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Yang D, Liu X, Li J, Xie J, Jiang L. Animal venoms: a novel source of anti- Toxoplasma gondii drug candidates. Front Pharmacol 2023; 14:1178070. [PMID: 37205912 PMCID: PMC10188992 DOI: 10.3389/fphar.2023.1178070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 04/20/2023] [Indexed: 05/21/2023] Open
Abstract
Toxoplasma gondii (T. gondii) is a nucleated intracellular parasitic protozoan with a broad host selectivity. It causes toxoplasmosis in immunocompromised or immunodeficient patients. The currently available treatments for toxoplasmosis have significant side effects as well as certain limitations, and the development of vaccines remains to be explored. Animal venoms are considered to be an important source of novel antimicrobial agents. Some peptides from animal venoms have amphipathic alpha-helix structures. They inhibit the growth of pathogens by targeting membranes to produce lethal pores and cause membrane rupture. Venom molecules generally possess immunomodulatory properties and play key roles in the suppression of pathogenic organisms. Here, we summarized literatures of the last 15 years on the interaction of animal venom peptides with T. gondii and attempt to explore the mechanisms of their interaction with parasites that involve membrane and organelle damage, immune response regulation and ion homeostasis. Finally, we analyzed some limitations of venom peptides for drug therapy and some insights into their development in future studies. It is hoped that more research will be stimulated to turn attention to the medical value of animal venoms in toxoplasmosis.
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Affiliation(s)
- Dongqian Yang
- Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Xiaohua Liu
- Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Jing Li
- Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Jing Xie
- Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Liping Jiang
- Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- China-Africa Research Center of Infectious Diseases, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- *Correspondence: Liping Jiang,
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2
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Clemente CM, Robledo SM, Ravetti S. Menthol carbonates as potent antiparasitic agents: synthesis and in vitro studies along with computer-aided approaches. BMC Complement Med Ther 2022; 22:156. [PMID: 35698116 PMCID: PMC9190099 DOI: 10.1186/s12906-022-03636-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/02/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Introduction
Despite the number of deaths and the significant economic and social costs associated with Chagas, Leishmaniasis and Malaria diseases worldwide, available drugs are limited and have serious side effects and high toxicity for the patient. Therefore, there is an urgent need for safe, low-cost, and effective treatments. Natural products are an important source of bioactive compounds and there is current interest in finding natural bioactive molecules that can be used for treating these parasitic diseases. In the present study we proposed to evaluate the in vitro antiparasitic activity of new menthol derivatives against Trypanosoma cruzi, Leishmania braziliensis and Plasmodium falciparum; moreover, we propose to explore their mode of action through in silico approaches.
Material and methods
A series of carbonate prodrugs (1–9) were synthesized from menthol with different aliphatic alcohols. Spectroscopic techniques were used to confirm the structures of the synthesized compounds. The cytotoxicity of the compounds was assessed using U-937 cells. In vitro trypanocidal, leishmanicidal and antiplasmodial activity were evaluated using a T. cruzi, L. braziliensis and P. falciparum organism, respectively. In addition, in silico studies were also performed through molecular dynamics simulations and MM-PBSA analysis.
Results
The assay revealed that most of the compounds were highly active against intracellular amastigotes of T. cruzi and L. braziliensis, and had moderate activity against the total forms of P. falciparum. Compound 2 was one of the drugs that showed a high selectivity index (SI) for the three organisms evaluated. The prediction of the ADME properties suggests that all the compounds have drug-like molecular properties and the probability to be lead candidates. Finally, molecular dynamics simulations, and MM-PBSA studies indicate that menthol at the substrate binding site of TcDHODH, LbDHODH and PfDHODH is structurally stable in the same order as the natural substrate; also, interactions of menthol with residues involved in the inhibition of TcDHODH and PfDHODH proteins were predicted.
Conclusions
The present study demonstrates that menthol prodrugs are promising antiparasitic agents; however, the mechanisms of action proposed in this study need to be experimentally verified by future enzymatic assays.
