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Identifying inhibitors of β-haematin formation with activity against chloroquine-resistant Plasmodium falciparum malaria parasites via virtual screening approaches. Sci Rep 2023; 13:2648. [PMID: 36788274 PMCID: PMC9929333 DOI: 10.1038/s41598-023-29273-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/01/2023] [Indexed: 02/16/2023] Open
Abstract
The biomineral haemozoin, or its synthetic analogue β-haematin (βH), has been the focus of several target-based screens for activity against Plasmodium falciparum parasites. Together with the known βH crystal structure, the availability of this screening data makes the target amenable to both structure-based and ligand-based virtual screening. In this study, molecular docking and machine learning techniques, including Bayesian and support vector machine classifiers, were used in sequence to screen the in silico ChemDiv 300k Representative Compounds library for inhibitors of βH with retained activity against P. falciparum. We commercially obtained and tested a prioritised set of inhibitors and identified the coumarin and iminodipyridinopyrimidine chemotypes as potent in vitro inhibitors of βH and whole cell parasite growth.
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2
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Jeena V, Majola N. Acid, Metal and Peroxide-Free Synthesis of 2,4,5-Trisubstituted Imidazoles Commencing from Internal Alkenes Using an Iodine/DMSO System. HETEROCYCLES 2023. [DOI: 10.3987/com-22-14781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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3
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El hajri F, Benzekri Z, Anahmadi H, Sibous S, Ouasri A, Souizi A, Hassikou A, Rhandour A, Boukhris S. Investigation of catalytic performance of Bis [hydrazinium (1+)] hexafluoridosilicate: (N2H5)2SiF6 in synthesis of 2,4,5-triaryl-1H-imidazoles and 2,3-dihydroquinazolin-4 (1H)-ones under Green conditions. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.120915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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Olivier T, Loots L, Kok M, de Villiers M, Reader J, Birkholtz LM, Arnott GE, de Villiers KA. Adsorption to the Surface of Hemozoin Crystals: Structure-Based Design and Synthesis of Amino-Phenoxazine β-Hematin Inhibitors. ChemMedChem 2022; 17:e202200139. [PMID: 35385211 PMCID: PMC9119941 DOI: 10.1002/cmdc.202200139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/05/2022] [Indexed: 11/07/2022]
Abstract
In silico adsorption of eight antimalarials that inhibit β-hematin (synthetic hemozoin) formation identified a primary binding site on the (001) face, which accommodates inhibitors via formation of predominantly π-π interactions. A good correlation (r2 =0.64, P=0.017) between adsorption energies and the logarithm of β-hematin inhibitory activity was found for this face. Of 53 monocyclic, bicyclic and tricyclic scaffolds, the latter yielded the most favorable adsorption energies. Five new amino-phenoxazine compounds were pursued as β-hematin inhibitors based on adsorption behaviour. The 2-substituted phenoxazines show good to moderate β-hematin inhibitory activity (<100 μM) and Plasmodium falciparum blood stage activity against the 3D7 strain. N1 ,N1 -diethyl-N4 -(10H-phenoxazin-2-yl)pentane-1,4-diamine (P2a) is the most promising hit with IC50 values of 4.7±0.6 and 0.64±0.05 μM, respectively. Adsorption energies are predictive of β-hematin inhibitory activity, and thus the in silico approach is a beneficial tool for structure-based development of new non-quinoline inhibitors.
