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de Sousa ACC, Combrinck JM, Maepa K, Egan TJ. THC shows activity against cultured Plasmodium falciparum. Bioorg Med Chem Lett 2021; 54:128442. [PMID: 34763083 DOI: 10.1016/j.bmcl.2021.128442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/19/2021] [Accepted: 11/02/2021] [Indexed: 10/19/2022]
Abstract
The FDA approved drug Dronabinol was identified in a previous study applying virtual screening using the haemozoin crystal as a target against malaria parasites. The active ingredient of dronabinol is synthetic tetrahydrocannabinol (THC), which is one of the major cannabinoids from Cannabis sativa. Traditional use of cannabis for malaria fever was reported in the world's oldest pharmacopoeia, dating to around 5000 years ago. In this research we report that THC inhibits β-haematin (synthetic haemozoin) and malaria parasite growth. Due the psychoactivity of THC, CBD, the other major naturally occurring cannabinoid that lacks the off-target psychoactive effects of THC, was also tested and inhibited β-haematin but showed only a mild antimalarial activity. To evaluate whether THC inhibit haemozoin formation, we performed a cellular haem fractionation assay that indicated that is not the likely mechanism of action. For the first time, the cannabinoid chemical structure is raised as a new chemical class to be further studied for malaria treatment, aiming to overcome the undesirable psychoactive effects of THC and optimize the antimalarial effects.
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Affiliation(s)
| | - Jill M Combrinck
- University of Cape Town, Division of Pharmacology, Department of Medicine, Observatory 7925, South Africa
| | - Keletso Maepa
- University of Cape Town, Division of Pharmacology, Department of Medicine, Observatory 7925, South Africa
| | - Timothy J Egan
- University of Cape Town, Department of Chemistry, Rondebosch 7701, South Africa; Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Horatscheck A, Andrijevic A, Nchinda AT, Le Manach C, Paquet T, Khonde LP, Dam J, Pawar K, Taylor D, Lawrence N, Brunschwig C, Gibhard L, Njoroge M, Reader J, van der Watt M, Wicht K, de Sousa ACC, Okombo J, Maepa K, Egan TJ, Birkholtz LM, Basarab GS, Wittlin S, Fish PV, Street LJ, Duffy J, Chibale K. Correction to "Identification of 2,4-Disubstituted Imidazopyridines as Hemozoin Formation Inhibitors with Fast-Killing Kinetics and In Vivo Efficacy in the Plasmodium falciparum NSG Mouse Model". J Med Chem 2021; 64:1762. [PMID: 33508187 DOI: 10.1021/acs.jmedchem.1c00064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Horatscheck A, Andrijevic A, Nchinda AT, Le Manach C, Paquet T, Khonde LP, Dam J, Pawar K, Taylor D, Lawrence N, Brunschwig C, Gibhard L, Njoroge M, Reader J, van der Watt M, Wicht K, de Sousa ACC, Okombo J, Maepa K, Egan TJ, Birkholtz LM, Basarab GS, Wittlin S, Fish PV, Street LJ, Duffy J, Chibale K. Identification of 2,4-Disubstituted Imidazopyridines as Hemozoin Formation Inhibitors with Fast-Killing Kinetics and In Vivo Efficacy in the Plasmodium falciparum NSG Mouse Model. J Med Chem 2020; 63:13013-13030. [PMID: 33103428 DOI: 10.1021/acs.jmedchem.0c01411] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A series of 2,4-disubstituted imidazopyridines, originating from a SoftFocus Kinase library, was identified from a high throughput phenotypic screen against the human malaria parasite Plasmodium falciparum. Hit compounds showed moderate asexual blood stage activity. During lead optimization, several issues were flagged such as cross-resistance against the multidrug-resistant K1 strain, in vitro cytotoxicity, and cardiotoxicity and were addressed through structure-activity and structure-property relationship studies. Pharmacokinetic properties were assessed in mice for compounds showing desirable in vitro activity, a selectivity window over cytotoxicity, and microsomal metabolic stability. Frontrunner compound 37 showed good exposure in mice combined with good in vitro activity against the malaria parasite, which translated into in vivo efficacy in the P. falciparum NOD-scid IL-2Rγnull (NSG) mouse model. Preliminary mechanistic studies suggest inhibition of hemozoin formation as a contributing mode of action.
