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1.
Malar J ; 21(1): 151, 2022 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-35570264

RESUMO

BACKGROUND: Targeting the asymptomatic liver stage of Plasmodium infection through chemoprevention could become a key intervention to reduce malaria-associated incidence and mortality. METHODS: M5717, a Plasmodium elongation factor 2 inhibitor, was assessed in vitro and in vivo with readily accessible Plasmodium berghei parasites. In an animal refinement, reduction, replacement approach, the in vitro IC99 value was used to feed a Population Pharmacokinetics modelling and simulation approach to determine meaningful effective doses for a subsequent Plasmodium sporozoite-induced volunteer infection study. RESULTS: Doses of 100 and 200 mg would provide exposures exceeding IC99 in 96 and 100% of the simulated population, respectively. CONCLUSIONS: This approach has the potential to accelerate the search for new anti-malarials, to reduce the number of healthy volunteers needed in a clinical study and decrease and refine the animal use in the preclinical phase.


Assuntos
Antimaláricos , Malária , Animais , Antimaláricos/farmacocinética , Antimaláricos/uso terapêutico , Humanos , Fígado/parasitologia , Malária/tratamento farmacológico , Malária/parasitologia , Malária/prevenção & controle , Fator 2 de Elongação de Peptídeos , Plasmodium berghei
2.
J Synchrotron Radiat ; 28(Pt 2): 609-617, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33650573

RESUMO

X-SPEC is a high-flux spectroscopy beamline at the KIT (Karlsruhe Institute of Technology) Synchrotron for electron and X-ray spectroscopy featuring a wide photon energy range. The beamline is equipped with a permanent magnet undulator with two magnetic structures of different period lengths, a focusing variable-line-space plane-grating monochromator, a double-crystal monochromator and three Kirkpatrick-Baez mirror pairs. By selectively moving these elements in or out of the beam, X-SPEC is capable of covering an energy range from 70 eV up to 15 keV. The flux of the beamline is maximized by optimizing the magnetic design of the undulator, minimizing the number of optical elements and optimizing their parameters. The beam can be focused into two experimental stations while maintaining the same spot position throughout the entire energy range. The first experimental station is optimized for measuring solid samples under ultra-high-vacuum conditions, while the second experimental station allows in situ and operando studies under ambient conditions. Measurement techniques include X-ray absorption spectroscopy (XAS), extended X-ray absorption fine structure (EXAFS), photoelectron spectroscopy (PES) and hard X-ray PES (HAXPES), as well as X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS).

3.
Artigo em Inglês | MEDLINE | ID: mdl-32041711

RESUMO

Antimalarial drug resistance in the Plasmodium falciparum parasite poses a constant challenge for drug development. To mitigate this risk, new antimalarial medicines should be developed as fixed-dose combinations. Assessing the pharmacodynamic interactions of potential antimalarial drug combination partners during early phases of development is essential in developing the targeted parasitological and clinical profile of the final drug product. Here, we have studied the combination of M5717, a P. falciparum translation elongation factor 2 inhibitor, and pyronaridine, an inhibitor of hemozoin formation. Our test cascade consisted of in vitro isobolograms as well as in vivo studies in the P. falciparum severe combined immunodeficient (SCID) mouse model. We also analyzed pharmacokinetic and pharmacodynamic parameters, including genomic sequencing of recrudescent parasites. We observed no pharmacokinetic interactions with the combination of M5717 and pyronaridine. M5717 did not negatively impact the rate of kill of the faster-acting pyronaridine, and the latter was able to suppress the selection of M5717-resistant mutants, as well as significantly delay the recrudescence of parasites both with suboptimal and optimal dosing regimens.


