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Fielding AJ, Lukinović V, Evans PG, Alizadeh-Shekalgourabi S, Bisby RH, Drew MGB, Male V, Del Casino A, Dunn JF, Randle LE, Dempster NM, Nahar L, Sarker SD, Cantú Reinhard FG, de Visser SP, Dascombe MJ, Ismail FMD. Modulation of Antimalarial Activity at a Putative Bisquinoline Receptor In Vivo Using Fluorinated Bisquinolines. Chemistry 2017; 23:6811-6828. [DOI: 10.1002/chem.201605099] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Alistair J. Fielding
- School of Chemistry and the Photon Science Institute; The University of Manchester; Manchester M13 9PL UK
| | - Valentina Lukinović
- School of Chemistry and the Photon Science Institute; The University of Manchester; Manchester M13 9PL UK
| | - Philip G. Evans
- Peakdale Molecular Limited; Discovery Park, Sandwich Kent CT13 9FF UK
| | | | - Roger H. Bisby
- Biomedical Sciences Research Institute; University of Salford; Salford M5 4WT UK
| | - Michael G. B. Drew
- School of Chemistry; The University of Reading, Whiteknights; Reading RG6 6AD UK
| | - Verity Male
- School of Chemistry; The University of Reading, Whiteknights; Reading RG6 6AD UK
| | - Alessio Del Casino
- Medicinal Chemistry and Natural Products Research Group; School of Pharmacy and Biomolecular Sciences; Liverpool John Moores University; Byrom Street Liverpool L3 3AF UK
| | - James F. Dunn
- Medicinal Chemistry and Natural Products Research Group; School of Pharmacy and Biomolecular Sciences; Liverpool John Moores University; Byrom Street Liverpool L3 3AF UK
| | - Laura E. Randle
- Medicinal Chemistry and Natural Products Research Group; School of Pharmacy and Biomolecular Sciences; Liverpool John Moores University; Byrom Street Liverpool L3 3AF UK
| | - Nicola M. Dempster
- Medicinal Chemistry and Natural Products Research Group; School of Pharmacy and Biomolecular Sciences; Liverpool John Moores University; Byrom Street Liverpool L3 3AF UK
| | - Lutfun Nahar
- Medicinal Chemistry and Natural Products Research Group; School of Pharmacy and Biomolecular Sciences; Liverpool John Moores University; Byrom Street Liverpool L3 3AF UK
| | - Satyajit D. Sarker
- Medicinal Chemistry and Natural Products Research Group; School of Pharmacy and Biomolecular Sciences; Liverpool John Moores University; Byrom Street Liverpool L3 3AF UK
| | - Fabián G. Cantú Reinhard
- Manchester Institute of Biotechnology; School of Chemical Engineering and Analytical Science; The University of Manchester; 131 Princess Street Manchester M1 7DN UK
| | - Sam P. de Visser
- Manchester Institute of Biotechnology; School of Chemical Engineering and Analytical Science; The University of Manchester; 131 Princess Street Manchester M1 7DN UK
| | - Mike J. Dascombe
- Faculty of Biology, Medicine and Health, Stopford Building 1.124; The University of Manchester; Oxford Road Manchester M13 9PT UK
| | - Fyaz M. D. Ismail
- Medicinal Chemistry and Natural Products Research Group; School of Pharmacy and Biomolecular Sciences; Liverpool John Moores University; Byrom Street Liverpool L3 3AF UK
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2
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Tukulula M, Njoroge M, Mugumbate GC, Gut J, Rosenthal PJ, Barteau S, Streckfuss J, Heudi O, Kameni-Tcheudji J, Chibale K. Tetrazole-based deoxyamodiaquines: synthesis, ADME/PK profiling and pharmacological evaluation as potential antimalarial agents. Bioorg Med Chem 2013; 21:4904-13. [PMID: 23896611 DOI: 10.1016/j.bmc.2013.06.067] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/19/2013] [Accepted: 06/28/2013] [Indexed: 10/26/2022]
Abstract
A series of new deoxyamodiaquine-based compounds was synthesized via the modified TMSN3-Ugi multi-component reaction and evaluated in vitro for antiplasmodial activity. The most potent compounds, 6b, 6c and 6j, showed IC50 values in the range of 6-77nM against chloroquine-resistant K1- and W2-strains of Plasmodium falciparum. In vitro ADME characterization of frontrunner compounds 6b and 6c indicates that these two compounds are rapidly metabolized and have a high clearance rate in human and rat liver microsomes. This result correlated well with an in vivo pharmacokinetics study, which showed low bioavailability of 6c in rats. Tentative metabolite identification was determined by LC-MS and suggested metabolic lability of groups attached to the tertiary nitrogen. Preliminary studies on 6b and 6c suggested strong inhibitory activity against the major CYP450 enzymes. In silico docking studies were used to rationalize strong inhibition of CYP3A4 by 6c. Full characterization and biological evaluation of the metabolites is currently underway in our laboratories.
