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Andreu-Perez J, Pérez-Espinosa H, Timonet E, Kiani M, Girón-Pérez MI, Benitez-Trinidad AB, Jarchi D, Rosales-Pérez A, Gatzoulis N, Reyes-Galaviz OF, Torres-García A, Reyes-García CA, Ali Z, Rivas F. A Generic Deep Learning Based Cough Analysis System From Clinically Validated Samples for Point-of-Need Covid-19 Test and Severity Levels. IEEE TRANSACTIONS ON SERVICES COMPUTING 2022; 15:1220-1232. [PMID: 35936760 PMCID: PMC9328729 DOI: 10.1109/tsc.2021.3061402] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 01/27/2021] [Accepted: 02/17/2021] [Indexed: 06/01/2023]
Abstract
In an attempt to reduce the infection rate of the COrona VIrus Disease-19 (Covid-19) countries around the world have echoed the exigency for an economical, accessible, point-of-need diagnostic test to identify Covid-19 carriers so that they (individuals who test positive) can be advised to self isolate rather than the entire community. Availability of a quick turn-around time diagnostic test would essentially mean that life, in general, can return to normality-at-large. In this regards, studies concurrent in time with ours have investigated different respiratory sounds, including cough, to recognise potential Covid-19 carriers. However, these studies lack clinical control and rely on Internet users confirming their test results in a web questionnaire (crowdsourcing) thus rendering their analysis inadequate. We seek to evaluate the detection performance of a primary screening tool of Covid-19 solely based on the cough sound from 8,380 clinically validated samples with laboratory molecular-test (2,339 Covid-19 positive and 6,041 Covid-19 negative) under quantitative RT-PCR (qRT-PCR) from certified laboratories. All collected samples were clinically labelled, i.e., Covid-19 positive or negative, according to the results in addition to the disease severity based on the qRT-PCR threshold cycle (Ct) and lymphocytes count from the patients. Our proposed generic method is an algorithm based on Empirical Mode Decomposition (EMD) for cough sound detection with subsequent classification based on a tensor of audio sonographs and deep artificial neural network classifier with convolutional layers called 'DeepCough'. Two different versions of DeepCough based on the number of tensor dimensions, i.e., DeepCough2D and DeepCough3D, have been investigated. These methods have been deployed in a multi-platform prototype web-app 'CoughDetect'. Covid-19 recognition results rates achieved a promising AUC (Area Under Curve) of [Formula: see text] 98 . 80 % ± 0 . 83 % , sensitivity of [Formula: see text] 96 . 43 % ± 1 . 85 % , and specificity of [Formula: see text] 96 . 20 % ± 1 . 74 % and average AUC of [Formula: see text] 81 . 08 % ± 5 . 05 % for the recognition of three severity levels. Our proposed web tool as a point-of-need primary diagnostic test for Covid-19 facilitates the rapid detection of the infection. We believe it has the potential to significantly hamper the Covid-19 pandemic across the world.
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Affiliation(s)
- Javier Andreu-Perez
- School of Computer Science and Electronic Engineering, Faculty of Science and HealthUniversity of EssexColchesterCO4 3SQU.K.
- Department of Computer ScienceUniversity of Jaén16747JaénSpain
| | - Humberto Pérez-Espinosa
- School of Computer Science and Electronic Engineering, Faculty of Science and HealthUniversity of EssexColchesterCO4 3SQU.K.
- UT3 Centro de Investigacion Cientifica y de Educacion Superior de EnsenadaEnsenada22860Mexico
| | - Eva Timonet
- Agencia Sanitaria Costa del SolJunta de Andalucia Consejeria de Salud41020SevilleSpain
| | - Mehrin Kiani
- School of Computer Science and Electronic Engineering, Faculty of Science and HealthUniversity of EssexColchesterCO4 3SQU.K.
| | | | | | - Delaram Jarchi
- School of Computer Science and Electronic Engineering, Faculty of Science and HealthUniversity of EssexColchesterCO4 3SQU.K.
| | | | - Nick Gatzoulis
- School of Computer Science and Electronic Engineering, Faculty of Science and HealthUniversity of EssexColchesterCO4 3SQU.K.
