10 research outputs found
Fragment-Based Phenotypic Lead Discovery: Cell-Based Assay to Target Leishmaniasis
International audienceA rapid and practical approach for the discovery of new chemical matter for targeting pathogens and diseases is described. Fragment-based phenotypic lead discovery (FPLD) combines aspects of traditional fragment-based lead discovery (FBLD), which involves the screening of small-molecule fragment libraries to target specific proteins, with phenotypic lead discovery (PLD), which typically involves the screening of drug-like compounds in cell-based assays. To enable FPLD, a diverse library of fragments was first designed, assembled, and curated. This library of soluble, low-molecular-weight compounds was then pooled to expedite screening. Axenic cultures of Leishmania promastigotes were screened, and single hits were then tested for leishmanicidal activity against intracellular amastigote forms in infected murine bone-marrow-derived macrophages without evidence of toxicity toward mammalian cells. These studies demonstrate that FPLD can be a rapid and effective means to discover hits that can serve as leads for further medicinal chemistry purposes or as tool compounds for identifying known or novel targets
SynthĂšse bibliographique des Ă©tudes de biosurveillance des populations vivant en zones miniĂšres ou Ă proximitĂ© dâindustries Ă©mettrices de mĂ©taux
- Ce rapport bibliographique constitue un prĂ©alable au programme « Niveaux dâimprĂ©gnation et dĂ©terminants de lâexposition humaine aux mĂ©taux en Nouvelle CalĂ©donie » (MĂ©texpo), Ă©tude de biosurveillance sur lâexposition au nickel, au cobalt, au chrome, et au manganĂšse en Nouvelle CalĂ©donie. En effet, la nappe de pĂ©ridotites qui recouvre un tiers du bĂąti calĂ©donien est constituĂ©e de roches ultrabasiques (essentiellement des hazburgites), pauvres en silice et gĂ©nĂ©ralement riches en magnĂ©sium et en fer. Aux cĂŽtĂ©s de ces Ă©lĂ©ments, divers mĂ©taux traces dont le nickel (Ni), le cobalt (Co), le chrome (Cr) et le manganĂšse (Mn), prĂ©sentent des concentrations relativement importantes. De fait une partie de la population de lâarchipel de Nouvelle-CalĂ©donie pourrait se rĂ©vĂ©ler particuliĂšrement exposĂ©e Ă ces mĂ©taux. Dâautant que certains de ces mĂ©taux (Ni, Cr et Co), font lâobjet dâune importante exploitation miniĂšre depuis le milieu du XIXĂšme siĂšcle.- Ce rapport vise principalement Ă faire une synthĂšse bibliographique des Ă©tudes nationales et internationales ayant portĂ© sur la biosurveillance du nickel, cobalt, chrome et manganĂšse dans des populations vivant en zone miniĂšre ou Ă proximitĂ© dâindustries Ă©mettrices de ces mĂ©taux.- AprĂšs un bref rappel sur la toxicitĂ© chronique de chaque mĂ©tal, les Ă©tudes publiĂ©es sâĂ©tant penchĂ© sur le lien potentiel avec une source dâexposition miniĂšre et/ou industrielle seront dĂ©crites
METEXPO : Niveaux d'imprégnation et déterminants de l'exposition humaine aux métaux. Tome Nickel et Santé
Environ un tiers de la superficie de la Nouvelle-CalĂ©donie est recouverte de formationsgĂ©ologiques riches en mĂ©taux dâintĂ©rĂȘt tels que le nickel (Ni) et le cobalt (Co), maisĂ©galement le chrome (Cr) et le manganĂšse (Mn).La prĂ©sence de ces formations constitue une source potentielle dâexposition des populationscalĂ©doniennes Ă ces Ă©lĂ©ments traces mĂ©talliques (ETM), notamment Ă proximitĂ© des zonesoĂč le couvert vĂ©gĂ©tal est dĂ©gradĂ© voire absent.Au droit de ces zones, les processus dâĂ©rosion chimique et mĂ©canique sont particuliĂšrementactifs et conduisent Ă la libĂ©ration des ETM qui sont ensuite dispersĂ©s dans lâenvironnementpar voie aĂ©rienne (vent) ou par les Ă©coulements dâeau de surface.Ces ETM sont donc susceptibles de se retrouver dans :- lâeau des creeks et riviĂšres, contaminant les captages dâeau destinĂ©e Ă laconsommation humaine, mais Ă©galement certains produits de la pĂȘche (crevettesde creek et poissons),- lâeau du lagon contaminant les produits de la pĂȘche lagonaire (coquillages,poissons et crustacĂ©s),- les sols alluvionnaires cultivĂ©s contaminant les cultures qui y sont produites,- les poussiĂšres qui se dĂ©posent dans les habitations ou Ă proximitĂ© susceptiblesdâĂȘtre inhalĂ©es ou avalĂ©es.Toutes ces voies sont susceptibles de contribuer Ă lâexposition Ă ces ETM des populationscalĂ©doniennes. Et ce dâautant plus que lâintĂ©gritĂ© du couvert vĂ©gĂ©tal des massifsultramafiques calĂ©doniens subit depuis plusieurs dĂ©cennies diffĂ©rents types de pressions quicontribuent Ă sa dĂ©gradation. Les trois principales pressions Ă lâorigine de ces dĂ©gradationssont les feux de brousse, les ongulĂ©s envahissants (cerfs et cochons sauvages), ainsi quelâactivitĂ© miniĂšre. Cette derniĂšre pression, outre le fait quâelle participe Ă lâaccentuation desprocessus dâĂ©rosion, est Ă©galement susceptible dâamplifier les Ă©missions aĂ©riennes depoussiĂšres chargĂ©es en ETM via les travaux dâexcavation, le roulage des engins miniers, lesactivitĂ©s de concassage et criblage effectuĂ©es sur site ou au travers les Ă©missionsatmosphĂ©riques des usines mĂ©tallurgiques.A ce jour aucune Ă©tude nâavait Ă©tĂ© menĂ©e pour Ă©valuer le risque potentiel dâexposition despopulations calĂ©doniennes aux ETM. Il nâexiste a priori aucune donnĂ©e quant aux niveauxdâimprĂ©gnation de la population gĂ©nĂ©rale nĂ©o-calĂ©donienne Ă ces quatre mĂ©taux
