Search Results (312)

A series of substituted pyrrolo[2,3-d]pyrimidines was designed, synthesized, and evaluated in vitro against two protozoan parasites: Plasmodium falciparum and Trypanosoma brucei brucei. Pharmacological studies revealed antiprotozoal activity with IC₅₀ values in the submicromolar to micromolar range. Additionally, the in vitro cytotoxicity of these new compounds was assessed using human HepG2 cells. Among them, the pyrrolopyrimidine derivative 1d emerged as the most potent antimalarial compound, exhibiting a selectivity index (SI) of 600.81 against the P. falciparum chloroquine-resistant W2 strain. For the chloroquine-sensitive 3D7 strain, the most notable selectivity index (SI) was observed for pyrrolo[2,3-d]pyrimidine 1c, with a value of approximately 123. Furthermore, compound 1b demonstrated the most interesting activity against Trypanosoma brucei brucei, with an SI of 39.52, marking it as a promising trypanocidal agent. FRET melting assays confirmed that these nitrogen-containing heterocyclic compounds bind to telomeric G-quadruplexes in P. falciparum and Trypanosoma. However, no clear correlation was found between G-quadruplex binding and antiparasitic activity or selectivity, suggesting that G-quadruplex targeting is unlikely to be the main mechanism underlying cytotoxicity. Full article

Trypanosomiasis remains a major constraint to small ruminant production in sub-Saharan Africa, particularly among smallholder farmers. Although WAD goats are considered trypanotolerant because of their relatively low mortality during chronic infection, recent findings show that this survival is at the expense of reproductive efficiency. To back up this claim with scientific evidence, this review followed PRISMA guidelines and systematically searched PubMed, Scopus, and Web of Science for important studies published between January 1980 and February 2026. Search terms included African animal trypanosomiasis, Trypanosoma spp., WAD goats, reproductive dysfunction, trypanotolerance, oxidative stress, and hypothalamic–pituitary–gonadal axis. Of the 1245 retrieved articles, 14 met the inclusion criteria. Evidence from the included studies indicates that chronic trypanosome infection disrupts reproduction through interconnected mechanisms involving systemic inflammation, oxidative stress, endocrine imbalance, and impaired gonadal function. Available evidence suggests that T. brucei is frequently associated with ovarian dysfunction and embryonic loss, whereas T. congolense has been linked in some studies to uterine pathology and gestational reproductive disturbances. Female goats commonly exhibit irregular oestrous cycles, embryonic loss, and prolonged kidding intervals, while males develop impaired spermatogenesis, abnormal sperm morphology, and reduced testosterone levels. These reproductive impairments reduce kid output, milk yield, herd productivity, and household livelihood resilience. Integrated control strategies combining vector control, targeted chemotherapy, nutritional support, and selective breeding are essential for preserving both fertility and survival in trypanosome-endemic areas. Full article

Di(hetero) aryl and alicyclic amine derivatives of thieno[2,3-b]pyridine were synthesized in good to high yields (45–76%) via palladium-catalyzed Buchwald–Hartwig amination. The reactions were performed using methyl 5-bromothieno[2,3-b]pyridine-2-carboxylate, prepared in this work, and a variety of substituted anilines bearing either electron-donating groups (EDGs) or electron-withdrawing groups (EWGs), as well as pyridinyl amines, and saturated heterocyclic amines such as morpholine and piperidine. For most substrates, the optimal conditions involved Pd(OAc)₂, rac-BINAP, and Cs₂CO₃ in toluene at 100 °C under argon. Substrate bearing EWGs and electron-deficient pyridinyl amines required Xantphos as the ligand, while reactions with piperidine were only successful using Pd₂(dba)₃ as a palladium (0) source. The antiparasitic activity of the synthesized compounds was evaluated against Trypanosoma brucei (T. brucei) and Leishmania infantum (L. infantum) in both promastigote and amastigote forms. Most compounds exhibited no significant cytotoxicity (CC₅₀ > 100 μM) in PMA-differentiated THP-1 derived macrophage cells. Analysis of substituent effects focusing on the nature of amino substitution at position C(5) revealed distinct trends in antiparasitic activity. Notably, one compound exhibited activity against Leishmania infantum promastigotes that was nearly four times higher than that of the reference drug miltefosine, and its selectivity index was also approximately fourfold higher. Full article

