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Lee J, Matuschewski K, van Dooren G, Maier AG, Rug M. Lipid droplet dynamics are essential for the development of the malaria parasite Plasmodium falciparum. J Cell Sci 2024; 137:jcs262162. [PMID: 38962997 DOI: 10.1242/jcs.262162] [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: 03/28/2024] [Accepted: 06/26/2024] [Indexed: 07/05/2024] Open
Abstract
Lipid droplets (LDs) are organelles that are central to lipid and energy homeostasis across all eukaryotes. In the malaria-causing parasite Plasmodium falciparum the roles of LDs in lipid acquisition from its host cells and their metabolism are poorly understood, despite the high demand for lipids in parasite membrane synthesis. We systematically characterised LD size, composition and dynamics across the disease-causing blood infection. Applying split fluorescence emission analysis and three-dimensional (3D) focused ion beam-scanning electron microscopy (FIB-SEM), we observed a decrease in LD size in late schizont stages. LD contraction likely signifies a switch from lipid accumulation to lipid utilisation in preparation for parasite egress from host red blood cells. We demonstrate connections between LDs and several parasite organelles, pointing to potential functional interactions. Chemical inhibition of triacylglyerol (TAG) synthesis or breakdown revealed essential LD functions for schizogony and in counteracting lipid toxicity. The dynamics of lipid synthesis, storage and utilisation in P. falciparum LDs might provide a target for new anti-malarial intervention strategies.
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Affiliation(s)
- Jiwon Lee
- Centre for Advanced Microscopy, The Australian National University, Canberra ACT, 2601, Australia
- Research School of Biology, The Australian National University, Canberra ACT, 2601, Australia
| | - Kai Matuschewski
- Molecular Parasitology, Humboldt University, 10099 Berlin, Germany
| | - Giel van Dooren
- Research School of Biology, The Australian National University, Canberra ACT, 2601, Australia
| | - Alexander G Maier
- Research School of Biology, The Australian National University, Canberra ACT, 2601, Australia
| | - Melanie Rug
- Centre for Advanced Microscopy, The Australian National University, Canberra ACT, 2601, Australia
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Leussa ANN, Rautenbach M. Antiplasmodial Cyclodecapeptides from Tyrothricin Share a Target with Chloroquine. Antibiotics (Basel) 2022; 11:antibiotics11060801. [PMID: 35740207 PMCID: PMC9219824 DOI: 10.3390/antibiotics11060801] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 06/03/2022] [Accepted: 06/09/2022] [Indexed: 12/10/2022] Open
Abstract
Previous research found that the six major cyclodecapeptides from the tyrothricin complex, produced by Brevibacillus parabrevis, showed potent activity against chloroquine sensitive (CQS) Plasmodium falciparum. The identity of the aromatic residues in the aromatic dipeptide unit in cyclo-(D-Phe1-Pro2-(Phe3/Trp3)-D-Phe4/D-Trp4)-Asn5-Gln6-(Tyr7/Phe7/Trp7)-Val8-(Orn9/Lys9)-Leu10 was proposed to have an important role in activity. CQS and resistant (CQR) P. falciparum strains were challenged with three representative cyclodecapeptides. Our results confirmed that cyclodecapeptides from tyrothricin had significantly higher antiplasmodial activity than the analogous gramicidin S, rivaling that of CQ. However, the previously hypothesized size and hydrophobicity dependent activity for these peptides did not hold true for P. falciparum strains, other than for the CQS 3D7 strain. The Tyr7 in tyrocidine A (TrcA) with Phe3-D-Phe4 seem to be related with loss in activity correlating with CQ antagonism and resistance, indicating a shared target and/or resistance mechanism in which the phenolic groups play a role. Phe7 in phenycidine A, the second peptide containing Phe3-D-Phe4, also showed CQ antagonism. Conversely, Trp7 in tryptocidine C (TpcC) with Trp3-D-Trp4 showed improved peptide selectivity and activity towards the more resistant strains, without overt antagonism towards CQ. However, TpcC lead to similar parasite stage inhibition and parasite morphology changes than previously observed for TrcA. The disorganization of chromatin packing and neutral lipid structures, combined with amorphous hemozoin crystals, could account for halted growth in late trophozoite/early schizont stage and the nanomolar non-lytic activity of these peptides. These targets related to CQ antagonism, changes in neural lipid distribution, leading to hemozoin malformation, indicate that the tyrothricin cyclodecapeptides and CQ share a target in the malaria parasite. The differing activities of these cyclic peptides towards CQS and CQR P. falciparum strains could be due to variable target interaction in multiple modes of activity. This indicated that the cyclodecapeptide activity and parasite resistance response depended on the aromatic residues in positions 3, 4 and 7. This new insight on these natural cyclic decapeptides could also benefit the design of unique small peptidomimetics in which activity and resistance can be modulated.
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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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Ommi NB, Abdullah M, Guruprasad L, Babu PP. Docosahexaenoic acid is potent against the growth of mature stages of Plasmodium falciparum; inhibition of hematin polymerization a possible target. Parasitol Int 2022; 89:102581. [PMID: 35395394 DOI: 10.1016/j.parint.2022.102581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 01/21/2022] [Accepted: 03/31/2022] [Indexed: 10/18/2022]
Abstract
The present study investigates the potential effect of externally added unsaturated fatty acids on P. falciparum growth. Our results indicate that polyunsaturated fatty acids (PUFAs) inhibit the growth of Plasmodium in proportional to their degree of unsaturation. At higher concentration the PUFA Docosahexaenoic acid (DHA) induces pyknotic nuclei in infected erythrocytes. When Plasmodium stages were treated transiently with DHA, the ring stage culture recovered from the drug effect and parasitemia was increased post DHA removal with delayed growth of 12 h, compared to untreated control. Schizont stage treated culture displayed a 36 h delay in growth to infect fresh erythrocytes signifying its recovery is less than the ring stage. However the trophozoite stage failed to recover and showed a decrease in parasitemia, similar to that of continuous treated culture. PUFAs inhibited β- hematin polymerization by binding to free heme derived from hemoglobin degradation. Digestive vacuole neutral lipid bodies, which are pivotal for β- hematin polymerization, decreased and subsequently abrogated with increasing concentration of DHA in trophozoite stage treated culture. Our study concludes that DHA interacts with heme monomers and inhibits the β- hematin polymerization and growth of mature stages i.e., trophozoite and schizont stages of plasmodium.
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Affiliation(s)
- Naidu Babu Ommi
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500 046, Telangana, India
| | - Maaged Abdullah
- School of Chemistry, University of Hyderabad, Gachibowli, Hyderabad 500 046, Telangana, India
| | - Lalitha Guruprasad
- School of Chemistry, University of Hyderabad, Gachibowli, Hyderabad 500 046, Telangana, India
| | - Phanithi Prakash Babu
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500 046, Telangana, India.
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Fader Kaiser CM, Romano PS, Vanrell MC, Pocognoni CA, Jacob J, Caruso B, Delgui LR. Biogenesis and Breakdown of Lipid Droplets in Pathological Conditions. Front Cell Dev Biol 2022; 9:826248. [PMID: 35198567 PMCID: PMC8860030 DOI: 10.3389/fcell.2021.826248] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 12/22/2021] [Indexed: 12/17/2022] Open
Abstract
Lipid droplets (LD) have long been considered as mere fat drops; however, LD have lately been revealed to be ubiquitous, dynamic and to be present in diverse organelles in which they have a wide range of key functions. Although incompletely understood, the biogenesis of eukaryotic LD initiates with the synthesis of neutral lipids (NL) by enzymes located in the endoplasmic reticulum (ER). The accumulation of NL leads to their segregation into nanometric nuclei which then grow into lenses between the ER leaflets as they are further filled with NL. The lipid composition and interfacial tensions of both ER and the lenses modulate their shape which, together with specific ER proteins, determine the proneness of LD to bud from the ER toward the cytoplasm. The most important function of LD is the buffering of energy. But far beyond this, LD are actively integrated into physiological processes, such as lipid metabolism, control of protein homeostasis, sequestration of toxic lipid metabolic intermediates, protection from stress, and proliferation of tumours. Besides, LD may serve as platforms for pathogen replication and defense. To accomplish these functions, from biogenesis to breakdown, eukaryotic LD have developed mechanisms to travel within the cytoplasm and to establish contact with other organelles. When nutrient deprivation occurs, LD undergo breakdown (lipolysis), which begins with the LD-associated members of the perilipins family PLIN2 and PLIN3 chaperone-mediated autophagy degradation (CMA), a specific type of autophagy that selectively degrades a subset of cytosolic proteins in lysosomes. Indeed, PLINs CMA degradation is a prerequisite for further true lipolysis, which occurs via cytosolic lipases or by lysosome luminal lipases when autophagosomes engulf portions of LD and target them to lysosomes. LD play a crucial role in several pathophysiological processes. Increased accumulation of LD in non-adipose cells is commonly observed in numerous infectious diseases caused by intracellular pathogens including viral, bacterial, and parasite infections, and is gradually recognized as a prominent characteristic in a variety of cancers. This review discusses current evidence related to the modulation of LD biogenesis and breakdown caused by intracellular pathogens and cancer.