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Affiliation(s)
- Tania Olivier
- Department of Chemistry and Polymer Science, Stellenbosch University, Private BagX1, Matieland, 7602, South Africa
| | - Leigh Loots
- Department of Chemistry and Polymer Science, Stellenbosch University, Private BagX1, Matieland, 7602, South Africa
| | - Michélle Kok
- Department of Biochemistry, Stellenbosch University, Private BagX1, Matieland, 7602, South Africa
| | - Marianne de Villiers
- Department of Biochemistry, Stellenbosch University, Private BagX1, Matieland, 7602, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, 0028, South Africa
| | - Lyn-Marié Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, 0028, South Africa
| | - Gareth E Arnott
- Department of Chemistry and Polymer Science, Stellenbosch University, Private BagX1, Matieland, 7602, South Africa
| | - Katherine A de Villiers
- Department of Chemistry and Polymer Science, Stellenbosch University, Private BagX1, Matieland, 7602, South Africa
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5
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Zhu P, Zhou B. The Antagonizing Role of Heme in the Antimalarial Function of Artemisinin: Elevating Intracellular Free Heme Negatively Impacts Artemisinin Activity in Plasmodium falciparum. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27061755. [PMID: 35335120 PMCID: PMC8949904 DOI: 10.3390/molecules27061755] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 03/02/2022] [Accepted: 03/04/2022] [Indexed: 11/25/2022]
Abstract
The rich source of heme within malarial parasites has been considered to underly the action specificity of artemisinin. We reasoned that increasing intraparasitic free heme levels might further sensitize the parasites to artemisinin. Various means, such as modulating heme synthesis, degradation, polymerization, or hemoglobin digestion, were tried to boost intracellular heme levels, and under several scenarios, free heme levels were significantly augmented. Interestingly, all results arrived at the same conclusion, i.e., elevating heme acted in a strongly negative way, impacting the antimalarial action of artemisinin, but exerted no effect on several other antimalarial drugs. Suppression of the elevated free heme level by introducing heme oxygenase expression effectively restored artemisinin potency. Consistently, zinc protoporphyrin IX/zinc mesoporphyrin, as analogues of heme, drastically increased free heme levels and, concomitantly, the EC50 values of artemisinin. We were unable to effectively mitigate free heme levels, possibly due to an unknown compensating heme uptake pathway, as evidenced by our observation of efficient uptake of a fluorescent heme homologue by the parasite. Our results thus indicate the existence of an effective and mutually compensating heme homeostasis network in the parasites, including an uncharacterized heme uptake pathway, to maintain a certain level of free heme and that augmentation of the free heme level negatively impacts the antimalarial action of artemisinin. Importance: It is commonly believed that heme is critical in activating the antimalarial action of artemisinins. In this work, we show that elevating free heme levels in the malarial parasites surprisingly negatively impacts the action of artemisinin. We tried to boost free heme levels with various means, such as by modulating heme synthesis, heme polymerization, hemoglobin degradation and using heme analogues. Whenever we saw elevation of free heme levels, reduction in artemisinin potency was also observed. The homeostasis of heme appears to be complex, as there exists an unidentified heme uptake pathway in the parasites, nullifying our attempts to effectively reduce intraparasitic free heme levels. Our results thus indicate that too much heme is not good for the antimalarial action of artemisinins. This research can help us better understand the biological properties of this mysterious drug.
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Affiliation(s)
- Pan Zhu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China;
| | - Bing Zhou
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China;
- Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- Correspondence:
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6
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Jeena V, P. Mabizela L. Molecular Iodine Mediated Synthesis of 2,4,5-Trisubstituted Imidazoles Commencing from α-Methylene Ketones and Benzylic Primary Alcohols Using a One-Pot, Two-Step Approach. HETEROCYCLES 2022. [DOI: 10.3987/com-22-14699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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de Villiers KA, Egan TJ. Heme Detoxification in the Malaria Parasite: A Target for Antimalarial Drug Development. Acc Chem Res 2021; 54:2649-2659. [PMID: 33982570 DOI: 10.1021/acs.accounts.1c00154] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Over the last century, malaria deaths have decreased by more than 85%. Nonetheless, there were 405 000 deaths in 2018, mostly resulting from Plasmodium falciparum infection. In the 21st century, much of the advance has arisen from the deployment of insecticide-treated bed nets and artemisinin combination therapy. However, over the past few decades parasites with a