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Srinivas S, Senthil Kumar A. Electrical Wiring of Malarial Parasite Intermediate Hematin on a Tailored N-Doped Carbon Nanomaterial Surface and Its Bioelectrocatalytic Hydrogen Peroxide Reduction and Sensing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:10634-10647. [PMID: 38723623 DOI: 10.1021/acs.langmuir.4c00583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Hematin, an iron-containing porphyrin compound, plays a crucial role in various biological processes, including oxygen transport, storage, and functionality of the malarial parasite. Specifically, hematin-Fe interacts with the nitrogen atom of antimalarial drugs, forming an intermediate step crucial for their function. The electron transfer functionality of hematin in biological systems has been scarcely investigated. In this study, we developed a biomimicking electrical wiring of hematin-Fe with a model N-drug system, represented as {hematin-Fe---N-drug}. We achieved this by immobilizing hematin on a multiwalled carbon nanotube (MWCNT)/N-graphene quantum dot (N-GQD) modified electrode (MWCNT/N-GQD@Hemat). N-GQD serves as a model molecular drug system containing nitrogen atoms to mimic the {hematin-Fe---N-drug} interaction. The prepared bioelectrode exhibited a distinct redox peak at a measured potential (E1/2) of -0.410 V vs Ag/AgCl, accompanied by a surface excess value of 3.54 × 10-9 mol cm-2. This observation contrasts significantly with the weak or electroinactive electrochemical responses documented in literature-based hematin systems. We performed a comprehensive set of physicochemical and electrochemical characterizations on the MWCNT/N-GQD@Hemat system, employing techniques including FESEM, TEM, Raman spectroscopy, IR spectroscopy, and AFM. To evaluate the biomimetic electrode's electroactivity, we investigated the selective-mediated reduction of H2O2 as a model system. As an important aspect of our research, we demonstrated the use of scanning electrochemical microscopy to visualize the in situ electron transfer reaction of the biomimicking electrode. In an independent study, we showed enzyme-less electrocatalytic reduction and selective electrocatalytic sensing of H2O2 with a detection limit of 319 nM. We achieved this using a batch injection analysis-coupled disposable screen-printed electrode system in physiological solution.
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Affiliation(s)
- Sakthivel Srinivas
- Nano and Bioelectrochemistry Research Laboratory, Carbon Dioxide Research and Green Technology Centre, Vellore 632014, India
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632 014, India
| | - Annamalai Senthil Kumar
- Nano and Bioelectrochemistry Research Laboratory, Carbon Dioxide Research and Green Technology Centre, Vellore 632014, India
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632 014, India
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Mogaka S, Molu H, Kagasi E, Ogila K, Waihenya R, Onditi F, Ozwara H. Senna occidentalis (L.) Link root extract inhibits Plasmodium growth in vitro and in mice. BMC Complement Med Ther 2023; 23:71. [PMID: 36879244 PMCID: PMC9987147 DOI: 10.1186/s12906-023-03854-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 01/20/2023] [Indexed: 03/08/2023] Open
Abstract
BACKGROUND Senna occidentalis (L.) Link has been used worldwide in traditional treatment of many diseases and conditions including snakebite. In Kenya, a decoction from the plant roots taken orally, is used as a cure for malaria. Several studies have demonstrated that extracts from the plant possess antiplasmodial activity, in vitro. However, the safety and curative potency of the plant root against established malaria infection is yet to be scientifically validated, in vivo. On the other hand, there are reports on variation in bioactivity of extracts obtained from this plant species, depending on the plant part used and place of origin among other factors. In this study, we demonstrated the antiplasmodial activity of Senna occidentalis roots extract in vitro, and in mice. METHODS Methanol, ethyl acetate, chloroform, hexane and water extracts of S. occidentalis root were tested for in vitro antiplasmodial activity against Plasmodium falciparum, strain 3D7. Cytotoxicity of the most active solvent extracts was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the curative potency in Plasmodium berghei infected mice evaluated by Rane's test. RESULTS All of the solvent extracts tested in this study inhibited the propagation of P. falciparum, strain 3D7, in vitro, with polar extracts being more active than non-polar ones. Methanolic extracts had the highest activity (IC50 = 1.76) while hexane extract displayed the lowest activity (IC50 = 18.47). At the tested concentrations, methanolic and aqueous extracts exhibited high selectivity index against P. falciparum strain 3D7 (SI > 10) in the cytotoxicity assay. Further, the extracts significantly suppressed the propagation of P. berghei parasites (P < 0.05) in vivo and increased the survival time of the infected mice (P < 0.0001). CONCLUSIONS Senna occidentalis (L.) Link root extract inhibits the propagation of malaria parasites in vitro and in BALB/c mice.
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Affiliation(s)
- Simeon Mogaka
- Department of Tropical and Infectious Diseases, Institute of Primate Research, P.O Box 24481, Karen, Nairobi, 00502, Kenya.
- Department of Zoology, Jomo Kenyatta University of Agriculture and Technology, P.O Box 62000-00200, Nairobi, Kenya.
| | - Halkano Molu
- Department of Tropical and Infectious Diseases, Institute of Primate Research, P.O Box 24481, Karen, Nairobi, 00502, Kenya
| | - Esther Kagasi
- Department of Tropical and Infectious Diseases, Institute of Primate Research, P.O Box 24481, Karen, Nairobi, 00502, Kenya
| | - Kenneth Ogila
- Department of Zoology, Jomo Kenyatta University of Agriculture and Technology, P.O Box 62000-00200, Nairobi, Kenya
| | - Rebeccah Waihenya
- Department of Zoology, Jomo Kenyatta University of Agriculture and Technology, P.O Box 62000-00200, Nairobi, Kenya
| | - Faith Onditi
- Department of Tropical and Infectious Diseases, Institute of Primate Research, P.O Box 24481, Karen, Nairobi, 00502, Kenya
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Hastings Ozwara
- Department of Tropical and Infectious Diseases, Institute of Primate Research, P.O Box 24481, Karen, Nairobi, 00502, Kenya
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The Role of the Iron Protoporphyrins Heme and Hematin in the Antimalarial Activity of Endoperoxide Drugs. Pharmaceuticals (Basel) 2022; 15:ph15010060. [PMID: 35056117 PMCID: PMC8779033 DOI: 10.3390/ph15010060] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/01/2021] [Accepted: 12/08/2021] [Indexed: 02/05/2023] Open
Abstract
Plasmodium has evolved to regulate the levels and oxidative states of iron protoporphyrin IX (Fe-PPIX). Antimalarial endoperoxides such as 1,2,4-trioxane artemisinin and 1,2,4-trioxolane arterolane undergo a bioreductive activation step mediated by heme (FeII-PPIX) but not by hematin (FeIII-PPIX), leading to the generation of a radical species. This can alkylate proteins vital for parasite survival and alkylate heme into hematin–drug adducts. Heme alkylation is abundant and accompanied by interconversion from the ferrous to the ferric state, which may induce an imbalance in the iron redox homeostasis. In addition to this, hematin–artemisinin adducts antagonize the spontaneous biomineralization of hematin into hemozoin crystals, differing strikingly from artemisinins, which do not directly suppress hematin biomineralization. These hematin–drug adducts, despite being devoid of the peroxide bond required for radical-induced alkylation, are powerful antiplasmodial agents. This review addresses our current understanding of Fe-PPIX as a bioreductive activator and molecular target. A compelling pharmacological model is that by alkylating heme, endoperoxide drugs can cause an imbalance in the iron homeostasis and that the hematin–drug adducts formed have strong cytocidal effects by possibly reproducing some of the toxifying effects of free Fe-PPIX. The antiplasmodial phenotype and the mode of action of hematin–drug adducts open new possibilities for reconciliating the mechanism of endoperoxide drugs and for malaria intervention.