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Affiliation(s)
- André Horatscheck
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Ana Andrijevic
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Aloysius T Nchinda
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Claire Le Manach
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Tanya Paquet
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Lutete Peguy Khonde
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Jean Dam
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Kailash Pawar
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Dale Taylor
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Nina Lawrence
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Christel Brunschwig
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Liezl Gibhard
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Mathew Njoroge
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, University of Cape Town, Rondebosch 7701, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Kathryn Wicht
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | | | - John Okombo
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Keletso Maepa
- 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
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Gregory S Basarab
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute ,Socinstrasse 57, 4002 Basel, Switzerland.,University of Basel, 4002 Basel, Switzerland
| | - Paul V Fish
- Alzheimer's Research UK, UCL Drug Discovery Institute, The Cruciform Building, University College London, Gower Street, London WC1E 6BT, U.K
| | - Leslie J Street
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - James Duffy
- Medicines for Malaria Venture, ICC, Route de Pré-Bois 20, P.O. Box 1826, 1215 Geneva, Switzerland
| | - Kelly Chibale
- South African Medical Research Council, Drug Discovery and Development Research Unit, 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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de Sousa ACC, Maepa K, Combrinck JM, Egan TJ. Lapatinib, Nilotinib and Lomitapide Inhibit Haemozoin Formation in Malaria Parasites. Molecules 2020; 25:molecules25071571. [PMID: 32235391 PMCID: PMC7180468 DOI: 10.3390/molecules25071571] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/25/2020] [Accepted: 03/25/2020] [Indexed: 12/20/2022] Open
Abstract
With the continued loss of antimalarials to resistance, drug repositioning may have a role in maximising efficiency and accelerating the discovery of new antimalarial drugs. Bayesian statistics was previously used as a tool to virtually screen USFDA approved drugs for predicted β-haematin (synthetic haemozoin) inhibition and in vitro antimalarial activity. Here, we report the experimental evaluation of nine of the highest ranked drugs, confirming the accuracy of the model by showing an overall 93% hit rate. Lapatinib, nilotinib, and lomitapide showed the best activity for inhibition of β-haematin formation and parasite growth and were found to inhibit haemozoin formation in the parasite, providing mechanistic insights into their mode of antimalarial action. We then screened the USFDA approved drugs for binding to the β-haematin crystal, applying a docking method in order to evaluate its performance. The docking method correctly identified imatinib, lapatinib, nilotinib, and lomitapide. Experimental evaluation of 22 of the highest ranked purchasable drugs showed a 24% hit rate. Lapatinib and nilotinib were chosen as templates for shape and electrostatic similarity screening for lead hopping using the in-stock ChemDiv compound catalogue. The actives were novel structures worthy of future investigation. This study presents a comparison of different in silico methods to identify new haemozoin-inhibiting chemotherapeutic alternatives for malaria that proved to be useful in different ways when taking into consideration their strengths and limitations.
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Affiliation(s)
- Ana Carolina C. de Sousa
- Department of Chemistry, Faculty of Science, University of Cape Town, Rondebosch 7701, South Africa;
| | - Keletso Maepa
- Department of Medicine, Division of Pharmacology, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa; (K.M.); (J.M.C.)
| | - Jill M. Combrinck
- Department of Medicine, Division of Pharmacology, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa; (K.M.); (J.M.C.)
- Institute of Infectious Disease and Molecular Medicine, Wellcome Centre for Infectious Diseases Research in Africa, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa
| | - Timothy J. Egan
- Department of Chemistry, Faculty of Science, University of Cape Town, Rondebosch 7701, South Africa;
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
- Correspondence:
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