| | | | | | | | - Zulfiqar Ali
- School of Computer Science and Electronic Engineering, Faculty of Science and HealthUniversity of EssexColchesterCO4 3SQU.K.
| | - Francisco Rivas
- Agencia Sanitaria Costa del SolJunta de Andalucia Consejeria de Salud41020SevilleSpain
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2
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Toviwek B, Phuangsawai O, Konsue A, Hannongbua S, Riley J, Mutter N, Anderson M, Webster L, Hallyburton I, Read KD, Gleeson MP. Preparation, biological & cheminformatics-based assessment of N 2,N 4-diphenylpyrimidine-2,4-diamine as potential Kinase-targeted antimalarials. Bioorg Med Chem 2021; 46:116348. [PMID: 34479064 DOI: 10.1016/j.bmc.2021.116348] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/21/2021] [Accepted: 07/30/2021] [Indexed: 11/25/2022]
Abstract
Twenty eight new N2,N4-diphenylpyrimidine-2,4-diamines have been prepared in order to expand our understanding of the anti-malarial SAR of the scaffold. The aim of the study was to make structural modifications to improve the overall potency, selectivity and solubility of the series by varying the anilino groups attached to the 2- and 4-position. We evaluated the activity of the compounds against Plasmodium falciparum (Pf) 3D7, cytotoxicity against HepG2, % inhibition at a panel of 10 human kinases, solubility, permeability and lipophilicity, and human and rat in vitro clearance. 11 was identified as a potent anti-malarial with an IC50 of 0.66 µM at the 3D7 strain and a selectivity (SI) of ~ 40 in terms of cytotoxicity against the HepG2 cell line. It also displayed low experimental logD7.4 (2.27), reasonable solubility (124 µg/ml), good metabolic stability, but low permeability. A proteo-chemometric workflow was employed to identify putative Pf targets of the most promising compounds. Ligand-based similarity searching of the ChEMBL database led to the identification of most probable human targets. These were then used as input for sequence-based searching of the Pf proteome. Homology modelling and molecular docking were used to evaluate whether compounds could indeed bind to these targets with valid binding modes. In vitro biological testing against close human analogs of these targets was subsequently undertaken. This allowed us to identify potential Pf targets and human anti-targets that could be exploited in future development.
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Affiliation(s)
- Borvornwat Toviwek
- Department of Biomedical Engineering, School of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand; Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Oraphan Phuangsawai
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Adchatawut Konsue
- Department of Biomedical Engineering, School of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
| | - Supa Hannongbua
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Jennifer Riley
- Drug Discovery Unit, Divison of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Nicole Mutter
- Drug Discovery Unit, Divison of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Mark Anderson
- Drug Discovery Unit, Divison of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Lauren Webster
- Drug Discovery Unit, Divison of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Irene Hallyburton
- Drug Discovery Unit, Divison of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Kevin D Read
- Drug Discovery Unit, Divison of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - M Paul Gleeson
- Department of Biomedical Engineering, School of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand.
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3
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Day J, Passecker A, Beck HP, Vakonakis I. The Plasmodium falciparum Hsp70-x chaperone assists the heat stress response of the malaria parasite. FASEB J 2019; 33:14611-14624. [PMID: 31690116 PMCID: PMC6894070 DOI: 10.1096/fj.201901741r] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 09/23/2019] [Indexed: 01/25/2023]
Abstract
Plasmodium falciparum is the most lethal of human-infective malaria parasites. A hallmark of P. falciparum malaria is extensive remodeling of host erythrocytes by the parasite, which facilitates the development of virulence properties such as host cell adhesion to the endothelial lining of the microvasculature. Host remodeling is mediated by a large complement of parasite proteins exported to the erythrocyte; among them is a single heat shock protein (Hsp)70-class protein chaperone, P. falciparum Hsp70-x (PfHsp70-x). PfHsp70-x was previously shown to assist the development of virulent cytoadherence characteristics. Here, we show that PfHsp70-x also supports parasite growth under elevated temperature conditions that simulate febrile episodes, especially at the beginning of the parasite life cycle when most of host cell remodeling takes place. Biochemical and biophysical analyses of PfHsp70-x, including crystallographic structures of its catalytic domain and the J-domain of its stimulatory Hsp40 cochaperone, suggest that PfHsp70-x is highly similar to human Hsp70 chaperones endogenous to the erythrocyte. Nevertheless, our results indicate that selective inhibition of PfHsp70-x function using small molecules may be possible and highlight specific sites of its catalytic domain as potentially of high interest. We discuss the likely roles of PfHsp70-x and human chaperones in P. falciparum biology and how specific inhibitors may assist us in disentangling their relative contributions.-Day, J., Passecker, A., Beck, H.-P., Vakonakis, I. The Plasmodium falciparum Hsp70-x chaperone assists the heat stress response of the malaria parasite.