Nickel and associated metals in New Caledonia Exposure levels and their determinants
International audienceThe ultramafic massifs of the New Caledonian archipelago contain about 10% of the world's nickel reserves, which also contain significant but lower amounts of cobalt, chromium, and manganese. Natural erosion of these massifs and mining activities may contribute to the exposure of local populations to these metals through contamination of air, food, and water resources. We conducted a biomonitoring survey to evaluate exposure to these four metals and its main determinants by constructing a stratified sample of 732 adults and children (> 3 years old) from visitors to 22 health centers across the archipelago. Urine was collected and analyzed by inductively-coupled plasma mass spectrometry to determine metal concentrations. A face-to-face interview was conducted to document sociodemographic characteristics, lifestyle and dietary habits, and residence-mine distance. Environmental samples (soil, house dust, water, and foodstuffs) were collected from two areas (one with and one without mining activity) to delineate determinants of exposure in more detail. Nickel and chromium were metals with the highest concentrations found in urine, especially in children, at levels exceeding reference values derived from representative national surveys elsewhere throughout the world (for children 4.7 mu g/g creatinine for nickel and 0.50 mu g/g creatinine for chromium) 13% of children exceeded the reference value for nickel and 90% for chromium. Large variations were observed by region, age, and sex. In this geological setting, urinary and environmental nickel concentrations appear to be driven mainly by soil content. This is the first archipelago-wide survey of metal exposure in New Caledonia. The potential health consequences of this chronic high exposure need to be assessed
Niveaux d'imprégnation et déterminants de l'exposition humaine aux métaux en Nouvelle-Calédonie. Rapport scientifique final
- Ce rapport du programme MĂ©texpo « Niveaux dâimprĂ©gnation et dĂ©terminants de lâexposition humaine aux mĂ©taux » constitue le volume 3 (sur 4) du programme intĂ©grĂ© « Dispersion et exposition humaine aux mĂ©taux en Nouvelle-CalĂ©donie » composĂ© de 3 projets (DMML, Dynamine, MĂ©texpo) Ă©tudiant les mĂ©taux et leur toxicitĂ©.- Le programme MĂ©texpo a proposĂ© une Ă©tude de biosurveillance visant Ă : - (i) Ă©valuer lâexposition de la population nĂ©o-calĂ©donienne aux quatre mĂ©taux cibles Ni, Cr, Co et Mn ; - (ii) Ă©valuer lâexistence dâune surexposition Ă ces Ă©lĂ©ments traces mĂ©talliques (ETM) des populations vivant au sein des rĂ©gions ultramafiques du territoire ; - (iii) Ă©valuer l'influence des exploitations miniĂšres sur ces niveaux dâexposition.- LâĂ©tude comportait deux phases : la premiĂšre phase consistait Ă obtenir une « photographie » du niveau dâexposition de la population gĂ©nĂ©rale de Nouvelle-CalĂ©donie au Ni, Co, Cr et Mn. La seconde phase cherchait Ă identifier les principales sources de contamination de la population gĂ©nĂ©rale vivant dans des zones sur sites ultramafiques avec ou sans activitĂ© miniĂšre Ă proximitĂ©.- A ce jour aucune Ă©tude nâavait Ă©tĂ© menĂ©e pour Ă©valuer le risque potentiel dâexposition des populations calĂ©doniennes aux ETM. Il nâexiste a priori aucune donnĂ©e quant aux niveaux dâimprĂ©gnation de la population gĂ©nĂ©rale nĂ©o-calĂ©donienne Ă ces quatre mĂ©taux
Fragment-Based Phenotypic Lead Discovery To Identify New Drug Seeds That Target Infectious Diseases
International audienceFragment-based lead discovery has emerged over the last decades as one of the most powerful techniques for identifying starting chemical matter to target specific proteins or nucleic acids in vitro. However, the use of such low-molecular-weight fragment molecules in cell-based phenotypic assays has been historically avoided because of concerns that bioassays would be insufficiently sensitive to detect the limited potency expected for such small molecules and that the high concentrations required would likely implicate undesirable artifacts. Herein, we applied phenotype cell-based screens using a curated fragment library to identify inhibitors against a range of pathogens including Leishmania, Plasmodium falciparum, Neisseria, Mycobacterium, and flaviviruses. This proof-of-concept shows that fragment-based phenotypic lead discovery (FPLD) can serve as a promising complementary approach for tackling infectious diseases and other drug-discovery programs
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N-Phenylpyridine-3-Carboxamide and 6-Acetyl-1H-Indazole Inhibit the RNA Replication Step of the Dengue Virus Life Cycle.