Rhodesain is a cysteine protease that plays a key role in the life cycle of Trypanosoma brucei rhodesiense, an endemic parasite in sub-Saharan Africa and responsible for Human African Trypanosomiasis (HAT), a disease that can be fatal if not treated promptly. Due to the limitations associated with current HAT pharmacological therapy, the search for new targets for the development of antitrypanosomal agents is urgently needed; in this context, rhodesain represents a promising therapeutic target. In this study, new chalcones were synthesized and tested against rhodesain. Given their affinity for the trypanosomal cysteine protease (K_i values in the micromolar range), chalcone 1a was selected to evaluate its effect in combination with the nutraceutical curcumin. The Combination Index (CI) was calculated using Chou and Talalay’s method. The analysis of the CI calculated at different f_a values of enzyme inhibition for the combination curcumin + 1a showed promising results. For all f_a values, the CI is less than one, indicating a synergistic effect when chalcone 1a is combined with curcumin. In particular, at the most significant f_a value (0.90), corresponding to 90% of enzyme inhibition, the CI value is 0.1781, indicating a strong synergism between the synthetic drug and the nutraceutical. The combined use of curcumin and chalcone 1a led to an enhancement of rhodesain inhibitory activity, resulting in a strong synergistic effect and supporting further investigation of this combination. Full article

Human African Trypanosomiasis (HAT) and Malaria are serious infectious diseases endemic in tropical regions, caused by protozoan parasites, and necessitating an urgent development of new antiprotozoal drugs. As part of our ongoing search for new antiprotozoal steroidal alkaloids from plants, we investigated the methanolic stem bark extract of Holarrhena pubescens (Apocynaceae). H. pubescens is a tropical tree that some Kenyan coastal communities have long used to treat various ailments, including fever and stomach pain. The crude extract, alkaloid fraction, and 16 subfractions acquired through centrifugal partition chromatography (CPC) displayed promising in vitro antiprotozoal activity against Trypanosoma brucei rhodesiense (Tbr) and Plasmodium falciparum (Pf). Partial least squares (PLS) regression modeling of UHPLC/+ESI QqTOF-MS data and the antiprotozoal activity data of the crude extract and its fractions was performed to predict compounds that may be responsible for the observed antiplasmodial activity. Chromatographic separation of the alkaloid fraction afforded one new steroidal alkaloid (5), along with 18 known compounds (1, 2, 4, 6–20), and one artifact (3) that was presumably formed during the acid–base extraction process. The structural characterization of the isolated compounds was accomplished using UHPLC/+ESI-QqTOF-MS/MS and NMR spectroscopy. The isolated compounds were tested for their in vitro antiprotozoal properties against the two aforementioned pathogens, as well as for their cytotoxicity against mammalian cells (L6 cell line). Compounds 2 and 16 (IC₅₀ = 0.2 μmol/L) demonstrated the highest antitrypanosomal activity, with compound 2 showing the highest selectivity (SI = 127). The new compound 5 exhibited the strongest antiplasmodial activity and selectivity against Pf (IC₅₀ = 0.7 μmol/L, SI = 43). Our findings provide further promising antiprotozoal leads for HAT and Malaria. Full article

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

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

Glycosylphosphatidylinositols (GPIs) are complex glycolipids that function as membrane anchors for a wide array of eukaryotic proteins, collectively referred to as GPI-anchored proteins (GPI-APs). These structures are critical for various cellular processes including signal transduction, host–pathogen interactions, and immune evasion. While GPI-APs have been extensively studied, increasing attention is being paid to non-protein-linked GPI, called free GPIs, which have been identified in both protozoan parasites and mammalian cells. In protozoa such as Trypanosoma brucei, Trypanosoma cruzi, Toxoplasma gondii, Plasmodium falciparum, and Leishmania spp., free GPIs play roles in virulence, immune modulation, and parasite survival. In mammals, free GPIs have been detected in several tissues and pathogenic conditions of paroxysmal nocturnal hemoglobinuria caused by PIGT mutation and rare blood group phenotypes. This review provides a comparative overview of the structure and biosynthesis of free GPIs and GPI-APs across species, highlighting unique adaptations in each. We also discuss the emerging physiological and pathological roles of free GPIs, proposing that these underexplored molecules may serve as important biomarkers and therapeutic targets. Understanding the diversity and function of free GPIs offers new insights into glycobiology and host–pathogen interactions. Full article