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Affiliation(s)
- Jemma Day
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Armin Passecker
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Hans-Peter Beck
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Ioannis Vakonakis
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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4
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Blasco B, Leroy D, Fidock DA. Antimalarial drug resistance: linking Plasmodium falciparum parasite biology to the clinic. Nat Med 2017; 23:917-928. [PMID: 28777791 DOI: 10.1038/nm.4381] [Citation(s) in RCA: 325] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 06/30/2017] [Indexed: 02/08/2023]
Abstract
The global adoption of artemisinin-based combination therapies (ACTs) in the early 2000s heralded a new era in effectively treating drug-resistant Plasmodium falciparum malaria. However, several Southeast Asian countries have now reported the emergence of parasites that have decreased susceptibility to artemisinin (ART) derivatives and ACT partner drugs, resulting in increasing rates of treatment failures. Here we review recent advances in understanding how antimalarials act and how resistance develops, and discuss new strategies for effectively combatting resistance, optimizing treatment and advancing the global campaign to eliminate malaria.
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Affiliation(s)
| | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland
| | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, New York, USA.,Division of Infectious Diseases, Department of Medicine, Columbia University Medical Center, New York, New York, USA
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5
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The need to compare: assessing the level of agreement of three high-throughput assays against Plasmodium falciparum mature gametocytes. Sci Rep 2017; 7:45992. [PMID: 28378767 PMCID: PMC5380998 DOI: 10.1038/srep45992] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/07/2017] [Indexed: 12/22/2022] Open
Abstract
Whole-cell High-Throughput Screening (HTS) is a key tool for the discovery of much needed malaria transmission blocking drugs. Discrepancies in the reported outcomes from various HTS Plasmodium falciparum gametocytocidal assays hinder the direct comparison of data and ultimately the interpretation of the transmission blocking potential of hits. To dissect the underlying determinants of such discrepancies and assess the impact that assay-specific factors have on transmission-blocking predictivity, a 39-compound subset from the Medicines for Malaria Venture Malaria Box was tested in parallel against three distinct mature stage gametocytocidal assays, under strictly controlled parasitological, chemical, temporal and analytical conditions resembling the standard membrane feeding assay (SMFA). Apart from a few assay-specific outliers, which highlighted the value of utilizing multiple complementary approaches, good agreement was observed (average ΔpIC50 of 0.12 ± 0.01). Longer compound incubation times improved the ability of the least sensitive assay to detect actives by 2-fold. Finally, combining the number of actives identified by any single assay with those obtained at longer incubation times yielded greatly improved outcomes and agreement with SMFA. Screening compounds using extended incubation times and using multiple in vitro assay technologies are valid approaches for the efficient identification of biologically relevant malaria transmission blocking hits.
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6
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Phuangsawai O, Beswick P, Ratanabunyong S, Tabtimmai L, Suphakun P, Obounchoey P, Srisook P, Horata N, Chuckowree I, Hannongbua S, Ward SE, Choowongkomon K, Gleeson MP. Evaluation of the anti-malarial activity and cytotoxicity of 2,4-diamino-pyrimidine-based kinase inhibitors. Eur J Med Chem 2016; 124:896-905. [PMID: 27668758 DOI: 10.1016/j.ejmech.2016.08.055] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 08/23/2016] [Accepted: 08/24/2016] [Indexed: 12/27/2022]
Abstract
A series of 2,4 diamino-pyrimidines have been identified from an analysis of open access high throughput anti-malarial screening data reported by GlaxoSmithKline at the 3D7 and resistant Dd2 strains. SAR expansion has been performed using structural knowledge of the most plausible parasite target. Seventeen new analogs have been synthesized and tested against the resistant K1 strain of Plasmodium falciparum (Pf). The cytotoxicity of the compounds was assessed in Vero and A549 cells and their selectivity towards human kinases including JAK2 and EGFR were undertaken. We identified compound 5n and 5m as sub-micromolar inhibitors, with equivalent anti-malarial activity to Chloroquine (CQ). Compounds 5d and 5k, μM inhibitors of Pf, displayed improved cytotoxicity with weak inhibition of the human kinases.