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Wu Y, Cao L, Zan M, Hou Z, Ge M, Dong WF, Li L. Iron and nitrogen-co-doped carbon quantum dots for the sensitive and selective detection of hematin and ferric ions and cell imaging. Analyst 2021; 146:4954-4963. [PMID: 34259240 DOI: 10.1039/d1an00828e] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Iron, nitrogen-co-doped carbon quantum dots (Fe,N-CDs) were prepared via a simple one-step hydrothermal method. The quantum yield of fluorescence reached about 27.6% and the blue-emissive Fe,N-CDs had a mean size of 3.76 nm. The as-prepared carbon quantum dots showed good solubility, a high quantum yield, good biocompatibility, low cytotoxicity, and high photostability. Interestingly, the as-prepared Fe,N-CDs exhibited good selectivity and sensitivity toward both hematin and ferric ions, and the limit of detection for hematin and ferric ions was calculated to be about 0.024 μM and 0.64 μM, respectively. At the same time, Fe,N-CDs were used for imaging HeLa cells and showed that most Fe,N-CDs were detained in the lysosome. Thus, this fluorescent probe has potential application in the quantitative detection of hematin or Fe3+ in a complex environment and for determining Fe3+ at the cellular level.
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Affiliation(s)
- Yuqing Wu
- CAS Key Laboratory of Biomedical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science (CAS), Suzhou 215163, P. R. China.
| | - Lei Cao
- CAS Key Laboratory of Biomedical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science (CAS), Suzhou 215163, P. R. China. and School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Minghui Zan
- CAS Key Laboratory of Biomedical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science (CAS), Suzhou 215163, P. R. China. and State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, P. R. China
| | - Zheng Hou
- CAS Key Laboratory of Biomedical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science (CAS), Suzhou 215163, P. R. China.
| | - Mingfeng Ge
- CAS Key Laboratory of Biomedical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science (CAS), Suzhou 215163, P. R. China. and Guokeyigong Science and Technology Development Co., Ltd, Jinan 250103, China
| | - Wen-Fei Dong
- CAS Key Laboratory of Biomedical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science (CAS), Suzhou 215163, P. R. China.
| | - Li Li
- CAS Key Laboratory of Biomedical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science (CAS), Suzhou 215163, P. R. China.
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Antimalarial Activity of Nigella sativa L. Seed Extracts and Selection of Resistance in Plasmodium berghei ANKA in a Mouse Model. J Pathog 2021; 2021:6165950. [PMID: 33623718 PMCID: PMC7875626 DOI: 10.1155/2021/6165950] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/10/2020] [Accepted: 01/21/2021] [Indexed: 11/17/2022] Open
Abstract
Background Chemotherapy plays a crucial role in malaria control. However, the main obstacle to treatment has been the rise of parasite resistance to most antimalarial drugs. Artemisinin-based combination therapies (ACTs) remain the most effective antimalarial medicines available today. However, malaria parasite tolerance to ACTs is now increasingly prevalent especially in Southeast Asia presenting the danger of the spread of ACTs resistance to other parts of the world. Consequently, this creates the need for alternative effective antimalarials. Therefore, this study sought out to determine antimalarial potential, safety, and resistance development of the extracts in a mouse model. Method Methanolic and ethyl acetate extracts were obtained by solvent extraction. The extracts were assayed for acute toxicity in vivo. Additionally, the two extracts were evaluated for antimalarial activity in vivo against Plasmodium berghei ANKA strain by the 4-day suppressive test at 500, 250, and 125 mg/kg/day. Packed cell volume was evaluated to determine anemia manifestation. Finally, continuous drug pressure experiment at 500 mg/kg and DNA amplification via PCR were conducted. The amplicons underwent through Sanger sequencing. Results There was no toxicity realized in the animals at 2000 mg/kg. Importantly, high parasitemia suppression of 75.52% and 75.30% using a dose of 500 mg/kg of methanolic and ethyl acetate extracts, respectively, was noted. The extracts were able to reverse packed cell volume reduction. Nigella sativa-resistant phenotype was selected as delayed parasite clearance. However, there was no change in the nucleotide sequences of PbMDR1 and PbCRT genes. Conclusion The results provide room for future exploitation of the plant as an antimalarial.
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Deda DK, Iglesias BA, Alves E, Araki K, Garcia CRS. Porphyrin Derivative Nanoformulations for Therapy and Antiparasitic Agents. Molecules 2020; 25:molecules25092080. [PMID: 32365664 PMCID: PMC7249045 DOI: 10.3390/molecules25092080] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/21/2020] [Accepted: 04/22/2020] [Indexed: 12/12/2022] Open
Abstract
Porphyrins and analogous macrocycles exhibit interesting photochemical, catalytic, and luminescence properties demonstrating high potential in the treatment of several diseases. Among them can be highlighted the possibility of application in photodynamic therapy and antimicrobial/antiparasitic PDT, for example, of malaria parasite. However, the low efficiency generally associated with their low solubility in water and bioavailability have precluded biomedical applications. Nanotechnology can provide efficient strategies to enhance bioavailability and incorporate targeted delivery properties to conventional pharmaceuticals, enhancing the effectiveness and reducing the toxicity, thus improving the adhesion to the treatment. In this way, those limitations can be overcome by using two main strategies: (1) Incorporation of hydrophilic substituents into the macrocycle ring while controlling the interaction with biological systems and (2) by including them in nanocarriers and delivery nanosystems. This review will focus on antiparasitic drugs based on porphyrin derivatives developed according to these two strategies, considering their vast and increasing applications befitting the multiple roles of these compounds in nature.
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Affiliation(s)
- Daiana K. Deda
- Department of Fundamental Chemistry, Institute of Chemistry, University of Sao Paulo, Av. Prof. Lineu Prestes 748, Butanta, Sao Paulo, SP 05508-000, Brazil; (D.K.D.); (K.A.)
| | - Bernardo A. Iglesias
- Bioinorganic and Porphyrinoid Materials Laboratory, Department of Chemistry, Federal University of Santa Maria, Av. Roraima 1000, Camobi, Santa Maria, RS 97105-900, Brazil;
| | - Eduardo Alves
- Department of Life Science, Imperial College London, Sir Alexander Fleming Building, South Kensington, London SW7 2AZ, UK;
| | - Koiti Araki
- Department of Fundamental Chemistry, Institute of Chemistry, University of Sao Paulo, Av. Prof. Lineu Prestes 748, Butanta, Sao Paulo, SP 05508-000, Brazil; (D.K.D.); (K.A.)
| | - Celia R. S. Garcia
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 580, Sao Paulo, SP 05508-900, Brazil
- Correspondence: ; Tel.: +55-11-2648-0954
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Evaluating Antiplasmodial and Antimalarial Activities of Soybean ( Glycine max) Seed Extracts on P. falciparum Parasite Cultures and P. berghei-Infected Mice. J Pathog 2020; 2020:7605730. [PMID: 32148966 PMCID: PMC7049415 DOI: 10.1155/2020/7605730] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/12/2020] [Accepted: 01/24/2020] [Indexed: 12/04/2022] Open
Abstract
Background Plasmodium parasite resistance to artemisinin-based combination therapies (ACTs) calls for development of new, affordable, safe, and effective antimalarial drugs. Studies conducted previously on soybean extracts have established that they possess antimicrobial, anti-inflammatory, anticancerous, and antioxidant properties. The activity of such extracts on Plasmodium parasite resistance to artemisinin-based combination therapies (ACTs) calls for development of new, affordable, safe, and effective antimalarial drugs. Studies conducted previously on soybean extracts have established that they possess antimicrobial, anti-inflammatory, anticancerous, and antioxidant properties. The activity of such extracts on Objectives The aim of this study was to determine the antiplasmodial activity of soybean extracts using Plasmodium falciparum cultures, followed by an in vivo evaluation of safety and antimalarial activity of the extracts in Plasmodium berghei ANKA strain-infected mice. Method Aqueous, methanol, and peptide extracts of soybean seeds were prepared. An in vitro evaluation of the extracts for antiplasmodial activity was carried out using two P. falciparum strains: D6, a chloroquine-sensitive Sierra Leone 1 strain and W2, a chloroquine-resistant Indochina 1 strain. Following the in vitro evaluation of the extracts for antiplasmodial activity was carried out using two in vivo evaluation of safety and antimalarial activity of the extracts in P. berghei ANKA strain. The two extracts were tested for their therapeutic potential (curative test). The peptide extract was further assessed to determine whether it could prevent the establishment of a P. berghei ANKA strain. The two extracts were tested for their therapeutic potential (curative test). The peptide extract was further assessed to determine whether it could prevent the establishment of a P. berghei ANKA strain. The two extracts were tested for their therapeutic potential (curative test). The peptide extract was further assessed to determine whether it could prevent the establishment of a Results Peptide and methanol extracts showed good activity with IC50 of 19.97 ± 2.57 μg/ml and 10.14 ± 9.04 μg/ml and 10.14 ± 9.04 μg/ml and 10.14 ± 9.04 μg/ml and 10.14 ± 9.04 P < 0.001) in suppression with lower doses. Conclusion The results show the presence of antimalarial properties in soybean extracts with higher curative activity when compared to the prophylactic activity. However, more research needs to be conducted on this plant to possibly establish lead compounds.
