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Mbaba M, Golding TM, Omondi RO, Mohunlal R, Egan TJ, Reader J, Birkholtz LM, Smith GS. Exploring the modulatory influence on the antimalarial activity of amodiaquine using scaffold hybridisation with ferrocene integration. Eur J Med Chem 2024; 271:116429. [PMID: 38663284 DOI: 10.1016/j.ejmech.2024.116429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 04/13/2024] [Accepted: 04/15/2024] [Indexed: 05/13/2024]
Abstract
Amodiaquine (AQ) is a potent antimalarial drug used in combination with artesunate as part of artemisinin-based combination therapies (ACTs) for malarial treatment. Due to the rising emergence of resistant malaria parasites, some of which have been reported for ACT, the usefulness of AQ as an efficacious therapeutic drug is threatened. Employing the organometallic hybridisation approach, which has been shown to restore the antimalarial activity of chloroquine in the form of an organometallic hybrid clinical candidate ferroquine (FQ), the present study utilises this strategy to modulate the biological performance of AQ by incorporating ferrocene. Presently, we have conceptualised ferrocenyl AQ derivatives and have developed facile, practical routes for their synthesis. A tailored library of AQ derivatives was assembled and their antimalarial activity evaluated against chemosensitive (NF54) and multidrug-resistant (K1) strains of the malaria parasite, Plasmodium falciparum. The compounds generally showed enhanced or comparable activities to those of the reference clinical drugs chloroquine and AQ, against both strains, with higher selectivity for the sensitive phenotype, mostly in the double-digit nanomolar IC50 range. Moreover, representative compounds from this series show the potential to block malaria transmission by inhibiting the growth of stage II/III and V gametocytes in vitro. Preliminary mechanistic insights also revealed hemozoin inhibition as a potential mode of action.
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Affiliation(s)
- Mziyanda Mbaba
- Department of Chemistry, Faculty of Science, University of Cape Town, Rondebosch, 7701, South Africa
| | - Taryn M Golding
- Department of Chemistry, Faculty of Science, University of Cape Town, Rondebosch, 7701, South Africa
| | - Reinner O Omondi
- Department of Chemistry, Faculty of Science, University of Cape Town, Rondebosch, 7701, South Africa
| | - Roxanne Mohunlal
- Department of Chemistry, Faculty of Science, University of Cape Town, Rondebosch, 7701, South Africa
| | - Timothy J Egan
- Department of Chemistry, Faculty of Science, 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, 0028, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, 0028, South Africa
| | - Gregory S Smith
- Department of Chemistry, Faculty of Science, University of Cape Town, Rondebosch, 7701, South Africa.
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2
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Luo AP, Giannangelo C, Siddiqui G, Creek DJ. Promising antimalarial hits from phenotypic screens: a review of recently-described multi-stage actives and their modes of action. Front Cell Infect Microbiol 2023; 13:1308193. [PMID: 38162576 PMCID: PMC10757594 DOI: 10.3389/fcimb.2023.1308193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024] Open
Abstract
Over the last two decades, global malaria cases caused by Plasmodium falciparum have declined due to the implementation of effective treatments and the use of insecticides. However, the COVID-19 pandemic caused major disruption in the timely delivery of medical goods and diverted public health resources, impairing malaria control. The emergence of resistance to all existing frontline antimalarials underpins an urgent need for new antimalarials with novel mechanisms of action. Furthermore, the need to reduce malaria transmission and/or prevent malaria infection has shifted the focus of antimalarial research towards the discovery of compounds that act beyond the symptomatic blood stage and also impact other parasite life cycle stages. Phenotypic screening has been responsible for the majority of new antimalarial lead compounds discovered over the past 10 years. This review describes recently reported novel antimalarial hits that target multiple parasite stages and were discovered by phenotypic screening during the COVID-19 pandemic. Their modes of action and targets in blood stage parasites are also discussed.