delayed artemisinin clearance phenotype have appeared in Southeast Asia, threatening further gains. The effort to find new drugs is thus urgent. A prominent process in blood stage malaria parasites, which we contend remains a viable drug target, is hemozoin formation. This crystalline material consisting of heme can be readily seen when parasites are viewed microscopically. The process of its formation in the parasite, however, is still not fully understood.In early work, we recognized hemozoin formation as a biomineralization process. We have subsequently investigated the kinetics of synthetic hemozoin (β-hematin) crystallization catalyzed at lipid-aqueous interfaces under biomimetic conditions. This led us to the use of neutral detergent-based high-throughput screening (HTS) for inhibitors of β-hematin formation. A good hit rate against malaria parasites was obtained. Simultaneously, we developed a pyridine-based assay which proved successful in measuring the concentrations of hematin not converted to β-hematin.The pyridine assay was adapted to determine the effects of chloroquine and other clinical antimalarials on hemozoin formation in the cell. This permitted the determination of the dose-dependent amounts of exchangeable heme and hemozoin in P. falciparum for the first time. These studies have shown that hemozoin inhibitors cause a dose-dependent increase in exchangeable heme, correlated with decreased parasite survival. Electron spectroscopic imaging (ESI) showed a relocation of heme iron into the parasite cytoplasm, while electron microscopy provided evidence of the disruption of hemozoin crystals. This cellular assay was subsequently extended to top-ranked hits from a wide range of scaffolds found by HTS. Intriguingly, the amounts of exchangeable heme at the parasite growth IC50 values of these scaffolds showed substantial variation. The amount of exchangeable heme was found to be correlated with the amount of inhibitor accumulated in the parasitized red blood cell. This suggests that heme-inhibitor complexes, rather than free heme, lead to parasite death. This was supported by ESI using a Br-containing compound which showed the colocalization of Fe and Br as well as by confocal Raman microscopy which confirmed the presence of a complex in the parasite. Current evidence indicates that inhibitors block hemozoin formation by surface adsorption. Indeed, we have successfully introduced molecular docking with hemozoin to find new inhibitors. It follows that the resulting increase in free heme leads to the formation of the parasiticidal heme-inhibitor complex. We have reported crystal structures of heme-drug complexes for several aryl methanol antimalarials in nonaqueous media. These form coordination complexes but most other inhibitors interact noncovalently, and the determination of their structures remains a major challenge.It is our view that key future developments will include improved assays to measure cellular heme levels, better in silico approaches for predicting β-hematin inhibition, and a concerted effort to determine the structure and properties of heme-inhibitor complexes.
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Affiliation(s)
- Katherine A. de Villiers
- Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag, Matieland 7600, South Africa
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory, Cape Town 7945, South Africa
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8
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Openshaw R, Maepa K, Benjamin SJ, Wainwright L, Combrinck JM, Hunter R, Egan TJ. A Diverse Range of Hemozoin Inhibiting Scaffolds Act on Plasmodium falciparum as Heme Complexes. ACS Infect Dis 2021; 7:362-376. [PMID: 33430579 DOI: 10.1021/acsinfecdis.0c00680] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A diverse series of hemozoin-inhibiting quinolines, benzamides, triarylimidazoles, quinazolines, benzimidazoles, benzoxazoles, and benzothiazoles have been found to lead to exchangeable heme levels in cultured Plasmodium falciparum (NF54) that ranged over an order of magnitude at the IC50. Surprisingly, less active compounds often exhibited higher levels of exchangeable heme than more active ones. Quantities of intracellular inhibitor measured using the inoculum effect exhibited a linear correlation with exchangeable heme, suggesting formation of heme-inhibitor complexes in the parasite. In an effort to confirm this, the presence of a Br atom in one of the benzimidazole derivatives was exploited to image its distribution in the parasite using electron spectroscopic imaging of Br, an element not naturally abundant in cells. This showed that the compound colocalized with iron, consistent with its presence as a heme complex. Direct evidence for this complex was then obtained using confocal Raman microscopy. Exchangeable heme and inhibitor were found to increase with decreased rate of killing, suggesting that slow-acting compounds have more time to build up exchangeable heme complexes. Lastly, some but not all compounds evidently cause pro-oxidant effects because their activity could be attenuated with N-acetylcysteine and potentiated with t-butyl hydroperoxide. Collectively, these findings suggest that hemozoin inhibitors act as complexes with free heme, each with its own unique activity.