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Abstract
The reaction between the antimalarial drug artesunate (ATS) and ferriprotoporphyrin_(IX) (FPIX) in the presence of glutathione (GSH) has been monitored by nuclear magnetic resonance (NMR) spectroscopy. By following the disappearance of resonances of protons near the endoperoxide group in ATS, the rate at which the drug is activated can be directly measured. In an aqueous medium, the rate of ATS activation is limited by the rate of reduction of the FPIX Fe(III) center by GSH. The reaction is observed to slow dramatically in the presence of other heme binding antimalarial drugs. These findings explain the long observed antagonism between artemisinin derivatives and quinoline-based drugs. This discovery suggests that combination therapy that involves artemisinin or any of its derivatives and a quinoline-based drug may be compromised.
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Affiliation(s)
- Laura Heller
- Dept. of Chemistry, Georgetown University, 37 and O Streets, Washington, DC
| | - Paul D Roepe
- Dept. of Chemistry, Georgetown University, 37 and O Streets, Washington, DC.,Dept, of Biochemistry and Cellular & Molecular Biology, Georgetown University, 37 and O Streets, Washington, DC.,Center for Infectious Disease, Georgetown University, 37 and O Streets, Washington, DC
| | - Angel C de Dios
- Dept. of Chemistry, Georgetown University, 37 and O Streets, Washington, DC.,Center for Infectious Disease, Georgetown University, 37 and O Streets, Washington, DC
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Obisesan OR, Adekunle AS, Oyekunle JAO, Sabu T, Nkambule TTI, Mamba BB. Development of Electrochemical Nanosensor for the Detection of Malaria Parasite in Clinical Samples. Front Chem 2019; 7:89. [PMID: 30859097 PMCID: PMC6397833 DOI: 10.3389/fchem.2019.00089] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 02/04/2019] [Indexed: 12/24/2022] Open
Abstract
In this study, electrochemical nanosensors were developed from the synthesized metal oxide (MO) nanoparticles by supporting it on a gold electrode (Au). The activity of the developed nanosensor toward the detection of malaria biomarker (β-hematin) was determined and the optimum conditions at which the maximum detection and quantification occurred were established. β-Hematin current response at the sensors was higher when compared with the bare Au electrode and followed the order Au-CuO (C) > Au-CuO (M) > Au-Fe2O3 (M) > Au-Fe2O3 (C) > Au-Al2O3 (M) > Au-Al2O3 (C) > bare Au. The developed sensors were stable with a relatively low current drop (10.61-17.35 %) in the analyte. Au-CuO sensor had the best performance toward the biomarker and quantitatively detected P. berghei in infected mice's serum samples at 3.60-4.8 mM and P. falciparum in human blood serum samples at 0.65-1.35 mM concentration.
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Affiliation(s)
- Olaoluwa R Obisesan
- Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.,International and Inter University Center for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, India
| | | | - John A O Oyekunle
- Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Thomas Sabu
- International and Inter University Center for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, India
| | - Thabo T I Nkambule
- Nanotechnology and Water Sustainability Research Unit, College of Science, Engineering and Technology, Univeristy of South Africa, Johannesburg, South Africa
| | - Bhekie B Mamba
- Nanotechnology and Water Sustainability Research Unit, College of Science, Engineering and Technology, Univeristy of South Africa, Johannesburg, South Africa
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Flores MC, Márquez EA, Mora JR. Molecular modeling studies of bromopyrrole alkaloids as potential antimalarial compounds: a DFT approach. Med Chem Res 2017. [DOI: 10.1007/s00044-017-2107-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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One-pot synthesis and negative ion mass spectrometric investigation of a densely functionalized cinnoline. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2015.10.104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Alves E, Iglesias BA, Deda DK, Budu A, Matias TA, Bueno VB, Maluf FV, Guido RVC, Oliva G, Catalani LH, Araki K, Garcia CRS. Encapsulation of metalloporphyrins improves their capacity to block the viability of the human malaria parasite Plasmodium falciparum. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 11:351-8. [PMID: 25461288 DOI: 10.1016/j.nano.2014.09.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 08/30/2014] [Accepted: 09/29/2014] [Indexed: 10/24/2022]
Abstract
UNLABELLED Several synthetic metallated protoporphyrins (M-PPIX) were tested for their ability to block the cell cycle of the lethal human malaria parasite Plasmodium falciparum. After encapsulating the porphyrin derivatives in micro- and nanocapsules of marine atelocollagen, their effects on cultures of red blood cells infected (RBC) with P. falciparum were verified. RBCs infected with synchronized P. falciparum incubated for 48 h showed a toxic effect over a micromolar range. Strikingly, the IC50 of encapsulated metalloporphyrins reached nanomolar concentrations, where Zn-PPIX showed the best antimalarial effect, with an IC50=330 nM. This value is an 80-fold increase in the antimalarial activity compared to the antimalarial effect of non-encapsulated Zn-PPIX. These findings reveal that the incubation of P. falciparum infected-RBCs with 20 μM Zn-PPIX reduced the size of hemozoin crystal by 34%, whereas a 28% reduction was noticed with chloroquine, confirming the importance of heme detoxification pathway in drug therapy. FROM THE CLINICAL EDITOR In this study, synthetic metalloporphyrins were tested as therapeutics that target Plasmodium falciparum. The IC50 of encapsulated metalloporphyrins was found to be in the nanomolar concentration range, with encapsulated Zn-PPIX showing an 80-fold increase in its antimalarial activity compared to the non-encapsulated form.
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Affiliation(s)
- Eduardo Alves
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo; Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo
| | - Bernardo A Iglesias
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo
| | - Daiana K Deda
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo
| | - Alexandre Budu
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo
| | - Tiago A Matias
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo
| | - Vânia B Bueno
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo
| | - Fernando V Maluf
- Centro de Biotecnologia Molecular Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo
| | - Rafael V C Guido
- Centro de Biotecnologia Molecular Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo
| | - Glaucius Oliva
- Centro de Biotecnologia Molecular Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo
| | - Luiz H Catalani
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo
| | - Koiti Araki
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo
| | - Celia R S Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo.
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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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Belorgey D, Lanfranchi DA, Davioud-Charvet E. 1,4-naphthoquinones and other NADPH-dependent glutathione reductase-catalyzed redox cyclers as antimalarial agents. Curr Pharm Des 2013; 19:2512-28. [PMID: 23116403 DOI: 10.2174/1381612811319140003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/30/2012] [Indexed: 11/22/2022]
Abstract
The homodimeric flavoenzyme glutathione reductase catalyzes NADPH-dependent glutathione disulfide reduction. This reaction is important for keeping the redox homeostasis in human cells and in the human pathogen Plasmodium falciparum. Different types of NADPH-dependent disulfide reductase inhibitors were designed in various chemical series to evaluate the impact of each inhibition mode on the propagation of the parasites. Against malaria parasites in cultures the most potent and specific effects were observed for redox-active agents acting as subversive substrates for both glutathione reductases of the Plasmodium-infected red blood cells. In their oxidized form, these redox-active compounds are reduced by NADPH-dependent flavoenzyme-catalyzed reactions in the cytosol of infected erythrocytes. In their reduced forms, these compounds can reduce molecular oxygen to reactive oxygen species, or reduce oxidants like methemoglobin, the major nutrient of the parasite, to indigestible hemoglobin. Furthermore, studies on a fluorinated suicide-substrate of the human glutathione reductase indicate that the glutathione reductase-catalyzed bioactivation of 3-benzylnaphthoquinones to the corresponding reduced 3-benzoyl metabolites is essential for the observed antimalarial activity. In conclusion, the antimalarial lead naphthoquinones are suggested to perturb the major redox equilibria of the targeted cells. These effects result in developmental arrest of the parasite and contribute to the removal of the parasitized erythrocytes by macrophages.
