiparasitic activity against bloodstream forms of T. brucei and extracellular L. major, with high selectivity indices when compared to MRC-5 healthy control cells. Derivatives 1 and 2 exhibited moderate biocidal effects against a range of Gram-positive and Gram-negative bacterial strains. Notably, a synergistic antibacterial effect was observed when these compounds were combined with traditional antibiotics, particularly against Acinetobacter baumannii, highlighting their potential utility in addressing drug-resistant bacterial infections. The differences in bioactivity among the OSB derivatives can be attributed to variations in cellular uptake, as proved by flow cytometry analysis. This suggests that the degree of cellular internalization plays a pivotal role in the observed antiparasitic and antibacterial efficacy. Full article

Apolipoprotein-L1 (APOL1) is a membrane-interacting protein induced by inflammation, which confers human resistance to infection by African trypanosomes. APOL1 kills Trypanosoma brucei through induction of apoptotic-like parasite death, but two T. brucei clones acquired resistance to APOL1, allowing them to cause sleeping sickness. An APOL1 C-terminal sequence alteration, such as occurs in natural West African variants G1 and G2, restored human resistance to these clones. However, APOL1 unfolding induced by G1 or G2 mutations enhances protein hydrophobicity, resulting in kidney podocyte dysfunctions affecting renal filtration. The mechanism involved in these dysfunctions is debated. The ability of APOL1 to generate ion pores in trypanosome intracellular membranes or in synthetic membranes was provided as an explanation. However, transmembrane insertion of APOL1 strictly depends on acidic conditions, and podocyte cytopathology mainly results from secreted APOL1 activity on the plasma membrane, which occurs under non-acidic conditions. In this review, I argue that besides inactivation of APOL3 functions in membrane dynamics (fission and fusion), APOL1 variants induce inflammation-linked podocyte toxicity not through pore formation, but through plasma membrane disturbance resulting from increased interaction with cholesterol, which enhances cation channels activity. A natural mutation in the membrane-interacting domain (N264K) abrogates variant APOL1 toxicity at the expense of slightly increased sensitivity to trypanosomes, further illustrating the continuous mutual adaptation between host and parasite. Full article

Trypanosoma brucei causes African trypanosomiasis in humans. Infection with T. brucei elicits a potent pro-inflammatory immune response within infected human hosts, and this response is thought to at least be partially due to Toll-like receptor (TLR) activation. In response to stimulation by lipopolysaccharide and other pathogen antigens, TLR4 translocates to lipid rafts, which induces the expression of pro-inflammatory genes. However, cholesterol efflux is acknowledged as anti-inflammatory due to promoting lipid raft disruption. In this study, we wanted to assess the impact of T. brucei “ghosts”, which are non-viable T. brucei essentially devoid of intracellular contents, in stimulating macrophage TLR4 translocation to lipid rafts, and whether promoting cholesterol efflux in macrophages incubated with T. brucei ghosts attenuates TLR4-target gene expression. When cultured macrophages were exposed to T. brucei ghosts, we observed an increase in lipid raft TLR4 protein content, which suggests certain surface molecules of T. brucei serve as ligands for TLR4. However, pretreating macrophages with cholesterol acceptors before T. brucei ghost exposure decreased lipid raft TLR4 protein content and the expression of pro-inflammatory TLR4-target genes. Taken together, these results imply that macrophage cholesterol efflux weakens pro-inflammatory responses which occur from T. brucei infection via increasing macrophage lipid raft disruption. Full article

Leishmaniasis and Human African trypanosomiasis pose significant public health threats in resource-limited regions, accentuated by the drawbacks of the current antiprotozoal treatments and the lack of approved vaccines. Considering the demand for novel therapeutic drugs, a series of BODIPY derivatives with several functionalizations at the meso, 2 and/or 6 positions of the core were synthesized and characterized. The in vitro activity against Trypanosoma brucei and Leishmania major parasites was carried out alongside a human healthy cell line (MRC-5) to establish selectivity indices (SIs). Notably, the meso-substituted BODIPY, with 1-dimethylaminonaphthalene (1b) and anthracene moiety (1c), were the most active against L. major, displaying IC₅₀ = 4.84 and 5.41 μM, with a 16 and 18-fold selectivity over MRC-5 cells, respectively. In contrast, the mono-formylated analogues 2b and 2c exhibited the highest toxicity (IC₅₀ = 2.84 and 6.17 μM, respectively) and selectivity (SI = 24 and 11, respectively) against T. brucei. Further insights on the activity of these compounds were gathered from molecular docking studies. The results suggest that these BODIPYs act as competitive inhibitors targeting the NADPH/NADP⁺ linkage site of the pteridine reductase (PR) enzyme. Additionally, these findings unveil a range of quasi-degenerate binding complexes formed between the PRs and the investigated BODIPY derivatives. These results suggest a potential correlation between the anti-parasitic activity and the presence of multiple configurations that block the same site of the enzyme. Full article

