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Berger F, Gomez GM, Sanchez CP, Posch B, Planelles G, Sohraby F, Nunes-Alves A, Lanzer M. pH-dependence of the Plasmodium falciparum chloroquine resistance transporter is linked to the transport cycle. Nat Commun 2023; 14:4234. [PMID: 37454114 PMCID: PMC10349806 DOI: 10.1038/s41467-023-39969-2] [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: 11/16/2022] [Accepted: 07/05/2023] [Indexed: 07/18/2023] Open
Abstract
The chloroquine resistance transporter, PfCRT, of the human malaria parasite Plasmodium falciparum is sensitive to acidic pH. Consequently, PfCRT operates at 60% of its maximal drug transport activity at the pH of 5.2 of the digestive vacuole, a proteolytic organelle from which PfCRT expels drugs interfering with heme detoxification. Here we show by alanine-scanning mutagenesis that E207 is critical for pH sensing. The E207A mutation abrogates pH-sensitivity, while preserving drug substrate specificity. Substituting E207 with Asp or His, but not other amino acids, restores pH-sensitivity. Molecular dynamics simulations and kinetics analyses suggest an allosteric binding model in which PfCRT can accept both protons and chloroquine in a partial noncompetitive manner, with increased proton concentrations decreasing drug transport. Further simulations reveal that E207 relocates from a peripheral to an engaged location during the transport cycle, forming a salt bridge with residue K80. We propose that the ionized carboxyl group of E207 acts as a hydrogen acceptor, facilitating transport cycle progression, with pH sensing as a by-product.
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Affiliation(s)
- Fiona Berger
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
| | - Guillermo M Gomez
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
| | - Cecilia P Sanchez
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
| | - Britta Posch
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
| | - Gabrielle Planelles
- INSERM, Centre de Recherche des Cordeliers, Unité 1138, CNRS ERL8228, Université Pierre et Marie Curie and Université Paris-Descartes, Paris, 75006, France
| | - Farzin Sohraby
- Institute of Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Ariane Nunes-Alves
- Institute of Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany.
| | - Michael Lanzer
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany.
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2
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Abstract
Ferric heme b (= ferric protoporphyrin IX = hemin) is an important prosthetic group of different types of enzymes, including the intensively investigated and widely applied horseradish peroxidase (HRP). In HRP, hemin is present in monomeric form in a hydrophobic pocket containing among other amino acid side chains the two imidazoyl groups of His170 and His42. Both amino acids are important for the peroxidase activity of HRP as an axial ligand of hemin (proximal His170) and as an acid/base catalyst (distal His42). A key feature of the peroxidase mechanism of HRP is the initial formation of compound I under heterolytic cleavage of added hydrogen peroxide as a terminal oxidant. Investigations of free hemin dispersed in aqueous solution showed that different types of hemin dimers can form, depending on the experimental conditions, possibly resulting in hemin crystallization. Although it has been recognized already in the 1970s that hemin aggregation can be prevented in aqueous solution by using micelle-forming amphiphiles, it remains a challenge to prepare hemin-containing micellar and vesicular systems with peroxidase-like activities. Such systems are of interest as cheap HRP-mimicking catalysts for analytical and synthetic applications. Some of the key concepts on which research in this fascinating and interdisciplinary field is based are summarized, along with major accomplishments and possible directions for further improvement. A systematic analysis of the physico-chemical properties of hemin in aqueous micellar solutions and vesicular dispersions must be combined with a reliable evaluation of its catalytic activity. Future studies should show how well the molecular complexity around hemin in HRP can be mimicked by using micelles or vesicles. Because of the importance of heme b in virtually all biological systems and the fact that porphyrins and hemes can be obtained under potentially prebiotic conditions, ideas exist about the possible role of heme-containing micellar and vesicular systems in prebiotic times.
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Bazedoxifene, a Postmenopausal Drug, Acts as an Antimalarial and Inhibits Hemozoin Formation. Microbiol Spectr 2022; 10:e0278121. [PMID: 35616371 PMCID: PMC9241896 DOI: 10.1128/spectrum.02781-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Despite a remarkable improvement in health care and continued drug discovery efforts, malaria control efforts are continuously challenged by the emergence of drug-resistant parasite strains. Given a long and risky development path of new drugs, repurposing existing drugs for the treatment of malaria is an attractive and shorter path. Tamoxifen, a selective estrogen receptor modulator (SERM) for the treatment and prevention of estrogen receptor-positive breast cancer, possesses antibacterial, antifungal, and antiparasitic activities. Hence, we assessed tamoxifen, raloxifene, and bazedoxifene, which represent the first-, second-, and third-generation SERMs, respectively, for antimalarial activity. Raloxifene and bazedoxifene inhibited the erythrocytic development of Plasmodium falciparum with submicromolar 50% inhibitory concentration (IC50) values. Among the three, bazedoxifene was the most potent and also decreased P. berghei infection in female mice but not in male mice. However, bazedoxifene similarly inhibited P. falciparum growth in erythrocytes of male and female origin, which highlights the importance of sex-specific host physiology in drug efficacy. Bazedoxifene was most potent on early ring-stage parasites, and about 35% of the treated parasites did not contain hemozoin in the food vacuole. Bazedoxifene-treated parasites had almost 34% less hemozoin content than the control parasites. However, both control and bazedoxifene-treated parasites had similar hemoglobin levels, suggesting that bazedoxifene inhibits hemozoin formation and that toxicity due to accumulation of free heme could be a mechanism of its antimalarial activity. Because bazedoxifene is in clinical use and bazedoxifene-chloroquine combination shows an additive antiparasitic effect, bazedoxifene could be an adjunctive partner of currently used antimalarial regimens. IMPORTANCE The emergence and spread of drug-resistant strains of the human malaria parasite Plasmodium falciparum has necessitated new drugs. Selective estrogen receptor modulators are in clinical use for the prevention and treatment of breast cancer and postmenopausal osteoporosis. We demonstrate that bazedoxifene, a third-generation selective estrogen receptor modulator, has potent inhibitory activity against both susceptible and drug-resistant strains of Plasmodium falciparum. It also blocked the development of Plasmodium berghei in mice. The inhibitory effect was strongest on the ring stage and resulted in the inhibition of hemozoin formation, which could be the major mechanism of bazedoxifene action. Hemozoin is a nontoxic polymer of heme, which is a by-product of hemoglobin degradation by the malaria parasite during its development within the erythrocyte. Because bazedoxifene is already in clinical use for the treatment of postmenopausal osteoporosis, our findings support repurposing of bazedoxifene as an antimalarial.
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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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Abid M, Singh S, Egan TJ, Joshi MC. Structural activity relationship of metallo-aminoquines as a next generation antimalarials. Curr Top Med Chem 2022; 22:436-472. [PMID: 34986771 DOI: 10.2174/1568026622666220105103751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 12/02/2021] [Accepted: 12/05/2021] [Indexed: 11/22/2022]
Abstract
Apicomplexian parasite of the genus Plasmodium is the causative agent of malaria, one of the most devastating, furious and common infectious disease throughout the world. According to the latest World malaria report, there were 229 million cases of malaria in 2019 majorly consisting of children under 5 years of age. Some of known analogues viz. quinine, quinoline-containing compounds have been used for last century in the clinical treatment of malaria. Past few decades have witnessed the emergence of multi-drug resistance (MDR) strains of Plasmodium species to existing antimalarials pressing the need for new drug candidates. For the past few decades bioorganometallic approach to malaria therapy has been introduced which led to the discovery of noval metalcontaining aminoquinolines analogues viz. ferroquine (FQ or 1), Ruthenoquine (RQ or 2) and other related potent metal-analogues. It observed that some metal containing analogues (Fe-, Rh-, Ru-, Re-, Au-, Zn-, Cr-, Pd-, Sn-, Cd-, Ir-, Co-, Cu-, and Mn-aminoquines) were more potent; however, some were equally potent as Chloroquine (CQ) and 1. This is probably due to the intertion of metals in the CQ via various approaches, which might be a very attractive strategy to develop a SAR of novel metal containing antimalarials. Thus, this review aims to summarize the SAR of metal containing aminoquines towards the discovery of potent antimalarial hybrids to provide an insight for rational designs of more effective and less toxic metal containing amoniquines.
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Affiliation(s)
- Mohammad Abid
- Department of Biosciences, Jamia Millia Islamia University, Jamia Nagar, New Delhi-110025, India
| | - Shailja Singh
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Mehroli Road, New Delhi-110067, India
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town-7700, South Africa
| | - Mukesh C Joshi
- Dept. of Chemistry, Motilal Nehru College, University of Delhi, Benito Juarez marg, South Campus, New Delhi-110021. India
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6
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Verma L, Vekilov PG, Palmer JC. Solvent Structure and Dynamics near the Surfaces of β-Hematin Crystals. J Phys Chem B 2021; 125:11264-11274. [PMID: 34609878 DOI: 10.1021/acs.jpcb.1c06589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hematin crystallization, which is an essential component of the physiology of malaria parasites and the most successful target for antimalarial drugs, proceeds in mixed organic-aqueous solvents both in vivo and in vitro. Here we employ molecular dynamics simulations to examine the structuring and dynamics of a water-normal octanol mixture (a solvent that mimics the environment hosting hematin crystallization in vivo) in the vicinity of the typical faces in the habit of a hematin crystal. The simulations reveal that the properties of the solvent in the layer adjacent to the crystal are strongly impacted by the distinct chemical and topological features presented by each crystal face. The solvent organizes into at least three distinct layers. We also show that structuring of the solvent near the different faces of β-hematin strongly impacts the interfacial dynamics. The relaxation time of n-octanol molecules is longest in the contact layers and correlates with the degree of structural ordering at the respective face. We show that the macroscopically homogeneous water-octanol solution holds clusters of water and n-octanol connected by hydrogen bonds that entrap the majority of the water but are mostly smaller than 30 water molecules. Near the crystal surface the clusters anchor on hematin carboxyl groups. These results provide a direct example that solvent structuring is not restricted to aqueous and other hydrogen-bonded solutions. Our findings illuminate two fundamental features of the mechanisms of hematin crystallization: the elongated shapes of natural and synthetic hematin crystals and the stabilization of charged groups of hematin and antimalarials by encasing in water clusters. In addition, these findings suggest that hematin crystallization may be controlled by additives that disrupt or reinforce solvent structuring.
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Affiliation(s)
- Laksmanji Verma
- William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Peter G Vekilov
- William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States.,Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Jeremy C Palmer
- William A. Brookshire Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
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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: 35] [Impact Index Per Article: 11.7] [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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Kapishnikov S, Hempelmann E, Elbaum M, Als‐Nielsen J, Leiserowitz L. Malaria Pigment Crystals: The Achilles' Heel of the Malaria Parasite. ChemMedChem 2021; 16:1515-1532. [PMID: 33523575 PMCID: PMC8252759 DOI: 10.1002/cmdc.202000895] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Indexed: 12/14/2022]
Abstract
The biogenic formation of hemozoin crystals, a crucial process in heme detoxification by the malaria parasite, is reviewed as an antimalarial drug target. We first focus on the in-vivo formation of hemozoin. A model is presented, based on native-contrast 3D imaging obtained by X-ray and electron microscopy, that hemozoin nucleates at the inner membrane leaflet of the parasitic digestive vacuole, and grows in the adjacent aqueous medium. Having observed quantities of hemoglobin and hemozoin in the digestive vacuole, we present a model that heme liberation from hemoglobin and hemozoin formation is an assembly-line process. The crystallization is preceded by reaction between heme monomers yielding hematin dimers involving fewer types of isomers than in synthetic hemozoin; this is indicative of protein-induced dimerization. Models of antimalarial drugs binding onto hemozoin surfaces are reviewed. This is followed by a description of bromoquine, a chloroquine drug analogue, capping a significant fraction of hemozoin surfaces within the digestive vacuole and accumulation of the drug, presumably a bromoquine-hematin complex, at the vacuole's membrane.