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Affiliation(s)
- Oraphan Phuangsawai
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Paul Beswick
- School of Life Sciences, University of Sussex, Brighton BN1 9QJ, United Kingdom
| | - Siriluk Ratanabunyong
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Lueacha Tabtimmai
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Praphasri Suphakun
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Phongphat Obounchoey
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; Interdisciplinary Program in Genetic Engineering, Graduate School, Kasetsart University, Chatuchak, Bangkok 10900, Thailand
| | - Pimonwan Srisook
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Natharinee Horata
- Faculty of Medicinal Technology, Huachiew Chalermprakiet University, Samut Prakarn 10540, Thailand
| | - Irina Chuckowree
- School of Life Sciences, University of Sussex, Brighton BN1 9QJ, United Kingdom
| | - Supa Hannongbua
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Simon E Ward
- School of Life Sciences, University of Sussex, Brighton BN1 9QJ, United Kingdom.
| | - Kiattawee Choowongkomon
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - M Paul Gleeson
- Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
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7
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Birkholtz LM, Coetzer TL, Mancama D, Leroy D, Alano P. Discovering New Transmission-Blocking Antimalarial Compounds: Challenges and Opportunities. Trends Parasitol 2016; 32:669-681. [PMID: 27209388 DOI: 10.1016/j.pt.2016.04.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 04/24/2016] [Accepted: 04/26/2016] [Indexed: 01/08/2023]
Abstract
The ability to target human-mosquito parasite transmission challenges global malaria elimination. However, it is not obvious what a transmission-blocking drug will look like; should it target only parasite transmission stages; be combined with a partner drug killing the pathogenic asexual stages; or kill both the sexual and asexual blood stages, preferably displaying polypharmacology? The development of transmission-blocking antimalarials requires objective analyses of the current strategies. Here, pertinent issues and questions regarding the target candidate profile of a transmission-blocking compound, and its role in malaria elimination strategies, are highlighted and novel perspectives proposed. The essential role of a test cascade that integrates screening and validation strategies to identify next-generation transmission-blocking antimalarials is emphasised.
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Affiliation(s)
- Lyn-Marie Birkholtz
- Department of Biochemistry, Centre for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.
| | - Theresa L Coetzer
- Department of Molecular Medicine and Haematology, Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa.
| | - Dalu Mancama
- Department of Biochemistry, Centre for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa; Biosciences, Council for Scientific and Industrial Research, Pretoria, South Africa.
| | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland.
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Parassitarie e Immunomediate, Istituto Superiore di Sanità, Rome, Italy.