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3
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Sussmann RAC, Gabriel HB, Ríos AG, Menchaca Vega DS, Yamaguchi LF, Doménech-Carbó A, Cebrián-Torrejón G, Kimura EA, Kato MJ, Bofill Verdaguer I, Crispim M, Katzin AM. Presence of Phylloquinone in the Intraerythrocytic Stages of Plasmodium falciparum. Front Cell Infect Microbiol 2022; 12:869085. [PMID: 35531326 PMCID: PMC9069557 DOI: 10.3389/fcimb.2022.869085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 03/21/2022] [Indexed: 11/13/2022] Open
Abstract
Malaria is one of the most widespread parasitic diseases, especially in Africa, Southeast Asia and South America. One of the greatest problems for control of the disease is the emergence of drug resistance, which leads to a need for the development of new antimalarial compounds. The biosynthesis of isoprenoids has been investigated as part of a strategy to identify new targets to obtain new antimalarial drugs. Several isoprenoid quinones, including menaquinone-4 (MK-4/vitamin K2), α- and γ-tocopherol and ubiquinone (UQ) homologs UQ-8 and UQ-9, were previously detected in in vitro cultures of Plasmodium falciparum in asexual stages. Herein, we described for the first time the presence of phylloquinone (PK/vitamin K1) in P. falciparum and discuss the possible origins of this prenylquinone. While our results in metabolic labeling experiments suggest a biosynthesis of PK prenylation via phytyl pyrophosphate (phytyl-PP) with phytol being phosphorylated, on the other hand, exogenous PK attenuated atovaquone effects on parasitic growth and respiration, showing that this metabolite can be transported from extracellular environment and that the mitochondrial electron transport system (ETS) of P. falciparum is capable to interact with PK. Although the natural role and origin of PK remains elusive, this work highlights the PK importance in plasmodial metabolism and future studies will be important to elucidate in seeking new targets for antimalarial drugs.
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Affiliation(s)
- Rodrigo A. C. Sussmann
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Center for Environmental Sciences, Institute of Humanities, Arts and Sciences, Federal University of Southern Bahia, Porto Seguro, Brazil
| | - Heloisa B. Gabriel
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Alejandro García Ríos
- Laboratory of Environmental Chemistry and Metalopharmaceuticals, Institute of Chemistry at the University of São Paulo, São Paulo, Brazil
- Chemistry Program, Universidad del Quindio, Quindio, Colombia
| | - Danielle S. Menchaca Vega
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Lydia F. Yamaguchi
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Antonio Doménech-Carbó
- Departament of Analytic Chemistry, Facultat de Química, Universitat de València, Valencia, Spain
| | - Gerardo Cebrián-Torrejón
- Laboratoire Connaissance et Valorisation Equipes d'Accueil (COVACHIM-M2E EA) 3592, Université des Antilles, Pointe-à-Pitre Cedex, Pointe-à-Pitre, Guadeloupe, France
| | - Emilia A. Kimura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Massuo J. Kato
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Ignasi Bofill Verdaguer
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Marcell Crispim
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Alejandro M. Katzin
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- *Correspondence: Alejandro M. Katzin,
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Usey MM, Huet D. Parasite powerhouse: A review of the Toxoplasma gondii mitochondrion. J Eukaryot Microbiol 2022; 69:e12906. [PMID: 35315174 PMCID: PMC9490983 DOI: 10.1111/jeu.12906] [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] [Indexed: 10/18/2022]
Abstract
Toxoplasma gondii is a member of the apicomplexan phylum, a group of single-celled eukaryotic parasites that cause significant human morbidity and mortality around the world. T. gondii harbors two organelles of endosymbiotic origin: a non-photosynthetic plastid, known as the apicoplast, and a single mitochondrion derived from the ancient engulfment of an α-proteobacterium. Due to excitement surrounding the novelty of the apicoplast, the T. gondii mitochondrion was, to a certain extent, overlooked for about two decades. However, recent work has illustrated that the mitochondrion is an essential hub of apicomplexan-specific biology. Development of novel techniques, such as cryo-electron microscopy, complexome profiling, and next-generation sequencing have led to a renaissance in mitochondrial studies. This review will cover what is currently known about key features of the T. gondii mitochondrion, ranging from its genome to protein import machinery and biochemical pathways. Particular focus will be given to mitochondrial features that diverge significantly from the mammalian host, along with discussion of this important organelle as a drug target.