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Affiliation(s)
- Roxanne Openshaw
- Department of Chemistry, University of Cape Town, Private Bag Rondebosch, Cape Town 7701, South Africa
| | | | - Stefan J. Benjamin
- Department of Chemistry, University of Cape Town, Private Bag Rondebosch, Cape Town 7701, South Africa
| | - Lauren Wainwright
- Department of Chemistry, University of Cape Town, Private Bag Rondebosch, Cape Town 7701, South Africa
| | | | - Roger Hunter
- Department of Chemistry, University of Cape Town, Private Bag Rondebosch, Cape Town 7701, South Africa
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Private Bag Rondebosch, Cape Town 7701, South Africa
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9
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Veale CGL, Müller R. Recent Highlights in Anti-infective Medicinal Chemistry from South Africa. ChemMedChem 2020; 15:809-826. [PMID: 32149446 DOI: 10.1002/cmdc.202000086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Indexed: 12/17/2022]
Abstract
Global advancements in biological technologies have vastly increased the variety of and accessibility to bioassay platforms, while simultaneously improving our understanding of druggable chemical space. In the South African context, this has resulted in a rapid expansion in the number of medicinal chemistry programmes currently operating, particularly on university campuses. Furthermore, the modern medicinal chemist has the advantage of being able to incorporate data from numerous related disciplines into the medicinal chemistry process, allowing for informed molecular design to play a far greater role than previously possible. Accordingly, this review focusses on recent highlights in drug-discovery programmes, in which South African medicinal chemistry groups have played a substantive role in the design and optimisation of biologically active compounds which contribute to the search for promising agents for infectious disease.
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Affiliation(s)
- Clinton G L Veale
- School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
| | - Ronel Müller
- School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
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10
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Molecular iodine/DMSO mediated oxidation of internal alkynes and primary alcohols using a one-pot, two step approach towards 2,4,5-trisubstituted imidazoles: Substrate scope and mechanistic studies. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131028] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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11
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Veale CGL, Jayram J, Naidoo S, Laming D, Swart T, Olivier T, Akerman MP, de Villiers KA, Hoppe HC, Jeena V. Insights into structural and physicochemical properties required for β-hematin inhibition of privileged triarylimidazoles. RSC Med Chem 2019; 11:85-91. [PMID: 33479606 DOI: 10.1039/c9md00468h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 10/22/2019] [Indexed: 11/21/2022] Open
Abstract
In this study, we investigated a series of triarylimidazoles, in an effort to elucidate critical SAR information pertaining to their anti-plasmodial and β-hematin inhibitory activity. Our results showed that in addition to the positional effects of ring substitution, subtle changes to lipophilicity and imidazole ionisability were important factors in SAR interpretation. Finally, in silico adsorption analysis indicated that these compounds exert their effect by inhibiting β-hematin crystal growth at the fast growing 001 face.