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Affiliation(s)
- Claudio M Fader Kaiser
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Patricia S Romano
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - M Cristina Vanrell
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Cristian A Pocognoni
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Julieta Jacob
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
| | - Benjamín Caruso
- Instituto de Investigaciones Biologicas y Tecnologicas, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Cordoba, Cordoba, Argentina
| | - Laura R Delgui
- CONICET Dr. Mario H. Burgos Institute of Histology and Embryology (IHEM), Mendoza, Argentina
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Ramaprasad A, Burda PC, Calvani E, Sait AJ, Palma-Duran SA, Withers-Martinez C, Hackett F, Macrae J, Collinson L, Gilberger TW, Blackman MJ. A choline-releasing glycerophosphodiesterase essential for phosphatidylcholine biosynthesis and blood stage development in the malaria parasite. eLife 2022; 11:82207. [PMID: 36576255 PMCID: PMC9886279 DOI: 10.7554/elife.82207] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
The malaria parasite Plasmodium falciparum synthesizes significant amounts of phospholipids to meet the demands of replication within red blood cells. De novo phosphatidylcholine (PC) biosynthesis via the Kennedy pathway is essential, requiring choline that is primarily sourced from host serum lysophosphatidylcholine (lysoPC). LysoPC also acts as an environmental sensor to regulate parasite sexual differentiation. Despite these critical roles for host lysoPC, the enzyme(s) involved in its breakdown to free choline for PC synthesis are unknown. Here, we show that a parasite glycerophosphodiesterase (PfGDPD) is indispensable for blood stage parasite proliferation. Exogenous choline rescues growth of PfGDPD-null parasites, directly linking PfGDPD function to choline incorporation. Genetic ablation of PfGDPD reduces choline uptake from lysoPC, resulting in depletion of several PC species in the parasite, whilst purified PfGDPD releases choline from glycerophosphocholine in vitro. Our results identify PfGDPD as a choline-releasing glycerophosphodiesterase that mediates a critical step in PC biosynthesis and parasite survival.
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Affiliation(s)
- Abhinay Ramaprasad
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Paul-Christian Burda
- Centre for Structural Systems BiologyHamburgGermany,Bernhard Nocht Institute for Tropical MedicineHamburgGermany,University of HamburgHamburgGermany
| | - Enrica Calvani
- Metabolomics Science Technology Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Aaron J Sait
- Electron Microscopy Science Technology Platform, The Francis Crick InstituteLondonUnited Kingdom
| | | | | | - Fiona Hackett
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - James Macrae
- Metabolomics Science Technology Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Lucy Collinson
- Electron Microscopy Science Technology Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Tim Wolf Gilberger
- Centre for Structural Systems BiologyHamburgGermany,Bernhard Nocht Institute for Tropical MedicineHamburgGermany,University of HamburgHamburgGermany
| | - Michael J Blackman
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom,Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical MedicineLondonUnited Kingdom
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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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Asad M, Yamaryo-Botté Y, Hossain ME, Thakur V, Jain S, Datta G, Botté CY, Mohmmed A. An essential vesicular-trafficking phospholipase mediates neutral lipid synthesis and contributes to hemozoin formation in Plasmodium falciparum. BMC Biol 2021; 19:159. [PMID: 34380472 PMCID: PMC8359613 DOI: 10.1186/s12915-021-01042-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 04/30/2021] [Indexed: 11/10/2022] Open
Abstract
Background Plasmodium falciparum is the pathogen responsible for the most devastating form of human malaria. As it replicates asexually in the erythrocytes of its human host, the parasite feeds on haemoglobin uptaken from these cells. Heme, a toxic by-product of haemoglobin utilization by the parasite, is neutralized into inert hemozoin in the food vacuole of the parasite. Lipid homeostasis and phospholipid metabolism are crucial for this process, as well as for the parasite’s survival and propagation within the host. P. falciparum harbours a uniquely large family of phospholipases, which are suggested to play key roles in lipid metabolism and utilization. Results Here, we show that one of the parasite phospholipase (P. falciparum lysophospholipase, PfLPL1) plays an essential role in lipid homeostasis linked with the haemoglobin degradation and heme conversion pathway. Fluorescence tagging showed that the PfLPL1 in infected blood cells localizes to dynamic vesicular structures that traffic from the host-parasite interface at the parasite periphery, through the cytosol, to get incorporated into a large vesicular lipid rich body next to the food-vacuole. PfLPL1 is shown to harbour enzymatic activity to catabolize phospholipids, and its transient downregulation in the parasite caused a significant reduction of neutral lipids in the food vacuole-associated lipid bodies. This hindered the conversion of heme, originating from host haemoglobin, into the hemozoin, and disrupted the parasite development cycle and parasite growth. Detailed lipidomic analyses of inducible knock-down parasites deciphered the functional role of PfLPL1 in generation of neutral lipid through recycling of phospholipids. Further, exogenous fatty-acids were able to complement downregulation of PfLPL1 to rescue the parasite growth as well as restore hemozoin levels. Conclusions We found that the transient downregulation of PfLPL1 in the parasite disrupted lipid homeostasis and caused a reduction in neutral lipids essentially required for heme to hemozoin conversion. Our study suggests a crucial link between phospholipid catabolism and generation of neutral lipids (TAGs) with the host haemoglobin degradation pathway. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01042-z.
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Affiliation(s)
- Mohd Asad
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110 067, India
| | - Yoshiki Yamaryo-Botté
- ApicoLipid Team, Institute for Advanced Biosciences, CNRS UMR5309, Université Grenoble Alpes, INSERM U1209, Grenoble, France
| | - Mohammad E Hossain
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110 067, India
| | - Vandana Thakur
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110 067, India
| | - Shaifali Jain
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110 067, India
| | - Gaurav Datta
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110 067, India
| | - Cyrille Y Botté
- ApicoLipid Team, Institute for Advanced Biosciences, CNRS UMR5309, Université Grenoble Alpes, INSERM U1209, Grenoble, France
| | - Asif Mohmmed
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110 067, India.
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de Villiers KA, Egan TJ. Heme Detoxification in the Malaria Parasite: A Target for Antimalarial Drug Development. Acc Chem Res 2021; 54:2649-2659. [PMID: 33982570 DOI: 10.1021/acs.accounts.1c00154] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Over the last century, malaria deaths have decreased by more than 85%. Nonetheless, there were 405 000 deaths in 2018, mostly resulting from Plasmodium falciparum infection. In the 21st century, much of the advance has arisen from the deployment of insecticide-treated bed nets and artemisinin combination therapy. However, over the past few decades parasites with a delayed artemisinin clearance phenotype have appeared in Southeast Asia, threatening further gains. The effort to find new drugs is thus urgent. A prominent process in blood stage malaria parasites, which we contend remains a viable drug target, is hemozoin formation. This crystalline material consisting of heme can be readily seen when parasites are viewed microscopically. The process of its formation in the parasite, however, is still not fully understood.In early work, we recognized hemozoin formation as a biomineralization process. We have subsequently investigated the kinetics of synthetic hemozoin (β-hematin) crystallization catalyzed at lipid-aqueous interfaces under biomimetic conditions. This led us to the use of neutral detergent-based high-throughput screening (HTS) for inhibitors of β-hematin formation. A good hit rate against malaria parasites was obtained. Simultaneously, we developed a pyridine-based assay which proved successful in measuring the concentrations of hematin not converted to β-hematin.The pyridine assay was adapted to determine the effects of chloroquine and other clinical antimalarials on hemozoin formation in the cell. This permitted the determination of the dose-dependent amounts of exchangeable heme and hemozoin in P. falciparum for the first time. These studies have shown that hemozoin inhibitors cause a dose-dependent increase in exchangeable heme, correlated with decreased parasite survival. Electron spectroscopic imaging (ESI) showed a relocation of heme iron into the parasite cytoplasm, while electron microscopy provided evidence of the disruption of hemozoin crystals. This cellular assay was subsequently extended to top-ranked hits from a wide range of scaffolds found by HTS. Intriguingly, the amounts of exchangeable heme at the parasite growth IC50 values of these scaffolds showed substantial variation. The amount of exchangeable heme was found to be correlated with the amount of inhibitor accumulated in the parasitized red blood cell. This suggests that heme-inhibitor complexes, rather than free heme, lead to parasite death. This was supported by ESI using a Br-containing compound which showed the colocalization of Fe and Br as well as by confocal Raman microscopy which confirmed the presence of a complex in the parasite. Current evidence indicates that inhibitors block hemozoin formation by surface adsorption. Indeed, we have successfully introduced molecular docking with hemozoin to find new inhibitors. It follows that the resulting increase in free heme leads to the formation of the parasiticidal heme-inhibitor complex. We have reported crystal structures of heme-drug complexes for several aryl methanol antimalarials in nonaqueous media. These form coordination complexes but most other inhibitors interact noncovalently, and the determination of their structures remains a major challenge.It is our view that key future developments will include improved assays to measure cellular heme levels, better in silico approaches for predicting β-hematin inhibition, and a concerted effort to determine the structure and properties of heme-inhibitor complexes.