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Affiliation(s)
- Madelaine M. Usey
- Department of Cellular BiologyUniversity of GeorgiaAthensGeorgiaUSA,Center for Tropical and Emerging Global DiseasesUniversity of GeorgiaAthensGeorgiaUSA
| | - Diego Huet
- Center for Tropical and Emerging Global DiseasesUniversity of GeorgiaAthensGeorgiaUSA,Department of Pharmaceutical and Biomedical SciencesUniversity of GeorgiaAthensGeorgiaUSA
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5
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Oxygen levels are key to understanding "Anaerobic" protozoan pathogens with micro-aerophilic lifestyles. Adv Microb Physiol 2021; 79:163-240. [PMID: 34836611 DOI: 10.1016/bs.ampbs.2021.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Publications abound on the physiology, biochemistry and molecular biology of "anaerobic" protozoal parasites as usually grown under "anaerobic" culture conditions. The media routinely used are poised at low redox potentials using techniques that remove O2 to "undetectable" levels in sealed containers. However there is growing understanding that these culture conditions do not faithfully resemble the O2 environments these organisms inhabit. Here we review for protists lacking oxidative energy metabolism, the oxygen cascade from atmospheric to intracellular concentrations and relevant methods of measurements of O2, some well-studied parasitic or symbiotic protozoan lifestyles, their homeodynamic metabolic and redox balances, organism-drug-oxygen interactions, and the present and future prospects for improved drugs and treatment regimes.
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6
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A Yeast-Based Drug Discovery Platform To Identify Plasmodium falciparum Type II NADH Dehydrogenase Inhibitors. Antimicrob Agents Chemother 2021; 65:AAC.02470-20. [PMID: 33722883 DOI: 10.1128/aac.02470-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/08/2021] [Indexed: 11/20/2022] Open
Abstract
Conventional methods utilizing in vitro protein activity assay or in vivo parasite survival to screen for malaria inhibitors suffer from high experimental background and/or inconvenience. Here, we introduce a yeast-based system to facilitate chemical screening for specific protein or pathway inhibitors. The platform comprises several isogeneic Pichia strains that differ only in the target of interest, so that a compound which inhibits one strain but not the other is implicated in working specifically against the target. We used Plasmodium falciparum NDH2 (PfNDH2), a type II NADH dehydrogenase, as a proof of principle to show how well this works. Three isogenic Pichia strains harboring, respectively, exogeneously introduced PfNDH2, its own complex I (a type I NADH dehydrogenase), and PfNDH2 with its own complex I, were constructed. In a pilot screen of more than 2,000 compounds, we identified a highly specific inhibitor that acts on PfNDH2. This compound poorly inhibits the parasites at the asexual blood stage; however, is highly effective in repressing oocyst maturation in the mosquito stage. Our results demonstrate that the yeast cell-based screen platform is feasible, efficient, economical, and has very low background noise. Similar strategies could be extended to the functional screen for interacting molecules of other targets.
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7
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Exploring Ubiquinone Biosynthesis Inhibition as a Strategy for Improving Atovaquone Efficacy in Malaria. Antimicrob Agents Chemother 2021; 65:AAC.01516-20. [PMID: 33495230 DOI: 10.1128/aac.01516-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 01/16/2021] [Indexed: 11/20/2022] Open
Abstract
Atovaquone (AV) acts on the malaria parasite by competing with ubiquinol (UQH2) for its union to the mitochondrial bc1 complex, preventing the ubiquinone-8 and ubiquinone-9 (UQ-8 and UQ-9) redox recycling, which is a necessary step in pyrimidine biosynthesis. This study focused on UQ biosynthesis in Plasmodium falciparum and adopted proof-of-concept research to better elucidate the mechanism of action of AV and improve its efficacy. Initially, UQ biosynthesis was evaluated using several radioactive precursors and chromatographic techniques. This methodology was suitable for studying the biosynthesis of both UQ homologs and its redox state. Additionally, the composition of UQ was investigated in parasites cultivated at different oxygen saturations or in the presence of AV. AV affected the redox states of both UQ-8 and UQ-9 homologs by increasing the levels of the respective reduced forms. Conversely, low-oxygen environments specifically inhibited UQ-9 biosynthesis and increased the antimalarial efficacy of AV. These findings encouraged us to investigate the biological importance and the potential of UQ biosynthesis as a drug target based on its inhibition by 4-nitrobenzoate (4-NB), a 4-hydroxybenzoate (4-HB) analog. 4-NB effectively inhibits UQ biosynthesis and enhances the effects of AV on parasitic growth and respiration rate. Although 4-NB itself exhibits poor antimalarial activity, its 50% inhibitory concentration (IC50) value increased significantly in the presence of a soluble UQ analog, p-aminobenzoic acid (pABA), or 4-HB. These results indicate the potential of AV combined with 4-NB as a novel therapy for malaria and other diseases caused by AV-sensitive pathogens.