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8
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Gambini L, Rizzi L, Pedretti A, Taglialatela-Scafati O, Carucci M, Pancotti A, Galli C, Read M, Giurisato E, Romeo S, Russo I. Picomolar Inhibition of Plasmepsin V, an Essential Malaria Protease, Achieved Exploiting the Prime Region. PLoS One 2015; 10:e0142509. [PMID: 26566224 PMCID: PMC4643876 DOI: 10.1371/journal.pone.0142509] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 10/22/2015] [Indexed: 01/09/2023] Open
Abstract
Malaria is an infectious disease caused by Plasmodium parasites. It results in an annual death-toll of ~ 600,000. Resistance to all medications currently in use exists, and novel antimalarial drugs are urgently needed. Plasmepsin V (PmV) is an essential Plasmodium protease and a highly promising antimalarial target, which still lacks molecular characterization and drug-like inhibitors. PmV, cleaving the PExEl motif, is the key enzyme for PExEl-secretion, an indispensable parasitic process for virulence and infection. Here, we describe the accessibility of PmV catalytic pockets to inhibitors and propose a novel strategy for PmV inhibition. We also provide molecular and structural data suitable for future drug development. Using high-throughput platforms, we identified a novel scaffold that interferes with PmV in-vitro at picomolar ranges (~ 1,000-fold more active than available compounds). Via systematic replacement of P and P' regions, we assayed the physico-chemical requirements for PmV inhibition, achieving an unprecedented IC50 of ~20 pM. The hydroxyethylamine moiety, the hydrogen acceptor group in P2', the lipophilic groups upstream to P3, the arginine and other possible substitutions in position P3 proved to be critically important elements in achieving potent inhibition. In-silico analyses provided essential QSAR information and model validation. Our inhibitors act ‘on-target’, confirmed by cellular interference of PmV function and biochemical interaction with inhibitors. Our inhibitors are poorly performing against parasite growth, possibly due to poor stability of their peptidic component and trans-membrane permeability. The lowest IC50 for parasite growth inhibition was ~ 15μM. Analysis of inhibitor internalization revealed important pharmacokinetic features for PExEl-based molecules. Our work disclosed novel pursuable drug design strategies for highly efficient PmV inhibition highlighting novel molecular elements necessary for picomolar activity against PmV. All the presented data are discussed in respect to human aspartic proteases and previously reported inhibitors, highlighting differences and proposing new strategies for drug development.
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Affiliation(s)
- Luca Gambini
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Milan, Italy
| | - Luca Rizzi
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Milan, Italy
| | - Alessandro Pedretti
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Milan, Italy
| | - Orazio Taglialatela-Scafati
- Department of Chemistry of Natural Substances, Faculty of Pharmacy, Università di Napoli "Federico II", Naples, Italy
| | - Mario Carucci
- Department of Experimental Medicine and Biochemical Sciences, Università degli Studi di Perugia, Perugia, Italy
| | - Andrea Pancotti
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Milan, Italy
| | - Corinna Galli
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Milan, Italy
| | - Martin Read
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Emanuele Giurisato
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Sergio Romeo
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Milan, Italy
| | - Ilaria Russo
- Department of Experimental Medicine and Biochemical Sciences, Università degli Studi di Perugia, Perugia, Italy
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail:
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9
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Asparagine requirement in Plasmodium berghei as a target to prevent malaria transmission and liver infections. Nat Commun 2015; 6:8775. [PMID: 26531182 PMCID: PMC4659947 DOI: 10.1038/ncomms9775] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 09/29/2015] [Indexed: 01/29/2023] Open
Abstract
The proteins of Plasmodium, the malaria parasite, are strikingly rich in asparagine. Plasmodium depends primarily on host haemoglobin degradation for amino acids and has a rudimentary pathway for amino acid biosynthesis, but retains a gene encoding asparagine synthetase (AS). Here we show that deletion of AS in Plasmodium berghei (Pb) delays the asexual- and liver-stage development with substantial reduction in the formation of ookinetes, oocysts and sporozoites in mosquitoes. In the absence of asparagine synthesis, extracellular asparagine supports suboptimal survival of PbAS knockout (KO) parasites. Depletion of blood asparagine levels by treating PbASKO-infected mice with asparaginase completely prevents the development of liver stages, exflagellation of male gametocytes and the subsequent formation of sexual stages. In vivo supplementation of asparagine in mice restores the exflagellation of PbASKO parasites. Thus, the parasite life cycle has an absolute requirement for asparagine, which we propose could be targeted to prevent malaria transmission and liver infections. Malaria parasites obtain amino acids primarily from the host, but possess a gene encoding a putative asparagine synthetase. Here, the authors show that this enzyme is functional and that asparagine is crucial for the development of the parasite's sexual stages in mosquitoes and liver stages in mice.