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Affiliation(s)
| | | | - Ghizal Siddiqui
- Drug Delivery Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Darren J. Creek
- Drug Delivery Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
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3
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Pal C. Redox modulating small molecules having antimalarial efficacy. Biochem Pharmacol 2023; 218:115927. [PMID: 37992998 DOI: 10.1016/j.bcp.2023.115927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 11/24/2023]
Abstract
The search for effective antimalarial agents remains a critical priority because malaria is widely spread and drug-resistant strains are becoming more prevalent. In this review, a variety of small molecules capable of modulating redox processes were showcased for their potential as antimalarial agents. The compounds were designed to target the redox balance of Plasmodium parasites, which has a pivotal function in their ability to survive and multiply within the host organism. A thorough screening method was utilized to assess the effectiveness of these compounds against both drug-sensitive and drug-resistant strains of Plasmodium falciparum, the malaria-causing parasite. The results revealed that several of the tested compounds exhibited significant effectiveness against malaria, displaying IC50 values at a low micromolar range. Furthermore, these compounds displayed promising selectivity for the parasite, as they exhibited low cytotoxicity towards mammalian cells. Thorough mechanistic studies were undertaken to clarify how the active compounds exert their mode of action. The findings revealed that these compounds disrupted the parasites' redox balance, causing oxidative stress and interfering with essential cellular functions. Additionally, the compounds showed synergistic effects when combined with existing antimalarial drugs, suggesting their potential for combination therapies to combat drug resistance. Overall, this study highlights the potential of redox-modulating small molecules as effective antimalarial agents. The identified compounds demonstrate promising antimalarial activity, and their mechanism of action offers insights into targeting the redox balance of Plasmodium parasites. Further optimization and preclinical studies are warranted to determine their efficacy, safety, and potential for clinical development as novel antimalarial therapeutics.
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Affiliation(s)
- Chinmay Pal
- Department of Chemistry, Gobardanga Hindu College, North 24 Parganas, West Bengal 743273, India.
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4
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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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5
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Escala N, Pineda LM, Ng MG, Coronado LM, Spadafora C, del Olmo E. Antiplasmodial activity, structure-activity relationship and studies on the action of novel benzimidazole derivatives. Sci Rep 2023; 13:285. [PMID: 36609676 PMCID: PMC9822940 DOI: 10.1038/s41598-022-27351-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/30/2022] [Indexed: 01/08/2023] Open
Abstract
Malaria cases and deaths keep being excessively high every year. Some inroads gained in the last two decades have been eroded especially due to the surge of resistance to most antimalarials. The search for new molecules that can replace the ones currently in use cannot stop. In this report, the synthesis of benzimidazole derivatives guided by structure-activity parameters is presented. Thirty-six molecules obtained are analyzed according to their activity against P. falciparum HB3 strain based on the type of substituent on rings A and B, their electron donor/withdrawing, as well as their dimension/spatial properties. There is a preference for electron donating groups on ring A, such as Me in position 5, or better, 5, 6-diMe. Ring B must be of the pyridine type such as picolinamide, other modifications are generally not favorable. Two molecules, 1 and 33 displayed antiplasmodial activity in the high nanomolar range against the chloroquine sensitive strain, with selectivity indexes above 10. Activity results of 1, 12 and 16 on a chloroquine resistance strain indicated an activity close to chloroquine for compound 1. Analysis of some of their effect on the parasites seem to suggest that 1 and 33 affect only the parasite and use a route other than interference with hemozoin biocrystallization, the route used by chloroquine and most antimalarials.
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Affiliation(s)
- Nerea Escala
- grid.452531.4Departamento de Ciencias Farmacéuticas: Química Farmacéutica, Facultad de Farmacia, Universidad de Salamanca, CIETUS, IBSAL, 37007 Salamanca, Spain
| | - Laura M. Pineda
- Center of Cellular and Molecular Biology of Diseases, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, City of Knowledge, Clayton, Apartado 0816-02852, Panama City, Panama
| | - Michelle G. Ng
- Center of Cellular and Molecular Biology of Diseases, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, City of Knowledge, Clayton, Apartado 0816-02852, Panama City, Panama
| | - Lorena M. Coronado
- Center of Cellular and Molecular Biology of Diseases, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, City of Knowledge, Clayton, Apartado 0816-02852, Panama City, Panama
| | - Carmenza Spadafora
- Center of Cellular and Molecular Biology of Diseases, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, City of Knowledge, Clayton, Apartado 0816-02852, Panama City, Panama.