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Affiliation(s)
- Clinton G L Veale
- School of Chemistry and Physics , Pietermaritzburg Campus , University of KwaZulu-Natal , Private Bag X01 , Scottsville , 3209 , South Africa
| | - Janeeka Jayram
- School of Chemistry and Physics , Pietermaritzburg Campus , University of KwaZulu-Natal , Private Bag X01 , Scottsville , 3209 , South Africa
| | - Shivani Naidoo
- School of Chemistry and Physics , Pietermaritzburg Campus , University of KwaZulu-Natal , Private Bag X01 , Scottsville , 3209 , South Africa
| | - Dustin Laming
- Department of Biochemistry and Microbiology , Rhodes University , Grahamstown , 6140 , South Africa
| | - Tarryn Swart
- Department of Biochemistry and Microbiology , Rhodes University , Grahamstown , 6140 , South Africa
| | - Tania Olivier
- Department of Chemistry and Polymer Science , Stellenbosch University , Private Bag X1 , Matieland , 7602 , South Africa . ;
| | - Matthew P Akerman
- School of Chemistry and Physics , Pietermaritzburg Campus , University of KwaZulu-Natal , Private Bag X01 , Scottsville , 3209 , South Africa
| | - Katherine A de Villiers
- Department of Chemistry and Polymer Science , Stellenbosch University , Private Bag X1 , Matieland , 7602 , South Africa . ;
| | - Heinrich C Hoppe
- Department of Biochemistry and Microbiology , Rhodes University , Grahamstown , 6140 , South Africa
| | - Vineet Jeena
- School of Chemistry and Physics , Pietermaritzburg Campus , University of KwaZulu-Natal , Private Bag X01 , Scottsville , 3209 , South Africa
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12
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Ni S, Li B, Xu Y, Mao F, Li X, Lan L, Zhu J, Li J. Targeting virulence factors as an antimicrobial approach: Pigment inhibitors. Med Res Rev 2019; 40:293-338. [PMID: 31267561 DOI: 10.1002/med.21621] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 05/30/2019] [Accepted: 06/13/2019] [Indexed: 12/19/2022]
Abstract
The fascinating and dangerous colored pathogens contain unique chemically pigmented molecules, which give varied and efficient assistance as virulence factors to the crucial reproduction and growth of microbes. Therefore, multiple novel strategies and inhibitors have been developed in recent years that target virulence factor pigments. However, despite the importance and significance of this topic, it has not yet been comprehensively reviewed. Moreover, research groups around the world have made successful progress against antibacterial infections by targeting pigment production, including our serial works on the discovery of CrtN inhibitors against staphyloxanthin production in Staphylococcus aureus. On the basis of the previous achievements and recent progress of our group in this field, this article will be the first comprehensive review of pigment inhibitors against colored pathogens, especially S. aureus infections, and this article includes design strategies, representative case studies, advantages, limitations, and perspectives to guide future research.
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Affiliation(s)
- Shuaishuai Ni
- Cancer Institute, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Baoli Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Yixiang Xu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Fei Mao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Xiaokang Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Lefu Lan
- State Key Laboratory of Drug Research, Shanghai Institute of Material Medical, Chinese Academy of Sciences, Shanghai, China
| | - Jin Zhu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Jian Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.,Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China
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13
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Cabrera AC. Collaborative drug discovery and the Tres Cantos Antimalarial Set (TCAMS). Drug Discov Today 2019; 24:1304-1310. [PMID: 30980903 DOI: 10.1016/j.drudis.2019.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 02/18/2019] [Accepted: 04/04/2019] [Indexed: 12/01/2022]
Abstract
Malaria affects a population of over 200 million people worldwide. New drugs are needed because of widespread resistance, and the hunt for such drugs involves a coordinated research effort from the scientific community. The release of the Tres Cantos Antimalarial Set (TCAMS) in 2010 represented a landmark in the field of collaborative drug discovery for malaria. This set of >13 000 molecules with confirmed activity against several strains of Plasmodium falciparum was publicly released with the goal of fostering additional research beyond the GlaxoSmithKline (GSK) network of collaborators. Here, we examine the outcomes realized from TCAMS over the past 8 years and whether the expectations surrounding this initiative have become a reality.
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Affiliation(s)
- Alvaro Cortes Cabrera
- Department of Pharmacology, Universidad de Alcalá, Crta Madrid-Zaragoza Km 33.6, Alcalá de Henares, Spain.