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Affiliation(s)
- Didier Belorgey
- European School of Chemistry, Polymers and Materials (ECPM), UMR7509 CNRS - Universite de Strasbourg, 25 rue Becquerel, F-67087 Strasbourg Cedex 2, France.
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The antimalarial activities of methylene blue and the 1,4-naphthoquinone 3-[4-(trifluoromethyl)benzyl]-menadione are not due to inhibition of the mitochondrial electron transport chain. Antimicrob Agents Chemother 2013; 57:2114-20. [PMID: 23439633 DOI: 10.1128/aac.02248-12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Methylene blue and a series of recently developed 1,4-naphthoquinones, including 3-[4-(substituted)benzyl]-menadiones, are potent antimalarial agents in vitro and in vivo. The activity of these structurally diverse compounds against the human malaria parasite Plasmodium falciparum might involve their peculiar redox properties. According to the current theory, redox-active methylene blue and 3-[4-(trifluoromethyl)benzyl]-menadione are "subversive substrates." These agents are thought to shuttle electrons from reduced flavoproteins to acceptors such as hemoglobin-associated or free Fe(III)-protoporphyrin IX. The reduction of Fe(III)-protoporphyrin IX could subsequently prevent essential hemoglobin digestion and heme detoxification in the parasite. Alternatively, owing to their structures and redox properties, methylene blue and 1,4-naphthoquinones might also affect the mitochondrial electron transport chain. Here, we tested the latter hypothesis using an established system of transgenic P. falciparum cell lines and the antimalarial agents atovaquone and chloroquine as controls. In contrast to atovaquone, methylene blue and 3-[4-(trifluoromethyl)benzyl]-menadione do not inhibit the mitochondrial electron transport chain. A systematic comparison of the morphologies of drug-treated parasites furthermore suggests that the three drugs do not share a mechanism of action. Our findings support the idea that methylene blue and 3-[4-(trifluoromethyl)benzyl]-menadione exert their antimalarial activity as redox-active subversive substrates.
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Affiliation(s)
- Paloma F. Salas
- Medicinal Inorganic Chemistry
Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia
V6T 1Z1, Canada
| | - Christoph Herrmann
- Medicinal Inorganic Chemistry
Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia
V6T 1Z1, Canada
- Advanced
Applied Physics Solutions, TRIUMF, 4004
Wesbrook Mall, Vancouver, British Columbia
V6T 2A3, Canada
| | - Chris Orvig
- Medicinal Inorganic Chemistry
Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia
V6T 1Z1, Canada
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Haynes RK, Cheu KW, Chan HW, Wong HN, Li KY, Tang MMK, Chen MJ, Guo ZF, Guo ZH, Sinniah K, Witte AB, Coghi P, Monti D. Interactions between artemisinins and other antimalarial drugs in relation to the cofactor model--a unifying proposal for drug action. ChemMedChem 2012; 7:2204-26. [PMID: 23112085 DOI: 10.1002/cmdc.201200383] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 09/30/2012] [Indexed: 01/14/2023]
Abstract
Artemisinins are proposed to act in the malaria parasite cytosol by oxidizing dihydroflavin cofactors of redox-active flavoenzymes, and under aerobic conditions by inducing their autoxidation. Perturbation of redox homeostasis coupled with the generation of reactive oxygen species (ROS) ensues. Ascorbic acid-methylene blue (MB), N-benzyl-1,4-dihydronicotinamide (BNAH)-MB, BNAH-lumiflavine, BNAH-riboflavin (RF), and NADPH-FAD-E. coli flavin reductase (Fre) systems at pH 7.4 generate leucomethylene blue (LMB) and reduced flavins that are rapidly oxidized in situ by artemisinins. These oxidations are inhibited by the 4-aminoquinolines piperaquine (PPQ), chloroquine (CQ), and others. In contrast, the arylmethanols lumefantrine, mefloquine (MFQ), and quinine (QN) have little or no effect. Inhibition correlates with the antagonism exerted by 4-aminoquinolines on the antimalarial activities of MB, RF, and artemisinins. Lack of inhibition correlates with the additivity/synergism between the arylmethanols and artemisinins. We propose association via π complex formation between the 4-aminoquinolines and LMB or the dihydroflavins; this hinders hydride transfer from the reduced conjugates to the artemisinins. The arylmethanols have a decreased tendency to form π complexes, and so exert no effect. The parallel between chemical reactivity and antagonism or additivity/synergism draws attention to the mechanism of action of all drugs described herein. CQ and QN inhibit the formation of hemozoin in the parasite digestive vacuole (DV). The buildup of heme-Fe(III) results in an enhanced efflux from the DV into the cytosol. In addition, the lipophilic heme-Fe(III) complexes of CQ and QN that form in the DV are proposed to diffuse across the DV membrane. At the higher pH of the cytosol, the complexes decompose to liberate heme-Fe(III) . The quinoline or arylmethanol reenters the DV, and so transfers more heme-Fe(III) out of the DV. In this way, the 4-aminoquinolines and arylmethanols exert antimalarial activities by enhancing heme-Fe(III) and thence free Fe(III) concentrations in the cytosol. The iron species enter into redox cycles through reduction of Fe(III) to Fe(II) largely mediated by reduced flavin cofactors and likely also by NAD(P)H-Fre. Generation of ROS through oxidation of Fe(II) by oxygen will also result. The cytotoxicities of artemisinins are thereby reinforced by the iron. Other aspects of drug action are emphasized. In the cytosol or DV, association by π complex formation between pairs of lipophilic drugs must adversely influence the pharmacokinetics of each drug. This explains the antagonism between PPQ and MFQ, for example. The basis for the antimalarial activity of RF mirrors that of MB, wherein it participates in redox cycling that involves flavoenzymes or Fre, resulting in attrition of NAD(P)H. The generation of ROS by artemisinins and ensuing Fenton chemistry accommodate the ability of artemisinins to induce membrane damage and to affect the parasite SERCA PfATP6 Ca(2+) transporter. Thus, the effect exerted by artemisinins is more likely a downstream event involving ROS that will also be modulated by mutations in PfATP6. Such mutations attenuate, but cannot abrogate, antimalarial activities of artemisinins. Overall, parasite resistance to artemisinins arises through enhancement of antioxidant defense mechanisms.
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Affiliation(s)
- Richard K Haynes
- Department of Chemistry, Institute of Molecular Technology for Drug Discovery and Synthesis, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
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18
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Blank O, Davioud-Charvet E, Elhabiri M. Interactions of the antimalarial drug methylene blue with methemoglobin and heme targets in Plasmodium falciparum: a physico-biochemical study. Antioxid Redox Signal 2012; 17:544-54. [PMID: 22256987 DOI: 10.1089/ars.2011.4239] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AIMS Resistance of Plasmodium falciparum to drugs has led to renewed interest of redox-active methylene blue (MB) for which no resistance has been reported so far. Moreover, MB displays unique interactions with glutathione reductase (GR). However, the mechanisms of action/interaction with potential targets of MB are yet to be elucidated. Our physico-biochemical study on MB and relevant hematin-containing targets was performed under quasi-physiological conditions. RESULTS The water deprotonation of the Fe(III)protoporphyrin dimer, the major building block of β-hematin, was studied. At pH 6, the predominant dimer possesses water coordinated to both metals. Below pH 6, spontaneous precipitation of β-hematin occurred reminiscent of hemozoin biomineralization at pH 5.0-5.5 in the food vacuole of the malarial parasite. MB also forms dimers (K(Dim)=6800 M(-1)) and firmly binds to hematin in a 2:1 hematin:MB sandwich complex (K(D)=3.16 μM). MB bioactivation catalyzed by GR induces efficient methemoglobin(Fe(III)) [metHb(Fe(III))] reduction to hemoglobin(Fe(II)). The reduction rate, mediated by leucomethylene blue (LMB), was determined (k(metHb)(red)=991 M(-1)·s(-1)) in an assay coupled to the GR/reduced form of nicotinamide adenine dinucleotide phosphate system. INNOVATION AND CONCLUSION Our work provides new insights into the understanding of (i) how MB interacts with hematin-containing targets, (ii) other relevant MB properties in corroboration with the distribution of the three major LMB species as a function of pH, and (iii) how this redox-active cycler induces efficient catalytic reduction of metHb(Fe(III)) to hemoglobin(Fe(II)) mediated by oxidoreductases. These physico-biochemical parameters of MB open promising perspectives for the interpretation of the pharmacology and pathophysiology of malaria and possibly new routes for antimalarial drug development.