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Affiliation(s)
- Katherine A. de Villiers
- Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag, Matieland 7600, South Africa
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Observatory, Cape Town 7945, South Africa
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10
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Matz JM, Drepper B, Blum TB, van Genderen E, Burrell A, Martin P, Stach T, Collinson LM, Abrahams JP, Matuschewski K, Blackman MJ. A lipocalin mediates unidirectional heme biomineralization in malaria parasites. Proc Natl Acad Sci U S A 2020; 117:16546-16556. [PMID: 32601225 PMCID: PMC7368307 DOI: 10.1073/pnas.2001153117] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
During blood-stage development, malaria parasites are challenged with the detoxification of enormous amounts of heme released during the proteolytic catabolism of erythrocytic hemoglobin. They tackle this problem by sequestering heme into bioinert crystals known as hemozoin. The mechanisms underlying this biomineralization process remain enigmatic. Here, we demonstrate that both rodent and human malaria parasite species secrete and internalize a lipocalin-like protein, PV5, to control heme crystallization. Transcriptional deregulation of PV5 in the rodent parasite Plasmodium berghei results in inordinate elongation of hemozoin crystals, while conditional PV5 inactivation in the human malaria agent Plasmodium falciparum causes excessive multidirectional crystal branching. Although hemoglobin processing remains unaffected, PV5-deficient parasites generate less hemozoin. Electron diffraction analysis indicates that despite the distinct changes in crystal morphology, neither the crystalline order nor unit cell of hemozoin are affected by impaired PV5 function. Deregulation of PV5 expression renders P. berghei hypersensitive to the antimalarial drugs artesunate, chloroquine, and atovaquone, resulting in accelerated parasite clearance following drug treatment in vivo. Together, our findings demonstrate the Plasmodium-tailored role of a lipocalin family member in hemozoin formation and underscore the heme biomineralization pathway as an attractive target for therapeutic exploitation.
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Affiliation(s)
- Joachim M Matz
- Malaria Biochemistry Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom;
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany
| | - Benjamin Drepper
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany
| | - Thorsten B Blum
- Laboratory of Nanoscale Biology, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Eric van Genderen
- Laboratory of Nanoscale Biology, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Alana Burrell
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Peer Martin
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany
| | - Thomas Stach
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany
| | - Lucy M Collinson
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - Jan Pieter Abrahams
- Laboratory of Nanoscale Biology, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, 4051 Basel, Switzerland
- Institute of Biology, Leiden University, 2311 EZ Leiden, The Netherlands
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, 10115 Berlin, Germany
| | - Michael J Blackman
- Malaria Biochemistry Laboratory, The Francis Crick Institute, NW1 1AT London, United Kingdom
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, WC1E 7HT London, United Kingdom
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Giannangelo C, Siddiqui G, De Paoli A, Anderson BM, Edgington-Mitchell LE, Charman SA, Creek DJ. System-wide biochemical analysis reveals ozonide antimalarials initially act by disrupting Plasmodium falciparum haemoglobin digestion. PLoS Pathog 2020; 16:e1008485. [PMID: 32589689 PMCID: PMC7347234 DOI: 10.1371/journal.ppat.1008485] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 07/09/2020] [Accepted: 05/13/2020] [Indexed: 01/23/2023] Open
Abstract
Ozonide antimalarials, OZ277 (arterolane) and OZ439 (artefenomel), are synthetic peroxide-based antimalarials with potent activity against the deadliest malaria parasite, Plasmodium falciparum. Here we used a "multi-omics" workflow, in combination with activity-based protein profiling (ABPP), to demonstrate that peroxide antimalarials initially target the haemoglobin (Hb) digestion pathway to kill malaria parasites. Time-dependent metabolomic profiling of ozonide-treated P. falciparum infected red blood cells revealed a rapid depletion of short Hb-derived peptides followed by subsequent alterations in lipid and nucleotide metabolism, while untargeted peptidomics showed accumulation of longer Hb-derived peptides. Quantitative proteomics and ABPP assays demonstrated that Hb-digesting proteases were increased in abundance and activity following treatment, respectively. Ozonide-induced depletion of short Hb-derived peptides was less extensive in a drug-treated K13-mutant artemisinin resistant parasite line (Cam3.IIR539T) than in the drug-treated isogenic sensitive strain (Cam3.IIrev), further confirming the association between ozonide activity and Hb catabolism. To demonstrate that compromised Hb catabolism may be a primary mechanism involved in ozonide antimalarial activity, we showed that parasites forced to rely solely on Hb digestion for amino acids became hypersensitive to short ozonide exposures. Quantitative proteomics analysis also revealed parasite proteins involved in translation and the ubiquitin-proteasome system were enriched following drug treatment, suggestive of the parasite engaging a stress response to mitigate ozonide-induced damage. Taken together, these data point to a mechanism of action involving initial impairment of Hb catabolism, and indicate that the parasite regulates protein turnover to manage ozonide-induced damage.
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Affiliation(s)
- Carlo Giannangelo
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Ghizal Siddiqui
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Amanda De Paoli
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Bethany M. Anderson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Laura E. Edgington-Mitchell
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
- Department of Maxillofacial Surgery, College of Dentistry, New York University, New York, New York, United States of America
| | - Susan A. Charman
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Darren J. Creek
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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12
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Stringer T, Wiesner L, Smith GS. Ferroquine-derived polyamines that target resistant Plasmodium falciparum. Eur J Med Chem 2019; 179:78-83. [DOI: 10.1016/j.ejmech.2019.06.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 06/07/2019] [Accepted: 06/07/2019] [Indexed: 01/14/2023]
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13
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Stringer T, Quintero MAS, Wiesner L, Smith GS, Nordlander E. Evaluation of PTA-derived ruthenium(II) and iridium(III) quinoline complexes against chloroquine-sensitive and resistant strains of the Plasmodium falciparum malaria parasite. J Inorg Biochem 2019; 191:164-173. [DOI: 10.1016/j.jinorgbio.2018.11.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 11/15/2018] [Accepted: 11/25/2018] [Indexed: 10/27/2022]
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14
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Pasupureddy R, Atul, Seshadri S, Pande V, Dixit R, Pandey KC. Current scenario and future strategies to fight artemisinin resistance. Parasitol Res 2018; 118:29-42. [PMID: 30478733 DOI: 10.1007/s00436-018-6126-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/19/2018] [Indexed: 02/05/2023]
Abstract
Despite several setbacks in the fight against malaria such as insecticide and drug resistance as well as low efficacy of available vaccines, considerable success in reducing malaria burden has been achieved in the past decade. Artemisinins (ARTs and their combination therapies, ACTs), the current frontline drugs against uncomplicated malaria, rapidly kill plasmodial parasites and are non-toxic at short exposures. Though the exact mode of action remains unclear, the endoperoxide bridge, indispensable for ART activity, is thought to react with heme released from hemoglobin hydrolysis and generate free radicals that alkylate multiple protein targets, thereby disrupting proteostasis pathways. However, rapid development of ART resistance in recent years with no potential alternatives on the horizon threaten the elimination efforts. The Greater Mekong Subregion in South-East Asia continues to churn out mutants resistant to multiple ACTs and detected in increasingly expanding geographies. Extensive research on ART-resistant strains have identified a potential candidate Kelch13, crucial for mediating ART resistance. Parasites with mutations in the propeller domains of Plasmodium falciparum Kelch13 protein were shown to have enhanced phosphatidylinositol 3-kinase levels that were concomitant with delayed parasite clearance. Current research focused on understanding the mechanism of Kelch13-mediated ART resistance could provide better insights into Plasmodium resistome. This review covers the current proposed mechanisms of ART activity, resistance strategies adopted by the parasite in response to ACTs and possible future approaches to mitigate the spread of resistance from South-East Asia.