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Affiliation(s)
- Sergey Kapishnikov
- Dept. of Chemical Research SupportWeizmann Institute of ScienceRehovot7610001Israel
| | - Ernst Hempelmann
- Center of Cellular and Molecular Biology of DiseasesInstituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP)City of Knowledge0843 (Republic ofPanama
| | - Michael Elbaum
- Dept. of Chemical and Biological PhysicsWeizmann Institute of ScienceRehovot7610001Israel
| | - Jens Als‐Nielsen
- Niels Bohr InstituteUniversity of Copenhagen2100CopenhagenDenmark
| | - Leslie Leiserowitz
- Dept. of Molecular Chemistry and Materials ScienceWeizmann Institute of ScienceRehovot7610001Israel
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Marinho JA, Martins Guimarães DS, Glanzmann N, de Almeida Pimentel G, Karine da Costa Nunes I, Gualberto Pereira HM, Navarro M, de Pilla Varotti F, David da Silva A, Abramo C. In vitro and in vivo antiplasmodial activity of novel quinoline derivative compounds by molecular hybridization. Eur J Med Chem 2021; 215:113271. [PMID: 33596489 DOI: 10.1016/j.ejmech.2021.113271] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/31/2021] [Accepted: 02/01/2021] [Indexed: 01/01/2023]
Abstract
Chloroquine (CQ) has been the main treatment for malaria in regions where there are no resistant strains. Molecular hybridization techniques have been used as a tool in the search for new drugs and was implemented in the present study in an attempt to produce compound candidates to treat malarial infections by CQ-resistant strains. Two groups of molecules were produced from the 4-aminoquinoline ring in conjugation to hydrazones (HQ) and imines (IQ). Physicochemical and pharmacokinetic properties were found to be favorable when analyzed in silico and cytotoxicity and antiplasmodial activity were assayed in vitro and in vivo showing low cytotoxicity and selectiveness to the parasites. Candidates IQ5 and IQ6 showed important values of parasite growth inhibition in vivo on the 5th day after infection (IQ5 15 mg/kg = 72.64% and IQ6 15 mg/kg = 71.15% and 25 mg/kg = 93.7%). IQ6 also showed interaction with ferriprotoporphyrin IX similarly to CQ. The process of applying condensation reactions to yield imines is promising and capable of producing molecules with antiplasmodial activity.
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Affiliation(s)
- Juliane Aparecida Marinho
- Departamento de Parasitologia, Microbiologia e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Campus Universitário, Juiz de Fora, Minas Gerais, CEP: 36036-900, Brazil.
| | - Daniel Silqueira Martins Guimarães
- Núcleo de Pesquisa Em Química Biológica, Universidade Federal de São João Del Rei - Campus Centro Oeste, 400 Sebastião Gonçalves Coelho Street, Divinópolis, MG, 35501-296, Brazil.
| | - Nícolas Glanzmann
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Campus Universitário, Juiz de Fora, Minas Gerais, CEP: 36036-900, Brazil.
| | - Giovana de Almeida Pimentel
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Campus Universitário, Juiz de Fora, Minas Gerais, CEP: 36036-900, Brazil.
| | - Izabelle Karine da Costa Nunes
- Laboratório de Apoio Ao Desenvolvimento Tecnológico, LADETEC/IQ, Universidade Federal Do Rio de Janeiro, Av. Horácio Macedo, 1281 - Polo de Química, Cidade Universitária, Ilha Do Fundão, RJ, 21941-598, Brazil.
| | - Henrique Marcelo Gualberto Pereira
- Laboratório de Apoio Ao Desenvolvimento Tecnológico, LADETEC/IQ, Universidade Federal Do Rio de Janeiro, Av. Horácio Macedo, 1281 - Polo de Química, Cidade Universitária, Ilha Do Fundão, RJ, 21941-598, Brazil.
| | - Maribel Navarro
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Campus Universitário, Juiz de Fora, Minas Gerais, CEP: 36036-900, Brazil.
| | - Fernando de Pilla Varotti
- Núcleo de Pesquisa Em Química Biológica, Universidade Federal de São João Del Rei - Campus Centro Oeste, 400 Sebastião Gonçalves Coelho Street, Divinópolis, MG, 35501-296, Brazil.
| | - Adilson David da Silva
- Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Campus Universitário, Juiz de Fora, Minas Gerais, CEP: 36036-900, Brazil.
| | - Clarice Abramo
- Departamento de Parasitologia, Microbiologia e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Campus Universitário, Juiz de Fora, Minas Gerais, CEP: 36036-900, Brazil.
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10
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Chen AJ, Huang KC, Bopp S, Summers R, Dong P, Huang Y, Zong C, Wirth D, Cheng JX. Quantitative imaging of intraerythrocytic hemozoin by transient absorption microscopy. JOURNAL OF BIOMEDICAL OPTICS 2019; 25:1-11. [PMID: 31849205 PMCID: PMC6916744 DOI: 10.1117/1.jbo.25.1.014507] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 11/22/2019] [Indexed: 06/10/2023]
Abstract
Hemozoin, the heme detoxification end product in malaria parasites during their growth in the red blood cells (RBCs), serves as an important marker for diagnosis and treatment target of malaria disease. However, the current method for hemozoin-targeted drug screening mainly relies on in vitro β-hematin inhibition assays, which may lead to false-positive events due to under-representation of the real hemozoin crystal. Quantitative in situ imaging of hemozoin is highly desired for high-throughput screening of antimalarial drugs and for elucidating the mechanisms of antimalarial drugs. We present transient absorption (TA) imaging as a high-speed single-cell analysis platform with chemical selectivity to hemozoin. We first demonstrated that TA microscopy is able to identify β-hematin, the artificial form of hemozoin, from the RBCs. We further utilized time-resolved TA imaging to in situ discern hemozoin from malaria-infected RBCs with optimized imaging conditions. Finally, we quantitatively analyzed the hemozoin amount in RBCs at different infection stages by single-shot TA imaging. These results highlight the potential of TA imaging for efficient antimalarial drug screening and drug mechanism investigation.
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Affiliation(s)
- Andy J. Chen
- Purdue University, Department of Biological Sciences, West Lafayette, Indiana, United States
| | - Kai-Chih Huang
- Boston University, Photonics Center, Boston, Massachusetts, United States
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Selina Bopp
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States
| | - Robert Summers
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States
| | - Puting Dong
- Boston University, Photonics Center, Boston, Massachusetts, United States
| | - Yimin Huang
- Boston University, Photonics Center, Boston, Massachusetts, United States
| | - Cheng Zong
- Boston University, Photonics Center, Boston, Massachusetts, United States
| | - Dyann Wirth
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States
| | - Ji-Xin Cheng
- Boston University, Photonics Center, Boston, Massachusetts, United States
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Department of Electrical and Computer Engineering, Boston, Massachusetts, United States
- Boston University, Department of Chemistry, Boston, Massachusetts, United States
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Herraiz T, Guillén H, González-Peña D, Arán VJ. Antimalarial Quinoline Drugs Inhibit β-Hematin and Increase Free Hemin Catalyzing Peroxidative Reactions and Inhibition of Cysteine Proteases. Sci Rep 2019; 9:15398. [PMID: 31659177 PMCID: PMC6817881 DOI: 10.1038/s41598-019-51604-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 10/03/2019] [Indexed: 01/06/2023] Open
Abstract
Malaria caused by Plasmodium affects millions people worldwide. Plasmodium consumes hemoglobin during its intraerythrocytic stage leaving toxic heme. Parasite detoxifies free heme through formation of hemozoin (β-hematin) pigment. Proteolysis of hemoglobin and formation of hemozoin are two main targets for antimalarial drugs. Quinoline antimarial drugs and analogs (β-carbolines or nitroindazoles) were studied as inhibitors of β-hematin formation. The most potent inhibitors were quinacrine, chloroquine, and amodiaquine followed by quinidine, mefloquine and quinine whereas 8-hydroxyquinoline and β-carbolines had no effect. Compounds that inhibited β-hematin increased free hemin that promoted peroxidative reactions as determined with TMB and ABTS substrates. Hemin-catalyzed peroxidative reactions were potentiated in presence of proteins (i.e. globin or BSA) while antioxidants and peroxidase inhibitors decreased peroxidation. Free hemin increased by chloroquine action promoted oxidative reactions resulting in inhibition of proteolysis by three cysteine proteases: papain, ficin and cathepsin B. Glutathione reversed inhibition of proteolysis. These results show that active quinolines inhibit hemozoin and increase free hemin which in presence of H2O2 that abounds in parasite digestive vacuole catalyzes peroxidative reactions and inhibition of cysteine proteases. This work suggests a link between the action of quinoline drugs with biochemical processes of peroxidation and inhibition of proteolysis.
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Affiliation(s)
- Tomás Herraiz
- Instituto de Ciencia y Tecnología de Alimentos y Nutrición (ICTAN). Spanish National Research Council (CSIC), Juan de la Cierva 3, 28006, Madrid, Spain.
| | - Hugo Guillén
- Instituto de Ciencia y Tecnología de Alimentos y Nutrición (ICTAN). Spanish National Research Council (CSIC), Juan de la Cierva 3, 28006, Madrid, Spain
| | - Diana González-Peña
- Instituto de Ciencia y Tecnología de Alimentos y Nutrición (ICTAN). Spanish National Research Council (CSIC), Juan de la Cierva 3, 28006, Madrid, Spain
| | - Vicente J Arán
- Instituto de Química Médica (IQM-CSIC), Juan de la Cierva 3, 28006, Madrid, Spain
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12
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Osman CP, Ismail NH, Widyawaruyanti A, Imran S, Tumewu L, Choo CY, Ideris S. Evaluation of a Series of 9,10-Anthraquinones as Antiplasmodial Agents. LETT DRUG DES DISCOV 2019. [DOI: 10.2174/1570180815666180607085102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background: A phytochemical study on medicinal plants used for the treatment of fever
and malaria in Africa yielded metabolites with potential antiplasmodial activity, many of which are
Anthraquinones (AQ). AQs have similar sub-structure as naphthoquinones and xanthones, which
were previously reported as novel antiplasmodial agents.
</P><P>
Objective: The present study aimed to investigate the structural requirements of 9,10-
anthraquinones with hydroxy, methoxy and methyl substituents to exert strong antiplasmodial activity
and to investigate their possible mode of action.