Assuntos
Antimaláricos/farmacologia , Malária Falciparum/tratamento farmacológico , Naftiridinas/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Quinolinas/farmacologia , Animais , Antimaláricos/farmacocinética , Resistência a Medicamentos/fisiologia , Quimioterapia Combinada , Hemeproteínas/antagonistas & inibidores , Malária Falciparum/prevenção & controle , Camundongos , Camundongos SCID , Naftiridinas/farmacocinética , Fator 2 de Elongação de Peptídeos/antagonistas & inibidores , Quinolinas/química , Quinolinas/farmacocinética
4.
Antimicrob Agents Chemother ; 59(4): 1935-41, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25583726

RESUMO

There is an unmet need to discover and develop novel antischistosomal drugs. As exemplified by MMV665852, N,N'-diarylureas have recently emerged as a promising antischistosomal chemotype. In this study, we evaluated the structure-activity relationships of 46 commercially available analogs of MMV665852 on newly transformed schistosomula (NTS) and adult Schistosoma mansoni worms in vitro. Active compounds were evaluated with a cytotoxicity assay, in silico calculations, metabolic stability studies, and an in vivo assay with mice harboring adult S. mansoni worms. Of the 46 compounds tested at 33.3 µM, 13 and 14 compounds killed NTS and adult worms, respectively, within 72 h. Nine compounds had 90% inhibitory concentrations (IC90s) of ≤10 µM against adult worms, with selectivity indexes of ≥2.8. Their physicochemical properties and permeation through an artificial membrane indicated good to moderate intestinal absorption. Their metabolic stabilities ranged from low to high. Despite satisfactory in vitro results and in silico predictions, only one compound resulted in a statistically significant worm burden reduction (66%) after administration of a single oral dose of 400 mg/kg of body weight to S. mansoni-infected mice. Worm burden reductions of 0 to 43% were observed for the remaining eight compounds tested. In conclusion, several analogs of the N,N'-diarylurea MMV665852 had high efficacy against S. mansoni in vitro and favorable physicochemical properties for permeation through the intestinal wall. To counteract the low efficacy observed in the mouse model, further investigations should focus on identifying compounds with improved solubility and pharmacokinetic properties.


Assuntos
Compostos de Fenilureia/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomicidas/farmacologia , Animais , Carga Corporal (Radioterapia) , Sobrevivência Celular/efeitos dos fármacos , Simulação por Computador , Feminino , Absorção Intestinal , Membranas Artificiais , Camundongos , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismo , Compostos de Fenilureia/farmacocinética , Ratos , Esquistossomose mansoni/tratamento farmacológico , Esquistossomose mansoni/parasitologia , Esquistossomicidas/farmacocinética , Relação Estrutura-Atividade
5.
Antimicrob Agents Chemother ; 59(2): 1110-8, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25487796

RESUMO

Plasmodium falciparum, the most deadly agent of malaria, displays a wide variety of resistance mechanisms in the field. The ability of antimalarial compounds in development to overcome these must therefore be carefully evaluated to ensure uncompromised activity against real-life parasites. We report here on the selection and phenotypic as well as genotypic characterization of a panel of sensitive and multidrug-resistant P. falciparum strains that can be used to optimally identify and deconvolute the cross-resistance signals from an extended panel of investigational antimalarials. As a case study, the effectiveness of the selected panel of strains was demonstrated using the 1,2,4-oxadiazole series, a newly identified antimalarial series of compounds with in vitro activity against P. falciparum at nanomolar concentrations. This series of compounds was to be found inactive against several multidrug-resistant strains, and the deconvolution of this signal implicated pfcrt, the genetic determinant of chloroquine resistance. Targeted mode-of-action studies further suggested that this new chemical series might act as falcipain 2 inhibitors, substantiating the suggestion that these compounds have a site of action similar to that of chloroquine but a distinct mode of action. New antimalarials must overcome existing resistance and, ideally, prevent its de novo appearance. The panel of strains reported here, which includes recently collected as well as standard laboratory-adapted field isolates, is able to efficiently detect and precisely characterize cross-resistance and, as such, can contribute to the faster development of new, effective antimalarial drugs.