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3
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Miller LH, Ackerman HC, Su XZ, Wellems TE. Malaria biology and disease pathogenesis: insights for new treatments. Nat Med 2013; 19:156-67. [PMID: 23389616 DOI: 10.1038/nm.3073] [Citation(s) in RCA: 371] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 12/17/2012] [Indexed: 12/12/2022]
Abstract
Plasmodium falciparum malaria, an infectious disease caused by a parasitic protozoan, claims the lives of nearly a million children each year in Africa alone and is a top public health concern. Evidence is accumulating that resistance to artemisinin derivatives, the frontline therapy for the asexual blood stage of the infection, is developing in southeast Asia. Renewed initiatives to eliminate malaria will benefit from an expanded repertoire of antimalarials, including new drugs that kill circulating P. falciparum gametocytes, thereby preventing transmission. Our current understanding of the biology of asexual blood-stage parasites and gametocytes and the ability to culture them in vitro lends optimism that high-throughput screenings of large chemical libraries will produce a new generation of antimalarial drugs. There is also a need for new therapies to reduce the high mortality of severe malaria. An understanding of the pathophysiology of severe disease may identify rational targets for drugs that improve survival.
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Affiliation(s)
- Louis H Miller
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, USA.
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4
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Kiorpelidou E, Foster B, Farrell J, Ogese MO, Faulkner L, Goldring CE, Park BK, Naisbitt DJ. IL-8 Release from Human Neutrophils Cultured with Pro-Haptenic Chemical Sensitizers. Chem Res Toxicol 2012; 25:2054-6. [DOI: 10.1021/tx300350s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Eva Kiorpelidou
- MRC Centre for Drug Safety Science, Department of Pharmacology, University of Liverpool, Sherrington Building, Ashton
Street, Liverpool L69 3GE, England
| | - Brian Foster
- MRC Centre for Drug Safety Science, Department of Pharmacology, University of Liverpool, Sherrington Building, Ashton
Street, Liverpool L69 3GE, England
| | - John Farrell
- MRC Centre for Drug Safety Science, Department of Pharmacology, University of Liverpool, Sherrington Building, Ashton
Street, Liverpool L69 3GE, England
| | - Monday O. Ogese
- MRC Centre for Drug Safety Science, Department of Pharmacology, University of Liverpool, Sherrington Building, Ashton
Street, Liverpool L69 3GE, England
| | - Lee Faulkner
- MRC Centre for Drug Safety Science, Department of Pharmacology, University of Liverpool, Sherrington Building, Ashton
Street, Liverpool L69 3GE, England
| | - Chris E. Goldring
- MRC Centre for Drug Safety Science, Department of Pharmacology, University of Liverpool, Sherrington Building, Ashton
Street, Liverpool L69 3GE, England
| | - B. Kevin Park
- MRC Centre for Drug Safety Science, Department of Pharmacology, University of Liverpool, Sherrington Building, Ashton
Street, Liverpool L69 3GE, England
| | - Dean J. Naisbitt
- MRC Centre for Drug Safety Science, Department of Pharmacology, University of Liverpool, Sherrington Building, Ashton
Street, Liverpool L69 3GE, England
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5
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Le Fur N, Hochart G, Larchanché PE, Melnyk P. Buchwald reaction as the key step for the synthesis of metabolically more stable analogs of amodiaquine. Eur J Med Chem 2011; 46:3052-7. [DOI: 10.1016/j.ejmech.2011.04.047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 04/14/2011] [Accepted: 04/15/2011] [Indexed: 11/30/2022]