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Affiliation(s)
- Olga Blank
- Laboratoire de Chimie Bioorganique et Médicinale, European School of Chemistry, Polymers and Materials (ECPM), University of Strasbourg and Centre National de la Recherche Scientifique, Strasbourg, France
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19
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Bohle DS, Dodd EL. [Gallium(III) protoporphyrin IX]2: A Soluble Diamagnetic Model for Malaria Pigment. Inorg Chem 2012; 51:4411-3. [DOI: 10.1021/ic2027303] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D. Scott Bohle
- Department of Chemistry, McGill University, Montreal H3A 2K6,
Canada
| | - Erin L. Dodd
- Department of Chemistry, McGill University, Montreal H3A 2K6,
Canada
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20
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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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21
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Analysis of the electrochemical reactivity of natural hemozoin and β-hemozoin in the presence of antimalarial drugs. Electrochim Acta 2011. [DOI: 10.1016/j.electacta.2011.08.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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22
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Müller T, Johann L, Jannack B, Brückner M, Lanfranchi DA, Bauer H, Sanchez C, Yardley V, Deregnaucourt C, Schrével J, Lanzer M, Schirmer RH, Davioud-Charvet E. Glutathione Reductase-Catalyzed Cascade of Redox Reactions To Bioactivate Potent Antimalarial 1,4-Naphthoquinones – A New Strategy to Combat Malarial Parasites. J Am Chem Soc 2011; 133:11557-71. [DOI: 10.1021/ja201729z] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tobias Müller
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Laure Johann
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
- European School of Chemistry, Polymers and Materials (ECPM), University of Strasbourg, UMR CNRS 7509, 25, rue Becquerel, F-67087 Strasbourg, France
| | - Beate Jannack
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Margit Brückner
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Don Antoine Lanfranchi
- European School of Chemistry, Polymers and Materials (ECPM), University of Strasbourg, UMR CNRS 7509, 25, rue Becquerel, F-67087 Strasbourg, France
| | - Holger Bauer
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Cecilia Sanchez
- Department of Infectiology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Vanessa Yardley
- Department of Infections and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - Christiane Deregnaucourt
- Muséum National d’Histoire Naturelle, FRE 3206 CNRS, BP 52, 61 rue Buffon, 75231 Paris cedex 05, France
| | - Joseph Schrével
- Muséum National d’Histoire Naturelle, FRE 3206 CNRS, BP 52, 61 rue Buffon, 75231 Paris cedex 05, France
| | - Michael Lanzer
- Department of Infectiology, University of Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - R. Heiner Schirmer
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
| | - Elisabeth Davioud-Charvet
- Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
- European School of Chemistry, Polymers and Materials (ECPM), University of Strasbourg, UMR CNRS 7509, 25, rue Becquerel, F-67087 Strasbourg, France
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23
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Coghi P, Basilico N, Taramelli D, Chan WC, Haynes R, Monti D. Interaction of Artemisinins with Oxyhemoglobin Hb-FeII, Hb-FeII, CarboxyHb-FeII, Heme-FeII, and Carboxyheme FeII: Significance for Mode of Action and Implications for Therapy of Cerebral Malaria. ChemMedChem 2009; 4:2045-53. [DOI: 10.1002/cmdc.200900342] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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24
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Ismail FMD, Drew MGB, Navaratnam S, Bisby RH. A pulse radiolysis study of free radicals formed by one-electron oxidation of the antimalarial drug pyronaridine. RESEARCH ON CHEMICAL INTERMEDIATES 2009. [DOI: 10.1007/s11164-009-0051-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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25
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Colorimetric high-throughput screen for detection of heme crystallization inhibitors. Antimicrob Agents Chemother 2009; 53:2564-8. [PMID: 19307367 DOI: 10.1128/aac.01466-08] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Malaria infects 500 million people annually, a number that is likely to rise as drug resistance to currently used antimalarials increases. During its intraerythrocytic stage, the causative parasite, Plasmodium falciparum, metabolizes hemoglobin and releases toxic heme, which is neutralized by a parasite-specific crystallization mechanism to form hemozoin. Evidence suggests that chloroquine, the most successful antimalarial agent in history, acts by disrupting the formation of hemozoin. Here we describe the development of a 384-well microtiter plate screen to detect small molecules that can also disrupt heme crystallization. This assay, which is based on a colorimetric assay developed by Ncokazi and Egan (K. K. Ncokazi and T. J. Egan, Anal. Biochem. 338:306-319, 2005), requires no parasites or parasite-derived reagents and no radioactive materials and is suitable for a high-throughput screening platform. The assay's reproducibility and large dynamic range are reflected by a Z factor of 0.74. A pilot screen of 16,000 small molecules belonging to diverse structural classes was conducted. The results of the target-based assay were compared with a whole-parasite viability assay of the same small molecules to identify small molecules active in both assays.
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26
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Abstract
The problem of endemic malaria continues unabated globally. Malaria affects 40 % of the global population, causing an estimated annual mortality of 1.5-2.7 million people. The World Health Organization (WHO) estimates that 90 % of these deaths occur in sub-Saharan Africa among infants under the age of five. While a vaccine against malaria continues to be elusive, chemotherapy remains the most viable alternative towards treatment of the disease. During last years, the situation has become urgent in many ways, but mainly because of the development of chloroquine-resistant (CQR) strains of Plasmodium falciparum (Pf). The discovery that artemisinin (ART, 1), an active principle of Artemisia annua L., expresses a significant antimalarial activity, especially against CQR strains, opened new approaches for combating malaria. Since the early 1980s, hundreds of semi-synthetic and synthetic peroxides have been developed and tested for their antimalarial activity, the results of which were extensively reviewed. In addition, in therapeutic practice, there is no reported case of drug resistance to these antimalarial peroxides. This review summarizes recent achievements in the area of peroxide drug development for malaria chemotherapy.