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Affiliation(s)
- Rahul Pasupureddy
- National Institute of Malaria Research, Dwarka Sector 8, New Delhi, 110077, India.,Institute of Science, Nirma University, SG Highway, Ahmedabad, Gujarat, 382481, India
| | - Atul
- National Institute of Malaria Research, Dwarka Sector 8, New Delhi, 110077, India.,Department of Biotechnology, Kumaun University, Nainital, Uttarakhand, 263001, India
| | - Sriram Seshadri
- Institute of Science, Nirma University, SG Highway, Ahmedabad, Gujarat, 382481, India
| | - Veena Pande
- Department of Biotechnology, Kumaun University, Nainital, Uttarakhand, 263001, India
| | - Rajnikant Dixit
- National Institute of Malaria Research, Dwarka Sector 8, New Delhi, 110077, India
| | - Kailash C Pandey
- National Institute of Malaria Research, Dwarka Sector 8, New Delhi, 110077, India. .,Department of Biochemistry, Indian Council of Medical Research, National Institute for Research in Environmental Health, Bhopal, Madhya Pradesh, 462001, India.
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15
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Woodland JG, Hunter R, Smith PJ, Egan TJ. Shining new light on ancient drugs: preparation and subcellular localisation of novel fluorescent analogues of Cinchona alkaloids in intraerythrocytic Plasmodium falciparum. Org Biomol Chem 2018; 15:589-597. [PMID: 27785512 DOI: 10.1039/c6ob02110g] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Fluorescent derivatives of the archetypal antimalarial quinine and its diastereomer, quinidine, suitable for cellular imaging have been synthesised by attaching the small extrinsic fluorophore, NBD. Interactions of these derivatives with ferriprotoporphyrin IX were evaluated to verify that insights generated by live-cell imaging were relevant to the parent molecules. These analogues are shown by confocal and super-resolution microscopy to accumulate selectively in Plasmodium falciparum. Localisation to the region corresponding to the digestive vacuole supports the putative primary role of these alkaloids as haemozoin inhibitors. Quantitative analysis revealed minimal accumulation within the nucleus, rejecting the disruption of DNA replication as a possible mode of action. While extensive localisation to phospholipid structures and associated organelles was observed, the analogues did not show evidence of association with neutral lipid bodies.
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Affiliation(s)
- John G Woodland
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa.
| | - Roger Hunter
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa.
| | - Peter J Smith
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, 7925, South Africa
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa.
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16
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Maknitikul S, Luplertlop N, Chaisri U, Maneerat Y, Ampawong S. Featured Article: Immunomodulatory effect of hemozoin on pneumocyte apoptosis via CARD9 pathway, a possibly retarding pulmonary resolution. Exp Biol Med (Maywood) 2018; 243:395-407. [PMID: 29402133 DOI: 10.1177/1535370218757458] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Plasmodium falciparum, the most virulent malaria parasite species, causes severe symptoms especially acute lung injury (ALI), of which characterized by alveolar epithelium and endothelium destruction and accelerated to blood-gas-barrier breakdown. Parasitized erythrocytes, endothelial cells, monocytes, and cytokines are all involved in this mechanism, but hemozoin (HZ), the parasitic waste from heme detoxification, also mainly contributes. In addition, it is not clear why type II pneumocyte proliferation, alveolar restorative stage, is rare in malaria-associated ALI. To address this, in vitro culture of A549 cells with Plasmodium HZ or with interleukin (IL)-1β triggered by HZ and monocytes (HZ-IL-1β) was conducted to determine their alveolar apoptotic effect using ethidium bromide/acridine orange staining, annexin-V-FITC/propidium iodide staining, and electron mircroscopic study. Caspase recruitment domain-containing protein 9 ( CARD9), the apoptotic regulator gene, and IL-1β were quantified by reverse-transcriptase PCR. Junctional cellular defects were characterized by immunohistochemical staining of E-cadherin. The results revealed that cellular apoptosis and CARD9 expression levels were extremely high 24 h after induction by HZ-IL-1β when compared to the HZ- and non-treated groups. E-cadherin was markedly down-regulated by HZ-IL-1β and HZ treatments. CARD9 expression was positively correlated with IL-1β expression and the number of apoptotic cells. Interestingly, the localization of HZ in the vesicular surfactant of apoptotic pneumocyte was also identified and submitted to be a cause of alveolar resolution abnormality. Thus, HZ triggers monocytes to produce IL-1β and induces pneumocyte type II apoptosis through CARD9 pathway in association with down-regulated E-cadherin, which probably impairs alveolar resolution in malaria-associated ALI. Impact statement The present work shows the physical and immunomodulatory properties of hemozoin on the induction of pneumocyte apoptosis in relation to IL-1β production through the CARD9 pathway. This occurrence may be a possible pathway for the retardation of lung resolution leading to blood-gas-barrier breakdown. Our findings lead to the understanding of the host-parasite relationship focusing on the dysfunction in ALI induced by HZ, a possible pathway of the recovering lung epithelial retardation in malaria-associated ARDS.
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Affiliation(s)
- Sitang Maknitikul
- 1 Department of Tropical Pathology, 115374 Faculty of Tropical Medicine, Mahidol University , Ratchathewi, Bangkok 10400, Thailand
| | - Natthanej Luplertlop
- 2 Department of Microbiology and Immunology, 115374 Faculty of Tropical Medicine, Mahidol University , Ratchathewi, Bangkok 10400, Thailand
| | - Urai Chaisri
- 1 Department of Tropical Pathology, 115374 Faculty of Tropical Medicine, Mahidol University , Ratchathewi, Bangkok 10400, Thailand
| | - Yaowapa Maneerat
- 1 Department of Tropical Pathology, 115374 Faculty of Tropical Medicine, Mahidol University , Ratchathewi, Bangkok 10400, Thailand
| | - Sumate Ampawong
- 1 Department of Tropical Pathology, 115374 Faculty of Tropical Medicine, Mahidol University , Ratchathewi, Bangkok 10400, Thailand
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17
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Uppal K, Salinas JL, Monteiro WM, Val F, Cordy RJ, Liu K, Melo GC, Siqueira AM, Magalhaes B, Galinski MR, Lacerda MVG, Jones DP. Plasma metabolomics reveals membrane lipids, aspartate/asparagine and nucleotide metabolism pathway differences associated with chloroquine resistance in Plasmodium vivax malaria. PLoS One 2017; 12:e0182819. [PMID: 28813452 PMCID: PMC5559093 DOI: 10.1371/journal.pone.0182819] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 07/25/2017] [Indexed: 11/18/2022] Open
Abstract
Background Chloroquine (CQ) is the main anti-schizontocidal drug used in the treatment of uncomplicated malaria caused by Plasmodium vivax. Chloroquine resistant P. vivax (PvCR) malaria in the Western Pacific region, Asia and in the Americas indicates a need for biomarkers of resistance to improve therapy and enhance understanding of the mechanisms associated with PvCR. In this study, we compared plasma metabolic profiles of P. vivax malaria patients with PvCR and chloroquine sensitive parasites before treatment to identify potential molecular markers of chloroquine resistance. Methods An untargeted high-resolution metabolomics analysis was performed on plasma samples collected in a malaria clinic in Manaus, Brazil. Male and female patients with Plasmodium vivax were included (n = 46); samples were collected before CQ treatment and followed for 28 days to determine PvCR, defined as the recurrence of parasitemia with detectable plasma concentrations of CQ ≥100 ng/dL. Differentially expressed metabolic features between CQ-Resistant (CQ-R) and CQ-Sensitive (CQ-S) patients were identified using partial least squares discriminant analysis and linear regression after adjusting for covariates and multiple testing correction. Pathway enrichment analysis was performed using Mummichog. Results Linear regression and PLS-DA methods yielded 69 discriminatory features between CQ-R and CQ-S groups, with 10-fold cross-validation classification accuracy of 89.6% using a SVM classifier. Pathway enrichment analysis showed significant enrichment (p<0.05) of glycerophospholipid metabolism, glycosphingolipid metabolism, aspartate and asparagine metabolism, purine and pyrimidine metabolism, and xenobiotics metabolism. Glycerophosphocholines levels were significantly lower in the CQ-R group as compared to CQ-S patients and also to independent control samples. Conclusions The results show differences in lipid, amino acids, and nucleotide metabolism pathways in the plasma of CQ-R versus CQ-S patients prior to antimalarial treatment. Metabolomics phenotyping of P. vivax samples from patients with well-defined clinical CQ-resistance is promising for the development of new tools to understand the biological process and to identify potential biomarkers of PvCR.