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6
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Fur NL, Larchanché PE, Melnyk P. Optimized and convergent synthesis of potent anti-malarial aminoquinoline compounds: easy access to analogs. HETEROCYCL COMMUN 2010. [DOI: 10.1515/hc.2010.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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7
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Păunescu E, Susplugas S, Boll E, Varga R, Mouray E, Grosu I, Grellier P, Melnyk P. Replacement of the 4'-hydroxy group of amodiaquine and amopyroquine by aromatic and aliphatic substituents: synthesis and antimalarial activity. ChemMedChem 2009; 4:549-61. [PMID: 19212949 DOI: 10.1002/cmdc.200800318] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The prophylactic administration of amodiaquine (AQ), a 4-aminoquinoline antimalarial drug, has been associated with side effects such as agranulocytosis and liver damage. The toxicity of this drug is mediated by amodiaquine quinone-imine, an electrophilic metabolite. Replacement of the 4'-hydroxy function of AQ with various alkyl, aryl, or heteroaryl substituents would provide analogues that avoid metabolism to potentially toxic derivatives. Following a multistep procedure, 33 compounds containing hydrophobic groups at the 4'-position were synthesized using Csp(2)-Csp(2) and Csp(2)-Csp(3) Suzuki-Miyaura cross-coupling reactions as the key step. The new derivatives were found to be active against both chloroquine (CQ)-sensitive and CQ-resistant strains of P. falciparum, with IC(50) values in the range of 7-200 nM. Alkyl analogues are more efficient than aryl or heteroaryl derivatives. All compounds were also assessed for their cytotoxicity and ability to inhibit beta-hematin formation in vitro. A detailed investigation of the structure-activity relationships for these new compounds was carried out; the 4'-methyl compound showed interesting in vivo antimalarial activity.
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8
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In vitro activity of ferroquine is independent of polymorphisms in transport protein genes implicated in quinoline resistance in Plasmodium falciparum. Antimicrob Agents Chemother 2008; 52:2755-9. [PMID: 18505855 DOI: 10.1128/aac.00060-08] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The in vitro activity of ferroquine (FQ) (SR97193), a 4-aminoquinoline antimalarial compound that contains a ferrocenic nucleus, against 15 Plasmodium falciparum strains was assessed and compared with those of chloroquine (CQ), quinine (QN), monodesethylamodiaquine (MDAQ), and mefloquine (MQ). These 15 strains were genotyped for polymorphisms in quinoline resistance-associated genes such as Pfcrt, Pfmdr1, Pfmrp, and Pfnhe-1. FQ was highly active against CQ-resistant parasites or in parasites with reduced susceptibility to QN, MDAQ, or MQ. Encouragingly, we did not find a correlation between responses to FQ and those to other quinoline drugs. These results suggest that no cross-resistance exits between FQ and CQ or quinoline antimalarial drugs. Mutations in codons 74, 75, 76, 220, 271, 326, 356, and 371 of the Pfcrt gene; codons 86, 184, 1034, 1042, and 1246 of the Pfmdr1 gene; and codons 191 and 437 of the Pfmrp gene were not significantly associated with P. falciparum susceptibility to FQ. Neither the number of ms4760 DNNND or DDNHNDNHNN repeats in Pfnhe-1 nor the profile of ms4760 was significantly associated with the FQ in vitro response. These data suggest the FQ may not interact with transport proteins in quinoline-resistant parasites. The present results justify further clinical trials of FQ in multidrug resistance areas.