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27
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Uyen DT, Huy NT, Trang DTX, Nhien NTT, Oida T, Hirayama K, Harada S, Kamei K. Effects of Amino Acids on Malarial Heme Crystallization. Biol Pharm Bull 2008; 31:1483-8. [DOI: 10.1248/bpb.31.1483] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Dinh Thanh Uyen
- Department of Applied Biology, Kyoto Institute of Technology
| | - Nguyen Tien Huy
- Department of Applied Biology, Kyoto Institute of Technology
- Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University
| | | | | | - Tatsuo Oida
- Department of Materials and Science, Kyoto Institute of Technology
| | - Kenji Hirayama
- Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University
| | | | - Kaeko Kamei
- Department of Applied Biology, Kyoto Institute of Technology
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28
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Okuma K, Yasuda T, Shioji K, Yokomori Y. Novel Formation of 2-Arylquinolines and 1,3-Benzoxazines from 2-(1-Alkenyl)acylanilides and Active Halogens. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2007. [DOI: 10.1246/bcsj.80.1824] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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29
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Chemaly SM, Chen CT, van Zyl RL. Naturally occurring cobalamins have antimalarial activity. J Inorg Biochem 2007; 101:764-73. [PMID: 17343914 DOI: 10.1016/j.jinorgbio.2007.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 12/14/2006] [Accepted: 01/11/2007] [Indexed: 10/23/2022]
Abstract
The acquisition of resistance by malaria parasites towards existing antimalarials has necessitated the development of new chemotherapeutic agents. The effect of vitamin B(12) derivatives on the formation of beta-haematin (synthetic haemozoin) was determined under conditions similar to those in the parasitic food vacuole (using chloroquine, a known inhibitor of haemozoin formation for comparison). Adenosylcobalamin (Ado-cbl), methylcobalamin (CH(3)-cbl) and aquocobalamin (H(2)O-cbl) were approximately forty times more effective inhibitors of beta-haematin formation than chloroquine, cyanocobalamin (CN-cbl) was slightly more inhibitory than chloroquine, while dicyanocobinamide had no effect. It is proposed that the cobalamins exert their inhibitory effect on beta-haematin formation by pi-interactions of their corrin ring with the Fe(III)-protoporphyrin ring and by hydrogen-bonding using their 5,6-dimethylbenzimidazole/ribose/sugar side-chain. The antimalarial activity for the cobalamins (Ado-cbl>CH(3)-cbl>H(2)O-cbl>CN-cbl) was found to be less than that for chloroquine or quinine. Ado-cbl, CH(3)-cbl and CN-cbl do not accumulate in the parasite food vacuole by pH trapping, but H(2)O-cbl does. Unlike humans, the malaria parasite has only one enzyme that uses cobalamin as a cofactor, namely methionine synthase, which is important for growth and metabolism. Thus cobalamins in very small amounts are necessary for Plasmodium falciparum growth but in larger amounts they display antimalarial properties.
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Affiliation(s)
- Susan M Chemaly
- Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
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30
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Kumar S, Guha M, Choubey V, Maity P, Bandyopadhyay U. Antimalarial drugs inhibiting hemozoin (β-hematin) formation: A mechanistic update. Life Sci 2007; 80:813-28. [PMID: 17157328 DOI: 10.1016/j.lfs.2006.11.008] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 10/24/2006] [Accepted: 11/06/2006] [Indexed: 11/30/2022]
Abstract
Digestion of hemoglobin in the food vacuole of the malaria parasite produces very high quantities of redox active toxic free heme. Hemozoin (beta-hematin) formation is a unique process adopted by Plasmodium sp. to detoxify free heme. Hemozoin formation is a validated target for most of the well-known existing antimalarial drugs and considered to be a suitable target to develop new antimalarials. Here we discuss the possible mechanisms of free heme detoxification in the malaria parasite and the mechanistic details of compounds, which offer antimalarial activity by inhibiting hemozoin formation. The chemical nature of new antimalarial compounds showing antimalarial activity through the inhibition of hemozoin formation has also been incorporated, which may help to design future antimalarials with therapeutic potential against multi-drug resistant malaria.
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Affiliation(s)
- Sanjay Kumar
- Division of Drug Target Discovery and Development, Central Drug Research Institute, Chatter Manzil Palace, Mahatma Gandhi Marg, Lucknow-226001, Uttar Pradesh, India
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31
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Scholl PF, Tripathi AK, Sullivan DJ. Bioavailable iron and heme metabolism in Plasmodium falciparum. Curr Top Microbiol Immunol 2006; 295:293-324. [PMID: 16265896 DOI: 10.1007/3-540-29088-5_12] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Iron metabolism is essential for cell function and potentially toxic because iron can catalyze oxygen radical production. Malaria-attributable anemia and iron deficiency anemia coincide as being treatable diseases in the developing world. In absolute amounts, more than 95% of Plasmodium metal biochemistry occurs in the acidic digestive vacuole where heme released from hemoglobin catabolism forms heme crystals. The antimalarial quinolines interfere with crystallization. Despite the completion of the Plasmodium genome, many 'gene gaps' exist in components of the metal pathways described in mammalian or yeast cells. Present evidence suggests that parasite bioavailable iron originates from a labile erythrocyte cytosolic pool rather than from abundant heme iron. Indeed the parasite has to make its own heme within two separate organelles, the mitochondrion and the apicomplast. Paradoxically, despite the abundance of iron within the erythrocyte, iron chelators are cytocidal to the Plasmodium parasite. Hemozoin has become a sensitive biomarker for laser desorption mass spectrometry detection of Plasmodium infection in both mice and humans.
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Affiliation(s)
- P F Scholl
- Department of Environmental Health Sciences, Baltimore, MD 21205, USA
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32
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Pradines B, Orlandi-Pradines E, Henry M, Bogreau H, Fusai T, Mosnier J, Baret E, Durand C, Bouchiba H, Penhoat K, Rogier C. [Metallocenes and malaria: a new therapeutic approach]. ANNALES PHARMACEUTIQUES FRANÇAISES 2005; 63:284-94. [PMID: 16142129 DOI: 10.1016/s0003-4509(05)82293-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rapid development of significant resistance to antimalarial drugs has been a major force driving research to identify and develop new compounds. The use of synthetic organometallic complexes seems to be promising for treatment of malaria infections. Recent progress in identification and development of new drugs promises to lead to a much greater range of antimalarial agents. Organometallic complexes and metalloporphyrins have shown in vitro activity against Plasmodium falciparum. Ferroquine (ferrocenyl chloroquine) is more active than chloroquine against strains and isolates of P. falciparum and shows efficacy against murine parasites.
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Affiliation(s)
- B Pradines
- Unité de recherche en biologie et épidémiologie parasitaires, Institut de médecine tropicale du Service de Santé des Armées, Parc le Pharo, BP46, Marseille, France.
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33
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Dascombe MJ, Drew MGB, Morris H, Wilairat P, Auparakkitanon S, Moule WA, Alizadeh-Shekalgourabi S, Evans PG, Lloyd M, Dyas AM, Carr P, Ismail FMD. Mapping Antimalarial Pharmacophores as a Useful Tool for the Rapid Discovery of Drugs Effective in Vivo: Design, Construction, Characterization, and Pharmacology of Metaquine. J Med Chem 2005; 48:5423-36. [PMID: 16107142 DOI: 10.1021/jm0408013] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Resistant strains of Plasmodium falciparum and the unavailability of useful antimalarial vaccines reinforce the need to develop new efficacious antimalarials. This study details a pharmacophore model that has been used to identify a potent, soluble, orally bioavailable antimalarial bisquinoline, metaquine (N,N'-bis(7-chloroquinolin-4-yl)benzene-1,3-diamine) (dihydrochloride), which is active against Plasmodium berghei in vivo (oral ID(50) of 25 micromol/kg) and multidrug-resistant Plasmodium falciparum K1 in vitro (0.17 microM). Metaquine shows strong affinity for the putative antimalarial receptor, heme at pH 7.4 in aqueous DMSO. Both crystallographic analyses and quantum mechanical calculations (HF/6-31+G) reveal important regions of protonation and bonding thought to persist at parasitic vacuolar pH concordant with our receptor model. Formation of drug-heme adduct in solution was confirmed using high-resolution positive ion electrospray mass spectrometry. Metaquine showed strong binding with the receptor in a 1:1 ratio (log K = 5.7 +/- 0.1) that was predicted by molecular mechanics calculations. This study illustrates a rational multidisciplinary approach for the development of new 4-aminoquinoline antimalarials, with efficacy superior to chloroquine, based on the use of a pharmacophore model.
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Affiliation(s)
- Michael J Dascombe
- Faculty of Life Sciences, Stopford Building 1.124, The University of Manchester, Oxford Road, Manchester M13 9PT, U.K.
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34
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Santelli-Rouvier C, Pradines B, Berthelot M, Parzy D, Barbe J. Arylsulfonyl acridinyl derivatives acting on Plasmodium falciparum. Eur J Med Chem 2005; 39:735-44. [PMID: 15337286 DOI: 10.1016/j.ejmech.2004.05.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 05/06/2004] [Accepted: 05/10/2004] [Indexed: 11/16/2022]
Abstract
Several arylacridinyl sulfones have been synthesized and their antimalarial action was tested on Plasmodium falciparum. PABA (para-aminobenzoic acid) has no antagonistic effect with these compounds as opposed to the observed effect with dapsone and sulfonamides previously studied. A possible relationship between the ability of cleavage of the S-9C acridinic bond and activity is suggested.