Assuntos
Antimaláricos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/metabolismo , Antimaláricos/química , Resistência a Medicamentos/fisiologia , Testes de Sensibilidade Parasitária
6.
Antimicrob Agents Chemother ; 58(5): 2731-9, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24566188

RESUMO

The apicomplexan parasites Cryptosporidium parvum and Cryptosporidium hominis are major etiologic agents of human cryptosporidiosis. The infection is typically self-limited in immunocompetent adults, but it can cause chronic fulminant diarrhea in immunocompromised patients and malnutrition and stunting in children. Nitazoxanide, the current standard of care for cryptosporidiosis, is only partially efficacious for children and is no more effective than a placebo for AIDS patients. Unfortunately, financial obstacles to drug discovery for diseases that disproportionately affect low-income countries and technical limitations associated with studies of Cryptosporidium biology impede the development of better drugs for treating cryptosporidiosis. Using a cell-based high-throughput screen, we queried the Medicines for Malaria Venture (MMV) Open Access Malaria Box for activity against C. parvum. We identified 3 novel chemical series derived from the quinolin-8-ol, allopurinol-based, and 2,4-diamino-quinazoline chemical scaffolds that exhibited submicromolar potency against C. parvum. Potency was conserved in a subset of compounds from each scaffold with varied physicochemical properties, and two of the scaffolds identified exhibit more rapid inhibition of C. parvum growth than nitazoxanide, making them excellent candidates for further development. The 2,4-diamino-quinazoline and allopurinol-based compounds were also potent growth inhibitors of the related apicomplexan parasite Toxoplasma gondii, and a good correlation was observed in the relative activities of the compounds in the allopurinol-based series against T. gondii and C. parvum. Taken together, these data illustrate the utility of the Open Access Malaria Box as a source of both potential leads for drug development and chemical probes to elucidate basic biological processes in C. parvum and other apicomplexan parasites.


Assuntos
Antiprotozoários/química , Antiprotozoários/farmacologia , Cryptosporidium parvum/efeitos dos fármacos , Reposicionamento de Medicamentos/métodos , Humanos , Hidroxiquinolinas/química , Nitrocompostos , Quinazolinas/química , Tiazóis/farmacologia , Toxoplasma/efeitos dos fármacos
7.
Antimicrob Agents Chemother ; 58(10): 5848-54, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25049259

RESUMO

Toxoplasmosis and amebiasis are important public health concerns worldwide. The drugs currently available to control these diseases have proven limitations. Therefore, innovative approaches should be adopted to identify and develop new leads from novel scaffolds exhibiting novel modes of action. In this paper, we describe results from the screening of compounds in the Medicines for Malaria Venture (MMV) open access Malaria Box in a search for new anti-Toxoplasma and anti-Entamoeba agents. Standard in vitro phenotypic screening procedures were adopted to assess their biological activities. Seven anti-Toxoplasma compounds with a 50% inhibitory concentration (IC50) of <5 µM and selectivity indexes (SI) of >6 were identified. The most interesting compound was MMV007791, a piperazine acetamide, which has an IC50 of 0.19 µM and a selectivity index of >157. Also, we identified two compounds, MMV666600 and MMV006861, with modest activities against Entamoeba histolytica, with IC50s of 10.66 µM and 15.58 µM, respectively. The anti-Toxoplasma compounds identified in this study belong to scaffold types different from those of currently used drugs, underscoring their novelty and potential as starting points for the development of new antitoxoplasmosis drugs with novel modes of action.


Assuntos
Antiprotozoários/farmacologia , Entamoeba histolytica/efeitos dos fármacos , Toxoplasma/efeitos dos fármacos , Testes de Sensibilidade Parasitária , Piperazina , Piperazinas/farmacologia
8.
Malar J ; 13: 190, 2014 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-24886460