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9
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Bujnowski K, Adamczyk A, Synoradzki L. o-AMINOMETHYL DERIVATIVES OF PHENOLS. PART 1. BENZYLAMINES: PROPERTIES, STRUCTURE, SYNTHESIS AND PURIFICATION. ORG PREP PROCED INT 2007. [DOI: 10.1080/00304940709356009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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10
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Naudé B, Brzostowski JA, Kimmel AR, Wellems TE. Dictyostelium discoideum expresses a malaria chloroquine resistance mechanism upon transfection with mutant, but not wild-type, Plasmodium falciparum transporter PfCRT. J Biol Chem 2005; 280:25596-603. [PMID: 15883156 PMCID: PMC1779819 DOI: 10.1074/jbc.m503227200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Chloroquine resistance in Plasmodium falciparum malaria results from mutations in PfCRT, a member of a unique family of transporters present in apicomplexan parasites and Dictyostelium discoideum. Mechanisms that have been proposed to explain chloroquine resistance are difficult to evaluate within malaria parasites. Here we report on the targeted expression of wild-type and mutant forms of PfCRT to acidic vesicles in D. discoideum. We show that wild-type PfCRT has minimal effect on the accumulation of chloroquine by D. discoideum, whereas forms of PfCRT carrying a key charge-loss mutation of lysine 76 (e.g. K76T) enable D. discoideum to expel chloroquine. As in P. falciparum, the chloroquine resistance phenotype conferred on transformed D. discoideum can be reversed by the channel-blocking agent verapamil. Although intravesicular pH levels in D. discoideum show small acidic changes with the expression of different forms of PfCRT, these changes would tend to promote intravesicular trapping of chloroquine (a weak base) and do not account for reduced drug accumulation in transformed D. discoideum. Our results instead support outward-directed chloroquine efflux for the mechanism of chloroquine resistance by mutant PfCRT. This mechanism shows structural specificity as D. discoideum transformants that expel chloroquine do not expel piperaquine, a bisquinoline analog of chloroquine used frequently against chloroquine-resistant parasites in Southeast Asia. PfCRT, nevertheless, may have some ability to act on quinine and quinidine. Transformed D. discoideum will be useful for further studies of the chloroquine resistance mechanism and may assist in the development and evaluation of new antimalarial drugs.
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Affiliation(s)
- Bronwen Naudé
- Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Bethesda, Maryland 20892-8132, USA
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11
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12
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Egan TJ, Koch KR, Swan PL, Clarkson C, Van Schalkwyk DA, Smith PJ. In Vitro Antimalarial Activity of a Series of Cationic 2,2‘-Bipyridyl- and 1,10-Phenanthrolineplatinum(II) Benzoylthiourea Complexes. J Med Chem 2004; 47:2926-34. [PMID: 15139771 DOI: 10.1021/jm031132g] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have synthesized a series of novel 2,2'-bipyridyl and 1,10-phenanthroline benzoylthiourea complexes of platinum(II) with various substituents on the bipyridyl and phenanthroline ligands. All of these square-planar mixed-ligand cationic complexes were found to form moderately strong complexes with ferriprotoporphyrin IX in 40% aqueous DMSO (log K ranging from 4.81 to 6.24). The complexes also all inhibit beta-hematin (synthetic hemozoin or malaria pigment) formation in acetate solution. Four of the compounds were found to exhibit in vitro antimalarial activity, with (N-benzoyl-N',N'-di(2-hydroxyethyl)thioureato)(4,4'-di-tert-butyl-2,2'-bipyridyl)platinum(II) chloride being particularly active. These active complexes exhibited equally strong activity against both the D10 chloroquine sensitive and K1 chloroquine resistant strains of malaria parasite. Cytotoxicity testing of the four most active compounds shows that they exhibit selective activity against malaria parasites with selectivity indices greater than 85. These compounds represent a new family of potential antimalarials.