</P><P>
Methods: Thirty-one AQs were synthesized through Friedel-Crafts reaction and assayed for antiplasmodial
activity in vitro against Plasmodium falciparum (3D7). The selected compounds were
tested for toxicity and probed for their mode of action against β-hematin dimerization through
HRP2 and lipid catalyses. The most active compounds were subjected to a docking study using
AutoDock 4.2.
</P><P>
Results: The active AQs have similar common structural characteristics. However, it is difficult to
establish a structure-activity relationship as certain compounds are active despite the absence of the
structural features exhibited by other active AQs. They have either ortho- or meta-arranged
substituents and one free hydroxyl and/or carbonyl groups. When C-6 is substituted with a methyl
group, the activity of AQs generally increased. 1,3-DihydroxyAQ (15) showed good antiplasmodial
activity with an IC50 value of 1.08 µM, and when C-6 was substituted with a methyl group, 1,3-
dihydroxy-6-methylAQ (24) showed stronger antiplasmodial activity with an IC50 value of 0.02
µM, with better selectivity index. Compounds 15 and 24 showed strong HRP2 activity and mild
toxicity against hepatocyte cells. Molecular docking studies showed that the hydroxyl groups at the
ortho (23) and meta (24) positions are able to form hydrogen bonds with heme, of 3.49 Å and 3.02
Å, respectively.
</P><P>
Conclusion: The activity of 1,3-dihydroxy-6-methylAQ (24) could be due to their inhibition against
the free heme dimerization by inhibiting the HRP2 protein. It was further observed that the
anthraquinone moiety of compound 24 bind in parallel to the heme ring through hydrophobic interactions,
thus preventing crystallization of heme into hemozoin.
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Affiliation(s)
- Che Puteh Osman
- Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
| | - Nor Hadiani Ismail
- Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
| | - Aty Widyawaruyanti
- Department of Pharmacognosy and Phytochemistry, Faculty of Pharmacy, Universitas Airlangga, Surabaya 60286, Indonesia
| | - Syahrul Imran
- Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
| | - Lidya Tumewu
- Department of Pharmacognosy and Phytochemistry, Faculty of Pharmacy, Universitas Airlangga, Surabaya 60286, Indonesia
| | - Chee Yan Choo
- MedChem Herbal Research Group, Faculty of Pharmacy, Universiti Teknologi MARA, 42300 Bandar Puncak Alam, Selangor, Malaysia
| | - Sharinah Ideris
- MedChem Herbal Research Group, Faculty of Pharmacy, Universiti Teknologi MARA, 42300 Bandar Puncak Alam, Selangor, Malaysia
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13
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Osman CP, Ismail NH. Antiplasmodial Anthraquinones from Medicinal Plants: The Chemistry and Possible Mode of Actions. Nat Prod Commun 2018. [DOI: 10.1177/1934578x1801301207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Malaria killed nearly half a million people in 2015, and 70% of this victims were young children. Malarial chemotherapy makes use of several drugs, each with its own pharmacological limitations, and with parasite resistance being the most challenging. People of low income nations often rely on traditional medicine as a treatment due to limited access to modern healthcare services. Despite uncertainties present in the outcome of traditional medicine, ethnomedicine approach has yielded important lead candidates. The investigation of medicinal plants utilized in the malaria endemic region yielded many antiplasmodial compounds with anthraquinone moiety. This paper describes natural anthraquinones extracted from medicinal plants utilized in traditional medicine for the treatment of malaria. In addition, the insight on structure-activity relationship and their mode of actions are also elaborated.
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Affiliation(s)
- Che Puteh Osman
- Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
- Atta-ur Rahman Institute of Natural Product Discovery, Universiti Teknologi MARA Cawangan Selangor, 42300 Bandar Puncak Alam, Selangor, Malaysia
| | - Nor Hadiani Ismail
- Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
- Atta-ur Rahman Institute of Natural Product Discovery, Universiti Teknologi MARA Cawangan Selangor, 42300 Bandar Puncak Alam, Selangor, Malaysia
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14
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McBirney SE, Chen D, Scholtz A, Ameri H, Armani AM. Rapid Diagnostic for Point-of-Care Malaria Screening. ACS Sens 2018; 3:1264-1270. [PMID: 29781606 DOI: 10.1021/acssensors.8b00269] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite significant success in therapeutic development, malaria remains a widespread and deadly infectious disease in the developing world. Given the nearly 100% efficacy of current malaria therapeutics, the primary barrier to eradication is lack of early diagnosis of the infected population. However, there are multiple strains of malaria. Although significant efforts and resources have been invested in developing antibody-based diagnostic methods for Plasmodium falciparum, a rapid and easy to use screening method capable of detecting all malaria strains has not been realized. Yet, until the entire malaria-infected population receives treatment, the disease will continue to impact society. Here, we report the development of a portable, magneto-optic technology for early stage malaria diagnosis based on the detection of the malaria pigment, hemozoin. Using β-hematin, a hemozoin mimic, we demonstrate detection limits of <0.0081 μg/mL in 500 μL of whole rabbit blood with no additional reagents required. This level corresponds to <26 parasites/μL, a full order of magnitude below clinical relevance and comparable to or less than existing technologies.
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Affiliation(s)
| | | | - Alexis Scholtz
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Hossein Ameri
- USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California 90033, United States
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15
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Perez-Guaita D, Marzec KM, Hudson A, Evans C, Chernenko T, Matthäus C, Miljkovic M, Diem M, Heraud P, Richards JS, Andrew D, Anderson DA, Doerig C, Garcia-Bustos J, McNaughton D, Wood BR. Parasites under the Spotlight: Applications of Vibrational Spectroscopy to Malaria Research. Chem Rev 2018; 118:5330-5358. [DOI: 10.1021/acs.chemrev.7b00661] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- David Perez-Guaita
- Centre for Biospectroscopy, School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Katarzyna M. Marzec
- Jagiellonian Centre for Experimental Therapeutics (JCET), Jagiellonian University, Bobrzyńskiego 14, Kraków 30-348, Poland
- Center for Medical Genomics (OMICRON), Jagiellonian University, Kopernika 7C, Krakow 31-034, Poland
| | - Andrew Hudson
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Corey Evans
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Tatyana Chernenko
- Becton Dickinson and Company, 2350 Qume Drive, San Jose, California 95131, United States
| | - Christian Matthäus
- Leibniz Institute of Photonic Technology, Albert Einstein Straße 9, Jena 07745, Germany
- Institute of Physical Chemistry and Abbe School of Photonics, Friedrich Schiller University, Helmholtz Weg 4, Jena 07743, Germany
| | - Milos Miljkovic
- Department of Mechanical Engineering, Tufts University, 200 Boston Avenue, Medford, Massachusetts 02155, United States
| | - Max Diem
- Laboratory for Spectral Diagnosis (LSpD), Department of Chemistry and Chemical Biology, Northeastern University, 316 Hurtig Hall, 360 Huntington Avenue, Boston, Massachusetts 02155, United States
| | - Philip Heraud
- Centre for Biospectroscopy, School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Jack S. Richards
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria 3004, Australia
- Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
- Department of Medicine, University of Melbourne, Parkville, Victoria 3050, Australia
| | - Dean Andrew
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - David A. Anderson
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria 3004, Australia
| | - Christian Doerig
- Department of Microbiology and the Biomedical Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - Jose Garcia-Bustos
- Department of Microbiology and the Biomedical Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - Don McNaughton
- Centre for Biospectroscopy, School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Bayden R. Wood
- Centre for Biospectroscopy, School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
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16
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Perez-Guaita D, Kochan K, Batty M, Doerig C, Garcia-Bustos J, Espinoza S, McNaughton D, Heraud P, Wood BR. Multispectral Atomic Force Microscopy-Infrared Nano-Imaging of Malaria Infected Red Blood Cells. Anal Chem 2018; 90:3140-3148. [PMID: 29327915 DOI: 10.1021/acs.analchem.7b04318] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Atomic force microscopy-infrared (AFM-IR) spectroscopy is a powerful new technique that can be applied to study molecular composition of cells and tissues at the nanoscale. AFM-IR maps are acquired using a single wavenumber value: they show either the absorbance plotted against a single wavenumber value or a ratio of two absorbance values. Here, we implement multivariate image analysis to generate multivariate AFM-IR maps and use this approach to resolve subcellular structural information in red blood cells infected with Plasmodium falciparum at different stages of development. This was achieved by converting the discrete spectral points into a multispectral line spectrum prior to multivariate image reconstruction. The approach was used to generate compositional maps of subcellular structures in the parasites, including the food vacuole, lipid inclusions, and the nucleus, on the basis of the intensity of hemozoin, hemoglobin, lipid, and DNA IR marker bands, respectively. Confocal Raman spectroscopy was used to validate the presence of hemozoin in the regions identified by the AFM-IR technique. The high spatial resolution of AFM-IR combined with hyperspectral modeling enables the direct detection of subcellular components, without the need for cell sectioning or immunological/biochemical staining. Multispectral-AFM-IR thus has the capacity to probe the phenotype of the malaria parasite during its intraerythrocytic development. This enables novel approaches to studying the mode of action of antimalarial drugs and the phenotypes of drug-resistant parasites, thus contributing to the development of diagnostic and control measures.