| | - Esther del Olmo
- grid.452531.4Departamento de Ciencias Farmacéuticas: Química Farmacéutica, Facultad de Farmacia, Universidad de Salamanca, CIETUS, IBSAL, 37007 Salamanca, Spain
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6
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Sovari SN, Golding TM, Mbaba M, Mohunlal R, Egan TJ, Smith GS, Zobi F. Rhenium(I) derivatives of aminoquinoline and imidazolopiperidine-based ligands: Synthesis, in vitro and in silico biological evaluation against Plasmodium falciparum. J Inorg Biochem 2022; 234:111905. [PMID: 35752063 DOI: 10.1016/j.jinorgbio.2022.111905] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/23/2022] [Accepted: 06/12/2022] [Indexed: 12/31/2022]
Abstract
A small library of aminoquinoline and imidazolopiperidine (IMP)-based ligands, containing the 1,2,3-triazole moiety, and their corresponding tricarbonyl rhenium complexes were synthesised and their inhibitory activities evaluated against the chloroquine-sensitive (CQS) and multidrug-resistant (MDR) strains (NF54 and K1, respectively) of P. falciparum. The quinoline-based compounds (L1, L2, ReL1, and ReL2) were at least six-fold more potent than their IMP-based counterparts (L3, L4, ReL3, and ReL4) against both strains of P. falciparum, with the most promising compound (L1) displaying activity comparable to chloroquine diphosphate (CQDP) in the MDR strain. Additionally, all of the synthesised compounds have resistance indices less than CQDP. To gain insight into a possible mechanism of action, in silico hemozoin docking simulations were performed. These studies proposed that the tested compounds may act via hemozoin inhibition, as the new aminoquinoline-derivatives, with the exception of complex ReL2 (binding affinity: -12.62 kcal/mol), showed higher binding affinities than the reference drug chloroquine (CQ, -13.56 kcal/mol). Furthermore, the ligands exhibited superior binding affinity relative to their corresponding Re(I) complexes, which is reflected in their antiplasmodial activity.
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Affiliation(s)
- Sara Nasiri Sovari
- Department of Chemistry, Fribourg University, Chemin Du Musée 9, 1700 Fribourg, Switzerland
| | - Taryn M Golding
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Mziyanda Mbaba
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Roxanne Mohunlal
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Gregory S Smith
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa.
| | - Fabio Zobi
- Department of Chemistry, Fribourg University, Chemin Du Musée 9, 1700 Fribourg, Switzerland.
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7
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Qi SL, Liu YP, Li Y, Luan YX, Ye M. Ni-catalyzed hydroarylation of alkynes with unactivated β-C(sp 2)-H bonds. Nat Commun 2022; 13:2938. [PMID: 35618702 PMCID: PMC9135730 DOI: 10.1038/s41467-022-30367-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 04/28/2022] [Indexed: 12/26/2022] Open
Abstract
Hydroarylation of alkynes with unactivated C(sp2)-H bonds via chelated C-H metalation mainly occurs at γ-position to the coordinating atom of directing groups via stable 5-membered metallacycles, while β-C(sp2)-H bond-involved hydroarylation has been a formidable challenge. Herein, we used a phosphine oxide-ligated Ni-Al bimetallic catalyst to enable β-C-H bond-involved hydroarylations of alkynes via a rare 7-membered nickelacycle.
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Affiliation(s)
- Shao-Long Qi
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Yu-Peng Liu
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Yi Li
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Yu-Xin Luan
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Mengchun Ye
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China. .,Haihe Laboratory of Sustainable Chemical Transformations, Tianjin, 300192, China.