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Verdaguer IB, Zafra CA, Crispim M, Sussmann RA, Kimura EA, Katzin AM. Prenylquinones in Human Parasitic Protozoa: Biosynthesis, Physiological Functions, and Potential as Chemotherapeutic Targets. Molecules 2019; 24:molecules24203721. [PMID: 31623105 PMCID: PMC6832408 DOI: 10.3390/molecules24203721] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 09/25/2019] [Accepted: 10/01/2019] [Indexed: 12/19/2022] Open
Abstract
Human parasitic protozoa cause a large number of diseases worldwide and, for some of these diseases, there are no effective treatments to date, and drug resistance has been observed. For these reasons, the discovery of new etiological treatments is necessary. In this sense, parasitic metabolic pathways that are absent in vertebrate hosts would be interesting research candidates for the identification of new drug targets. Most likely due to the protozoa variability, uncertain phylogenetic origin, endosymbiotic events, and evolutionary pressure for adaptation to adverse environments, a surprising variety of prenylquinones can be found within these organisms. These compounds are involved in essential metabolic reactions in organisms, for example, prevention of lipoperoxidation, participation in the mitochondrial respiratory chain or as enzymatic cofactors. This review will describe several prenylquinones that have been previously characterized in human pathogenic protozoa. Among all existing prenylquinones, this review is focused on ubiquinone, menaquinone, tocopherols, chlorobiumquinone, and thermoplasmaquinone. This review will also discuss the biosynthesis of prenylquinones, starting from the isoprenic side chains to the aromatic head group precursors. The isoprenic side chain biosynthesis maybe come from mevalonate or non-mevalonate pathways as well as leucine dependent pathways for isoprenoid biosynthesis. Finally, the isoprenic chains elongation and prenylquinone aromatic precursors origins from amino acid degradation or the shikimate pathway is reviewed. The phylogenetic distribution and what is known about the biological functions of these compounds among species will be described, as will the therapeutic strategies associated with prenylquinone metabolism in protozoan parasites.
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Affiliation(s)
- Ignasi B. Verdaguer
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
| | - Camila A. Zafra
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
| | - Marcell Crispim
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
| | - Rodrigo A.C. Sussmann
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
- Centro de Formação em Ciências Ambientais, Universidade Federal do Sul da Bahia, Porto Seguro 45810-000 Bahia, Brazil
| | - Emília A. Kimura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
| | - Alejandro M. Katzin
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508000, Brazil; (I.B.V.); (C.A.Z.); (M.C.); (E.A.K.)