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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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13
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O'Neill PM, Mukhtar A, Stocks PA, Randle LE, Hindley S, Ward SA, Storr RC, Bickley JF, O'Neil IA, Maggs JL, Hughes RH, Winstanley PA, Bray PG, Park BK. Isoquine and Related Amodiaquine Analogues: A New Generation of Improved 4-Aminoquinoline Antimalarials. J Med Chem 2003; 46:4933-45. [PMID: 14584944 DOI: 10.1021/jm030796n] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amodiaquine (AQ) (2) is a 4-aminoquinoline antimalarial that can cause adverse side effects including agranulocytosis and liver damage. The observed drug toxicity is believed to involve the formation of an electrophilic metabolite, amodiaquine quinoneimine (AQQI), which can bind to cellular macromolecules and initiate hypersensitivity reactions. We proposed that interchange of the 3' hydroxyl and the 4' Mannich side-chain function of amodiaquine would provide a new series of analogues that cannot form toxic quinoneimine metabolites via cytochrome P450-mediated metabolism. By a simple two-step procedure, 10 isomeric amodiaquine analogues were prepared and subsequently examined against the chloroquine resistant K1 and sensitive HB3 strains of Plasmodium falciparum in vitro. Several analogues displayed potent antimalarial activity against both strains. On the basis of the results of in vitro testing, isoquine (ISQ1 (3a)) (IC(50) = 6.01 nM +/- 8.0 versus K1 strain), the direct isomer of amodiaquine, was selected for in vivo antimalarial assessment. The potent in vitro antimalarial activity of isoquine was translated into excellent oral in vivo ED(50) activity of 1.6 and 3.7 mg/kg against the P. yoelii NS strain compared to 7.9 and 7.4 mg/kg for amodiaquine. Subsequent metabolism studies in the rat model demonstrated that isoquine does not undergo in vivo bioactivation, as evidenced by the complete lack of glutathione metabolites in bile. In sharp contrast to amodiaquine, isoquine (and Phase I metabolites) undergoes clearance by Phase II glucuronidation. On the basis of these promising initial studies, isoquine (ISQ1 (3a)) represents a new second generation lead worthy of further investigation as a cost-effective and potentially safer alternative to amodiaquine.
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Affiliation(s)
- Paul M O'Neill
- Department of Chemistry, The Robert Robinson Laboratories, University of Liverpool, Liverpool L69 7ZD, UK.
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14
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Abstract
Genetic and biochemical research is providing new information on the mechanism of chloroquine resistance. Drug discovery initiatives are finding new leads that have favorable pharmaceutical properties and efficacy against chloroquine-resistant malaria.
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MESH Headings
- ATP-Binding Cassette Transporters
- Alleles
- Animals
- Antimalarials/metabolism
- Antimalarials/pharmacology
- Antimalarials/therapeutic use
- Biological Evolution
- Chloroquine/metabolism
- Chloroquine/pharmacology
- Chloroquine/therapeutic use
- Databases, Nucleic Acid
- Drug Resistance
- Genes, Protozoan
- Genetic Variation
- Genome, Protozoan
- Heme/metabolism
- Humans
- Malaria/drug therapy
- Malaria/immunology
- Malaria/parasitology
- Malaria, Falciparum/drug therapy
- Malaria, Falciparum/genetics
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Membrane Transport Proteins
- Plasmodium/drug effects
- Plasmodium/genetics
- Plasmodium/metabolism
- Plasmodium falciparum/drug effects
- Plasmodium falciparum/genetics
- Plasmodium falciparum/metabolism
- Point Mutation
- Polymorphism, Single Nucleotide
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- Selection, Genetic
- Sequence Analysis, DNA
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Affiliation(s)
- Thomas E Wellems
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892, USA.
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15
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Abstract
Quinoline compounds, such as chloroquine, are used widely to treat malaria; however, the malarial parasite is rapidly becoming resistant to the drugs currently available. Presently, rational drug design is hindered considerably due to the mode of action of chloroquine being poorly understood. We rely on serendipity, rather than solid structural evidence, to generate new antimalarials. Hence any insight into the possible modes of action of quinoline antimalarials, including the bisquinolines, would greatly aid rational drug design. The quinoline antimalarial drugs, chloroquine, quinine and mefloquine, are thought to act by interfering with the digestion of haemoglobin in the blood stages of the malaria life-cycle. These quinoline antimalarials traverse down the pH gradient to accumulate to millimolar concentrations in the acidic vacuole of the parasite. It has been suggested that this high intravacuolar concentration prevents haem sequestration, causing a build up of the toxic haem moiety and the death of the parasite by its own toxic waste. The actual mechanism by which the parasite sequesters haem and the drug target(s) during this process, however, still remains elusive. As a consequence, haem polymerisation and the efficiency of quinoline antimalarials, including the bisquinolines, as inhibitors of this process has been investigated. In this paper, the potential role of the bisquinolines in the fight against chloroquine-resistant malaria is addressed.