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Affiliation(s)
- Karan Uppal
- Clinical Biomarkers Laboratory, Division of Pulmonary Medicine, Department of Medicine, Emory University, Atlanta, Georgia, United States of America
- Malaria Host–Pathogen Interaction Center, Atlanta, Georgia, United States of America
- * E-mail: ;
| | - Jorge L. Salinas
- Malaria Host–Pathogen Interaction Center, Atlanta, Georgia, United States of America
- International Center for Malaria Research, Education and Development, Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road, Atlanta, Georgia, United States of America
- Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
| | - Wuelton M. Monteiro
- Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brazil
| | - Fernando Val
- Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brazil
| | - Regina J. Cordy
- Malaria Host–Pathogen Interaction Center, Atlanta, Georgia, United States of America
- International Center for Malaria Research, Education and Development, Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road, Atlanta, Georgia, United States of America
| | - Ken Liu
- Clinical Biomarkers Laboratory, Division of Pulmonary Medicine, Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Gisely C. Melo
- Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brazil
| | - Andre M. Siqueira
- Instituto Nacional de Infectologia Evandro Chagas (FIOCRUZ), Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Mary R. Galinski
- Malaria Host–Pathogen Interaction Center, Atlanta, Georgia, United States of America
- International Center for Malaria Research, Education and Development, Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road, Atlanta, Georgia, United States of America
- Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
| | - Marcus V. G. Lacerda
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brazil
- Instituto Leônidas & Maria Deane (FIOCRUZ), Manaus, Amazonas, Brazil
- * E-mail: ;
| | - Dean P. Jones
- Clinical Biomarkers Laboratory, Division of Pulmonary Medicine, Department of Medicine, Emory University, Atlanta, Georgia, United States of America
- Malaria Host–Pathogen Interaction Center, Atlanta, Georgia, United States of America
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18
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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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19
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Stringer T, Seldon R, Liu N, Warner DF, Tam C, Cheng LW, Land KM, Smith PJ, Chibale K, Smith GS. Antimicrobial activity of organometallic isonicotinyl and pyrazinyl ferrocenyl-derived complexes. Dalton Trans 2017; 46:9875-9885. [DOI: 10.1039/c7dt01952a] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Isonicotinyl and pyrazinyl ferrocenyl-derived complexes were evaluatedin vitrofor antimycobacterial and antiparasitic activity.
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20
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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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21
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Stringer T, De Kock C, Guzgay H, Okombo J, Liu J, Kanetake S, Kim J, Tam C, Cheng LW, Smith PJ, Hendricks DT, Land KM, Egan TJ, Smith GS. Mono- and multimeric ferrocene congeners of quinoline-based polyamines as potential antiparasitics. Dalton Trans 2016; 45:13415-26. [DOI: 10.1039/c6dt02685k] [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
A series of mono- and multimeric polyamine-containing ferrocenyl complexes bearing a quinoline motif were prepared.
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22
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Tempera C, Franco R, Caro C, André V, Eaton P, Burke P, Hänscheid T. Characterization and optimization of the haemozoin-like crystal (HLC) assay to determine Hz inhibiting effects of anti-malarial compounds. Malar J 2015; 14:403. [PMID: 26458401 PMCID: PMC4603294 DOI: 10.1186/s12936-015-0913-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 09/25/2015] [Indexed: 01/13/2023] Open
Abstract
Background The haem-haemozoin biocrystallization pathway is an attractive target where several efficacious and safe anti-malarial drugs act. Consequently, in vitro haemozoin (Hz) inhibition assays have been developed to identify novel compounds. However, results may differ between assays and often require complex methods or sophisticated infrastructure. The recently reported growth of haemozoin-like crystals (HLC) appears to be a simple alternative although the endproduct is structurally different to Hz. This study set out to characterize this assay in depth, optimize it, and assess its performance. Methods The HLC assay was used as previously described but a range of different growth conditions were examined. Obtained HLCs were investigated and compared to synthetic (sHz) and natural haemozoin (nHz) using scanning electron microscopy, powder X-ray diffraction (PXRD), Fourier Transform Infrared spectroscopy (FTIR) and Raman spectroscopy (RS). Interactions of HLC with quinolines was analysed using RS. Inhibitory effects of currently used anti-malarial drugs under four final growth conditions were established. Results HLC growth requires Mycoplasma Broth Base, Tween 80, pancreatin, and lysed blood or haemin. HLCs are similar to nHz and sHz in terms of solubility, macroscopic and microscopic appearance although PXRD, FTIR and RS confirm that the haem aggregates of HLCs are structurally different. RS reveals that CQ seems to interact with HLCs in similar ways as with Hz. Inhibition of quinoline drugs ranged from 62.5 µM (chloroquine, amodiaquine, piperaquine) to 500 µM in mefloquine. Conclusions The HLC assay provides data on inhibiting properties of compounds. Even if the end-product is not structurally identical to Hz, the inhibitory effects appear consistent with those obtained with sHz assays, as illustrated by the results obtained for quinolines. The assay is simple, inexpensive, robust, reproducible and can be performed under basic laboratory conditions with a simple visual positive/negative read-out. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0913-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Carolina Tempera
- Faculdade de Medicina de Lisboa, Instituto de Medicina Molecular, Av. Prof. Egas Moniz, 1649-028, Lisbon, Portugal.
| | - Ricardo Franco
- Departamento de Química, Faculdade de Ciências e Tecnologia, UCIBIO, REQUIMTE, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal.
| | - Carlos Caro
- Departamento de Química, Faculdade de Ciências e Tecnologia, UCIBIO, REQUIMTE, Universidade NOVA de Lisboa, 2829-516, Caparica, Portugal.
| | - Vânia André
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal.
| | - Peter Eaton
- , Departamento de Química e Bioquímica, Faculdade de Ciências, REQUIMTE/UCIBIO, Universidade do Porto, 4169-007, Porto, Portugal.
| | - Peter Burke
- STERIS Corporation, 5960 Heisley Road, Mentor, OH, 44060, USA.
| | - Thomas Hänscheid
- Faculdade de Medicina de Lisboa, Instituto de Medicina Molecular, Av. Prof. Egas Moniz, 1649-028, Lisbon, Portugal. .,Faculdade de Medicina, Instituto de Microbiologia, Lisbon, Portugal.
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23
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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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Synthesis, characterization and pharmacological evaluation of ferrocenyl azines and their rhodium(I) complexes. J Organomet Chem 2015. [DOI: 10.1016/j.jorganchem.2015.04.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Kuter D, Streltsov V, Davydova N, Venter GA, Naidoo KJ, Egan TJ. Solution structures of chloroquine-ferriheme complexes modeled using MD simulation and investigated by EXAFS spectroscopy. J Inorg Biochem 2015; 154:114-25. [PMID: 26088729 DOI: 10.1016/j.jinorgbio.2015.06.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 06/07/2015] [Accepted: 06/09/2015] [Indexed: 10/23/2022]
Abstract
The interaction of chloroquine (CQ) and the μ-oxo dimer of iron(III) protoporphyrin IX (ferriheme) in aqueous solution was modeled using molecular dynamics (MD) simulations. Two models of the CQ-(μ-oxo ferriheme) complex were investigated, one involving CQ π-stacked with an unligated porphyrin face of μ-oxo ferriheme and the other in which CQ was docked between the two porphyrin rings. The feasibility of both models was tested by fitting computed structures to the experimental extended X-ray absorption fine structure (EXAFS) spectrum of the CQ-(μ-oxo ferriheme) complex in frozen aqueous solution. The docked model produced better agreement with experimental data, suggesting that this is the more likely structure in aqueous solution. The EXAFS fit indicated a longer than expected Fe-O bond of 1.87Å, accounting for the higher than expected magnetic moment of the complex. As a consequence, the asymmetric Fe-O-Fe stretch shifts much lower in frequency and was identified in the precipitated solid at 744cm(-1) with the aid of the O(18) isomer shift. Three important CQ-ferriheme interactions were identified in the docked structure. These were a hydrogen bond between the oxide bridge of μ-oxo ferriheme and the protonated quinolinium nitrogen atom of CQ; π-stacking between the quinoline ring of CQ and the porphyrin rings; and a close contact between the 7-chloro substituent of CQ and the porphyrin methyl hydrogen atoms. These interactions can be used to rationalize previously observed structure-activity relationships for quinoline-ferriheme association.
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Affiliation(s)
- David Kuter
- Scientific Computing Research Unit, Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Victor Streltsov
- Manufacturing Flagship, CSIRO, Parkville, Victoria 3050, Australia
| | - Natalia Davydova
- Manufacturing Flagship, CSIRO, Parkville, Victoria 3050, Australia
| | - Gerhard A Venter
- Scientific Computing Research Unit, Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Kevin J Naidoo
- Scientific Computing Research Unit, Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa.