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8
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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 new amino-phenoxazine β-hematin inhibitors. ChemMedChem 2022; 17:e202200139. [PMID: 35385211 DOI: 10.1002/cmdc.202200139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [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
- Stellenbosch University Faculty of Science, Chemistry and Polymer Science, SOUTH AFRICA
| | - Leigh Loots
- Stellenbosch University Faculty of Science, Chemistry and Polymer Science, SOUTH AFRICA
| | - Michélle Kok
- Stellenbosch University Faculty of Science, Biochemistry, SOUTH AFRICA
| | | | - Janette Reader
- University of Pretoria, Biochemistry, Genetics and Microbiology, SOUTH AFRICA
| | - Lyn-Marié Birkholtz
- University of Pretoria, Biochemistry, Genetics and Microbiology, SOUTH AFRICA
| | - Gareth E Arnott
- Stellenbosch University Faculty of Science, Chemistry and Polymer Science, 49 Almond Drive, Helderberg Estate, 7130, Somerset West, SOUTH AFRICA
| | - Katherine A de Villiers
- Stellenbosch University Faculty of Science, Chemistry and Polymer Science, Merriman Avenue, 7600, Stellenbosch, SOUTH AFRICA
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9
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Guo T, Liu T, He J, Zhang Y. One‐Pot Transformation of Lignin and Lignin Model Compounds into Benzimidazoles. European J Org Chem 2022. [DOI: 10.1002/ejoc.202101152] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Tao Guo
- Institution State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun Jilin 130012 China
| | - Tianwei Liu
- Institution State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun Jilin 130012 China
| | - Jianghua He
- Institution State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun Jilin 130012 China
| | - Yuetao Zhang
- Institution State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun Jilin 130012 China
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10
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Leshabane M, Dziwornu GA, Coertzen D, Reader J, Moyo P, van der Watt M, Chisanga K, Nsanzubuhoro C, Ferger R, Erlank E, Venter N, Koekemoer L, Chibale K, Birkholtz LM. Benzimidazole Derivatives Are Potent against Multiple Life Cycle Stages of Plasmodium falciparum Malaria Parasites. ACS Infect Dis 2021; 7:1945-1955. [PMID: 33673735 DOI: 10.1021/acsinfecdis.0c00910] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The continued emergence of resistance to front-line antimalarial treatments is of great concern. Therefore, new compounds that potentially have a novel target in various developmental stages of Plasmodium parasites are needed to treat patients and halt the spread of malaria. Here, several benzimidazole derivatives were screened for activity against the symptom-causing intraerythrocytic asexual blood stages and the transmissible gametocyte stages of P. falciparum. Submicromolar activity was obtained for 54 compounds against asexual blood stage parasites with 6 potent at IC50 < 100 nM while not displaying any marked toxicity against mammalian cells. Nanomolar potency was also observed against gametocytes with two compounds active against early stage gametocytes and two compounds active against late-stage gametocytes. The transmission-blocking potential of the latter was confirmed as they could prevent male gamete exflagellation and the lead compound reduced transmission by 72% in an in vivo mosquito feeding model. These compounds therefore have activity against multiple stages of Plasmodium parasites with potential for differential targets.
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Affiliation(s)
- Meta Leshabane
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | | | - Dina Coertzen
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Phanankosi Moyo
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Kelly Chisanga
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | | | - Richard Ferger
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Erica Erlank
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Nelius Venter
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Lizette Koekemoer
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Kelly Chibale
- 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
- South African Medical Research Council Drug Discovery and Development Research Unit, 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, Private Bag X20, Hatfield 0028, South Africa
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11
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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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12
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Bokosi FRB, Beteck RM, Mbaba M, Mtshare TE, Laming D, Hoppe HC, Khanye SD. Design, synthesis and biological evaluation of mono- and bisquinoline methanamine derivatives as potential antiplasmodial agents. Bioorg Med Chem Lett 2021; 38:127855. [PMID: 33609655 DOI: 10.1016/j.bmcl.2021.127855] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/01/2021] [Accepted: 02/05/2021] [Indexed: 11/29/2022]
Abstract
Several classes of antimalarial drugs are currently available, although issues of toxicity and the emergence of drug resistant malaria parasites have reduced their overall therapeutic efficiency. Quinoline based antiplasmodial drugs have unequivocally been long-established and continue to inspire the design of new antimalarial agents. Herein, a series of mono- and bisquinoline methanamine derivatives were synthesised through sequential steps; Vilsmeier-Haack, reductive amination, and nucleophilic substitution, and obtained in low to excellent yields. The resulting compounds were investigated for in vitro antiplasmodial activity against the 3D7 chloroquine-sensitive strain of Plasmodium falciparum, and compounds 40 and 59 emerged as the most promising with IC50 values of 0.23 and 0.93 µM, respectively. The most promising compounds were also evaluated in silico by molecular docking protocols for binding affinity to the {001} fast-growing face of a hemozoin crystal model.