- Correspondence: ; Tel.: +55-11-3091-7330; Fax: +5511-3091-7417
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Kumar S, Bhardwaj TR, Prasad DN, Singh RK. Drug targets for resistant malaria: Historic to future perspectives. Biomed Pharmacother 2018; 104:8-27. [PMID: 29758416 DOI: 10.1016/j.biopha.2018.05.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/22/2018] [Accepted: 05/07/2018] [Indexed: 01/05/2023] Open
Abstract
New antimalarial targets are the prime need for the discovery of potent drug candidates. In order to fulfill this objective, antimalarial drug researches are focusing on promising targets in order to develop new drug candidates. Basic metabolism and biochemical process in the malaria parasite, i.e. Plasmodium falciparum can play an indispensable role in the identification of these targets. But, the emergence of resistance to antimalarial drugs is an escalating comprehensive problem with the progress of antimalarial drug development. The development of resistance has highlighted the need for the search of novel antimalarial molecules. The pharmaceutical industries are committed to new drug development due to the global recognition of this life threatening resistance to the currently available antimalarial therapy. The recent developments in the understanding of parasite biology are exhilarating this resistance issue which is further being ignited by malaria genome project. With this background of information, this review was aimed to highlights and provides useful information on various present and promising treatment approaches for resistant malaria, new progresses, pursued by some innovative targets that have been explored till date. This review also discusses modern and futuristic multiple approaches to antimalarial drug discovery and development with pictorial presentations highlighting the various targets, that could be exploited for generating promising new drugs in the future for drug resistant malaria.
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Affiliation(s)
- Sahil Kumar
- School of Pharmacy and Emerging Sciences, Baddi University of Emerging Sciences & Technology, Baddi, Dist. Solan, 173205, Himachal Pradesh, India
| | - T R Bhardwaj
- School of Pharmacy and Emerging Sciences, Baddi University of Emerging Sciences & Technology, Baddi, Dist. Solan, 173205, Himachal Pradesh, India
| | - D N Prasad
- Department of Pharmaceutical Chemistry, Shivalik College of Pharmacy, Nangal, Dist. Rupnagar, 140126, Punjab, India
| | - Rajesh K Singh
- Department of Pharmaceutical Chemistry, Shivalik College of Pharmacy, Nangal, Dist. Rupnagar, 140126, Punjab, India.
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10
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Synthesis, leishmanicidal activity and theoretical evaluations of a series of substituted bis-2-hydroxy-1,4-naphthoquinones. Molecules 2014; 19:15180-95. [PMID: 25247686 PMCID: PMC6271274 DOI: 10.3390/molecules190915180] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 08/29/2014] [Accepted: 09/09/2014] [Indexed: 11/17/2022] Open
Abstract
A series of eight substituted bis-2-hydroxy-1,4-naphthoquinone derivatives was synthesized through lawsone condensation with various aromatic and aliphatic aldehydes under mild acidic conditions. The title compounds were evaluated for antileishmanial activity in vitro against Leishmania amazonensis and Leishmania braziliensis promastigotes; six compounds showed good activity without significant toxic effects. The compound with the highest activity was used for an in vivo assay with Leishmania amazonensis.
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11
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Targeting the mitochondrial electron transport chain of Plasmodium falciparum: new strategies towards the development of improved antimalarials for the elimination era. Future Med Chem 2014; 5:1573-91. [PMID: 24024949 DOI: 10.4155/fmc.13.121] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Despite intense efforts, there has not been a truly new antimalarial, possessing a novel mechanism of action, registered for over 10 years. By virtue of a novel mode of action, it is hoped that the global challenge of multidrug-resistant parasites can be overcome, as well as developing drugs that possess prophylaxis and/or transmission-blocking properties, towards an elimination agenda. Many target-based and whole-cell screening drug development programs have been undertaken in recent years and here an overview of specific projects that have focused on targeting the parasite's mitochondrial electron transport chain is presented. Medicinal chemistry activity has largely focused on inhibitors of the parasite cytochrome bc1 Complex (Complex III) including acridinediones, pyridones and quinolone aryl esters, as well as inhibitors of dihydroorotate dehydrogenase that includes triazolopyrimidines and benzimidazoles. Common barriers to progress and opportunities for novel chemistry and potential additional electron transport chain targets are discussed in the context of the target candidate profiles for uncomplicated malaria.