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa.
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26
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Fong KY, Sandlin RD, Wright DW. Identification of β-hematin inhibitors in the MMV Malaria Box. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2015; 5:84-91. [PMID: 26150923 PMCID: PMC4486462 DOI: 10.1016/j.ijpddr.2015.05.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 05/15/2015] [Accepted: 05/19/2015] [Indexed: 11/22/2022]
Abstract
The Malaria Box, assembled by the Medicines for Malaria Venture, is a set of 400 structurally diverse, commercially available compounds with demonstrated activity against blood-stage Plasmodium falciparum. The compounds are a representative subset of the 20,000 in vitro antimalarials identified from the high-throughput screening efforts of St. Jude Children's Research Hospital (TN, USA), Novartis and GlaxoSmithKline. In addition, a small set of active compounds from commercially available libraries was added to this group, but it has not previously been published. Elucidation of the biochemical pathways on which these compounds act is a major challenge; therefore, access to these compounds has been made available free of charge to the investigator community. Here, the Malaria Box compounds were tested for activity against the formation of β-hematin, a synthetic form of the heme detoxification biomineral, hemozoin. Further, the mechanism of action of these compounds within the malaria parasite was explored. Ten of the Malaria Box compounds demonstrated significant inhibition of β-hematin formation. In this assay, dose–response data revealed IC50 values ranging from 8.7 to 22.7 μM for these hits, each of which is more potent than chloroquine (a known inhibitor of hemozoin formation). The in vitro antimalarial activity of these ten hits was confirmed in cultures of the chloroquine sensitive D6 strain of the parasite resulting in IC50 values of 135–2165 nM, followed by testing in the multidrug resistant strain, C235. Cultures of P. falciparum (D6) were then examined for their heme distribution following treatment with nine of the commercially available confirmed compounds, seven of which disrupted the hemozoin pathway. Ten of 400 Malaria Box compounds were found to be potent β-hematin inhibitors. We confirmed similar in vitro antimalarial activity to results from previous screens. 7 of the 9 commercially available hits were validated hemozoin inhibitors in culture.
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Affiliation(s)
- Kim Y Fong
- Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235, USA
| | - Rebecca D Sandlin
- Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235, USA
| | - David W Wright
- Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235, USA
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Mechanisms of hematin crystallization and inhibition by the antimalarial drug chloroquine. Proc Natl Acad Sci U S A 2015; 112:4946-51. [PMID: 25831526 DOI: 10.1073/pnas.1501023112] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hematin crystallization is the primary mechanism of heme detoxification in malaria parasites and the target of the quinoline class of antimalarials. Despite numerous studies of malaria pathophysiology, fundamental questions regarding hematin growth and inhibition remain. Among them are the identity of the crystallization medium in vivo, aqueous or organic; the mechanism of crystallization, classical or nonclassical; and whether quinoline antimalarials inhibit crystallization by sequestering hematin in the solution, or by blocking surface sites crucial for growth. Here we use time-resolved in situ atomic force microscopy (AFM) and show that the lipid subphase in the parasite may be a preferred growth medium. We provide, to our knowledge, the first evidence of the molecular mechanisms of hematin crystallization and inhibition by chloroquine, a common quinoline antimalarial drug. AFM observations demonstrate that crystallization strictly follows a classical mechanism wherein new crystal layers are generated by 2D nucleation and grow by the attachment of solute molecules. We identify four classes of surface sites available for binding of potential drugs and propose respective mechanisms of drug action. Further studies reveal that chloroquine inhibits hematin crystallization by binding to molecularly flat {100} surfaces. A 2-μM concentration of chloroquine fully arrests layer generation and step advancement, which is ∼10(4)× less than hematin's physiological concentration. Our results suggest that adsorption at specific growth sites may be a general mode of hemozoin growth inhibition for the quinoline antimalarials. Because the atomic structures of the identified sites are known, this insight could advance the future design and/or optimization of new antimalarials.
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Stringer T, Taylor D, Guzgay H, Shokar A, Au A, Smith PJ, Hendricks DT, Land KM, Egan TJ, Smith GS. Polyamine quinoline rhodium complexes: synthesis and pharmacological evaluation as antiparasitic agents against Plasmodium falciparum and Trichomonas vaginalis. Dalton Trans 2015. [DOI: 10.1039/c5dt02378e] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Salicylaldimine ligands and their corresponding Rh(i) complexes were prepared and evaluated as antiparasitic agents.
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Affiliation(s)
- Tameryn Stringer
- Department of Chemistry
- University of Cape Town
- Rondebosch 7701
- South Africa
| | - Dale Taylor
- Division of Clinical Pharmacology
- Department of Medicine
- University of Cape Town Medical School
- South Africa
| | - Hajira Guzgay
- Division of Medical Biochemistry
- University of Cape Town
- Rondebosch 7701
- South Africa
| | - Ajit Shokar
- Department of Biological Sciences
- University of the Pacific
- Stockton
- USA
| | - Aaron Au
- Department of Biological Sciences
- University of the Pacific
- Stockton
- USA
| | - Peter J. Smith
- Division of Clinical Pharmacology
- Department of Medicine
- University of Cape Town Medical School
- South Africa
| | - Denver T. Hendricks
- Division of Medical Biochemistry
- University of Cape Town
- Rondebosch 7701
- South Africa
| | - Kirkwood M. Land
- Department of Biological Sciences
- University of the Pacific
- Stockton
- USA
| | - Timothy J. Egan
- Department of Chemistry
- University of Cape Town
- Rondebosch 7701
- South Africa
| | - Gregory S. Smith
- Department of Chemistry
- University of Cape Town
- Rondebosch 7701
- South Africa
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29
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Vekilov PG, Rimer JD, Olafson KN, Ketchum MA. Lipid or aqueous medium for hematin crystallization? CrystEngComm 2015. [DOI: 10.1039/c5ce01178g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hematin crystallization, the primary heme detoxification mechanism of malaria parasites infecting human erythrocytes, most likely requires the participation of lipid structures.
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Affiliation(s)
- Peter G. Vekilov
- Department of Chemical and Biomolecular Engineering
- University of Houston
- Houston, USA
- Department of Chemistry
- University of Houston
| | - Jeffrey D. Rimer
- Department of Chemical and Biomolecular Engineering
- University of Houston
- Houston, USA
| | - Katy N. Olafson
- Department of Chemical and Biomolecular Engineering
- University of Houston
- Houston, USA
| | - Megan A. Ketchum
- Department of Chemical and Biomolecular Engineering
- University of Houston
- Houston, USA
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30
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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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31
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Tran PN, Brown SHJ, Mitchell TW, Matuschewski K, McMillan PJ, Kirk K, Dixon MWA, Maier AG. A female gametocyte-specific ABC transporter plays a role in lipid metabolism in the malaria parasite. Nat Commun 2014; 5:4773. [DOI: 10.1038/ncomms5773] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 07/21/2014] [Indexed: 11/09/2022] Open
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32
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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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34
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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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36
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Coronado LM, Nadovich CT, Spadafora C. Malarial hemozoin: from target to tool. Biochim Biophys Acta Gen Subj 2014; 1840:2032-41. [PMID: 24556123 DOI: 10.1016/j.bbagen.2014.02.009] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 01/26/2014] [Accepted: 02/10/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND Malaria is an extremely devastating disease that continues to affect millions of people each year. A distinctive attribute of malaria infected red blood cells is the presence of malarial pigment or the so-called hemozoin. Hemozoin is a biocrystal synthesized by Plasmodium and other blood-feeding parasites to avoid the toxicity of free heme derived from the digestion of hemoglobin during invasion of the erythrocytes. SCOPE OF REVIEW Hemozoin is involved in several aspects of the pathology of the disease as well as in important processes such as the immunogenicity elicited. It is known that the once best antimalarial drug, chloroquine, exerted its effect through interference with the process of hemozoin formation. In the present review we explore what is known about hemozoin, from hemoglobin digestion, to its final structural analysis, to its physicochemical properties, its role in the disease and notions of the possible mechanisms that could kill the parasite by disrupting the synthesis or integrity of this remarkable crystal. MAJOR CONCLUSIONS The importance and peculiarities of this biocrystal have given researchers a cause to consider it as a target for new antimalarials and to use it through unconventional approaches for diagnostics and therapeutics against the disease. GENERAL SIGNIFICANCE Hemozoin plays an essential role in the biology of malarial disease. Innovative ideas could use all the existing data on the unique chemical and biophysical properties of this macromolecule to come up with new ways of combating malaria.
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Affiliation(s)
- Lorena M Coronado
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Panama; Department of Biotechnology, Acharya Nagarjuna University, Guntur 522 510, A.P., India
| | | | - Carmenza Spadafora
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad del Saber, Panama.