Dengue virus (DENV) is a Flavivirus that causes the most prevalent arthropod-borne viral disease. Clinical manifestation of DENV infection ranges from asymptomatic to severe symptoms that can lead to death. Unfortunately, no antiviral treatments against DENV are currently available. In order to identify novel DENV inhibitors, we screened a library of 1,604 chemically diversified fragment-based compounds using DENV reporter viruses that allowed quantification of viral replication in infected cells. Following a validation screening, the two best inhibitor candidates were N-phenylpyridine-3-carboxamide (NPP3C) and 6-acetyl-1H-indazole (6A1HI). The half maximal effective concentration of NPP3C and 6A1H1 against DENV were 7.1âÎŒM and 6.5âÎŒM, respectively. 6A1H1 decreased infectious DENV particle production up to 1,000-fold without any cytotoxicity at the used concentrations. While 6A1HI was DENV-specific, NPP3C also inhibited the replication of other flaviviruses such as West Nile virus and Zika virus. Structure-activity relationship (SAR) studies with 151 analogues revealed key structural elements of NPP3C and 6A1HI required for their antiviral activity. Time-of-drug-addition experiments identified a postentry step as a target of these compounds. Consistently, using a DENV subgenomic replicon, we demonstrated that these compounds specifically impede the viral RNA replication step and exhibit a high genetic barrier-to-resistance. In contrast, viral RNA translation and the de novo biogenesis of DENV replication organelles were not affected. Overall, our data unveil NPP3C and 6A1H1 as novel DENV inhibitors. The information revealed by our SAR studies will help chemically optimize NPP3C and 6A1H1 in order to improve their anti-flaviviral potency and to challenge them in in vivo models
Dynamic microfluidic single-cell screening identifies pheno-tuning compounds to potentiate tuberculosis therapy
International audienceAbstract Drug-recalcitrant infections are a leading global-health concern. Bacterial cells benefit from phenotypic variation, which can suggest effective antimicrobial strategies. However, probing phenotypic variation entails spatiotemporal analysis of individual cells that is technically challenging, and hard to integrate into drug discovery. In this work, we develop a multi-condition microfluidic platform suitable for imaging two-dimensional growth of bacterial cells during transitions between separate environmental conditions. With this platform, we implement a dynamic single-cell screening for pheno-tuning compounds, which induce a phenotypic change and decrease cell-to-cell variation, aiming to undermine the entire bacterial population and make it more vulnerable to other drugs. We apply this strategy to mycobacteria, as tuberculosis poses a major public-health threat. Our lead compound impairs Mycobacterium tuberculosis via a peculiar mode of action and enhances other anti-tubercular drugs. This work proves that harnessing phenotypic variation represents a successful approach to tackle pathogens that are increasingly difficult to treat
Robust Strategy for Hit-to-Lead Discovery: NMR for SAR
Establishing robust structureâactivity relationships
(SARs)
is key to successful drug discovery campaigns, yet it often remains
elusive due to screening and hit validation artifacts (false positives
and false negatives), which frequently result in unproductive downstream
expenditures of time and resources. To address this issue, we developed
an integrative biophysics-driven strategy that expedites hit-to-lead
discovery, mitigates false positives/negatives and common hit validation
errors, and provides a robust approach to obtaining accurate binding
and affinity measurements. The advantage of this method is that it
vastly improves the clarity and reproducibility for affinity-driven
SAR by monitoring and eliminating confounding factors. We demonstrate
the ease at which high-quality micromolar binders can be generated
from the initial millimolar fragment screening hits against an âundruggableâ
protein target, HRas
Dispersion et exposition humaine aux métaux en Nouvelle-Calédonie : synthÚse des résultats
- Cette synthĂšse constitue le volume 4 (sur 4) du programme intĂ©grĂ© « Dispersion et exposition humaine aux mĂ©taux en Nouvelle-CalĂ©donie » composĂ© de 3 programmes complĂ©mentaires Ă©tudiant les mĂ©taux et leur toxicitĂ© : DMML « Dispersion des mĂ©taux de la mine au lagon », Dynamine « Dynamique des mĂ©taux de la mine au lagon », MĂ©texpo « Niveaux dâimprĂ©gnation et dĂ©terminants de lâexposition humaine aux mĂ©taux ».- Elle regroupe les synthĂšses de chacun des trois programmes et propose une conclusion commune ouvrant sur les perspectives en termes de recherche