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Affiliation(s)
- Fostino R B Bokosi
- Department of Chemistry, Faculty of Science, Rhodes University, Makhanda 6140, South Africa.
| | - Richard M Beteck
- Department of Chemistry, Faculty of Science, Rhodes University, Makhanda 6140, South Africa; Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom 2520, South Africa
| | - Mziyanda Mbaba
- Department of Chemistry, Faculty of Science, Rhodes University, Makhanda 6140, South Africa; Department of Chemistry, Faculty of Science, University of Cape Town, Rondebosch 7701, South Africa
| | - Thanduxolo E Mtshare
- Division of Pharmaceutical Chemistry, Faculty of Pharmacy, Rhodes University, Makhanda 6140, South Africa
| | - Dustin Laming
- Centre for Chemico- and Biomedicinal Research, Rhodes University, Makhanda 6140, South Africa
| | - Heinrich C Hoppe
- Centre for Chemico- and Biomedicinal Research, Rhodes University, Makhanda 6140, South Africa; Department of Biochemistry and Microbiology, Faculty of Science, Rhodes University, Makhanda 6140, South Africa
| | - Setshaba D Khanye
- Department of Chemistry, Faculty of Science, Rhodes University, Makhanda 6140, South Africa; Division of Pharmaceutical Chemistry, Faculty of Pharmacy, Rhodes University, Makhanda 6140, South Africa; Centre for Chemico- and Biomedicinal Research, Rhodes University, Makhanda 6140, South Africa.
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13
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Dziwornu GA, Coertzen D, Leshabane M, Korkor CM, Cloete CK, Njoroge M, Gibhard L, Lawrence N, Reader J, van der Watt M, Wittlin S, Birkholtz LM, Chibale K. Antimalarial Benzimidazole Derivatives Incorporating Phenolic Mannich Base Side Chains Inhibit Microtubule and Hemozoin Formation: Structure-Activity Relationship and In Vivo Oral Efficacy Studies. J Med Chem 2021; 64:5198-5215. [PMID: 33844521 DOI: 10.1021/acs.jmedchem.1c00354] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A novel series of antimalarial benzimidazole derivatives incorporating phenolic Mannich base side chains at the C2 position, which possess dual asexual blood and sexual stage activities, is presented. Structure-activity relationship studies revealed that the 1-benzylbenzimidazole analogues possessed submicromolar asexual blood and sexual stage activities in contrast to the 1H-benzimidazole analogues, which were only active against asexual blood stage (ABS) parasites. Further, the former demonstrated microtubule inhibitory activity in ABS parasites but more significantly in stage II/III gametocytes. In addition to being bona fide inhibitors of hemozoin formation, the 1H-benzimidazole analogues also showed inhibitory effects on microtubules. In vivo efficacy studies in Plasmodium berghei-infected mice revealed that the frontrunner compound 41 exhibited high efficacy (98% reduction in parasitemia) when dosed orally at 4 × 50 mg/kg. Generally, the compounds were noncytotoxic to mammalian cells.
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Affiliation(s)
| | - Dina Coertzen
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Meta Leshabane
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Constance M Korkor
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Cleavon K Cloete
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Mathew Njoroge
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa
| | - Liezl Gibhard
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa
| | - Nina Lawrence
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute, Socinstrasse 57, Basel 4002, Switzerland.,University of Basel, Basel 4003, Switzerland
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Kelly Chibale
- 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.,South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa
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14
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Kotzé TJ, Duffy S, Avery VM, Jordaan A, Warner DF, Loots L, Smith GS, Chellan P. Synthesis and antimicrobial study of organoiridium amido-sulfadoxine complexes. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2020.120175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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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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16
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Ishmail FZ, Melis DR, Mbaba M, Smith GS. Diversification of quinoline-triazole scaffolds with CORMs: Synthesis, in vitro and in silico biological evaluation against Plasmodium falciparum. J Inorg Biochem 2020; 215:111328. [PMID: 33340802 DOI: 10.1016/j.jinorgbio.2020.111328] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 11/25/2020] [Accepted: 12/01/2020] [Indexed: 10/22/2022]
Abstract
A discrete series of tricarbonyl manganese and rhenium complexes conjugated to a quinoline-triazole hybrid scaffold were synthesised and their inhibitory activities evaluated against Plasmodium falciparum. In general, the complexes show moderate activity with improved inhibitory activities for the photoactivatable manganese(I) tricarbonyl complexes in the malaria parasite. All complexes are active in the dark against the NF54 CQS (chloroquine-sensitive) and K1 MDR (multidrug-resistant) strains of Plasmodium falciparum, with IC50 values in the low micromolar range. Of significance, the complexes retain their activity in the MDR strain with resistance indices ranging between 1.1 and 2.1. The Mn(I) analogues display photodissociation of all three CO ligands upon irradiation at 365 nm. More importantly, the complexes show increased antimalarial activity in vitro upon photoactivation, something not observed by the clinically used reference drug, chloroquine. As a purported mechanism of action, the compounds were evaluated as β-haematin inhibitors. To further understand the interactions of the complexes, in silico hemozoin docking simulations were performed, attesting to the fact that CO-release could be vital for blocking the hemozoin formation pathway. These results show that this strategy may be a valuable, novel route to design antimalarial agents with higher efficacy.