RESUMO

BACKGROUND: In view of the need to continuously feed the pipeline with new anti-malarial agents adapted to differentiated and more stringent target product profiles (e.g., new modes of action, transmission-blocking activity or long-duration chemo-protection), a chemical library consisting of more than 250,000 compounds has been evaluated in a blood-stage Plasmodium falciparum growth inhibition assay and further assessed for chemical diversity and novelty. METHODS: The selection cascade used for the triaging of hits from the chemical library started with a robust three-step in vitro assay followed by an in silico analysis of the resulting confirmed hits. Upon reaching the predefined requirements for selectivity and potency, the set of hits was subjected to computational analysis to assess chemical properties and diversity. Furthermore, known marketed anti-malarial drugs were co-clustered acting as 'signposts' in the chemical space defined by the hits. Then, in cerebro evaluation of the chemical structures was performed to identify scaffolds that currently are or have been the focus of anti-malarial medicinal chemistry programmes. Next, prioritization according to relaxed physicochemical parameters took place, along with the search for structural analogues. Ultimately, synthesis of novel chemotypes with desired properties was performed and the resulting compounds were subsequently retested in a P. falciparum growth inhibition assay. RESULTS: This screening campaign led to a 1.25% primary hit rate, which decreased to 0.77% upon confirmatory repeat screening. With the predefined potency (EC50 < 1 µM) and selectivity (SI > 10) criteria, 178 compounds progressed to the next steps where chemical diversity, physicochemical properties and novelty assessment were taken into account. This resulted in the selection of 15 distinct chemical series. CONCLUSION: A selection cascade was applied to prioritize hits resulting from the screening of a medium-sized chemical library against blood-stage P. falciparum. Emphasis was placed on chemical novelty whereby computational clustering, data mining of known anti-malarial chemotypes and the application of relaxed physicochemical filters, were key to the process. This led to the selection of 15 chemical series from which ten confirmed their activity when newly synthesized sample were tested.


Assuntos
Antimaláricos/isolamento & purificação , Avaliação Pré-Clínica de Medicamentos , Plasmodium falciparum/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas , Algoritmos , Antimaláricos/química , Antimaláricos/farmacologia , Humanos
9.
Parasitology ; 141(1): 128-39, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23863111

RESUMO

Malaria is a disease that still affects a significant proportion of the global human population. Whilst advances have been made in lowering the numbers of cases and deaths, it is clear that a strategy based solely on disease control year on year, without reducing transmission and ultimately eradicating the parasite, is unsustainable. This article highlights the current mainstay treatments alongside a selection of emerging new clinical molecules from the portfolio of Medicines for Malaria Venture (MMV) and our partners. In each case, the key highlights from each research phase are described to demonstrate how these new potential medicines were discovered. Given the increased focus of the community on eradicating the disease, the strategy for next generation combination medicines that will provide such potential is explained.


Assuntos
Antimaláricos/farmacologia , Descoberta de Drogas , Estágios do Ciclo de Vida/efeitos dos fármacos , Malária/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Plasmodium vivax/efeitos dos fármacos , Antimaláricos/síntese química , Ensaios Clínicos como Assunto , Erradicação de Doenças , Combinação de Medicamentos , Desenho de Fármacos , Humanos , Malária/parasitologia , Malária/prevenção & controle , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/metabolismo , Plasmodium vivax/crescimento & desenvolvimento , Plasmodium vivax/metabolismo , Relação Estrutura-Atividade
10.
ACS Med Chem Lett ; 15(5): 626-630, 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38746890

RESUMO

To investigate the physicochemical properties of anti-schistosomal compounds reported between 2008 and 2023, a simple but extensive literature scrutiny was conducted. Keywords were searched in Chemical Abstracts Service (CAS) SciFinder and primary medicinal chemistry and pharmacology literature to locate publications with compounds displaying ex vivo and/or in vivo anti-schistosomal activity. A total of 57 repurposed U.S. Food and Drug Administration (FDA)-approved drugs, hits and their derivatives were manually extracted, curated and compared to known anti-schistosomal oral drugs in view of establishing trends of calculated critical molecular properties. From this analysis, it was determined that more than 65% of the compounds display cLogD7.4 > 3 values, whereas oxamniquine, metrifonate and praziquantel (PZQ), previous and currently used oral anti-schistosomal drugs, possess lower cLogD7.4 values (≤2.5). Furthermore, the lipophilicity associated with PZQ corresponds to a highly permeable and sparingly soluble compound, characteristics that favor drug absorption and compound penetration in the parasite. These physicochemical properties together with PZQ's anti-schistosomal activity make PZQ an essential medicine for the treatment of schistosomiasis and demonstrate the importance of finding the right balance among potency (e.g., EC50 < 5 and 0.5 µM), cell permeability (e.g., Papp > 2 × 106 cm/s) and kinetic aqueous solubility (e.g., >10 µM) to provide high-quality hits and/or leads for the discovery of new oral anti-schistosomal therapeutics.