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Affiliation(s)
- David Perez-Guaita
- Centre for Biospectroscopy , Monash University , Clayton , Victoria 3800 , Australia
| | - Kamila Kochan
- Centre for Biospectroscopy , Monash University , Clayton , Victoria 3800 , Australia
| | - Mitchell Batty
- Department of Microbiology and Infection & Immunity, Program Monash, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
| | - Christian Doerig
- Department of Microbiology and Infection & Immunity, Program Monash, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
| | - Jose Garcia-Bustos
- Department of Microbiology and Infection & Immunity, Program Monash, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
| | - Shirly Espinoza
- ELI Beamlines, Institute of Physics , Czech Academy of Science , Na Slovance 2 , 18221 Prague , Czech Republic
| | - Don McNaughton
- Centre for Biospectroscopy , Monash University , Clayton , Victoria 3800 , Australia
| | - Phil Heraud
- Centre for Biospectroscopy , Monash University , Clayton , Victoria 3800 , Australia.,Department of Microbiology and Infection & Immunity, Program Monash, Biomedicine Discovery Institute , Monash University , Clayton , Victoria 3800 , Australia
| | - Bayden R Wood
- Centre for Biospectroscopy , Monash University , Clayton , Victoria 3800 , Australia
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17
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Osman CP, Ismail NH. A REVIEW ON THE CHEMISTRY AND PHARMACOLOGY OF Rennellia elliptica Korth. INDONESIAN JOURNAL OF TROPICAL AND INFECTIOUS DISEASE 2017. [DOI: 10.20473/ijtid.v6i6.6642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Rennellia elliptica, popularly dubbed as Malaysian Ginseng, is widely used in traditional medicine among the local Jakun community in Endau-Rompin State Park, Pahang, Malaysia. The decoction of the roots is traditionally taken for treatment of body aches, as postpartum tonic, as aphrodisiac and for the treatment of jaundice. In the effort of searching new botanical drugs and drug candidates from tropical rainforest, the team from this laboratory had conducted a sizeable phytochemical and biological screening program of tropical plant at Endau Rompin State Park, Pahang with the help from the indigenous people. R. elliptica showed strong antiplasmodial activity in vitro with the IC50 value of 4.04µg/mL. The comprehensive study on the root extract of R. elliptica in this laboratory yielded seventeen compounds from four different classes, including 2 new pyranoanthraquinones, one new anthraquinone, eleven known anthraquinones, one lactone triterpenoid, one coumarin and one phenolic acid. The chemical profile of the root extract was established using HPLC and the selected marker compounds were used as external standards and quantified using standard calibration curve. Nordamnacanthal 5, damnacanthal 7, 2-formyl-3-hydroxy-9,10-anthraquinone 6, 2-methyl-3-hydroxy-9,10-anthraquinone 11 and 1,2-dimethoxy-6-methyl-9,10-anthraquinone 3 were determined at 3.57, 10.32, 4.47, 12.18 and 4.09 µg/g, respectively. Owing to the toxicity of dichloromethane, the extraction of the desired marker compounds was attempted using accelerated solvent extraction and soxhlet extraction using ethanol and water at different compositions. R. elliptica root extract and the isolated anthraquinones showed potential antiplasmodial activity, and the active compounds were probed for their mode of action. In addition, the dichloromethane root extract of R. elliptica and the selected anthraquinones were screened for anticancer, antioxidant, and α-glucosidase inhibitory activities as well as toxicity study in vitro. The review summarizes the findings on Rennellia elliptica which includes phytochemistry, toxicity and its biological activities. The chemotaxonomic significance of Rennellia elliptica is also discussed
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18
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In Vivo and In Vitro Activities and ADME-Tox Profile of a Quinolizidine-Modified 4-Aminoquinoline: A Potent Anti-P. falciparum and Anti-P. vivax Blood-Stage Antimalarial. Molecules 2017; 22:molecules22122102. [PMID: 29194347 PMCID: PMC6149971 DOI: 10.3390/molecules22122102] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 11/20/2017] [Accepted: 11/29/2017] [Indexed: 11/17/2022] Open
Abstract
Natural products are a prolific source for the identification of new biologically active compounds. In the present work, we studied the in vitro and in vivo antimalarial efficacy and ADME-Tox profile of a molecular hybrid (AM1) between 4-aminoquinoline and a quinolizidine moiety derived from lupinine (Lupinus luteus). The aim was to find a compound endowed with the target product profile-1 (TCP-1: molecules that clear asexual blood-stage parasitaemia), proposed by the Medicine for Malaria Venture to accomplish the goal of malaria elimination/eradication. AM1 displayed a very attractive profile in terms of both in vitro and in vivo activity. By using standard in vitro antimalarial assays, AM1 showed low nanomolar inhibitory activity against chloroquine-sensitive and resistant P. falciparum strains (range IC50 16–53 nM), matched with a high potency against P. vivax field isolates (Mean IC50 29 nM). Low toxicity and additivity with artemisinin derivatives were also demonstrated in vitro. High in vivo oral efficacy was observed in both P.berghei and P. yoelii mouse models with IC50 values comparable or better than those of chloroquine. The metabolic stability in different species and the pharmacokinetic profile in the mouse model makes AM1 a compound worth further investigation as a potential novel schizonticidal agent.
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19
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Olafson KN, Nguyen TQ, Vekilov PG, Rimer JD. Deconstructing Quinoline-Class Antimalarials to Identify Fundamental Physicochemical Properties of Beta-Hematin Crystal Growth Inhibitors. Chemistry 2017; 23:13638-13647. [PMID: 28833627 DOI: 10.1002/chem.201702251] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Indexed: 11/12/2022]
Abstract
A versatile approach to control crystallization involves the use of modifiers, which are additives that interact with crystal surfaces and alter their growth rates. Elucidating a modifier's binding specificity to anisotropic crystal surfaces is a ubiquitous challenge that is critical to their design. In this study, we select hematin, a byproduct of malaria parasites, as a model system to examine the complementarity of modifiers (i.e., antimalarial drugs) to β-hematin crystal surfaces. We divide two antimalarials, chloroquine and amodiaquine, into segments consisting of a quinoline base, common to both drugs, and side chains that differentiate their modes of action. Using a combination of scanning probe microscopy, bulk crystallization, and analytical techniques, we show that the base and side chain work synergistically to reduce the rate of hematin crystallization. In contrast to general observations that modifiers retain their function upon segmentation, we show that the constituents do not act as modifiers. A systematic study of quinoline isomers and analogues shows how subtle rearrangement and removal of functional moieties can create effective constituents from previously ineffective modifiers, along with tuning their inhibitory modes of action. These findings highlight the importance of specific functional moieties in drug compounds, leading to an improved understanding of modifier-crystal interactions that could prove to be applicable to the design of new antimalarials.
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Affiliation(s)
- Katy N Olafson
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA
| | - Tam Q Nguyen
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA
| | - Peter G Vekilov
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA.,Department of Chemistry, University of Houston, 3585 Cullen Boulevard, Houston, TX 77204, USA
| | - Jeffrey D Rimer
- Department of Chemical and Biomolecular Engineering, University of Houston, 4726 Calhoun Road, Houston, TX 77204, USA.,Department of Chemistry, University of Houston, 3585 Cullen Boulevard, Houston, TX 77204, USA
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20
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Fitzroy SM, Gildenhuys J, Olivier T, Tshililo NO, Kuter D, de Villiers KA. The Effects of Quinoline and Non-Quinoline Inhibitors on the Kinetics of Lipid-Mediated β-Hematin Crystallization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:7529-7537. [PMID: 28689414 PMCID: PMC5709178 DOI: 10.1021/acs.langmuir.7b01132] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The throughput of a biomimetic lipid-mediated assay used to investigate the effects of inhibitors on the kinetics of β-hematin formation has been optimized through the use of 24-well microplates. The rate constant for β-hematin formation mediated by monopalmitoyl-rac-glycerol was reduced from 0.17 ± 0.04 min-1 previously measured in Falcon tubes to 0.019 ± 0.002 min-1 in the optimized assay. While this necessitated longer incubation times, transferring aliquots from multiple 24-well plates to a single 96-well plate for final absorbance measurements actually improved the overall turnaround time per inhibitor. This assay has been applied to investigate the effects of four clinically relevant antimalarial drugs (chloroquine, amodiaquine, quinidine, and quinine) as well as several short-chain 4-aminoquinoline derivatives and non-quinoline (benzamide) compounds on the kinetics of β-hematin formation. The adsorption strength of these inhibitors to crystalline β-hematin (Kads) was quantified using a theoretical kinetic model that is based on the Avrami equation and the Langmuir isotherm. Statistically significant linear correlations between lipid-mediated β-hematin inhibitory activity and Kads values for quinoline (r2 = 0.76, P-value = 0.0046) and non-quinoline compounds (r2 = 0.99, P-stat = 0.0006), as well as between parasite inhibitory activity (D10) and Kads values for quinoline antimalarial drugs and short-chain chloroquine derivatives (r2 = 0.64, P-value = 0.0098), provide a strong indication that drug action involves adsorption to the surface of β-hematin crystals. Independent support in this regard is provided by experiments that spectrophotometrically monitor the direct adsorption of antimalarial drugs to preformed β-hematin.
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21
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Pisciotta JM, Scholl PF, Shuman JL, Shualev V, Sullivan DJ. Quantitative characterization of hemozoin in Plasmodium berghei and vivax. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 7:110-119. [PMID: 28279945 PMCID: PMC5342986 DOI: 10.1016/j.ijpddr.2017.02.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 02/01/2017] [Accepted: 02/03/2017] [Indexed: 12/21/2022]
Abstract
The incidence and global distribution of chloroquine resistant (CR) Plasmodium vivax infection has increased since emerging in 1989. The mechanism of resistance in CR P. vivax has not been defined. The resistance likely relates to the formation and disposition of hemozoin as chloroquine's primary mechanism of action involves disruption of hemozoin formation. CR P. berghei strains, like CR P. vivax strains, are confined to reticulocyte host cells and reportedly they do not accumulate appreciable intraerythrocytic hemozoin. Reports comparing hemozoin production between P. vivax strains and CR to chloroquine sensitive (CS) P. berghei are absent. Here we compare in vivo patterns of hemozoin formation and distribution in blood, spleen and liver tissue of male Swiss mice infected with CS or CR P. berghei not treated with chloroquine and CR P. berghei also treated with chloroquine. Light microscopy, laser desorption mass spectrometry and a colorimetric hemozoin assay detect trace hemozoin in the blood of CR P. berghei infected mice but significant hemozoin accumulation in liver and spleen tissue. Field emission in lens scanning electron microscopy reveals CR P. berghei hemozoin crystals are morphologically smaller but similar to those formed by CS parasites. CR P. berghei produces approximately five-fold less total hemozoin than CS strain. Lipid analysis of CS and CR P. berghei sucrose gradient purified bloodstage hemozoin indicates a similar lipid environment around the isolated hemozoin, predominately monopalmitic glycerol and monostearic glycerol. In contrast to CR and CS P. berghei, colorimetric hemozoin analysis of P. vivax strains indicates similar amounts of hemozoin are produced despite differing chloroquine sensitivities. These results suggest CR P. berghei forms significant hemozoin which accumulates in liver and spleen tissues and that the P. vivax chloroquine resistance mechanism differs from P. berghei. Chloroquine resistant Plasmodium berghei release measurable hemozoin into tissues with blood hemozoin 100 times less per parasite while total in all tissues is only 5 times less than chloroquine sensitive. Chloroquine resistant P. bergheihemozoin crystals are morphologically smaller but similar to those formed by chloroquine sensitive parasites. Chloroquine resistance in P. vivax is distinct from P. berghei even though both infect reticulocytes.
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Affiliation(s)
- John M Pisciotta
- Department of Molecular Microbiology and Immunology, Johns Hopkins University, Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205-2179, USA
| | - Peter F Scholl
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205-2103, USA
| | - Joel L Shuman
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Vladimir Shualev
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - David J Sullivan
- Department of Molecular Microbiology and Immunology, Johns Hopkins University, Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205-2179, USA.
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22
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High-Throughput Screening and Prediction Model Building for Novel Hemozoin Inhibitors Using Physicochemical Properties. Antimicrob Agents Chemother 2017; 61:AAC.01607-16. [PMID: 27919903 DOI: 10.1128/aac.01607-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 10/14/2016] [Indexed: 12/13/2022] Open
Abstract
It is essential to continue the search for novel antimalarial drugs due to the current spread of resistance against artemisinin by Plasmodium falciparum parasites. In this study, we developed in silico models to predict hemozoin inhibitors as a potential first-step screening for novel antimalarials. An in vitro colorimetric high-throughput screening assay of hemozoin formation was used to identify hemozoin inhibitors from 9,600 structurally diverse compounds. The physicochemical properties of positive hits and randomly selected compounds were extracted from the ChemSpider database; they were used for developing prediction models to predict hemozoin inhibitors using two different approaches, i.e., traditional multivariate logistic regression and Bayesian model averaging. Our results showed that a total of 224 positive-hit compounds exhibited the ability to inhibit hemozoin formation, with 50% inhibitory concentrations (IC50s) ranging from 3.1 μM to 199.5 μM. The best model according to traditional multivariate logistic regression included the three variables octanol-water partition coefficient, number of hydrogen bond donors, and number of atoms of hydrogen, while the best model according to Bayesian model averaging included the three variables octanol-water partition coefficient, number of hydrogen bond donors, and index of refraction. Both models had a good discriminatory power, with area under the curve values of 0.736 and 0.781 for the traditional multivariate model and Bayesian model averaging, respectively. In conclusion, the prediction models can be a new, useful, and cost-effective approach for the first screen of hemozoin inhibition-based antimalarial drug discovery.