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37
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Tyberghein A, Deroost K, Schwarzer E, Arese P, Van den Steen PE. Immunopathological effects of malaria pigment or hemozoin and other crystals. Biofactors 2014; 40:59-78. [PMID: 23907956 DOI: 10.1002/biof.1119] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/01/2013] [Accepted: 05/07/2013] [Indexed: 01/26/2023]
Abstract
Blood-stage malaria parasites produce insoluble hemozoin (Hz) crystals that are released in the blood circulation upon schizont rupture. In general, endogenous crystal formation or inhalation of crystalline materials is often associated with pathology. As the immune system responds differently to crystalline particles than to soluble molecules, in this review, the properties, immunological recognition, and pathogenic responses of Hz are discussed, and compared with two other major pathogenic crystals, monosodium urate (MSU) and asbestos. Because of the size and shape of MSU crystals and asbestos fibers, phagolysosomal formation is inefficient and often results in leakage of lysosomal content in the cell cytoplasm and/or in the extracellular environment with subsequent cell damage and cell death. Phagolysosomal formation after Hz ingestion is normal, but Hz remains stored inside these cells for months or even longer without any detectable degradation. Nonetheless, the different types of crystals are recognized by similar immune receptors, involving Toll-like receptors, the inflammasome, antibodies, and/or complement factors, and through similar signaling cascades, they activate both proinflammatory and anti-inflammatory immune responses that contribute to inflammation-associated pathology.
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Affiliation(s)
- Ariane Tyberghein
- Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven - University of Leuven, Leuven, Belgium
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Visser BJ, Wieten RW, Nagel IM, Grobusch MP. Serum lipids and lipoproteins in malaria--a systematic review and meta-analysis. Malar J 2013; 12:442. [PMID: 24314058 PMCID: PMC4029227 DOI: 10.1186/1475-2875-12-442] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/04/2013] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Serum lipid profile changes have been observed during malaria infection. The underlying biological mechanisms remain unclear. The aim of this paper is to provide an overview on those serum lipid profile changes, and to discuss possible underlying biological mechanisms and the role of lipids in malaria pathogenesis. METHODS A systematic review and meta-analysis to determine lipid profile changes during malaria was conducted, following PRISMA guidelines. Without language restrictions, Medline/PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, Biosis Previews and the African Index Medicus were searched for studies published up to 11 July, 2013, that measured serum lipid parameters in malaria patients. Also, major trial registries were searched. Mean differences in lipid profile parameters were combined in fixed and random effects meta-analysis, with a separate analysis for different groups of controls (healthy, other febrile illnesses or very low parasitaemia). These parameters were also compared between severe malaria and uncomplicated malaria. Funnel plots were used to test for publication bias. RESULTS Of 2,518 studies reviewed, 42 met the criteria for inclusion in the qualitative analysis, and of these, 15 reported the necessary data for inclusion in the meta-analysis for cholesterol; nine for high-density lipoprotein (HDL), eight for low-density lipoprotein (LDL), and nine for triglycerides, respectively. Total cholesterol, HDL and LDL concentrations were lower in malaria and other febrile diseases compared to healthy controls. The decline was more pronounced and statistically significant during malaria compared to other febrile diseases. These results were consistent across included studies. Triglycerides were raised compared to healthy controls, but not statistically significant when compared to symptomatic controls. CONCLUSIONS This meta-analysis suggests that the observed lipid profile changes are characteristic for malaria. Although a definite link with the pathogenesis of malaria cannot yet be demonstrated, plausible hypotheses of biological mechanisms involving host lipid alterations and the pathogenesis of malaria exist. An increased research effort to elucidate the precise pathways is warranted, since this could lead to better understanding of malaria pathophysiology and consequently to novel treatment approaches.
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Affiliation(s)
| | | | | | - Martin P Grobusch
- Centre of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, PO Box 226601100 DD, Amsterdam, The Netherlands.
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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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Phospholipid membrane-mediated hemozoin formation: the effects of physical properties and evidence of membrane surrounding hemozoin. PLoS One 2013; 8:e70025. [PMID: 23894579 PMCID: PMC3720957 DOI: 10.1371/journal.pone.0070025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 06/20/2013] [Indexed: 11/19/2022] Open
Abstract
Phospholipid membranes are thought to be one of the main inducers of hemozoin formation in Plasmodia and other blood-feeding parasites. The “membrane surrounding hemozoin” has been observed in infected cells but has not been observed in in vitro experiments. This study focused on observing the association of phospholipid membranes and synthetic β-hematin, which is chemically identical to hemozoin, and on a further exploration into the mechanism of phospholipid membrane-induced β-hematin formation. Our results showed that β-hematin formation was induced by phospholipids in the fluid phase but not in the gel phase. The ability of phospholipids to induce β-hematin formation was inversely correlated with gel-to-liquid phase transition temperatures, suggesting an essential insertion of heme into the hydrocarbon chains of the phospholipid membrane to form β-hematin. For this study, a cryogenic transmission electron microscope was used to achieve the first direct observation of the formation of a monolayer of phospholipid membrane surrounding β-hematin.
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Combrinck JM, Mabotha TE, Ncokazi KK, Ambele MA, Taylor D, Smith PJ, Hoppe HC, Egan TJ. Insights into the role of heme in the mechanism of action of antimalarials. ACS Chem Biol 2013; 8:133-7. [PMID: 23043646 DOI: 10.1021/cb300454t] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
By using cell fractionation and measurement of Fe(III)heme-pyridine, the antimalarial chloroquine (CQ) has been shown to cause a dose-dependent decrease in hemozoin and concomitant increase in toxic free heme in cultured Plasmodium falciparum that is directly correlated with parasite survival. Transmission electron microscopy techniques have further shown that heme is redistributed from the parasite digestive vacuole to the cytoplasm and that CQ disrupts hemozoin crystal growth, resulting in mosaic boundaries in the crystals formed in the parasite. Extension of the cell fractionation study to other drugs has shown that artesunate, amodiaquine, lumefantrine, mefloquine, and quinine, all clinically important antimalarials, also inhibit hemozoin formation in the parasite cell, while the antifolate pyrimethamine and its combination with sulfadoxine do not. This study finally provides direct evidence in support of the hemozoin inhibition hypothesis for the mechanism of action of CQ and shows that other quinoline and related antimalarials inhibit cellular hemozoin formation.
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Affiliation(s)
- Jill M. Combrinck
- Department of Chemistry and ‡Division of Pharmacology, Department of Medicine, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa
| | - Tebogo E. Mabotha
- Department of Chemistry and ‡Division of Pharmacology, Department of Medicine, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa
| | - Kanyile K. Ncokazi
- Department of Chemistry and ‡Division of Pharmacology, Department of Medicine, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa
| | - Melvin A. Ambele
- Department of Chemistry and ‡Division of Pharmacology, Department of Medicine, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa
| | - Dale Taylor
- Department of Chemistry and ‡Division of Pharmacology, Department of Medicine, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa
| | - Peter J. Smith
- Department of Chemistry and ‡Division of Pharmacology, Department of Medicine, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa
| | - Heinrich C. Hoppe
- Department of Chemistry and ‡Division of Pharmacology, Department of Medicine, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa
| | - Timothy J. Egan
- Department of Chemistry and ‡Division of Pharmacology, Department of Medicine, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa
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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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Ambele MA, Egan TJ. Neutral lipids associated with haemozoin mediate efficient and rapid β-haematin formation at physiological pH, temperature and ionic composition. Malar J 2012; 11:337. [PMID: 23043460 PMCID: PMC3479076 DOI: 10.1186/1475-2875-11-337] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 10/03/2012] [Indexed: 11/10/2022] Open
Abstract
Background The malaria parasite disposes of host-derived ferrihaem (iron(III)protoporphyrin IX, Fe(III)PPIX) by conversion to crystalline haemozoin in close association with neutral lipids. Lipids mediate synthetic haemozoin (β-haematin) formation very efficiently. However, the effect on reaction rates of concentrations of lipid, Fe(III)PPIX and physiologically relevant ions and biomolecules are unknown. Methods Lipid emulsions containing Fe(III)PPIX were prepared in aqueous medium (pH 4.8, 37°C) to mediate β-haematin formation. The reaction was quenched at various times and free Fe(III)PPIX measured colorimetrically as a pyridine complex and the kinetics and yields analysed. Products were also characterized by FTIR, TEM and electron diffraction. Autofluorescence was also used to monitor β-haematin formation by confocal microscopy. Results At fixed Fe(III)PPIX concentration, β-haematin yields remained constant with decreasing lipid concentration until a cut-off ratio was reached whereupon efficiency decreased dramatically. For the haemozoin-associated neutral lipid blend (NLB) and monopalmitoylglycerol (MPG), this occurred below a lipid/Fe(III)PPIX (L/H) ratio of 0.54. Rate constants were found to increase with L/H ratio above the cut-off. At 16 μM MPG, Fe(III)PPIX concentration could be raised until the L/H ratio reached the same ratio before a sudden decline in yield was observed. MPG-mediated β-haematin formation was relatively insensitive to biologically relevant cations (Na+, K+, Mg2+, Ca2+), or anions (H2PO4−, HCO3−, ATP, 2,3-diphosphoglycerate, glutathione). Confocal microscopy demonstrated β-haematin formation occurs in association with the lipid particles. Conclusions Kinetics of β-haematin formation have shown that haemozoin-associated neutral lipids alone are capable of mediating β-haematin formation at adequate rates under physiologically realistic conditions of ion concentrations to account for haemozoin formation.