Tsetse flies are major vectors of trypanosomes in Sub-Saharan Africa, posing risks to livestock and human health. This study investigated the diversity, distribution, and infection rates of tsetse species, as well as the genetic diversity of drug resistance-associated trypanosome strains in Kenya. Flies were collected from Kwale, Taita-Taveta, Kajiado, Narok, and Turkana counties between November 2024 and February 2025. DNA analyses targeting rRNA and transporter genes (TbAT/P2, E6M6, DMT, TcoAde2) identified infections and resistance-associated mutations among 4693 sampled flies. Apparent density was highest in Kwale (101.52 flies/trap/day) and lowest in Turkana (1.18). Species distribution varied by county, with Kwale dominated by G. pallidipes, G. austeni, and G. brevipalpis; Taita-Taveta G. pallidipes, and G. brevipalpis; Kajiado G. pallidipes and G. longipennis; Narok G. pallidipes, G. brevipalpis, G. swynnertoni, and G. longipennis; and Turkana only G. pallidipes. Trypanosoma congolense was most prevalent, especially in Kwale, while T. brucei was common in Kajiado and Kwale. G. brevipalpis, G. austeni, and G. pallidipes showed higher infection risks. Drug resistance-associated T. congolense strains were found in Kwale and Taita-Taveta, with TcoAde2 and E6M6 gene diversity linked to Kenyan isolates. These findings highlight the need for targeted control of high-risk tsetse species and drug-resistant trypanosomes in Kenya. Full article

Human African Trypanosomiasis (HAT; sleeping sickness) and Malaria are life-threatening protozoan infections in tropical regions, with limited treatment options. As part of our ongoing efforts to discover new aminosteroid alkaloids from the Buxaceae family with antiprotozoal activity, which might serve as leads to new drugs against these infections, we investigated the dichloromethane extract from the leaves of Buxus obtusifolia (Mildbr.) Hutch. collected in Kenya, a species native to Kenya and Tanzania. To the best of our knowledge, and based on the most recent comprehensive literature review, this study represents the first phytochemical investigation of this plant. The alkaloid-enriched fraction yielded a total of 24 aminosteroid alkaloids, including 18 hitherto undescribed compounds (2, 3, 5–9, 11, 12, 15–19, and 21–24), along with six known compounds, two of which (1 and 4) are described as constituents of a natural source for the first time. Obtusiaminocyclin (24) represents the first Buxus alkaloid with a novel carbocyclic steroid skeleton with a cyclopropane ring comprising C-9, C-19 and C-11 accompanied by an unprecedented amino bridge between C-3 and C-10. The structures of the isolated compounds were determined using UHPLC/+ESI-QqTOF-MS/MS and NMR spectroscopy. The total crude extract, the alkaloid-enriched fraction, CPC subfractions and all isolated compounds were tested for in vitro antiprotozoal activity against Trypanosoma brucei rhodesiense (Tbr, responsible for East African HAT) and Plasmodium falciparum (Pf, responsible for tropical Malaria) as well as cytotoxicity against mammalian cells (L6 cell line). Deoxycyclovirobuxeine-B (12) (IC₅₀ = 0.8 µmol/L, SI = 108) and 29-trimethoxybenzoyloxy-obtusibuxoline (5) (IC₅₀ = 0.5 µmol/L, SI = 11) showed the highest activities with good selectivity indices against Tbr and Pf, respectively. Consequently, our findings provide valuable aminosteroid candidates that can serve as promising leads in our ongoing search for new drugs against HAT and Malaria. Full article

The naphthoquinone skeleton is known for broad biological applications and, in particular, for antiparasitic efficacy. As part of our ongoing search for new antiprotozoal naphthoquinone derivatives, we incorporated computer-aided optimization models utilizing physicochemical parameters into our approach. Herein, we report on the synthesis of 21 new benzamido–menadione and naphthoquinone derivatives via the Kochi–Anderson reaction. The antiprotozoal activity of all the synthesized compounds was evaluated against Plasmodium falciparum NF54 and Trypanosoma brucei rhodesiense STIB900. Cytotoxicity towards L6 cells was also determined, and the respective selectivity indices (SI) were calculated. Several ligand efficiency metrics, such as LLE, SILE, and FQ, were calculated, and the results were visualized in scatterplots. Almost all of the synthesized benzamido–menadione derivatives exhibited high activity against NF54 (IC₅₀ < 1 µM), with the strongest activity and excellent selectivity observed in the 2-fluoro-5-trifluoromethylbenzamido derivative 2f (IC₅₀ = 0.021 µM, SI = 10,000). Specific ligand efficiency metrics, such as SILE, LLE or FQ, showed a clear correlation with the corresponding antiplasmodial activities. Toxicity predictions confirmed low acute oral toxicity for most compounds, further supporting their potential as safe drug candidates. Our findings highlight the benzamido–menadione scaffold as a viable option for new antiplasmodial drugs. Full article