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Affiliation(s)
- K Raynes
- School of Biochemistry, La Trobe University, Bundoora, Vic., Australia.
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16
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Bray PG, Mungthin M, Ridley RG, Ward SA. Access to hematin: the basis of chloroquine resistance. Mol Pharmacol 1998; 54:170-9. [PMID: 9658203 DOI: 10.1124/mol.54.1.170] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The saturable uptake of chloroquine by parasites of Plasmodium falciparum has been attributed to specific carrier-mediated transport of chloroquine. It is suggested that chloroquine is transported in exchange for protons by the parasite membrane Na+/H+ exchanger [J Biol Chem 272:2652-2658 (1997)]. Once inside the parasite, it is proposed that chloroquine inhibits the polymerization of hematin, allowing this toxic hemoglobin metabolite to accumulate and kill the cell [Pharmacol Ther 57:203-235 (1993)]. To date, the contribution of these proposed mechanisms to the uptake and antimalarial activity of chloroquine has not been assessed. Using sodium-free medium, we demonstrate that chloroquine is not directly exchanged for protons by the plasmodial Na+/H+ exchanger. Furthermore, we show that saturable chloroquine uptake at equilibrium is due solely to the binding of chloroquine to hematin rather than active uptake: using Ro 40-4388, a potent and specific inhibitor of hemoglobin digestion and, by implication, hematin release, we demonstrate a concentration-dependent reduction in the number of chloroquine binding sites. An equal number of chloroquine binding sites are found in both resistant and susceptible clones, but the apparent affinity of chloroquine binding is found to correlate with drug activity (r2 = 0.93, p < 0.0001). This completely accounts for both the reduced drug accumulation and activity observed in resistant clones and the "reversal" of resistance produced by verapamil. The data presented here reconcile most of the available biochemical data from studies of the mode of action of chloroquine and the mechanism of chloroquine resistance. We show that the activity of chloroquine and amodiaquine is directly dependent on the saturable binding of the drugs to hematin and that the inhibition of hematin polymerization may be secondary to this binding. The chloroquine-resistance mechanism regulates the access of chloroquine to hematin. Our model is consistent with a resistance mechanism that acts specifically at the food vacuole to alter the binding of chloroquine to hematin rather than changing the active transport of chloroquine across the parasite plasma membrane.
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Affiliation(s)
- P G Bray
- Department of Pharmacology and Therapeutics, The University of Liverpool, Liverpool L69 3BX, UK
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17
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Hawley SR, Bray PG, Mungthin M, Atkinson JD, O'Neill PM, Ward SA. Relationship between antimalarial drug activity, accumulation, and inhibition of heme polymerization in Plasmodium falciparum in vitro. Antimicrob Agents Chemother 1998; 42:682-6. [PMID: 9517951 PMCID: PMC105517 DOI: 10.1128/aac.42.3.682] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/1997] [Accepted: 12/10/1997] [Indexed: 02/06/2023] Open
Abstract
We have investigated the contribution of drug accumulation and inhibition of heme polymerization to the in vitro activities of a series of antimalarial drugs. Only those compounds exhibiting structural relatedness to the quinolines inhibited heme polymerization. We could find no direct correlation between in vitro activity against chloroquine-susceptible or chloroquine-resistant isolates and either inhibition of heme polymerization or cellular drug accumulation for the drugs studied. However, in vitro activity against a chloroquine-susceptible isolate but not a chloroquine-resistant isolate showed a significant correlation with inhibition of heme polymerization when the activity was normalized for the extent of drug accumulation. The importance of these observations to the rational design of new quinoline-type drugs and the level of agreement of these conclusions with current views on quinoline drug action and resistance are discussed.