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Affiliation(s)
- Melvin A Ambele
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
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van Dooren GG, Kennedy AT, McFadden GI. The use and abuse of heme in apicomplexan parasites. Antioxid Redox Signal 2012; 17:634-56. [PMID: 22320355 DOI: 10.1089/ars.2012.4539] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SIGNIFICANCE Heme is an essential prosthetic group for most life on Earth. It functions in numerous cellular redox reactions, including in antioxidant defenses and at several stages of the electron transport chain in prokaryotes and eukaryotic mitochondria. Heme also functions as a sensor and transport molecule for gases such as oxygen. Heme is a complex organic molecule and can only be synthesized through a multienzyme pathway from simpler precursors. Most free-living organisms synthesize their own heme by a broadly conserved metabolic pathway. Parasites are adept at scavenging molecules from their hosts, and heme is no exception. RECENT ADVANCES In this review we examine recent advances in understanding heme usage and acquisition in Apicomplexa, a group of parasites that include the causative agents of malaria, toxoplasmosis, and several major parasites of livestock. CRITICAL ISSUES Heme is critical to the survival of Apicomplexa, although the functions of heme in these organisms remain poorly understood. Some Apicomplexa likely scavenge heme from their host organisms, while others retain the ability to synthesize heme. Surprisingly, some Apicomplexa may be able to both synthesize and scavenge heme. Several Apicomplexa live in intracellular environments that contain high levels of heme. Since heme is toxic at high concentrations, parasites must carefully regulate intracellular heme levels and develop mechanisms to detoxify excess heme. Indeed, drugs interfering with heme detoxification serve as major antimalarials. FUTURE DIRECTIONS Understanding heme requirements and regulation in apicomplexan parasites promises to reveal multiple targets for much-needed therapeutic intervention against these parasites.
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Affiliation(s)
- Giel G van Dooren
- Research School of Biology, Australian National University, Canberra, ACT, Australia.
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Biot C, Castro W, Botté CY, Navarro M. The therapeutic potential of metal-based antimalarial agents: Implications for the mechanism of action. Dalton Trans 2012; 41:6335-49. [DOI: 10.1039/c2dt12247b] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Dubar F, Bohic S, Slomianny C, Morin JC, Thomas P, Kalamou H, Guérardel Y, Cloetens P, Khalife J, Biot C. In situ nanochemical imaging of label-free drugs: a case study of antimalarials in Plasmodium falciparum-infected erythrocytes. Chem Commun (Camb) 2011; 48:910-2. [PMID: 22143053 DOI: 10.1039/c1cc16211j] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report here for the first time the in vitro localization of unlabeled antimalarial drugs with high spatial resolution. This strategy further enhances our understanding of the action mechanisms of antimalarial drugs. Our approach may be applied to a wide range of domains where quantitative chemical imaging of drugs at the sub-cellular level appears critical.
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Affiliation(s)
- Faustine Dubar
- Université Lille Nord de France, Université Lille1, UCCS-UMR CNRS 8181, 59652 Villeneuve d'Ascq Cedex, France
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Hartwig CL, Lauterwasser EMW, Mahajan SS, Hoke JM, Cooper RA, Renslo AR. Investigating the antimalarial action of 1,2,4-trioxolanes with fluorescent chemical probes. J Med Chem 2011; 54:8207-13. [PMID: 22023506 DOI: 10.1021/jm2012003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The 1,2,4-trioxolanes are a new class of synthetic peroxidic antimalarials currently in human clinical trials. The well-known reactivity of the 1,2,4-trioxolane ring toward inorganic ferrous iron and ferrous iron heme is proposed to play a role in the antimalarial action of this class of compounds. We have designed structurally relevant fluorescent chemical probes to study the subcellular localization of 1,2,4-trioxolanes in cultured Plasmodium falciparum parasites. Microscopy experiments revealed that a probe fluorescently labeled on the adamantane ring accumulated specifically in digestive vacuole-associated neutral lipid bodies within the parasite while an isosteric, but nonperoxidic, congener did not. Probes fluorescently labeled on the cyclohexane ring showed no distinct localization pattern. In their subcellular localization and peroxidative effects, 1,2,4-trioxolane probes behave much like artemisinin-based probes studied previously. Our results are consistent with a role for adamantane-derived carbon-centered radicals in the antimalarial action of 1,2,4-trioxolanes, as hypothesized previously on the basis of chemical reactivity studies.
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Affiliation(s)
- Carmony L Hartwig
- Department of Biological Sciences, Old Dominion University, Norfolk, Virginia, United States
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Use of the NP-40 detergent-mediated assay in discovery of inhibitors of beta-hematin crystallization. Antimicrob Agents Chemother 2011; 55:3363-9. [PMID: 21518844 DOI: 10.1128/aac.00121-11] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The protozoan parasite responsible for malaria affects over 500 million people each year. Current antimalarials have experienced decreased efficacy due to the development of drug-resistant strains of Plasmodium spp., resulting in a critical need for the discovery of new antimalarials. Hemozoin, a crystalline by-product of heme detoxification that is necessary for parasite survival, serves as an important drug target. The quinoline antimalarials, including amodiaquine and chloroquine, act by inhibiting the formation of hemozoin. The formation of this crystal does not occur spontaneously, and recent evidence suggests crystallization occurs in the presence of neutral lipid particles located in the acidic digestive vacuole of the parasite. To mimic these conditions, the lipophilic detergent NP-40 has previously been shown to successfully mediate the formation of β-hematin, synthetic hemozoin. Here, an NP-40 detergent-based assay was successfully adapted for use as a high-throughput screen to identify inhibitors of β-hematin formation. The resulting assay exhibited a favorable Z' of 0.82 and maximal drift of less than 4%. The assay was used in a pilot screen of 38,400 diverse compounds at a screening concentration of 19.3 μM, resulting in the identification of 161 previously unreported β-hematin inhibitors. Of these, 48 also exhibited ≥ 90% inhibition of parasitemia in a Plasmodium falciparum whole-cell assay at a screening concentration of 23 μM. Eight of these compounds were identified to have nanomolar 50% inhibitory concentration values near that of chloroquine in this assay.
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Kuter D, Chibale K, Egan TJ. Linear free energy relationships predict coordination and π-stacking interactions of small molecules with ferriprotoporphyrin IX. J Inorg Biochem 2011; 105:684-92. [PMID: 21450272 DOI: 10.1016/j.jinorgbio.2011.02.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 02/17/2011] [Accepted: 02/18/2011] [Indexed: 11/29/2022]
Abstract
In order to better understand the interaction of antimalarial compounds with ferriprotoporphyrin IX (Fe(III)PPIX), association constants of pyridines, imidazoles, amines and phenolates with Fe(III)PPIX and protoporphyrin IX (PPIX) have been measured spectrophotometrically in 40% (v/v) aq. DMSO at pH 7.4. The pH independent log association constants for coordination of nitrogen donor ligands exhibit a linear free energy relationship (LFER) with the pK(a) of the donor atom. Association through π-stacking interactions (log K(π)) with PPIX and Fe(III)PPIX increases with the number of π-electrons in the aromatic ring system. These findings indicate that in the aqueous milieu of the malaria parasite digestive vacuole, coordination to the Fe(III) center of the porphyrin is necessarily very weak, while π-stacking interactions will be much stronger. On the other hand, in environments in which proton competition is absent, coordination will dominate, with the most basic donor atoms forming the strongest complexes with Fe(III)PPIX. The lipid nanospheres within the digestive vacuole which are now known to be the location of conversion of Fe(III)PPIX to hemozoin could possibly be such an environment, making both types of interaction relevant to the design of new hemozoin inhibitors.
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Affiliation(s)
- David Kuter
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
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