11.
Malar J ; 12: 168, 2013 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-23706107

RESUMO

The challenge of controlling and eventually eradicating malaria means that new tools are urgently needed. South America's role in this fight spans both ends of the research and development spectrum: both as a continent capable of discovering and developing new medicines, and also as a continent with significant numbers of malaria patients. This article reviews the contribution of groups in the South American continent to the research and development of new medicines over the last decade. Therefore, the current situation of research targeting malaria control and eradication is discussed, including endemicity, geographical distribution, treatment, drug-resistance and diagnosis. This sets the scene for a review of efforts within South America to discover and optimize compounds with anti-malarial activity.


Assuntos
Antimaláricos/isolamento & purificação , Avaliação Pré-Clínica de Medicamentos/tendências , Malária/epidemiologia , Malária/prevenção & controle , Resistência a Medicamentos , Humanos , Malária/diagnóstico , Malária/tratamento farmacológico , América do Sul
12.
ACS Med Chem Lett ; 14(7): 875-878, 2023 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-37465315

RESUMO

This viewpoint outlines the case for developing new chemical entities (NCEs) as racemates in infectious diseases and where both enantiomers and racemate retain similar on- and off-target activities as well as similar PK profiles. There are not major regulatory impediments for the development of a racemic drug, and minimizing the manufacturing costs becomes a particularly important objective when bringing an anti-infective therapeutic to the marketplace in the endemic settings of infectious diseases.

13.
ChemMedChem ; 18(18): e202300140, 2023 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-37272317

RESUMO

Praziquantel (PZQ) is an essential anthelmintic drug recently established to be an activator of a Transient Receptor Potential Melastatin (TRPMPZQ ) ion channel in trematode worms. Bioinformatic, mutagenesis and drug metabolism work indicate that the cyclohexyl ring of PZQ is a key pharmacophore for activation of trematode TRPMPZQ , as well as serving as the primary site of oxidative metabolism which results in PZQ being a short-lived drug. Based on our recent findings, the hydrophobic cleft in schistosome TRPMPZQ defined by three hydrophobic residues surrounding the cyclohexyl ring has little tolerance for polarity. Here we evaluate the in vitro and in vivo activities of PZQ analogues with improved metabolic stability relative to the challenge of maintaining activity on the channel. Finally, an estimation of the respective contribution to the overall activity of both the parent and the main metabolite of PZQ in humans is reported.


Assuntos
Anti-Helmínticos , Parasitos , Canais de Cátion TRPM , Canais de Potencial de Receptor Transitório , Humanos , Animais , Praziquantel/farmacologia , Praziquantel/química , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêutico , Schistosoma mansoni
14.
ACS Med Chem Lett ; 14(11): 1537-1543, 2023 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-37970586

RESUMO

The anthelmintic drug praziquantel remains a key clinical therapy for treating various diseases caused by parasitic flatworms. The parasite target of praziquantel has remained undefined despite longstanding usage in the clinic, although a candidate ion channel target, named TRPMPZQ, has recently been identified. Intriguingly, certain praziquantel derivatives show different activities against different parasites: for example, some praziquantel analogs are considerably more active against cestodes than against schistosomes. Here we interrogate whether the different activities of praziquantel analogs against different parasites are also reflected by unique structure-activity relationships at the TRPMPZQ channels found in these different organisms. To do this, several praziquantel analogs were synthesized and functionally profiled against schistosome and cestode TRPMPZQ channels. Data demonstrate that structure-activity relationships are closely mirrored between parasites and their TRPMPZQ orthologs, providing further support for TRPMPZQ as the therapeutically relevant target of praziquantel.