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Affiliation(s)
- Fatima-Zahra Ishmail
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Diana R Melis
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Mziyanda Mbaba
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Gregory S Smith
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7700, South Africa.
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17
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Korkor CM, Garnie LF, Amod L, Egan TJ, Chibale K. Intrinsic fluorescence properties of antimalarial pyrido[1,2- a]benzimidazoles facilitate subcellular accumulation and mechanistic studies in the human malaria parasite Plasmodium falciparum. Org Biomol Chem 2020; 18:8668-8676. [PMID: 33078179 PMCID: PMC7710849 DOI: 10.1039/d0ob01730b] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The intrinsic fluorescence properties of two related pyrido[1,2-a]benzimidazole antimalarial compounds suitable for the cellular imaging of the human malaria parasite Plasmodium falciparum without the need to attach extrinsic fluorophores are described. Although these compounds are structurally related, they have been shown by confocal microscopy to not only accumulate selectively within P. falciparum but to also accumulate differently in the organelles investigated. Localization to the digestive vacuole and nearby neutral lipids was observed for compound 2 which was shown to inhibit hemozoin formation using a cellular fractionation assay indicating that this is a contributing mechanism of action. By contrast, compound 1, which differs from compound 2 by the replacement of the imidazole[1,2-a:4,5-b']dipyridine core with the benzimidazole core as well as the presence of Cl substituents, shows very different localisation patterns and shows no evidence of hemozoin inhibition, suggesting a different mechanism of antimalarial action. Docking profiles of both compounds on the hemozoin surface further provided insight into their mechanisms of action.
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Affiliation(s)
- Constance M Korkor
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa.
| | - Larnelle F Garnie
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa.
| | - Leah Amod
- 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. and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa. and South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town, Department of Chemistry, Rondebosch 7701, South Africa and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
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18
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Mbaba M, Dingle LMK, Swart T, Cash D, Laming D, de la Mare JA, Taylor D, Hoppe HC, Biot C, Edkins AL, Khanye SD. The in Vitro Antiplasmodial and Antiproliferative Activity of New Ferrocene-Based α-Aminocresols Targeting Hemozoin Inhibition and DNA Interaction. Chembiochem 2020; 21:2643-2658. [PMID: 32307798 DOI: 10.1002/cbic.202000132] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/15/2020] [Indexed: 01/30/2023]
Abstract
The conjugation of organometallic complexes to known bioactive organic frameworks is a proven strategy revered for devising new drug molecules with novel modes of action. This approach holds great promise for the generation of potent drug leads in the quest for therapeutic chemotypes with the potential to overcome the development of clinical resistance. Herein, we present the in vitro antiplasmodial and antiproliferative investigation of ferrocenyl α-aminocresol conjugates assembled by amalgamation of the organometallic ferrocene unit and an α-aminocresol scaffold possessing antimalarial activity. The compounds pursued in the study exhibited higher toxicity towards the chemosensitive (3D7) and -resistant (Dd2) strains of the Plasmodium falciparum parasite than to the human HCC70 triple-negative breast cancer cell line. Indication of cross-resistance was absent for the compounds evaluated against the multi-resistant Dd2 strain. Structure-activity analysis revealed that the phenolic hydroxy group and rotatable σ bond between the α-carbon and NH group of the α-amino-o-cresol skeleton are crucial for the biological activity of the compounds. Spectrophotometric techniques and in silico docking simulations performed on selected derivatives suggest that the compounds show a dual mode of action involving hemozoin inhibition and DNA interaction via minor-groove binding. Lastly, compound 9 a, identified as a possible lead, exhibited preferential binding for the plasmodial DNA isolated from 3D7 P. falciparum trophozoites over the mammalian calf thymus DNA, thereby substantiating the enhanced antiplasmodial activity of the compounds. The presented research demonstrates the strategy of incorporating organometallic complexes into known biologically active organic scaffolds as a viable avenue to fashion novel multimodal compounds with potential to counter the development drug resistance.