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12
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de Freitas RM, Gomes KN, Saldanha GB. Neuropharmacological effects of lipoic acid and ubiquinone on the mRNA level of interleukin-1β and acetylcholinesterase activity in rat hippocampus after seizures. Fundam Clin Pharmacol 2011; 25:354-61. [DOI: 10.1111/j.1472-8206.2010.00838.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Sahu NK, Sahu S, Kohli DV. Novel Molecular Targets for Antimalarial Drug Development. Chem Biol Drug Des 2008; 71:287-97. [DOI: 10.1111/j.1747-0285.2008.00640.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Saleh A, Friesen J, Baumeister S, Gross U, Bohne W. Growth inhibition of Toxoplasma gondii and Plasmodium falciparum by nanomolar concentrations of 1-hydroxy-2-dodecyl-4(1H)quinolone, a high-affinity inhibitor of alternative (type II) NADH dehydrogenases. Antimicrob Agents Chemother 2007; 51:1217-22. [PMID: 17242151 PMCID: PMC1855512 DOI: 10.1128/aac.00895-06] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Both apicomplexan parasites Toxoplasma gondii and Plasmodium falciparum lack type I NADH dehydrogenases (complex I) but instead carry alternative (type II) NADH dehydrogenases, which are absent in mammalian cells and are thus considered promising antimicrobial drug targets. The quinolone-like compound 1-hydroxy-2-dodecyl-4(1H)quinolone (HDQ) was recently described as a high-affinity inhibitor of fungal alternative NADH dehydrogenases in enzymatic assays, probably by interfering with the ubiquinol binding site of the enzyme. We describe here that HDQ effectively inhibits the replication rates of P. falciparum and T. gondii in tissue culture. The 50% inhibitory concentration (IC50) of HDQ for T. gondii was determined to be 2.4+/-0.3 nM with a growth assay based on vacuole sizes and 3.7+/-1.4 nM with a growth assay based on beta-galactosidase activity. Quantification of the P. falciparum replication rate using a fluorometric assay revealed an IC50 of 14.0+/-1.9 nM. An important feature of the HDQ structure is the length of the alkyl side chain at position 2. Derivatives with alkyl side chains of C6, C8, C12 (HDQ), and C14 all displayed excellent anti-T. gondii activity, while a C5 derivative completely failed to inhibit parasite replication. A combined treatment of T. gondii-infected cells with HDQ and the antimalarial agent atovaquone, which blocks the ubiquinol oxidation site of cytochrome b in complex III, resulted in synergism, with a calculated fractional inhibitory concentration of 0.16 nM. Interference of the mitochondrial ubiquinone/ubiquinol cycle at two different locations thus appears to be a highly effective strategy for inhibiting parasite replication. HDQ and its derivatives, particularly in combination with atovaquone, represent promising compounds with a high potential for antimalarial and antitoxoplasmal therapy.
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Affiliation(s)
- Ahmad Saleh
- Institute of Medical Microbiology, University of Göttingen, Kreuzbergring 57, D-37075 Göttingen, Germany
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15
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Ferella M, Montalvetti A, Rohloff P, Miranda K, Fang J, Reina S, Kawamukai M, Búa J, Nilsson D, Pravia C, Katzin A, Cassera MB, Aslund L, Andersson B, Docampo R, Bontempi EJ. A solanesyl-diphosphate synthase localizes in glycosomes of Trypanosoma cruzi. J Biol Chem 2006; 281:39339-48. [PMID: 17062572 DOI: 10.1074/jbc.m607451200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report the cloning of a Trypanosoma cruzi gene encoding a solanesyl-diphosphate synthase, TcSPPS. The amino acid sequence (molecular mass approximately 39 kDa) is homologous to polyprenyl-diphosphate synthases from different organisms, showing the seven conserved motifs and the typical hydrophobic profile. TcSPPS preferred geranylgeranyl diphosphate as the allylic substrate. The final product, as determined by TLC, had nine isoprene units. This suggests that the parasite synthesizes mainly ubiquinone-9 (UQ-9), as described for Trypanosoma brucei and Leishmania major. In fact, that was the length of the ubiquinone extracted from epimastigotes, as determined by high-performance liquid chromatography. Expression of TcSPPS was able to complement an Escherichia coli ispB mutant. A punctuated pattern in the cytoplasm of the parasite was detected by immunofluorescence analysis with a specific polyclonal antibody against TcSPPS. An overlapping fluorescence pattern was observed using an antibody directed against the glycosomal marker pyruvate phosphate dikinase, suggesting that this step of the isoprenoid biosynthetic pathway is located in the glycosomes. Co-localization in glycosomes was confirmed by immunogold electron microscopy and subcellular fractionation. Because UQ has a central role in energy production and in reoxidation of reduction equivalents, TcSPPS is promising as a new chemotherapeutic target.