15.
Nat Commun ; 14(1): 5205, 2023 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-37626093

RESUMO

We report an analysis of the propensity of the antimalarial agent cabamiquine, a Plasmodium-specific eukaryotic elongation factor 2 inhibitor, to select for resistant Plasmodium falciparum parasites. Through in vitro studies of laboratory strains and clinical isolates, a humanized mouse model, and volunteer infection studies, we identified resistance-associated mutations at 11 amino acid positions. Of these, six (55%) were present in more than one infection model, indicating translatability across models. Mathematical modelling suggested that resistant mutants were likely pre-existent at the time of drug exposure across studies. Here, we estimated a wide range of frequencies of resistant mutants across the different infection models, much of which can be attributed to stochastic differences resulting from experimental design choices. Structural modelling implicates binding of cabamiquine to a shallow mRNA binding site adjacent to two of the most frequently identified resistance mutations.


Assuntos
Antimaláricos , Parasitos , Animais , Camundongos , Antimaláricos/farmacologia , Aminoácidos , Sítios de Ligação , Modelos Animais de Doenças
16.
Parasit Vectors ; 16(1): 263, 2023 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-37542265

RESUMO

BACKGROUND: Although schistosomiasis is a public health issue in Mali, little is known about the parasite genetic profile. The purpose of this study was to analyze the genetic profile of the schistosomes of Schistosoma haematobium group in school-aged children in various sites in Mali. METHODS: Urine samples were collected from 7 to 21 November 2021 and subjected to a filtration method for the presence S. haematobium eggs. The study took place in two schistosomiasis endemic villages (Fangouné Bamanan and Diakalèl), qualified as hotspots according to the World Health Organization (WHO) definition. Molecular genotyping on both Cox1 and ITS2/18S was used for eggs' taxonomic assignation. RESULTS: A total of 970 miracidia were individually collected from 63 school-aged children and stored on Whatman FTA cards for molecular analysis. After genotyping 42.0% (353/840) and 58.0% (487/840) of miracidia revealed Schistosoma bovis and S. haematobium Cox1 profiles, respectively; 95.7 (885/925) and 4.3% (40/925) revealed S. haematobium and S. haematobium/S. curassoni profiles for ITS/18S genes, respectively. There was a significant difference in the Cox1 and ITS2/18S profile distribution according to the village (P < 0.0001). Overall, 45.6% (360/789) were hybrids, of which 72.0% (322/447) were from Diakalèl. Three hybrids' profiles (Sb/Sc_ShxSc with 2.3%; Sb/Sc_ShxSh with 40.5%; Sh_ShxSc with 2.8%) and one pure profile (Sh_ShxSh with 54.4%) were identified. CONCLUSION: Our findings show, for the first time to our knowledge, high prevalence of hybrid schistosomes in Mali. More studies are needed on population genetics of schistosomes at the human and animal interface to evaluate the parasite's gene flow and its consequences on epidemiology of the disease as well as the transmission to humans.


Assuntos
Parasitos , Esquistossomose Urinária , Esquistossomose , Criança , Animais , Humanos , Schistosoma haematobium/genética , Hotspot de Doença , Perfil Genético , Schistosoma/genética , Esquistossomose/epidemiologia
17.
ACS Infect Dis ; 9(5): 1046-1055, 2023 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-37083395