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Sandlin R, Fong KY, Stiebler R, Gulka C, Nesbitt JE, Oliveira MP, Oliveira MF, Wright DW. Detergent-Mediated Formation of β-Hematin: Heme Crystallization Promoted by Detergents Implicates Nanostructure Formation for Use as a Biological Mimic. CRYSTAL GROWTH & DESIGN 2016; 16:2542-2551. [PMID: 27175104 PMCID: PMC4860678 DOI: 10.1021/acs.cgd.5b01580] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 03/07/2016] [Indexed: 06/05/2023]
Abstract
Hemozoin is a unique biomineral that results from the sequestration of toxic free heme liberated as a consequence of hemoglobin degradation in the malaria parasite. Synthetic neutral lipid droplets (SNLDs) and phospholipids were previously shown to support the rapid formation of β-hematin, abiological hemozoin, under physiologically relevant pH and temperature, though the mechanism by which heme crystallization occurs remains unclear. Detergents are particularly interesting as a template because they are amphiphilic molecules that spontaneously organize into nanostructures and have been previously shown to mediate β-hematin formation. Here, 11 detergents were investigated to elucidate the physicochemical properties that best recapitulate crystal formation in the parasite. A strong correlation between the detergent's molecular structure and the corresponding kinetics of β-hematin formation was observed, where higher molecular weight polar chains promoted faster reactions. The larger hydrophilic chains correlated to the detergent's ability to rapidly sequester heme into the lipophilic core, allowing for crystal nucleation to occur. The data presented here suggest that detergent nanostructures promote β-hematin formation in a similar manner to SNLDs and phospholipids. Through understanding mediator properties that promote optimal crystal formation, we are able to establish an in vitro assay to probe this drug target pathway.
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Affiliation(s)
- Rebecca
D. Sandlin
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee, United States
| | - Kim Y. Fong
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee, United States
| | - Renata Stiebler
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee, United States
- Laboratório de
Biologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo
Cruz, Rio de Janeiro, Brazil
| | - Christopher
P. Gulka
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee, United States
| | - Jenny E. Nesbitt
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee, United States
| | - Matheus P. Oliveira
- Laboratório
de Bioquímica de Resposta ao Estresse, Programa de Biologia
Molecular e Biotecnologia, Instituto de Bioquímica Médica,
Leopoldo de Meis, Universidade Federal do
Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Marcus F. Oliveira
- Laboratório
de Bioquímica de Resposta ao Estresse, Programa de Biologia
Molecular e Biotecnologia, Instituto de Bioquímica Médica,
Leopoldo de Meis, Universidade Federal do
Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - David W. Wright
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee, United States
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Electron tomography characterization of hemoglobin uptake in Plasmodium chabaudi reveals a stage-dependent mechanism for food vacuole morphogenesis. J Struct Biol 2016; 194:171-9. [PMID: 26882843 DOI: 10.1016/j.jsb.2016.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 02/11/2016] [Indexed: 02/07/2023]
Abstract
In the course of their intraerythrocytic development, malaria parasites incorporate and degrade massive amounts of the host cell cytoplasm. This mechanism is essential for parasite development and represents a physiological step used as target for many antimalarial drugs; nevertheless, the fine mechanisms underlying these processes in Plasmodium species are still under discussion. Here, we studied the events of hemoglobin uptake and hemozoin nucleation in the different stages of the intraerythrocytic cycle of the murine malaria parasite Plasmodium chabaudi using transmission electron tomography of cryofixed and freeze-substituted cells. The results showed that hemoglobin uptake in P. chabaudi starts at the early ring stage and is present in all developmental stages, including the schizont stage. Hemozoin nucleation occurs near the membrane of small food vacuoles. At the trophozoite stage, food vacuoles are found closely localized to cytostomal tubes and mitochondria, whereas in the schizont stage, we observed a large food vacuole located in the central portion of the parasite. Taken together, these results provide new insights into the mechanisms of hemoglobin uptake and degradation in rodent malaria parasites.
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Hemozoin is a product of heme detoxification in the gut of the most medically important species of the family Opisthorchiidae. Int J Parasitol 2016; 46:147-156. [PMID: 26812025 DOI: 10.1016/j.ijpara.2015.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/08/2015] [Accepted: 12/10/2015] [Indexed: 02/06/2023]
Abstract
Many species of trematodes such as Schistosoma spp., Fasciola hepatica and Echinostoma trivolvis are blood-feeding parasites. Nevertheless, there is no consensus on the feeding habits of the family Opisthorchiidae (Opisthorchis felineus, Opisthorchis viverrini and Clonorchis sinensis). Previously, histological studies of O. felineus and C. sinensis revealed some dark stained material in their gut lumen. In this study we conducted a comprehensive analysis of the gut contents of three members of the family Opisthorchiidae (O. felineus, O. viverrini and C. sinensis). Using transmission electron microscopy, we demonstrated for the first known time the presence of disintegrating blood cells in the gut of O. felineus as well as electron-dense crystals in the gut of O. felineus and C. sinensis. Electron energy loss spectroscopy revealed iron atoms in these crystals, and mass spectrometry of the purified pigment demonstrated the presence of heme. Fourier-transform infrared spectroscopy identified the signature peaks of the common iron-carboxylate bond characteristic in crystals isolated from O. felineus and C. sinensis. Scanning electron microscopy showed layered ovoid crystals of various sizes from 50 nm to 2 μm. Morphological, chemical and paramagnetic properties of these crystals were similar to those of hemozoin from Schistosoma mansoni. Crystal formation occurs on the surface of lipid droplets in O. felineus and C. sinensis guts. Our results suggest that the diet of O. felineus and C. sinensis includes blood. Detoxification of the free heme produced during the digestion proceeds via formation of insoluble crystals that contain iron and heme dimers, i.e. crystals of hemozoin. Furthermore, we believe that biocrystallisation of hemozoin takes place on the surface of the lipid droplets, similar to S. mansoni. Hemozoin was not detected in the closely related species O. viverrini.
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Kuter D, Mohunlal R, Fitzroy SM, Asher C, Smith PJ, Egan TJ, de Villiers KA. Insights into the initial stages of lipid-mediated haemozoin nucleation. CrystEngComm 2016. [DOI: 10.1039/c6ce00866f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lipid-mediated haemozoin nucleation, as probed by molecular dynamics, proceeds via aggregation of ferrihaem π–π dimers at a lipid–aqueous interface.
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Affiliation(s)
- David Kuter
- Department of Chemistry and Polymer Science
- Stellenbosch University
- Matieland 7602, South Africa
| | - Roxanne Mohunlal
- Department of Chemistry
- University of Cape Town
- Rondebosch 7701, South Africa
| | - Sharné-Maré Fitzroy
- Department of Chemistry and Polymer Science
- Stellenbosch University
- Matieland 7602, South Africa
| | - Constance Asher
- Department of Chemistry
- University of Cape Town
- Rondebosch 7701, South Africa
| | - Peter J. Smith
- Division of Pharmacology
- Department of Medicine
- University of Cape Town Medical School
- Observatory 7925, South Africa
| | - Timothy J. Egan
- Department of Chemistry
- University of Cape Town
- Rondebosch 7701, South Africa
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de la Lande A, Ha-Thi MH, Chen S, Soep B, Shafizadeh N. Structure of cobalt protoporphyrin chloride and its dimer, observation and DFT modeling. Phys Chem Chem Phys 2016; 18:16700-8. [DOI: 10.1039/c6cp02304e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this article we present a joint study by using time-of-flight mass spectroscopy and density functional theory of cobalt protoporphyrin dimer complexes.
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Affiliation(s)
- Aurélien de la Lande
- Laboratoire de Chimie Physique
- CNRS
- Université Paris-Sud
- Université Paris Saclay
- Orsay F-91405
| | - Minh-Huong Ha-Thi
- ISMO
- Univ Paris-Sud
- CNRS UMR 8214
- bat 210 Université Paris-Sud
- Université Paris Saclay
| | - Shufeng Chen
- Laboratoire de Chimie Physique
- CNRS
- Université Paris-Sud
- Université Paris Saclay
- Orsay F-91405
| | - Benoît Soep
- Laboratoire Francis Perrin CEA/DSM/IRAMIS/LIDyL – CNRS URA 2453
- CEA Saclay
- 91191 Gif-sur-Yvette Cedex
- France
| | - Niloufar Shafizadeh
- ISMO
- Univ Paris-Sud
- CNRS UMR 8214
- bat 210 Université Paris-Sud
- Université Paris Saclay
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Gildenhuys J, Sammy CJ, Müller R, Streltsov VA, le Roex T, Kuter D, de Villiers KA. Alkoxide coordination of iron(III) protoporphyrin IX by antimalarial quinoline methanols: a key interaction observed in the solid-state and solution. Dalton Trans 2015; 44:16767-77. [PMID: 26335948 DOI: 10.1039/c5dt02671g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The quinoline methanol antimalarial drug mefloquine is a structural analogue of the Cinchona alkaloids, quinine and quinidine. We have elucidated the single crystal X-ray diffraction structure of the complexes formed between racemic erythro mefloquine and ferriprotoporphyrin IX (Fe(iii)PPIX) and show that alkoxide coordination is a key interaction in the solid-state. Mass spectrometry confirms the existence of coordination complexes of quinine, quinidine and mefloquine to Fe(iii)PPIX in acetonitrile. The length of the iron(iii)-O bond in the quinine and quinidine complexes as determined by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy unequivocally confirms that coordination of the quinoline methanol compounds to Fe(iii)PPIX occurs in non-aqueous aprotic solution via their benzylic alkoxide functional group. UV-visible spectrophotometric titrations of the low-spin bis-pyridyl-Fe(iii)PPIX complex with each of the quinoline methanol compounds results in the displacement of a single pyridine molecule and subsequent formation of a six-coordinate pyridine-Fe(iii)PPIX-drug complex. We propose that formation of the drug-Fe(iii)PPIX coordination complexes is favoured in a non-aqueous environment, such as that found in lipid bodies or membranes in the malaria parasite, and that their existence may contribute to the mechanism of haemozoin inhibition or other toxicity effects that lead ultimately to parasite death. In either case, coordination is a key interaction to be considered in the design of novel antimalarial drug candidates.
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Affiliation(s)
- Johandie Gildenhuys
- Stellenbosch University, Department of Chemistry and Polymer Science, Private Bag X1, Matieland, 7602, Stellenbosch, South Africa.