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14
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Veale CGL. Unpacking the Pathogen Box-An Open Source Tool for Fighting Neglected Tropical Disease. ChemMedChem 2019; 14:386-453. [PMID: 30614200 DOI: 10.1002/cmdc.201800755] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Indexed: 12/13/2022]
Abstract
The Pathogen Box is a 400-strong collection of drug-like compounds, selected for their potential against several of the world's most important neglected tropical diseases, including trypanosomiasis, leishmaniasis, cryptosporidiosis, toxoplasmosis, filariasis, schistosomiasis, dengue virus and trichuriasis, in addition to malaria and tuberculosis. This library represents an ensemble of numerous successful drug discovery programmes from around the globe, aimed at providing a powerful resource to stimulate open source drug discovery for diseases threatening the most vulnerable communities in the world. This review seeks to provide an in-depth analysis of the literature pertaining to the compounds in the Pathogen Box, including structure-activity relationship highlights, mechanisms of action, related compounds with reported activity against different diseases, and, where appropriate, discussion on the known and putative targets of compounds, thereby providing context and increasing the accessibility of the Pathogen Box to the drug discovery community.
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Affiliation(s)
- Clinton G L Veale
- School of Chemistry and Physics, Pietermaritzburg Campus, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
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15
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Jayram J, Jeena V. An iodine/DMSO-catalyzed sequential one-pot approach to 2,4,5-trisubstituted-1 H-imidazoles from α-methylene ketones. RSC Adv 2018; 8:37557-37563. [PMID: 35558600 PMCID: PMC9089320 DOI: 10.1039/c8ra07238h] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 11/01/2018] [Indexed: 01/08/2023] Open
Abstract
A sequential one-pot approach to 2,4,5-trisubstituted imidazoles has been developed from α-methylene ketones and aldehydes. This methodology employs air-moisture stable reaction conditions and an inexpensive iodine/DMSO system affording a diverse range of known and novel (substrate scope) 2,4,5-trisubstituted imidazoles in moderate to excellent yields. The iodine/DMSO system was extended to the domino convergent synthesis of two functionalized intermediates, benzil and benzaldehyde, to produce the final product.
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Affiliation(s)
- Janeeka Jayram
- School of Chemistry and Physics, University of KwaZulu-Natal Scottsville Pietermaritzburg 3209 South Africa
| | - Vineet Jeena
- School of Chemistry and Physics, University of KwaZulu-Natal Scottsville Pietermaritzburg 3209 South Africa
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16
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L'abbate FP, Müller R, Openshaw R, Combrinck JM, de Villiers KA, Hunter R, Egan TJ. Hemozoin inhibiting 2-phenylbenzimidazoles active against malaria parasites. Eur J Med Chem 2018; 159:243-254. [PMID: 30296683 DOI: 10.1016/j.ejmech.2018.09.060] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/22/2018] [Accepted: 09/24/2018] [Indexed: 12/23/2022]
Abstract
The 2-phenylbenzimidazole scaffold has recently been discovered to inhibit β-hematin (synthetic hemozoin) formation by high throughput screening. Here, a library of 325,728 N-4-(1H-benzo[d]imidazol-2-yl)aryl)benzamides was enumerated, and Bayesian statistics used to predict β-hematin and Plasmodium falciparum growth inhibition. Filtering predicted inactives and compounds with negligible aqueous solubility reduced the library to 35,124. Further narrowing to compounds with terminal aryl ring substituents only, reduced the library to 18, 83% of which were found to inhibit β-hematin formation <100 μM and 50% parasite growth <2 μM. Four compounds showed nanomolar parasite growth inhibition activities, no cross-resistance in a chloroquine resistant strain and low cytotoxicity. QSAR analysis showed a strong association of parasite growth inhibition with inhibition of β-hematin formation and the most active compound inhibited hemozoin formation in P. falciparum, with consequent increasing exchangeable heme. Pioneering use of molecular docking for this system demonstrated predictive ability and could rationalize observed structure activity trends.
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Affiliation(s)
- Fabrizio P L'abbate
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, South Africa
| | - Ronel Müller
- Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Roxanne Openshaw
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, South Africa
| | - Jill M Combrinck
- Department of Medicine, Division of Clinical Pharmacology, University of Cape Town, Observatory, 7925, South Africa
| | - Katherine A de Villiers
- Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Roger Hunter
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, South Africa
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, South Africa; Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch, 7701, South Africa.
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