RESUMO

In September 2022, the Drug Discovery Unit at the University of Dundee, UK, organised an international meeting at the Wellcome Collection in London to explore the current clinical situation and challenges associated with treating schistosomiasis. The aim of this meeting was to discuss the need for new treatments in view of the clinical situation and to ascertain what the key requirements would be for any potential new anti-schistosomals. This information will be essential to inform ongoing drug discovery efforts for schistosomiasis. We also discussed the potential drug discovery pathway and associated criteria for progressing compounds to the clinic. To date, praziquantel (PZQ) is the only drug available to treat all species causing schistosomiasis, but it is often unable to completely clear parasites from an infected patient, partially due to its inactivity against juvenile worms. PZQ-mediated mass drug administration campaigns conducted in endemic areas (e.g., sub-Saharan Africa, where schistosomiasis is primarily prevalent) have contributed to reducing the burden of disease but will not eliminate the disease as a public health problem. The potential for Schistosoma to develop resistance towards PZQ, as the sole treatment available, could become a concern. Consequently, new anthelmintic medications are urgently needed, and this Perspective aims to capture some of the learnings from our discussions on the key criteria for new treatments.


Assuntos
Anti-Helmínticos , Esquistossomose , Animais , Londres , Esquistossomose/tratamento farmacológico , Praziquantel/farmacologia , Praziquantel/uso terapêutico , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêutico , Schistosoma
18.
Lancet Infect Dis ; 23(10): 1164-1174, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37414066

RESUMO

BACKGROUND: Cabamiquine is a novel antimalarial that inhibits Plasmodium falciparum translation elongation factor 2. We investigated the causal chemoprophylactic activity and dose-exposure-response relationship of single oral doses of cabamiquine following the direct venous inoculation (DVI) of P falciparum sporozoites in malaria-naive, healthy volunteers. METHODS: This was a phase 1b, randomised, double-blind, placebo-controlled, adaptive, dose-finding, single-centre study performed in Leiden, Netherlands. Malaria-naive, healthy adults aged 18-45 years were divided into five cohorts and randomly assigned (3:1) to receive cabamiquine or placebo. Randomisation was done by an independent statistician using codes in a permuted block schedule with a block size of four. Participants, investigators, and study personnel were masked to treatment allocation. A single, oral dose regimen of cabamiquine (200, 100, 80, 60, or 30 mg) or matching placebo was administered either at 2 h (early liver-stage) or 96 h (late liver-stage) after DVI. The primary endpoints based on a per-protocol analysis set were the number of participants who developed parasitaemia within 28 days of DVI, time to parasitaemia, number of participants with documented parasite blood-stage growth, clinical symptoms of malaria, and exposure-efficacy modelling. The impact of cabamiquine on liver stages was evaluated indirectly by the appearance of parasitaemia in the blood. The Clopper-Pearson CI (nominal 95%) was used to express the protection rate. The secondary outcomes were safety and tolerability, assessed in those who had received DVI and were administered one dose of the study intervention. The trial was prospectively registered on ClinicalTrials.gov (NCT04250363). FINDINGS: Between Feb 17, 2020 and April 29, 2021, 39 healthy participants were enrolled (early liver-stage: 30 mg [n=3], 60 mg [n=6], 80 mg [n=6], 100 mg [n=3], 200 mg [n=3], pooled placebo [n=6]; late liver-stage: 60 mg [n=3], 100 mg [n=3], 200 mg [n=3], pooled placebo [n=3]). A dose-dependent causal chemoprophylactic effect was observed, with four (67%) of six participants in the 60 mg, five (83%) of six participants in the 80 mg, and all three participants in the 100 and 200 mg cabamiquine dose groups protected from parasitaemia up to study day 28, whereas all participants in the pooled placebo and 30 mg cabamiquine dose group developed parasitaemia. A single, oral dose of 100 mg cabamiquine or higher provided 100% protection against parasitaemia when administered during early or late liver-stage malaria. The median time to parasitaemia in those with early liver-stage malaria was prolonged to 15, 22, and 24 days for the 30, 60, and 80 mg dose of cabamiquine, respectively, compared with 10 days for the pooled placebo. All participants with positive parasitaemia showed documented blood-stage parasite growth, apart from one participant in the pooled placebo group and one participant in the 30 mg cabamiquine group. Most participants did not exhibit any malaria symptoms in both the early and late liver-stage groups, and those reported were mild in severity. A positive dose-exposure-efficacy relationship was established across exposure metrics. The median maximum concentration time was 1-6 h, with a secondary peak observed between 6 h and 12 h in all cabamiquine dose groups (early liver-stage). All cabamiquine doses were safe and well tolerated. Overall, 26 (96%) of 27 participants in the early liver-stage group and ten (83·3%) of 12 participants in the late liver-stage group reported at least one treatment-emergent adverse event (TEAE) with cabamiquine or placebo. Most TEAEs were of mild severity, transient, and resolved without sequelae. The most frequently reported cabamiquine-related TEAE was headache. No dose-related trends were observed in the incidence, severity, or causality of TEAEs. INTERPRETATION: The results from this study show that cabamiquine has a dose-dependent causal chemoprophylactic activity. Together with previously demonstrated activity against the blood stages combined with a half-life of more than 150 h, these results indicate that cabamiquine could be developed as a single-dose monthly regimen for malaria prevention. FUNDING: The healthcare business of Merck KGaA, Darmstadt, Germany.