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Affiliation(s)
- S R Hawley
- Department of Human Anatomy and Cell Biology, University of Liverpool, United Kingdom
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18
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O'Neill PM, Bray PG, Hawley SR, Ward SA, Park BK. 4-Aminoquinolines--past, present, and future: a chemical perspective. Pharmacol Ther 1998; 77:29-58. [PMID: 9500158 DOI: 10.1016/s0163-7258(97)00084-3] [Citation(s) in RCA: 187] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The 4-aminoquinoline chloroquine (1) can be considered to be one of the most important synthetic chemotherapeutic agents in history. Since its discovery, chloroquine has proved to be a highly effective, safe, and well-tolerated drug for the treatment and prophylaxis of malaria. However, the emergence of chloroquine-resistant strains of the malarial parasite has underlined the requirement for a synthetic alternative to chloroquine. This review describes structure-activity relationships for the 4-aminoquinolines, along with views on the mechanism of action and parasite resistance. A description of drug metabolism and toxicity also is included, with a brief description of potential approaches to the design of new synthetic derivatives.
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Affiliation(s)
- P M O'Neill
- Department of Pharmacology and Therapeutics, University of Liverpool, UK
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19
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Bray PG, Ward SA. A comparison of the phenomenology and genetics of multidrug resistance in cancer cells and quinoline resistance in Plasmodium falciparum. Pharmacol Ther 1998; 77:1-28. [PMID: 9500157 DOI: 10.1016/s0163-7258(97)00083-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Plasmodium falciparum is the causative agent of the most deadly form of human malaria. Chemotherapy traditionally has been the main line of defense against this parasite, and chloroquine, the drug of choice, has been one of the most successful drugs ever developed. Unfortunately, the evolution and spread of resistance to chloroquine and other quinoline-containing drugs means that these compounds are now virtually useless in many endemic areas. Future prospects for the use of quinoline compounds improved considerably when it was demonstrated that chloroquine resistance could be circumvented in vitro by a number of structurally and functionally unrelated compounds such as verapamil and desipramine. The phenomenon of resistance reversal by compounds such as verapamil is also a key feature of drug resistance in mammalian cells, and this has raised the possibility that the underlying mechanisms of drug resistance of the two cell types could be similar. This hypothesis has prompted a large number of studies into the genetics and biochemistry of resistance to quinoline-containing drugs in P. falciparum. Both the genetic and the biochemical studies have raised issues of controversy and stimulated much debate. These issues are discussed in this review, in the context of a comparison with the genetics and biochemistry of multidrug resistance in mammalian cells.
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Affiliation(s)
- P G Bray
- Department of Pharmacology and Therapeutics, University of Liverpool, UK
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Su X, Kirkman LA, Fujioka H, Wellems TE. Complex polymorphisms in an approximately 330 kDa protein are linked to chloroquine-resistant P. falciparum in Southeast Asia and Africa. Cell 1997; 91:593-603. [PMID: 9393853 DOI: 10.1016/s0092-8674(00)80447-x] [Citation(s) in RCA: 259] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chloroquine resistance in a P. falciparum cross maps as a Mendelian trait to a 36 kb segment of chromosome 7. This segment harbors cg2, a gene encoding a unique approximately 330 kDa protein with complex polymorphisms. A specific set of polymorphisms in 20 chloroquine-resistant parasites from Asia and Africa, in contrast with numerous differences in 21 sensitive parasites, suggests selection of a cg2 allele originating in Indochina over 40 years ago. One chloroquine-sensitive clone exhibited this allele, suggesting another resistance component. South American parasites have cg2 polymorphisms consistent with a separate origin of resistance. CG2 protein is found at the parasite periphery, a site of chloroquine transport, and in association with hemozoin of the digestive vacuole, where chloroquine inhibits heme polymerization.
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Affiliation(s)
- X Su
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0425, USA
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