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Wu X, Gowda NM, Gowda DC. Phagosomal Acidification Prevents Macrophage Inflammatory Cytokine Production to Malaria, and Dendritic Cells Are the Major Source at the Early Stages of Infection: IMPLICATION FOR MALARIA PROTECTIVE IMMUNITY DEVELOPMENT. J Biol Chem 2015; 290:23135-47. [PMID: 26240140 DOI: 10.1074/jbc.m115.671065] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 12/15/2022] Open
Abstract
Inflammatory cytokines produced at the early stages of malaria infection contribute to shaping protective immunity and pathophysiology. To gain mechanistic insight into these processes, it is important to understand the cellular origin of cytokines because both cytokine input and cytokine-producing cells play key roles. Here, we determined cytokine responses by monocytes, macrophages, and dendritic cells (DCs) to purified Plasmodium falciparum and Plasmodium berghei ANKA, and by spleen macrophages and DCs from Plasmodium yoelii 17NXL-infected and P. berghei ANKA-infected mice. The results demonstrate that monocytes and macrophages do not produce inflammatory cytokines to malaria parasites and that DCs are the primary source early in infection, and DC subsets differentially produce cytokines. Importantly, blocking of phagosomal acidification by inhibiting vacuolar-type H(+)-ATPase enabled macrophages to elicit cytokine responses. Because cytokine responses to malaria parasites are mediated primarily through endosomal Toll-like receptors, our data indicate that the inability of macrophages to produce cytokines is due to the phagosomal acidification that disrupts endosomal ligand-receptor engagement. Macrophages efficiently produced cytokines to LPS upon simultaneously internalizing parasites and to heat-killed Escherichia coli, demonstrating that phagosomal acidification affects endosomal receptor-mediated, but not cell surface receptor-mediated, recognition of Toll-like receptor agonists. Enabling monocytes/macrophages to elicit immune responses to parasites by blocking endosomal acidification can be a novel strategy for the effective development of protective immunity to malaria. The results have important implications for enhancing the efficacy of a whole parasite-based malaria vaccine and for designing strategies for the development of protective immunity to pathogens that induce immune responses primarily through endosomal receptors.
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Affiliation(s)
- Xianzhu Wu
- From the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Nagaraj M Gowda
- From the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - D Channe Gowda
- From the Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
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Ali ME, Oppeneer PM. Unraveling the Electronic Structure, Spin States, Optical and Vibrational Spectra of Malaria Pigment. Chemistry 2015; 21:8544-53. [DOI: 10.1002/chem.201406208] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Indexed: 12/19/2022]
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N10,N11-di-alkylamine indolo[3,2-b]quinolines as hemozoin inhibitors: Design, synthesis and antiplasmodial activity. Bioorg Med Chem 2015; 23:1530-9. [DOI: 10.1016/j.bmc.2015.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/02/2015] [Accepted: 02/04/2015] [Indexed: 11/20/2022]
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Identification and deconvolution of cross-resistance signals from antimalarial compounds using multidrug-resistant Plasmodium falciparum strains. Antimicrob Agents Chemother 2014; 59:1110-8. [PMID: 25487796 DOI: 10.1128/aac.03265-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum, the most deadly agent of malaria, displays a wide variety of resistance mechanisms in the field. The ability of antimalarial compounds in development to overcome these must therefore be carefully evaluated to ensure uncompromised activity against real-life parasites. We report here on the selection and phenotypic as well as genotypic characterization of a panel of sensitive and multidrug-resistant P. falciparum strains that can be used to optimally identify and deconvolute the cross-resistance signals from an extended panel of investigational antimalarials. As a case study, the effectiveness of the selected panel of strains was demonstrated using the 1,2,4-oxadiazole series, a newly identified antimalarial series of compounds with in vitro activity against P. falciparum at nanomolar concentrations. This series of compounds was to be found inactive against several multidrug-resistant strains, and the deconvolution of this signal implicated pfcrt, the genetic determinant of chloroquine resistance. Targeted mode-of-action studies further suggested that this new chemical series might act as falcipain 2 inhibitors, substantiating the suggestion that these compounds have a site of action similar to that of chloroquine but a distinct mode of action. New antimalarials must overcome existing resistance and, ideally, prevent its de novo appearance. The panel of strains reported here, which includes recently collected as well as standard laboratory-adapted field isolates, is able to efficiently detect and precisely characterize cross-resistance and, as such, can contribute to the faster development of new, effective antimalarial drugs.
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Metal-chloroquine derivatives as possible anti-malarial drugs: evaluation of anti-malarial activity and mode of action. Malar J 2014; 13:471. [PMID: 25470995 PMCID: PMC4289335 DOI: 10.1186/1475-2875-13-471] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 11/29/2014] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Malaria still has significant impacts on the world; particularly in Africa, South America and Asia where spread over several millions of people and is one of the major causes of death. When chloroquine diphosphate (CQDP) lost its efficiency as a first-line anti-malarial drug, this was a major setback in the effective control of malaria. Currently, malaria is treated with a combination of two or more drugs with different modes of action to provide an adequate cure rate and delay the development of resistance. Clearly, a new effective and non-toxic anti-malarial drug is urgently needed. METHODS All metal-chloroquine (CQ) and metal-CQDP complexes were synthesized under N(2) using Schlenk techniques. Their interactions with haematin and the inhibition of β-haematin formation were examined, in both aqueous medium and near water/n-octanol interfaces at pH 5. The anti-malarial activities of these metal- CQ and metal-CQDP complexes were evaluated in vitro against two strains, the CQ-susceptible strain (CQS) 3D7 and the CQ-resistant strain (CQR) W2. RESULTS The previously synthesized Au(CQ)(Cl) (1), Au(CQ)(TaTg) (2), Pt(CQDP)(2)Cl(2) (3), Pt(CQDP)(2)I(2) (4), Pd(CQ)(2)Cl(2) (5) and the new one Pd(CQDP)(2)I(2) (6) showed better anti-malarial activity than CQ, against the CQS strain; moreover, complexes 2, 3 and 4 were very active against CQR strain. These complexes (1-6) interacted with haem and inhibited β-haematin formation both in aqueous medium and near water/n-octanol interfaces at pH 5 to a greater extent than chloroquine diphosphate (CQDP) and other known metal-based anti-malarial agents. CONCLUSIONS The high anti-malarial activity displayed for these metal-CQ and metal-CQDP complexes (1-6) could be attributable to their effective interaction with haem and the inhibition of β-haematin formation in both aqueous medium and near water/n-octanol interfaces at pH 5.
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Involvement of Nod2 in the innate immune response elicited by malarial pigment hemozoin. Microbes Infect 2014; 17:184-94. [PMID: 25462568 DOI: 10.1016/j.micinf.2014.11.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 10/15/2014] [Accepted: 11/11/2014] [Indexed: 02/07/2023]
Abstract
In malaria, the evidence concerning the nucleotide-binding, oligomerization domain (NOD) 2 (NOD2) receptor is fragmented and the stimuli that might activate NOD2 are not well characterized. We investigated the role of NOD2 in vitro in the response of macrophages to Plasmodium falciparum products. Immortalized or primary bone marrow derived macrophages from wild type C57Bl/6 mice, or knockout mice for NOD2 or its adaptor proteins, were either primed with interferon gamma or left untreated, and stimulated with parasite products. Both lysates of infected erythrocytes or hemozoin induced higher levels of nitric oxide in primed than in unprimed wild type macrophages. When stimulated with hemozoin, primed macrophages knockout for NOD2, or for its adaptor proteins, produced significantly lower nitric oxide levels compared to wild type cells. Differently from hemozoin, the use of β-hematin (synthetic hemozoin) as stimulus showed that NOD2 is dispensable. Furthermore, the production of inflammatory cytokines by wild type cells treated with hemozoin was not dependent on NOD2. These data indicate that parasite components present in the hemozoin, differently from β-hematin, induce the production of nitric oxide through the activation of NOD2, whereas the production of inflammatory cytokines, like TNF-α or MIP-2 (CXCL2), seems to be NOD2 independent.
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35
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Kuter D, Streltsov V, Davydova N, Venter GA, Naidoo KJ, Egan TJ. Molecular structures and solvation of free monomeric and dimeric ferriheme in aqueous solution: insights from molecular dynamics simulations and extended X-ray absorption fine structure spectroscopy. Inorg Chem 2014; 53:10811-24. [PMID: 25275882 DOI: 10.1021/ic500454d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
CHARMM force field parameters have been developed to model nonprotein bound five-coordinate ferriheme (ferriprotoporphyrin IX) species in aqueous solution. Structures and solvation were determined from molecular dynamics (MD) simulations at 298 K of monomeric [HO-ferriheme](2-), [H2O-ferriheme](-), and [H2O-ferriheme](0); π-π dimeric [(HO-ferriheme)2](4-), [(H2O-ferriheme)(HO-ferriheme)](3-), [(H2O-ferriheme)2](2-), and [(H2O-ferriheme)2](0); and μ-oxo dimeric [μ-(ferriheme)2O](4-). Solvation of monomeric species predominated around the axial ligand, meso-hydrogen atoms of the porphyrin ring (Hmeso), and the unligated face. Existence of π-π ferriheme dimers in aqueous solution was supported by MD calculations where such dimers remained associated over the course of the simulation. Porphyrin rings were essentially coplanar. In these dimers major and minor solvation was observed around the axial ligand and Hmeso positions, respectively. In μ-oxo ferriheme, strong solvation of the unligated face and bridging oxide ligand was observed. The solution structure of the μ-oxo dimer was investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy. The EXAFS spectrum obtained from frozen solution was markedly different from that recorded on dried μ-oxo ferriheme solid. Inclusion of five solvent molecules obtained from spatial distribution functions in the structure generated from MD simulation was required to produce acceptable fits to the EXAFS spectra of the dimer in solution, while the solid was suitably fitted using the crystal structure of μ-oxo ferriheme dimethyl ester which included no solvent molecules.
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Affiliation(s)
- David Kuter
- Scientific Computing Research Unit, †Department of Chemistry, University of Cape Town , Private Bag, Rondebosch 7701, South Africa
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Sandlin RD, Fong KY, Wicht KJ, Carrell HM, Egan TJ, Wright DW. Identification of β-hematin inhibitors in a high-throughput screening effort reveals scaffolds with in vitro antimalarial activity. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2014; 4:316-25. [PMID: 25516843 PMCID: PMC4266794 DOI: 10.1016/j.ijpddr.2014.08.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Hemozoin formation is a prime drug target pathway to probe for new lead compounds. We examined the VICB library of compounds for in vitro β-hematin inhibition. β-Hematin inhibitors were tested for in vitro antimalarial activity in two P. falciparum strains. Chemical scaffolds with target-specific and in vitro antimalarial activity were identified.