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Affiliation(s)
- Christiane Santelli-Rouvier
- GERCTOP-UMR CNRS 6009, faculté de pharmacie, université de la Méditerranée, 27, boulevard Jean Moulin, 13385 Marseille cedex 5, France.
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35
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Kannan R, Kumar K, Sahal D, Kukreti S, Chauhan V. Reaction of artemisinin with haemoglobin: implications for antimalarial activity. Biochem J 2005; 385:409-18. [PMID: 15361062 PMCID: PMC1134711 DOI: 10.1042/bj20041170] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 08/26/2004] [Accepted: 09/10/2004] [Indexed: 11/17/2022]
Abstract
Elucidation of the principal targets of the action of the antimalarial drug artemisinin is an ongoing pursuit that is important for understanding the action of this drug and for the development of more potent analogues. We have examined the chemical reaction of Hb with artemisinin. The protein-bound haem in Hb has been found to react with artemisinin much faster than is the case with free haem. It appears that the uptake of Hb and the accumulation of artemisinin into the food vacuole, together with the preferred reactivity of artemisinin with haem in Hb, may make Hb the primary target of artemisinin's antimalarial action. Both monoalkylated (HA) and dialkylated (HAA) haem derivatives of artemisinin have been isolated. These 'haemarts' bind to PfHRP II (Plasmodium falciparum histidine-rich protein II), inhibiting haemozoin formation, and possess a significantly decreased ability to oxidize ascorbic acid. The accelerated formation of HAA from Hb is expected to decrease the ratio of haem to its alkylated derivatives. The haemarts that are generated from 'haemartoglobins' may bring about the death of malaria parasite by a two-pronged effect of stalling the formation of haemozoin by the competitive inhibition of haem binding to its templates and creating a more reducing environment that is not conducive to the formation of haemozoin.
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Key Words
- artemisinin
- haemoglobin
- haemozoin
- plasmodium falciparum histidine-rich protein ii (pfhrp ii)
- redox activity
- dab, diaminobenzidine
- dma, dimethyl acetamide
- ha, monoalkylated haem–artemisinin adduct
- haa, dialkylated haem–artemisinin adduct
- hrp, histidine-rich protein
- maldi, matrix-assisted laser-desorption ionization–time-of-flight
- pfhrp ii, plasmodium falciparum histidine-rich protein ii
- mb, myoglobin
- opd, o-phenylene diamine
- serca, sarcoplasmic/endoplasmic-reticulum ca2+-atpase
- tctp, translationally controlled tumour protein
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Affiliation(s)
- Rangiah Kannan
- *Department of Chemistry, University of Delhi, New Delhi-110007, India
- †International Centre of Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Krishan Kumar
- †International Centre of Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Dinkar Sahal
- †International Centre of Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Shrikant Kukreti
- *Department of Chemistry, University of Delhi, New Delhi-110007, India
| | - Virander S. Chauhan
- †International Centre of Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India
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36
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Wood BR, Langford SJ, Cooke BM, Glenister FK, Lim J, McNaughton D. Raman imaging of hemozoin within the food vacuole ofPlasmodium falciparumtrophozoites. FEBS Lett 2003; 554:247-52. [PMID: 14623074 DOI: 10.1016/s0014-5793(03)00975-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Micro-Raman spectra of hemozoin encapsulated within the food vacuole of a Plasmodium falciparum-infected erythrocyte are presented. The spectrum of hemozoin is identical to the spectrum of beta-hematin at all applied excitation wavelengths. The unexpected observation of dramatic band enhancement of A(1g) modes including nu(4) (1374 cm(-1)) observed when applying 780 nm excitation enabled Raman imaging of hemozoin in the food vacuole. This unusual enhancement, resulting from excitonic coupling between linked porphyrin moieties in the extended porphyrin array, enables the investigation of hemozoin within its natural environment for the first time.
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Affiliation(s)
- Bayden R Wood
- Centre for Biospectroscopy and School of Chemistry, Monash University, Clayton, Vic. 3800, Australia.
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Begum K, Kim HS, Kumar V, Stojiljkovic I, Wataya Y. In vitro antimalarial activity of metalloporphyrins against Plasmodium falciparum. Parasitol Res 2003; 90:221-4. [PMID: 12783311 DOI: 10.1007/s00436-003-0830-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2002] [Accepted: 01/09/2003] [Indexed: 10/24/2022]
Abstract
The in vitro antimalarial activity against Plasmodium falciparum and heme polymerization were evaluated for ten metalloporphyrins: gallium protoporphyrin IX (GaPPIX), sodium salt of gallium protoporphyrin IX, silver protoporphyrin IX, palladium protoporphyrin IX, cobalt protoporphyrin IX, manganese protoporphyrin IX, tin protoporphyrin IX (SnPPIX), chromium protoporphyrin IX, gallium deuteroporphyrin IX (GaDPIX) and gallium hematoporphyrin IX. Metalloporphyrins inhibited parasite growth with 50% inhibitory concentrations (IC(50)) ranging from 15.5 microM to 190 microM. In trophozoite lysate-mediated heme polymerization assays, SnPPIX, GaPPIX and GaDPIX exerted potent inhibitory activity similar to that of artemisinin and chloroquine.
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Affiliation(s)
- Khurshida Begum
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Okayama University, Tsushima, Okayama 700-8530, Japan
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38
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Ueda T, Takeyama Y, Takase K, Hori Y, Kuroda Y, Ho HS. Hematin is one of the cytotoxic factors in pancreatitis-associated ascitic fluid that causes hepatocellular injury. Surgery 2002; 131:66-74. [PMID: 11812965 DOI: 10.1067/msy.2002.118317] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND We recently demonstrated that pancreatitis-associated ascitic fluid (PAAF) contains cytotoxic factor(s), inducing apoptosis in hepatocytes, and that PAAF induces hepatic adenosine triphosphate depletion, hepatocellular acidosis, and accumulation of hepatic intracellular sodium. Because ascitic fluid and serum from patients with hemorrhagic pancreatitis contain a lot of hematin, we aimed to test the hypothesis that hematin can induce hepatocellular injury, and then we compared its cytotoxicity with that of PAAF. METHODS In vivo effects of intraperitoneal injection of hematin into the liver of healthy rats were evaluated with in situ nick-end labeling, blood biochemical analysis, and nuclear magnetic resonance spectroscopy. In vitro cytotoxic and apoptosis-inducing activities of hematin on rat primary culture hepatocytes were investigated with a cellular proliferation assay kit and DNA fragmentation enzyme-linked immunosorbent assay, respectively. Furthermore, PAAF was fractionated with Sephacryl S-300 gel column chromatography, and cytotoxic activities of its fractions on a human hepatoma cell line (HuH-7) were compared with those of hematin. RESULTS Intraperitoneal injection of hematin into healthy rats caused apoptosis in the hepatocytes and elevated serum glutamate oxaloacetic transaminase and lactate dehydrogenase levels. Intraperitoneal injection of hematin also caused a significant decrease in the hepatic beta-adenosine triphosphate/inorganic phosphate ratio, severe hepatic intracellular acidosis, and a significant increase of hepatic intracellular sodium (Na(+)) concentration, similar to the effects of PAAF. In vitro, hematin decreased hepatocyte viability and increased the DNA fragmentation of hepatocytes, similar to the effects of 10% PAAF. Albumin reversed the cytotoxic effects of hematin and PAAF on HuH-7 cells nearly completely and partially, respectively. Fractionation of PAAF and hematin by gel column chromatography revealed that the first peak of cytotoxic activity of PAAF corresponded to that of hematin and that the cytotoxic activity was reversed by albumin nearly completely. CONCLUSIONS These results suggest that hematin is one of the cytotoxic factors in PAAF that causes hepatocellular injury and that cellular injuries caused by hematin may be involved in the development of multiple organ failure associated with severe acute pancreatitis.