Assuntos
Antimaláricos , Malária Falciparum , Adulto , Humanos , Plasmodium falciparum , Países Baixos , Malária Falciparum/tratamento farmacológico , Malária Falciparum/prevenção & controle , Malária Falciparum/parasitologia , Voluntários Saudáveis , Método Duplo-Cego
19.
Methods Mol Biol ; 2387: 131-149, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34643909

RESUMO

By means of thin layer chromatography coupled to a fluorescence enhancer, a highly sensitive and operationally simple method to detect the mycolactones stemming from the human pathogen Mycobacterium ulcerans was developed and applied to various sample sources.


Assuntos
Cromatografia em Camada Fina , Humanos , Macrolídeos , Mycobacterium ulcerans
20.
Front Immunol ; 13: 878029, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35833137

RESUMO

Alongside the wide distribution throughout sub Saharan Africa of schistosomiasis, the morbidity associated with this chronic parasitic disease in endemic regions is often coupled with infection-driven immunomodulatory processes which modify inflammatory responses. Early life parasite exposure is theorized to drive immune tolerance towards cognate infection as well as bystander immune responses, beginning with in utero exposure to maternal infection. Considering that 40 million women of childbearing-age are at risk of infection worldwide, treatment with Praziquantel during pregnancy as currently recommended by WHO could have significant impact on disease outcomes in these populations. Here, we describe the effects of anthelminthic treatment on parasite-induced changes to fetomaternal cross talk in a murine model of maternal schistosomiasis. Praziquantel administration immediately prior to mating lead to clear re-awakening of maternal anti-parasite immune responses, with persistent maternal immune activation that included enhanced anti-schistosome cytokine responses. Clearance of parasites also improved capacity of dams to endure the additional pressure of pregnancy during infection. Maternal treatment also drove lasting functional alterations to immune system development of exposed offspring. Prenatal anthelminthic treatment skewed offspring immune responses towards parasite clearance and reduced morbidity during cognate infection. Maternal treatment also restored offspring protective IgE antibody responses directed against schistosome antigens, which were otherwise suppressed following exposure to untreated maternal infection. This was further associated with enhanced anti-schistosome cytokine responses from treatment-exposed offspring during infection. In the absence of cognate infection, exposed offspring further demonstrated imprinting across cellular populations. We provide further evidence that maternal treatment can restore a more normalized immune profile to such offspring exposed in utero to parasite infection, particularly in B cell populations, which may underlie improved responsiveness to cognate infection, and support the WHO recommendation of anthelminthic treatment during pregnancy.


Assuntos
Anti-Helmínticos , Esquistossomose , Animais , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêutico , Formação de Anticorpos , Citocinas/uso terapêutico , Feminino , Humanos , Mortalidade Materna , Mebendazol/uso terapêutico , Camundongos , Morbidade , Praziquantel/farmacologia , Praziquantel/uso terapêutico , Gravidez , Schistosoma , Esquistossomose/tratamento farmacológico
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