The emergence of drug resistant strains of Plasmodium spp. creates a critical need for the development of novel antimalarials. Formation of hemozoin, a crystalline heme detoxification process vital to parasite survival serves as an important drug target. The quinoline antimalarials including chloroquine and amodiaquine owe their antimalarial activity to inhibition of hemozoin formation. Though in vivo formation of hemozoin occurs within the presence of neutral lipids, the lipophilic detergent NP-40 was previously shown to serve as a surrogate in the β-hematin (synthetic hemozoin) formation process. Consequently, an NP-40 mediated β-hematin formation assay was developed for use in high-throughput screening. Here, the assay was utilized to screen 144,330 compounds for the identification of inhibitors of crystallization, resulting in 530 hits. To establish the effectiveness of these target-based β-hematin inhibitors against Plasmodiumfalciparum, each hit was further tested in cultures of parasitized red blood cells. This effort revealed that 171 of the β-hematin inhibitors are also active against the parasite. Dose–response data identified 73 of these β-hematin inhibitors have IC50 values ⩽5 μM, including 25 compounds with nanomolar activity against P. falciparum. A scaffold-based analysis of this data identified 14 primary scaffolds that represent 46% of the 530 total hits. Representative compounds from each of the classes were further assessed for hemozoin inhibitory activity in P. falciparum infected human erythrocytes. Each of the hit compounds tested were found to be positive inhibitors, while a negative control did not perturb this biological pathway in culture.
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Affiliation(s)
- Rebecca D Sandlin
- Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235, USA
| | - Kim Y Fong
- Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235, USA
| | - Kathryn J Wicht
- Department of Chemistry, University of Cape Town, Rondebosch 7700, South Africa
| | - Holly M Carrell
- Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235, USA
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Rondebosch 7700, South Africa
| | - David W Wright
- Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235, USA
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Olafson KN, Rimer JD, Vekilov PG. Growth of Large Hematin Crystals in Biomimetic Solutions. CRYSTAL GROWTH & DESIGN 2014; 14:2123-2127. [PMID: 24839403 PMCID: PMC4018177 DOI: 10.1021/cg5002682] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 04/07/2014] [Indexed: 06/03/2023]
Abstract
Hematin crystallization is an essential component of the physiology of malaria parasites. Several antimalarial drugs are believed to inhibit crystallization and expose the parasites to toxic soluble hematin. Hence, understanding the mechanisms of hematin crystal growth and inhibition is crucial for the design of new drugs. A major obstacle to microscopic, spectroscopic, and crystallographic studies of hematin crystallization has been the unavailability of large hematin crystals grown under conditions representative of the parasite anatomy. We have developed a biomimetic method to reproducibly grow large hematin crystals reaching 50 μm in length. We imitate the digestive vacuole of Plasmodium falciparum and employ a two-phase solution of octanol and citric buffer. The nucleation of seeds is enhanced at the interface between the aqueous and organic phases, where an ordered layer of octanol molecules is known to serve as substrate for nucleation. The seeds are transferred to hematin-saturated octanol in contact with citric buffer. We show that the crystals grow in the octanol layer, while the buffer supplies hydrogen ions needed for bonds that link the hematin molecules in the crystal. The availability of large hematin crystals opens new avenues for studies of hematin detoxification of malaria parasites in host erythrocytes.
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Affiliation(s)
- Katy N. Olafson
- Department
of Chemical and Biomolecular Engineering,
and Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Jeffrey D. Rimer
- Department
of Chemical and Biomolecular Engineering,
and Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Peter G. Vekilov
- Department
of Chemical and Biomolecular Engineering,
and Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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38
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Ketchum MA, Olafson KN, Petrova EV, Rimer JD, Vekilov PG. Hematin crystallization from aqueous and organic solvents. J Chem Phys 2014; 139:121911. [PMID: 24089723 DOI: 10.1063/1.4816106] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Hematin crystallization is the main mechanism of detoxification of heme that is released in malaria-infected erythrocytes as a byproduct of the hemoglobin catabolism by the parasite. A controversy exists over whether hematin crystals grow from the aqueous medium of the parasite's digestive vacuole or in the lipid bodies present in the vacuole. To this end, we compare the basic thermodynamic and structural features of hematin crystallization in an aqueous buffer at pH 4.8, as in the digestive vacuole, and in water-saturated octanol that mimics the environment of the lipid nanospheres. We show that in aqueous solutions, hematin aggregation into mesoscopic disordered clusters is insignificant. We determine the solubility of the β-hematin crystals in the pH range 4.8-7.6. We image by atomic force microscopy crystals grown at pH 4.8 and show that their macroscopic and mesoscopic morphology features are incompatible with those reported for biological hemozoin. In contrast, crystals grown in the presence of octanol are very similar to those extracted from parasites. We determine the hematin solubility in water-saturated octanol at three temperatures. These solubilities are four orders of magnitude higher than that at pH 4.8, providing for faster crystallization from organic than from aqueous solvents. These observations further suggest that the lipid bodies play a role in mediating biological hemozoin crystal growth to ensure faster heme detoxification.
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Affiliation(s)
- Megan A Ketchum
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, USA
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Paulo A, Figueiras M, Machado M, Charneira C, Lavrado J, Santos SA, Lopes D, Gut J, Rosenthal PJ, Nogueira F, Moreira R. Bis-alkylamine Indolo[3,2-b]quinolines as Hemozoin Ligands: Implications for Antimalarial Cytostatic and Cytocidal Activities. J Med Chem 2014; 57:3295-313. [DOI: 10.1021/jm500075d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Alexandra Paulo
- Instituto
de Investigação do Medicamento (iMed.ULisboa), Faculdade
de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Marta Figueiras
- Instituto
de Investigação do Medicamento (iMed.ULisboa), Faculdade
de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Marta Machado
- UEI
Malaria, Centro da Malária e Doenças Tropicais, IHMT, Universidade Nova de Lisboa, Rua da Junqueira, 100, P-1349-008 Lisboa, Portugal
| | - Catarina Charneira
- Instituto
de Investigação do Medicamento (iMed.ULisboa), Faculdade
de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - João Lavrado
- Instituto
de Investigação do Medicamento (iMed.ULisboa), Faculdade
de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Sofia A. Santos
- Instituto
de Investigação do Medicamento (iMed.ULisboa), Faculdade
de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Dinora Lopes
- UEI
Malaria, Centro da Malária e Doenças Tropicais, IHMT, Universidade Nova de Lisboa, Rua da Junqueira, 100, P-1349-008 Lisboa, Portugal
| | - Jiri Gut
- Department
of Medicine, San Francisco General Hospital, University of California, San Francisco, Box 0811, San Francisco, California 94143, United States
| | - Philip J. Rosenthal
- Department
of Medicine, San Francisco General Hospital, University of California, San Francisco, Box 0811, San Francisco, California 94143, United States
| | - Fátima Nogueira
- UEI
Malaria, Centro da Malária e Doenças Tropicais, IHMT, Universidade Nova de Lisboa, Rua da Junqueira, 100, P-1349-008 Lisboa, Portugal
| | - Rui Moreira
- Instituto
de Investigação do Medicamento (iMed.ULisboa), Faculdade
de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
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40
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Stiebler R, Majerowicz D, Knudsen J, Gondim KC, Wright DW, Egan TJ, Oliveira MF. Unsaturated glycerophospholipids mediate heme crystallization: biological implications for hemozoin formation in the kissing bug Rhodnius prolixus. PLoS One 2014; 9:e88976. [PMID: 24586467 PMCID: PMC3935856 DOI: 10.1371/journal.pone.0088976] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 01/17/2014] [Indexed: 11/19/2022] Open
Abstract
Hemozoin (Hz) is a heme crystal produced by some blood-feeding organisms, as an efficient way to detoxify heme derived from hemoglobin digestion. In the triatomine insect Rhodnius prolixus, Hz is essentially produced by midgut extracellular phospholipid membranes known as perimicrovillar membranes (PMVM). Here, we investigated the role of commercial glycerophospholipids containing serine, choline and ethanolamine as headgroups and R. prolixus midgut lipids (RML) in heme crystallization. All commercial unsaturated forms of phospholipids, as well as RML, mediated fast and efficient β-hematin formation by means of two kinetically distinct mechanisms: an early and fast component, followed by a late and slow one. The fastest reactions observed were induced by unsaturated forms of phosphatidylethanolamine (uPE) and phosphatidylcholine (uPC), with half-lives of 0.04 and 0.7 minutes, respectively. β-hematin crystal morphologies were strikingly distinct among groups, with uPE producing homogeneous regular brick-shaped crystals. Interestingly, uPC-mediated reactions resulted in two morphologically distinct crystal populations: one less representative group of regular crystals, resembling those induced by uPE, and the other largely represented by crystals with numerous sharp edges and tapered ends. Heme crystallization reactions induced by RML were efficient, with a heme to β-hematin conversion rate higher than 70%, but clearly slower (t1/2 of 9.9-17.7 minutes) than those induced by uPC and uPE. Interestingly, crystals produced by RML were homogeneous in shape and quite similar to those mediated by uPE. Thus, β-hematin formation can be rapidly and efficiently induced by unsaturated glycerophospholipids, particularly uPE and uPC, and may play a role on biological heme crystallization in R. prolixus midgut.
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Affiliation(s)
- Renata Stiebler
- Laboratório de Bioquímica de Resposta ao Estresse, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, RJ, Brazil
- Laboratório de Inflamação e Metabolismo, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - David Majerowicz
- Laboratório de Bioquímica e Fisiologia de Insetos, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, RJ, Brazil
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Departamento de Biotecnologia Farmacêutica, Faculdade de Farmácia,Universidade Federal do Rio de Janeiro, RJ, Brazil
| | - Jens Knudsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Katia C. Gondim
- Laboratório de Bioquímica e Fisiologia de Insetos, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, RJ, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ, Brazil
| | - David W. Wright
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch, South Africa
| | - Marcus F. Oliveira
- Laboratório de Bioquímica de Resposta ao Estresse, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, RJ, Brazil
- Laboratório de Inflamação e Metabolismo, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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Abstract
Recent initiatives to develop more effective and affordable drugs, controlling mosquitoes and development of a preventative vaccine have been launched with the goal of completely eradicating malaria. To this end, Novartis (Surrey, UK) and GlaxoSmithKline (Middlesex, UK) screened their chemical libraries of approximately two million small molecules for antimalarial properties, which resulted in a set of over 20,000 'highly druggable' initial hits. Efforts in academia are centered on specific pathway targets. One such high-throughput screening effort has been focused on hemozoin formation, a unique heme detoxification pathway found in the malaria parasite. This review discusses the current approaches and limitations of high-throughput screening discovery of hemozoin inhibitors. In the future, new methods must be developed to validate the mechanism of action of these hit compounds within the parasite.
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42
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Roepe PD. To kill or not to kill, that is the question: cytocidal antimalarial drug resistance. Trends Parasitol 2014; 30:130-5. [PMID: 24530127 DOI: 10.1016/j.pt.2014.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/07/2014] [Accepted: 01/09/2014] [Indexed: 02/03/2023]
Abstract
Elucidating mechanisms of antimalarial drug resistance accelerates development of improved diagnostics and the design of new, effective malaria therapy. Recently, several studies have emphasized that chloroquine (CQ) resistance (CQR) can be quantified in two very distinct ways, depending on whether sensitivity to the growth inhibitory effects or parasite-kill effects of the drug are being measured. It is now clear that these cytostatic and cytocidal CQR phenotypes are not equivalent, and recent genetic, cell biological, and biophysical evidence suggests how the molecular mechanisms may overlap. These conclusions have important implications for elucidating other drug resistance phenomena and emphasize new concepts that are essential for the development of new drug therapy.