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Affiliation(s)
- Mziyanda Mbaba
- Faculty of Science, Department of Chemistry, Rhodes University, Grahamstown, 6140, South Africa
| | - Laura M K Dingle
- Faculty of Science, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6140, South Africa.,Biomedical Biotechnology Research Unit, Rhodes University, Grahamstown, 6140, South Africa
| | - Tarryn Swart
- Faculty of Science, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6140, South Africa.,Centre for Chemico- and Biomedicinal Research, Rhodes University, Grahamstown, 6140, South Africa
| | - Devon Cash
- Faculty of Science, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6140, South Africa.,Biomedical Biotechnology Research Unit, Rhodes University, Grahamstown, 6140, South Africa
| | - Dustin Laming
- Faculty of Science, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6140, South Africa.,Centre for Chemico- and Biomedicinal Research, Rhodes University, Grahamstown, 6140, South Africa
| | - Jo-Anne de la Mare
- Faculty of Science, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6140, South Africa.,Biomedical Biotechnology Research Unit, Rhodes University, Grahamstown, 6140, South Africa.,Centre for Chemico- and Biomedicinal Research, Rhodes University, Grahamstown, 6140, South Africa
| | - Dale Taylor
- Faculty of Medicine, Division of Clinical Pharmacology, University of Cape Town Observatory, Cape Town, 7925, South Africa
| | - Heinrich C Hoppe
- Faculty of Science, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6140, South Africa.,Centre for Chemico- and Biomedicinal Research, Rhodes University, Grahamstown, 6140, South Africa
| | - Christophe Biot
- Université de Lille, CNRS, UMR 8576 UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, 59000, Lille, France
| | - Adrienne L Edkins
- Faculty of Science, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, 6140, South Africa.,Biomedical Biotechnology Research Unit, Rhodes University, Grahamstown, 6140, South Africa.,Centre for Chemico- and Biomedicinal Research, Rhodes University, Grahamstown, 6140, South Africa
| | - Setshaba D Khanye
- Faculty of Science, Department of Chemistry, Rhodes University, Grahamstown, 6140, South Africa.,Centre for Chemico- and Biomedicinal Research, Rhodes University, Grahamstown, 6140, South Africa.,Faculty of Pharmacy, Division of Pharmaceutical Chemistry, Rhodes University, Grahamstown, 6140, South Africa
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19
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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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20
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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] [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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21
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Virtual screening as a tool to discover new β-haematin inhibitors with activity against malaria parasites. Sci Rep 2020; 10:3374. [PMID: 32099045 PMCID: PMC7042288 DOI: 10.1038/s41598-020-60221-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 02/10/2020] [Indexed: 12/24/2022] Open
Abstract
Malaria remains a major public health problem. With the loss of antimalarials to resistance, the malaria burden will likely continue for decades. New antimalarial scaffolds are crucial to avoid cross-resistance. Here, we present the first structure based virtual screening using the β-haematin crystal as a target for new inhibitor scaffolds by applying a docking method. The ZINC15 database was searched for compounds with high binding affinity with the surface of the β-haematin crystal using the PyRx Virtual Screening Tool. Top-ranked compounds predicted to interact with β-haematin were submitted to a second screen applying in silico toxicity and drug-likeness predictions using Osiris DataWarrior. Fifteen compounds were purchased for experimental testing. An NP-40 mediated β-haematin inhibition assay and parasite growth inhibition activity assay were performed. The benzoxazole moiety was found to be a promising scaffold for further development, showing intraparasitic haemozoin inhibition using a cellular haem fractionation assay causing a decrease in haemozoin in a dose dependent manner with a corresponding increase in exchangeable haem. A β-haematin inhibition hit rate of 73% was found, a large enrichment over random screening, demonstrating that virtual screening can be a useful and cost-effective approach in the search for new haemozoin inhibiting antimalarials.
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22
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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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