Background/Objectives: Neglected tropical diseases (NTDs) caused by protozoan parasites such as Trypanosoma cruzi, Trypanosoma brucei, Leishmania spp., and Plasmodium falciparum remain a global health challenge due to limited therapies and increasing drug resistance. Natural products provide diverse scaffolds for antiparasitic drug discovery. This study aimed to investigate the multitarget inhibitory potential of alkaloids isolated from Croton linearis Jacq. against validated protozoan enzymes. Methods: Eighteen alkaloids were virtually screened against 17 molecular targets relevant to protozoan parasites. Protein–ligand docking simulations were performed using crystallographic structures of enzymes, including Cyp51, DHFR-TS, PTR1, AD-kinase, and DHODH. Predicted interactions were analyzed to identify hydrogen bonds, hydrophobic contacts, and π–π stacking with key residues in the active sites. Results: Several alkaloids exhibited high binding affinities, in some cases surpassing co-crystallized ligands. Reticuline, norsalutaridine, laudanosine, and jacularine consistently showed the strongest activity, with docking scores ranging from −8.0 to −9.3 kcal/mol across multiple targets. Notably, norsalutaridine displayed the highest predicted affinity for L. infantum Cyp51, while reticuline showed strong binding to T. cruzi DHFR-TS and L. major PTR1. Conclusions: The study highlights the potential of C. linearis alkaloids as multitarget inhibitors against protozoan parasites. These compounds represent promising lead candidates for the development of antiparasitic agents, while emphasizing the value of natural product scaffolds for neglected disease drug discovery. The findings also support the future exploration of semisynthetic derivatives to optimize activity and selectivity. Full article

The mitochondrial DNA of trypanosomatid parasites consists of thousands of catenated minicircles and dozens of maxicircles that form a complex network structure, the kinetoplast (kDNA). Although kDNA replication and segregation during mitotic division are well studied, its inheritance during genetic exchange events remains unclear. In Trypanosoma brucei, hybrids inherit minicircles biparentally but retain maxicircles from a single parent. Although biparental inheritance of minicircles has been described in natural Trypanosoma cruzi hybrids, this process has not been explored in laboratory-generated hybrids of this parasite. In the present study, we analyzed kDNA inheritance in T. cruzi experimental hybrids using a comprehensive minicircle hypervariable region (mHVR) database and genome sequencing data. Our findings revealed biparental inheritance of minicircles, with hybrid lines retaining mHVRs from both parents for over 800 generations. In contrast, maxicircles were exclusively inherited from one parent. Unexpectedly, we observed an increase in kDNA content in hybrids, affecting both minicircles and maxicircles, and exhibiting instability over time. To explain these findings, we propose a Replicative Mixing (REMIX) model, where the hybrid inherits one kinetoplast from each parent and they are replicated allowing minicircle mixing. Instead maxicircle networks remain physically separated, leading to uniparental fixation after segregation in the first cell division of the hybrid. This model challenges previous assumptions regarding kDNA inheritance and provides a new framework for understanding kinetoplast dynamics in hybrid trypanosomes. Full article

African trypanosomiasis is a protozoan disease that affects both humans and animals. Human African Trypanosomiasis (HAT) is a Neglected Tropical Disease targeted for elimination in 2030. Although WHO has not reported HAT from Nigeria in the last decade, there are published studies reporting seroprevalence, parasite detection/isolation, and animal reservoirs potentially involved in HAT transmission in Nigeria. Interestingly, the burden of Animal African Trypanosomiasis (AAT) continues to increase. In this study, we synthesized published reports on the prevalence of HAT and AAT in Nigeria from 1993–2021, the trypanosome species involved, the spread of animal reservoirs, and the variability in diagnostic methodologies employed. A scoping review was performed following the methodological framework outlined in PRISMA-ScR checklist. Sixteen eligible studies published between 1993 and 2021 were reviewed: 13 for AAT and 3 for HAT. Varying prevalence rates were recorded depending on the diagnostic methods employed. The average prevalence reported from these studies was 3.3% (HAT), and 27.3% (AAT). Diagnostic methods employed include microscopy, PCR and Card Agglutination Test for Trypanosomiasis (CATT). Cattle, pigs, and dogs were identified as carriers of human-infective trypanosomes. This study highlights the scarcity of HAT epidemiological studies/data from Nigeria, the high prevalence, complex epidemiology, limited attention and surveillance of African Trypanosomiasis in Nigeria. Remarkably, WHO records do not reflect the published data showing evidence of HAT prevalence/cases in Nigeria. Unfortunately, diagnostics challenges and unrealistic disease reporting protocols seem to limit HAT reporting from Nigeria. Therefore, adequately coordinated epidemiological surveys and targeted intervention policies are imperative to ascertain the true epidemiological status of HAT in Nigeria and prevent disease re-emergence towards achieving WHO’s elimination targets. The presence of animal carriers of human-infective trypanosomes underscores the importance of a one-health approach to combat African trypanosomiasis effectively. Full article