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Affiliation(s)
- Paul D Roepe
- Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington DC 20057, USA; Department of Biochemistry and Cellular and Molecular Biology, Georgetown University, 37th and O Streets NW, Washington DC 20057, USA.
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Abstract
In recent years, the field of Raman spectroscopy has witnessed a surge in technological development, with the incorporation of ultrasensitive, charge-coupled devices, improved laser sources and precision Rayleigh-filter systems. This has led to the development of sensitive confocal micro-Raman spectrometers and imaging spectrometers that are capable of obtaining high spatial-resolution spectra and images of subcellular components within single living cells. This review reports on the application of resonance micro-Raman spectroscopy to the study of malaria pigment (hemozoin), a by-product of hemoglobin catabolization by the malaria parasite, which is an important target site for antimalarial drugs. The review aims to briefly describe recent studies on the application of this technology, elucidate molecular and electronic properties of the malaria pigment and its synthetic analog beta-hematin, provide insight into the mechanism of hemozoin formation within the food vacuole of the parasite, and comment on developing strategies for using this technology in drug-screening protocols.
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Affiliation(s)
- Bayden R Wood
- Monash University, Centre for Biospectroscopy and School of Chemistry, Victoria, 3800, Australia.
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44
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Kapishnikov S, Weiner A, Shimoni E, Schneider G, Elbaum M, Leiserowitz L. Digestive vacuole membrane in Plasmodium falciparum-infected erythrocytes: relevance to templated nucleation of hemozoin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:14595-14602. [PMID: 24237179 DOI: 10.1021/la402545c] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Crystallization of the malaria pigment hemozoin sequesters the toxic heme byproduct of hemoglobin digestion in Plasmodium -infected red blood cells (RBCs). Recently, we applied electron and X-ray imaging and diffraction methods to elucidate this process. We observed crystals oriented with their {100} faces at the inner membrane surface of the digestive vacuole (DV) of Plasmodium falciparum in parasitized RBCs. Modeling of the soft X-ray tomographic (SXT) images of a trophozoite-stage parasite indicated a 4-16 nm DV membrane thickness, suggesting a possible role for lipid multilayers. Here, we reanalyzed the trophozoite SXT images quantitatively via X-ray absorption to map the DV membrane thickness. Making use of the chemical structure and crystal density of the lipid, we found, predominantly, a bilayer 4.2 nm thick, and the remainder was interpreted as patches ∼8 nm thick. Image analysis of electron micrographs also yielded a 4-5 nm DV membrane thickness. The DV lipid membrane is thus mainly a bilayer, so induced hemozoin nucleation occurs primarily via the inner of the membrane's two leaflets. We argue that such a leaflet embodying mono- and di-acyl lipids with appropriate OH or NH bearing head groups may catalyse hemozoin nucleation by stereochemical and lattice match to the {100} crystal face, involving a two-dimensional nucleation aggregate of ∼100 molecules.
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Affiliation(s)
- Sergey Kapishnikov
- Department of Materials and Interfaces, Weizmann Institute of Science , Rehovot 76100, Israel
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45
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Ambele MA, Sewell BT, Cummings FR, Smith PJ, Egan TJ. Synthetic Hemozoin (β-Hematin) Crystals Nucleate at the Surface of Neutral Lipid Droplets that Control Their Sizes. CRYSTAL GROWTH & DESIGN 2013; 13:10.1021/cg4009416. [PMID: 24244110 PMCID: PMC3826461 DOI: 10.1021/cg4009416] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Emulsions of monopalmitoylglycerol (MPG) and of a neutral lipid blend (NLB), consisting of MPG, monostearoylglycerol, dipalmitoylglycerol, dioleoylglycerol and dilineoylglycerol (4:2:1:1:1), the composition associated with hemozoin from the malaria parasite Plasmodium falciparum, have been used to mediate the formation of β-hematin microcrystals. Transmission electron microscopy (TEM), electron diffraction and electron spectroscopic imaging/electron energy loss spectroscopy (ESI/EELS) have been used to characterize both the lipid emulsion and β-hematin crystals. The latter have been compared with β-hematin formed at a pentanol/aqueous interface and with hemozoin both within P. falciparum parasites and extracted from the parasites. When lipid and ferriprotoporphyrin IX solutions in 1:9 v/v acetone/methanol were thoroughly pre-mixed either using an extruder or ultrasound, β-hematin crystals were found formed in intimate association with the lipid droplets. These crystals resembled hemozoin crystals, with prominent {100} faces. Lattice fringes in TEM indicated that these faces made contact with the lipid surface. The average length of these crystals was 0.62 times the average diameter of NLB droplets and their size distributions were statistically equivalent after 10 min incubation, suggesting that the lipid droplets also controlled the sizes of the crystals. This most closely resembles hemozoin formation in the helminth worm Schistosoma mansoni, while in P. falciparum, crystal formation appears to be associated with the much more gently curved digestive vacuole membrane which apparently leads to formation of much larger hemozoin crystals, similar to those formed at the flat pentanol-water interface.
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Affiliation(s)
- Melvin A. Ambele
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
| | - B. Trevor Sewell
- Electron Microscope Unit, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
| | - Franscious R. Cummings
- Electron Microscope Unit, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
| | - Peter J. Smith
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
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Egan TJ, Kuter D. Dual-functioning antimalarials that inhibit the chloroquine-resistance transporter. Future Microbiol 2013; 8:475-89. [PMID: 23534360 PMCID: PMC7099626 DOI: 10.2217/fmb.13.18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Malaria remains a major international health challenge. Resistance to a number of existing drugs and evidence of the emergence of artemisinin resistance has emphasized the need for new antimalarials. A new approach has been the preparation of dual-function compounds that include a chloroquine-like antimalarial group and a group that resembles a chloroquine chemosensitizer. This article reviews the recent discovery of such dual-function antimalarials that are proposed to target both hemozoin formation and the chloroquine resistance transporter, PfCRT. These are discussed in relation to the mechanism of action of 4-aminoquinolines, chloroquine resistance and resistance reversal.
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Affiliation(s)
- Timothy J Egan
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701, South Africa.
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47
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Gorka AP, de Dios A, Roepe PD. Quinoline drug-heme interactions and implications for antimalarial cytostatic versus cytocidal activities. J Med Chem 2013; 56:5231-46. [PMID: 23586757 DOI: 10.1021/jm400282d] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Historically, the most successful molecular target for antimalarial drugs has been heme biomineralization within the malarial parasite digestive vacuole. Heme released from catabolized host red blood cell hemoglobin is toxic, so malarial parasites crystallize heme to nontoxic hemozoin. For years it has been accepted that a number of effective quinoline antimalarial drugs (e.g., chloroquine, quinine, amodiaquine) function by preventing hemozoin crystallization. However, recent studies over the past decade have revealed a surprising molecular diversity in quinoline-heme molecular interactions. This diversity shows that even closely related quinoline drugs may have quite different molecular pharmacology. This paper reviews the molecular diversity and highlights important implications for understanding quinoline antimalarial drug resistance and for future drug design.
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Affiliation(s)
- Alexander P Gorka
- Department of Chemistry, Department of Biochemistry, Cellular, and Molecular Biology, and Center for Infectious Diseases, Georgetown University , 37th and O Streets, NW, Washington, D.C. 20057, United States
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48
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Affiliation(s)
- Paloma F. Salas
- Medicinal Inorganic Chemistry
Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia
V6T 1Z1, Canada
| | - Christoph Herrmann
- Medicinal Inorganic Chemistry
Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia
V6T 1Z1, Canada
- Advanced
Applied Physics Solutions, TRIUMF, 4004
Wesbrook Mall, Vancouver, British Columbia
V6T 2A3, Canada
| | - Chris Orvig
- Medicinal Inorganic Chemistry
Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia
V6T 1Z1, Canada
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49
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Gildenhuys J, le Roex T, Egan TJ, de Villiers KA. The single crystal X-ray structure of β-hematin DMSO solvate grown in the presence of chloroquine, a β-hematin growth-rate inhibitor. J Am Chem Soc 2013; 135:1037-47. [PMID: 23253048 DOI: 10.1021/ja308741e] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single crystals of solvated β-hematin were grown from a DMSO solution containing the antimalarial drug chloroquine, a known inhibitor of β-hematin formation. In addition, a kinetics study employing biomimetic lipid-water emulsion conditions was undertaken to further investigate the effect of chloroquine and quinidine on the formation of β-hematin. Scanning electron microscopy shows that the external morphology of the β-hematin DMSO solvate crystals is almost indistinguishable from that of malaria pigment (hemozoin), and single crystal X-ray diffraction confirms the presence of μ-propionato coordination dimers of iron(III) protoporphyrin IX. The free propionic acid functional groups of adjacent dimers hydrogen bond to included DMSO molecules, rather than forming carboxylic acid dimers. The observed exponential kinetics were modeled using the Avrami equation, with an Avrami constant equal to 1. The decreased rate of β-hematin formation observed at low concentrations of both drugs could be accounted for by assuming a mechanism of drug adsorption to sites on the fastest growing face of β-hematin. This behavior was modeled using the Langmuir isotherm. Higher concentrations of drug resulted in decreased final yields of β-hematin, and an irreversible drug-induced precipitation of iron(III) protoporphyrin IX was postulated to account for this. The model permits determination of the equilibrium adsorption constant (K(ads)). The values for chloroquine (log K(ads) = 5.55 ± 0.03) and quinidine (log K(ads) = 4.92 ± 0.01) suggest that the approach may be useful as a relative probe of the mechanism of action of novel antimalarial compounds.
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Affiliation(s)
- Johandie Gildenhuys
- Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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50
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Cytostatic versus cytocidal activities of chloroquine analogues and inhibition of hemozoin crystal growth. Antimicrob Agents Chemother 2012; 57:356-64. [PMID: 23114783 DOI: 10.1128/aac.01709-12] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We report an improved, nonhazardous, high-throughput assay for in vitro quantification of antimalarial drug inhibition of β-hematin (hemozoin) crystallization performed under conditions that are more physiological relative to previous assays. The assay uses the differential detergent solubility of crystalline and noncrystalline forms of heme and is optimized via the use of lipid catalyst. Using this assay, we quantify the effect of pH on the crystal growth-inhibitory activities of current quinoline antimalarials, evaluate the catalytic efficiencies of different lipids, and test for a possible correlation between hemozoin inhibition by drugs versus their antiplasmodial activity. Consistent with several previous reports, we found a good correlation between hemozoin inhibition potency versus cytostatic antiplasmodial potency (50% inhibitory concentration) for a series of chloroquine (CQ) analogues. However, we found no correlation between hemozoin inhibition potency and cytocidal antiplasmodial potency (50% lethal dose) for the same drugs, suggesting that cellular targets for these two layers of 4-aminoquinoline drug activity differ. This important concept is also explored further for QN and its stereoisomers in the accompanying paper (A. P. Gorka, K. S. Sherlach, A. C. de Dios, and P. D. Roepe, Antimicrob. Agents Chemother. 57:365-374, 2013).
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