Herein, we report a series of 1,3-diarylpyrazoles that are analogues of compound 26/HIT 8. We previously identified this molecule as a ‘hit’ during a high-throughput screening campaign for autophagy inducers. A variety of synthetic strategies were utilized to modify the 1,3-diarylpyrazole core at its 1-, 3-, and 4-position. Compounds were assessed in vitro to identify their cytotoxicity properties. Of note, several compounds in the series displayed relevant cytotoxicity, which warrants scrutiny while interpreting biological activities that have been reported for structurally related molecules. In addition, antiparasitic activities were recorded against a range of human-infective protozoa, including Trypanosoma cruzi, T. brucei rhodesiense, and Leishmania infantum. The most interesting compounds displayed low micromolar whole-cell potencies against individual or several parasitic species, while lacking cytotoxicity against human cells. Full article

Chagas disease is one of the world’s neglected tropical diseases, caused by the human pathogenic protozoan parasite Trypanosoma cruzi. There is currently a lack of effective and tolerable clinically available therapeutics to treat this life-threatening illness and the discovery of modern alternative options is an urgent matter. T. cruzi glucokinase (TcGlcK) is a potential drug target because its product, d-glucose-6-phosphate, serves as a key metabolite in the pentose phosphate pathway, glycolysis, and gluconeogenesis. In 2019, we identified a novel cluster of TcGlcK inhibitors that also exhibited anti-T. cruzi efficacy called the 3-nitro-2-phenyl-2H-chromene analogues. This was achieved by performing a target-based high-throughput screening (HTS) campaign of 13,040 compounds. The selection criteria were based on first determining which compounds strongly inhibited TcGlcK in a primary screen, followed by establishing on-target confirmed hits from a confirmatory assay. Compounds that exhibited notable in vitro trypanocidal activity over the T. cruzi infective form (trypomastigotes and intracellular amastigotes) co-cultured in NIH-3T3 mammalian host cells, as well as having revealed low NIH-3T3 cytotoxicity, were further considered. Compounds GLK2-003 and GLK2-004 were determined to inhibit TcGlcK quite well with IC₅₀ values of 6.1 µM and 4.8 µM, respectively. Illuminated by these findings, we herein screened a small compound library consisting of thirteen commercially available 3-nitro-2-phenyl-2H-chromene analogues, two of which were GLK2-003 and GLK2-004 (compounds 1 and 9, respectively). Twelve of these compounds had a one-point change from the chemical structure of GLK2-003. The analogues were run through a similar primary screening and confirmatory assay protocol to our previous HTS campaign. Subsequently, three in vitro biological assays were performed where compounds were screened against (a) T. cruzi (Tulahuen strain) infective form co-cultured within NIH-3T3 cells, (b) T. brucei brucei (427 strain) bloodstream form, and (c) NIH-3T3 host cells alone. We report on the TcGlcK inhibitor constant determinations, mode of enzyme inhibition, in vitro antitrypanosomal IC₅₀ determinations, and an assessment of structure–activity relationships. Our results reveal that the 3-nitro-2-phenyl-2H-chromene scaffold holds promise and can be further optimized for both Chagas disease and human African trypanosomiasis early-stage drug discovery research. Full article

2,6-Diaryl-4H-tetrahydro-thiopyran-4-ones and corresponding sulfoxide and sulfone derivatives were designed to lower the major toxicity of their parent anti-kinetoplatidal diarylideneacetones through a prodrug effect. Novel diastereoselective methodologies were developed and generalized from diarylideneacetones and 2,6-diaryl-4H-tetrahydro-thiopyran-4-ones to allow the introduction of a wide substitution profile and to prepare the related S-oxides. The in vitro biological activity and selectivity of diarylideneacetones, 2,6-diaryl-4H-tetrahydro-thiopyran-4-ones, and their S-sulfoxide and sulfone metabolites were evaluated against Trypanosoma brucei brucei, Trypanosoma cruzi, and various Leishmania species in comparison with their cytotoxicity against human fibroblasts hMRC-5. The data revealed that the sulfides, sulfoxides, and sulfones, in which the Michael acceptor sites are temporarily masked, are less toxic against mammal cells while the anti-trypanosomal potency was maintained against T. b. brucei, T. cruzi, L. infantum, and L. donovani, thus confirming the validity of the prodrug strategy. The mechanism of action is proposed to be due to the involvement of diarylideneacetones in cascades of redox reactions involving the trypanothione system. After Michael addition of the dithiol to the double bonds, resulting in an elongated polymer, the latter—upon S-oxidation, followed by syn-eliminations—fragments, under continuous release of reactive oxygen species and sulfenic/sulfonic species, causing the death of the trypanosomal parasites in the micromolar or submicromolar range with high selectivity indexes. Full article