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10
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Cohen A, Suzanne P, Lancelot JC, Verhaeghe P, Lesnard A, Basmaciyan L, Hutter S, Laget M, Dumètre A, Paloque L, Deharo E, Crozet MD, Rathelot P, Dallemagne P, Lorthiois A, Sibley CH, Vanelle P, Valentin A, Mazier D, Rault S, Azas N. Discovery of new thienopyrimidinone derivatives displaying antimalarial properties toward both erythrocytic and hepatic stages of Plasmodium. Eur J Med Chem 2015; 95:16-28. [DOI: 10.1016/j.ejmech.2015.03.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 03/03/2015] [Accepted: 03/04/2015] [Indexed: 11/24/2022]
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11
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In vitro antimalarial activity of novel semisynthetic nocathiacin I antibiotics. Antimicrob Agents Chemother 2015; 59:3174-9. [PMID: 25779576 DOI: 10.1128/aac.04294-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 03/09/2015] [Indexed: 12/24/2022] Open
Abstract
Presently, the arsenal of antimalarial drugs is limited and needs to be replenished. We evaluated the potential antimalarial activity of two water-soluble derivatives of nocathiacin (BMS461996 and BMS411886) against the asexual blood stages of Plasmodium falciparum. Nocathiacins are a thiazolyl peptide group of antibiotics, are structurally related to thiostrepton, have potent activity against a wide spectrum of multidrug-resistant Gram-positive bacteria, and inhibit protein synthesis. The in vitro growth inhibition assay was done using three laboratory strains of P. falciparum displaying various levels of chloroquine (CQ) susceptibility. Our results indicate that BMS461996 has potent antimalarial activity and inhibits parasite growth with mean 50% inhibitory concentrations (IC50s) of 51.55 nM for P. falciparum 3D7 (CQ susceptible), 85.67 nM for P. falciparum Dd2 (accelerated resistance to multiple drugs [ARMD]), and 99.44 nM for P. falciparum K1 (resistant to CQ, pyrimethamine, and sulfadoxine). Similar results at approximately 7-fold higher IC50s were obtained with BMS411886 than with BMS461996. We also tested the effect of BMS491996 on gametocytes; our results show that at a 20-fold excess of the mean IC50, gametocytes were deformed with a pyknotic nucleus and growth of stage I to IV gametocytes was arrested. This preliminary study shows a significant potential for nocathiacin analogues to be developed as antimalarial drug candidates and to warrant further investigation.
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12
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Sinha S, Medhi B, Sehgal R. Challenges of drug-resistant malaria. ACTA ACUST UNITED AC 2014; 21:61. [PMID: 25402734 PMCID: PMC4234044 DOI: 10.1051/parasite/2014059] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 10/23/2014] [Indexed: 01/09/2023]
Abstract
Over the past six decades, the drug resistance of Plasmodium falciparum has become an issue of utmost concern. Despite the remarkable progress that has been made in recent years in reducing the mortality rate to about 30% with the scaling-up of vector control, introduction of artemisinin-based combination therapies and other malaria control strategies, the confirmation of artemisinin resistance on the Cambodia–Thailand border threatened all the previous success. This review addresses the global scenario of antimalarial resistance and factors associated with it, with the main emphasis on futuristic approaches like nanotechnology and stem cell therapy that may impede resistant malaria, along with novel medications which are preparing to enter the global antimalarial market. These novel studies are likely to escalate over the coming years and will hopefully help to reduce the burden of malaria.
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Affiliation(s)
- Shweta Sinha
- Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Bikash Medhi
- Department of Pharmacology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Rakesh Sehgal
- Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
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13
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A male and female gametocyte functional viability assay to identify biologically relevant malaria transmission-blocking drugs. Antimicrob Agents Chemother 2014; 58:7292-302. [PMID: 25267664 DOI: 10.1128/aac.03666-14] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Malaria elimination will require interventions that prevent parasite transmission from the human host to the mosquito. Experimentally, this is usually determined by the expensive and laborious Plasmodium falciparum standard membrane feeding assay (PfSMFA), which has limited utility for high-throughput drug screening. In response, we developed the P. falciparum dual gamete formation assay (PfDGFA), which faithfully simulates the initial stages of the PfSMFA in vitro. It utilizes a dual readout that individually and simultaneously reports on the functional viability of male and female mature stage V gametocytes. To validate, we screen the Medicines for Malaria Venture (MMV) Malaria Box library with the PfDGFA. Unique to this assay, we find compounds that target male gametocytes only and also compounds with reversible and irreversible activity. Most importantly, we show that compound activity in the PfDGFA accurately predicts activity in PfSMFAs, which validates and supports its adoption into the transmission-stage screening pipeline.
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