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Affiliation(s)
- Marcela Ferella
- Instituto Nacional de Parasitología Dr. M. Fatala Chabén, Av. Paseo Colón 568, Administración Nacional de Laboratorios e Institutos de Salud, Ministerio de Salud, Buenos Aires 1063, Argentina
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16
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van Hellemond JJ, Tielens AGM. Adaptations in the lipid metabolism of the protozoan parasite Trypanosoma brucei. FEBS Lett 2006; 580:5552-8. [PMID: 16920110 DOI: 10.1016/j.febslet.2006.07.056] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Accepted: 07/14/2006] [Indexed: 11/19/2022]
Abstract
Trypanosomes are unicellular parasites and like all decent parasites, they try to obtain from the host as much material as possible, including lipids. However, the needs of a parasite are not always the same as those of the host, and therefore, mostly, some biosynthetic work still has to be done by the parasite itself. Very often at least modifications of the lipid components that are acquired from the host have to be made. Furthermore, next to the lipids Trypanosoma brucei indeed obtains from the host, some other lipid components have to be synthesized de novo. Especially the processes where the metabolism of T. brucei differs from that of the host, will be discussed, as at least some of them are excellent targets for the development of urgently needed new chemotherapeutics.
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Affiliation(s)
- Jaap J van Hellemond
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine and Institute of Biomembranes, Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands
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17
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Biagini GA, Viriyavejakul P, O'neill PM, Bray PG, Ward SA. Functional characterization and target validation of alternative complex I of Plasmodium falciparum mitochondria. Antimicrob Agents Chemother 2006; 50:1841-51. [PMID: 16641458 PMCID: PMC1472221 DOI: 10.1128/aac.50.5.1841-1851.2006] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 02/03/2006] [Indexed: 11/20/2022] Open
Abstract
This study reports on the first characterization of the alternative NADH:dehydrogenase (also known as alternative complex I or type II NADH:dehydrogenase) of the human malaria parasite Plasmodium falciparum, known as PfNDH2. PfNDH2 was shown to actively oxidize NADH in the presence of quinone electron acceptors CoQ(1) and decylubiquinone with an apparent K(m) for NADH of approximately 17 and 5 muM, respectively. The inhibitory profile of PfNDH2 revealed that the enzyme activity was insensitive to rotenone, consistent with recent genomic data indicating the absence of the canonical NADH:dehydrogenase enzyme. PfNDH2 activity was sensitive to diphenylene iodonium chloride and diphenyl iodonium chloride, known inhibitors of alternative NADH:dehydrogenases. Spatiotemporal confocal imaging of parasite mitochondria revealed that loss of PfNDH2 function provoked a collapse of mitochondrial transmembrane potential (Psi(m)), leading to parasite death. As with other alternative NADH:dehydrogenases, PfNDH2 lacks transmembrane domains in its protein structure, and therefore, it is proposed that this enzyme is not directly involved in mitochondrial transmembrane proton pumping. Rather, the enzyme provides reducing equivalents for downstream proton-pumping enzyme complexes. As inhibition of PfNDH2 leads to a depolarization of mitochondrial Psi(m), this enzyme is likely to be a critical component of the electron transport chain (ETC). This notion is further supported by proof-of-concept experiments revealing that targeting the ETC's Q-cycle by inhibition of both PfNDH2 and the bc(1) complex is highly synergistic. The potential of targeting PfNDH2 as a chemotherapeutic strategy for drug development is discussed.
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Affiliation(s)
- Giancarlo A Biagini
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L35QA, United Kingdom.