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Affiliation(s)
- Takashi Ueda
- First Department of Surgery, Kobe University School of Medicine, Kobe, Japan
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Omodeo-Salè F, Monti D, Olliaro P, Taramelli D. Prooxidant activity of beta-hematin (synthetic malaria pigment) in arachidonic acid micelles and phospholipid large unilamellar vesicles. Biochem Pharmacol 2001; 61:999-1009. [PMID: 11286991 DOI: 10.1016/s0006-2952(01)00558-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Intraerythrocytic malaria parasite has evolved a unique pathway to detoxify hemoglobin-derived heme by forming a crystal of Ferri-protoporphyrin IX dimers, known as hemozoin or "malaria pigment." The prooxidant activity of beta-hematin (BH), the synthetic malaria pigment obtained from hematin at acidic pH, was studied in arachidonic acid micelles and phospholipid Large Unilamellar Vesicles (LUVs) and compared to that of alpha-hematin (AH, Ferri-protoporphyrin IX-hydroxide) and hemin (HE, Ferri-protoporphyrin-chloride). Lipid peroxidation was measured as production of thiobarbituric acid reactive substances (TBARS). The extent of peroxidation induced by either AH or BH was strongly dependent upon the content of pre-existing hydroperoxides and efficiently inhibited by triphenylphosphine, a deoxygenating agent able to reduce hydroperoxides to hydroxides and by lipophilic scavengers. BH prooxidant activity was linearly related to the material, whereas that of AH seemed dependent on the aggregation state of the porphyrin. Maximal activity was observed when AH was present in concentration lower than 2 microM. In this case a shift of spectra in the Soret region, leading to the increase of the O.D. 400/385 nm ratio, suggested a transition toward a less aggregated state. BH prooxidant activity was significantly lower than that of monomeric AH, yet higher than that of AH aggregates. Differently from AH aggregates, BH-induced peroxidation was unaffected by GSH and inhibited rather than enhanced by acidic pH (5.7) and chloroquine. UV/Vis spectroscopy of AH aggregates at acidic pH, low GSH concentrations and chloroquine suggests a shift of AH aggregates toward the less aggregated state, more active as peroxidation catalyst.
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Affiliation(s)
- F Omodeo-Salè
- Institute of General Physiology and Biochemistry, University of Milan, Via Trentacoste 2, I-20134-, Milan, Italy
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40
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Parapini S, Basilico N, Pasini E, Egan TJ, Olliaro P, Taramelli D, Monti D. Standardization of the physicochemical parameters to assess in vitro the beta-hematin inhibitory activity of antimalarial drugs. Exp Parasitol 2000; 96:249-56. [PMID: 11162378 DOI: 10.1006/expr.2000.4583] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intraerythrocytic plasmodia form hemozoin as a detoxification product of hemoglobin-derived heme. An identical substance, beta-hematin (BH), can be obtained in vitro from hematin at acidic pH. Quinoline-antimalarials inhibit BH formation. Standardization of test conditions is essential for studying the interaction of compounds with this process and screening potential inhibitors. A spectrophotometric microassay of heme polymerization inhibitory activity (HPIA) (Basilico et al., Journal of Antimicrobial Chemotherapy 42, 55-60, 1998) previously reported was used to investigate the effect of pH and salt concentration on BH formation. The yield of BH formation decreased with pH. Moreover, under conditions used in the above HPIA assay (18 h, 37 degrees C, pH = 2.7), several salts including chloride and phosphate inhibited the process. Aminoquinoline drugs formulated as salts (chloroquine-phosphate, primaquine-diphosphate), but not chloroquine-base, also inhibited the reaction. Interference by salts was highest at low pH and decreased at higher pH (pH 4). Here, we describe different assay conditions that eliminate these problems (BHIA, beta-hematin inhibitory activity). By replacing hematin with hemin as the porphyrin and NaOH solution with DMSO as solvent, the formation of BH was independent of pH up to pH 5.1. No interference by salts was observed over the pH range 2.7-5.1. Dose-dependent inhibition of BH formation was obtained with chloroquine-base, chloroquine-phosphate, and chloroquine-sulfate at pH 5.1. Primaquine was not inhibitory. The final product, characterized by solubility in DMSO, consists of pure BH by FT-IR spectroscopy. The BHIA assay (hemin in DMSO, acetate buffer pH 5 +/- 0.1, 18 h at 37 degrees C) is designed to screen for those molecules forming pi-pi interactions with hematin and thus inhibiting beta-hematin formation.
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Affiliation(s)
- S Parapini
- Istituto di Microbiologia, Universitá di Milano, Via Pascal 36, 20133 Milano, Italy
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41
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Kurosawa Y, Dorn A, Kitsuji-Shirane M, Shimada H, Satoh T, Matile H, Hofheinz W, Masciadri R, Kansy M, Ridley RG. Hematin polymerization assay as a high-throughput screen for identification of new antimalarial pharmacophores. Antimicrob Agents Chemother 2000; 44:2638-44. [PMID: 10991837 PMCID: PMC90128 DOI: 10.1128/aac.44.10.2638-2644.2000] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hematin polymerization is a parasite-specific process that enables the detoxification of heme following its release in the lysosomal digestive vacuole during hemoglobin degradation, and represents both an essential and a unique pharmacological drug target. We have developed a high-throughput in vitro microassay of hematin polymerization based on the detection of (14)C-labeled hematin incorporated into polymeric hemozoin (malaria pigment). The assay uses 96-well filtration microplates and requires 12 h and a Wallac 1450 MicroBeta liquid scintillation counter. The robustness of the assay allowed the rapid screening and evaluation of more than 100, 000 compounds. Random screening was complemented by the development of a pharmacophore hypothesis using the "Catalyst" program and a large amount of data available on the inhibitory activity of a large library of 4-aminoquinolines. Using these methods, we identified "hit" compounds belonging to several chemical structural classes that had potential antimalarial activity. Follow-up evaluation of the antimalarial activity of these compounds in culture and in the Plasmodium berghei murine model further identified compounds with actual antimalarial activity. Of particular interest was a triarylcarbinol (Ro 06-9075) and a related benzophenone (Ro 22-8014) that showed oral activity in the murine model. These compounds are chemically accessible and could form the basis of a new antimalarial medicinal chemistry program.
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Affiliation(s)
- Y Kurosawa
- Department of Pharmaceutical Screening, Nippon Roche Research Center, 200 Kajiwara, Kamakura, Kanagawa Prefecture 247, Japan
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42
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Cole KA, Ziegler J, Evans CA, Wright DW. Metalloporphyrins inhibit beta-hematin (hemozoin) formation. J Inorg Biochem 2000; 78:109-15. [PMID: 10766333 DOI: 10.1016/s0162-0134(99)00216-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Metal-substituted protoporphyrin IXs (Cr(III)PPIX (1), Co(III)PPIX (2), Mn(III)PPIX (3), Cu(II)PPIX (4), Mg(II)PPIX (5), Zn(II)PPIX (6), and Sn(IV)PPIX (7)) act as inhibitors to beta-hematin (hemozoin) formation, a critical detoxification biopolymer of malarial parasites. The central metal ion plays a significant role in the efficacy of the metalloprotoporphyrins to inhibit beta-hematin formation. The efficacy of these compounds correlates well with the water exchange rate for the octahedral aqua complexes of the porphyrin's central metal ion. Under these in vitro reaction conditions, metalloporphyrins 5, 6 and 7 are as much as six times more efficacious than the free ligand protoporphyrin IX in preventing beta-hematin formation and four times as efficacious as chloroquine, while metalloporphyrins 3 and 4 are three to four times more effective at preventing beta-hematin formation than the free protoporphyrin IX base. In contrast, the relatively exchange inert metalloporphyrins 1 and 2 are only as efficacious as the free ligand and only two-thirds as effective as chloroquine. Aggregation studies of the heme:MPPIX using UV-Vis and fluorescence spectroscopies are indicative of the formation of pi-pi hetero-metalloporphyrin assemblies. Thus, hemozoin inhibition is likely prevented by the formation of heme:MPPIX complexes through pi-stacking interactions. The ramifications of such hetero-metalloporphyrin assemblies, in the context of the emerging structural picture of hemozoin, are discussed.
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Affiliation(s)
- K A Cole
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282-1530, USA
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