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18
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Basselin M, Hunt SM, Abdala-Valencia H, Kaneshiro ES. Ubiquinone synthesis in mitochondrial and microsomal subcellular fractions of Pneumocystis spp.: differential sensitivities to atovaquone. EUKARYOTIC CELL 2005; 4:1483-92. [PMID: 16087753 PMCID: PMC1214522 DOI: 10.1128/ec.4.8.1483-1492.2005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The lung pathogen Pneumocystis spp. is the causative agent of a type of pneumonia that can be fatal in people with defective immune systems, such as AIDS patients. Atovaquone, an analog of ubiquinone (coenzyme Q [CoQ]), inhibits mitochondrial electron transport and is effective in clearing mild to moderate cases of the infection. Purified rat-derived intact Pneumocystis carinii cells synthesize de novo four CoQ homologs, CoQ7, CoQ8, CoQ9, and CoQ10, as demonstrated by the incorporation of radiolabeled precursors of both the benzoquinone ring and the polyprenyl chain. A central step in CoQ biosynthesis is the condensation of p-hydroxybenzoic acid (PHBA) with a long-chain polyprenyl diphosphate molecule. In the present study, CoQ biosynthesis was evaluated by the incorporation of PHBA into completed CoQ molecules using P. carinii cell-free preparations. CoQ synthesis in whole-cell homogenates was not affected by the respiratory inhibitors antimycin A and dicyclohexylcarbodiimide but was diminished by atovaquone. Thus, atovaquone has inhibitory activity on both electron transport and CoQ synthesis in this pathogen. Furthermore, both the mitochondrial and microsomal fractions were shown to synthesize de novo all four P. carinii CoQ homologs. Interestingly, atovaquone inhibited microsomal CoQ synthesis, whereas it had no effect on mitochondrial CoQ synthesis. This is the first pathogenic eukaryotic microorganism in which biosynthesis of CoQ molecules from the initial PHBA:polyprenyl transferase reaction has been unambiguously shown to occur in two distinct compartments of the same cell.
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Affiliation(s)
- Mireille Basselin
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, USA
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19
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20
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Mäntylä A, Rautio J, Nevalainen T, Vepsälainen J, Juvonen R, Kendrick H, Garnier T, Croft SL, Järvinen T. Synthesis and antileishmanial activity of novel buparvaquone oxime derivatives. Bioorg Med Chem 2005; 12:3497-502. [PMID: 15186834 DOI: 10.1016/j.bmc.2004.04.032] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Accepted: 04/27/2004] [Indexed: 11/17/2022]
Abstract
Novel oxime derivatives (2, 3 and 5) of buparvaquone (1) and O-methyl-buparvaquone (4) were synthesized and their in vitro activities against Leishmania donovani, the causative agent of visceral leishmaniasis (VL), were determined. Buparvaquone-oxime (2) was also studied as a bioreversible prodrug structure of buparvaquone (1). Buparvaquone-oxime (2) released buparvaquone (1) in vitro when it was incubated with induced rat liver microsomes, which suggests that the oxime-structure is a useful prodrug template for developing novel prodrugs of buparvaquone and other hydroxynaphthoquinones. Moreover, the formation of NO(2)(-) , formed via oxidation of NO, was confirmed during the bioconversion. The release of NO from buparvaquone-oxime (2) may provide an additional therapeutic effect in the treatment of leishmaniasis. Buparvaquone-oxime (2) and buparvaquone-O-methyloxime (3) demonstrated moderate activity against amastigotes of the Leishmania species that causes VL. However, the studied oximes (2, 3) most probably did not release buparvaquone (1) and NO during the present in vitro experiment. Further in vivo studies are needed to verify the biological activity of buparvaquone-oximes in the treatment of leishmaniasis.
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Affiliation(s)
- Antti Mäntylä
- Department of Pharmaceutical Chemistry, University of Kuopio, Finland.
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21
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Abstract
Mitochondria of the malaria parasitePlasmodium falciparumare morphologically different between the asexual and sexual blood stages (gametocytes). In this paper recent findings of mitochondrial heterogeneity are reviewed based on their ultrastructural characteristics, metabolic activities and the differential expression of their genes in these 2 blood stages of the parasite. The existence of NADH dehydrogenase (complex I), succinate dehydrogenase (complex II), cytochrome c reductase (complex III) and cytochrome c oxidase (complex IV) suggests that the biochemically active electron transport system operates in this parasite. There is also an alternative electron transport branch pathway, including an anaerobic function of complex II. One of the functional roles of the mitochondrion in the parasite is the coordination of pyrimidine biosynthesis, the electron transport system and oxygen utilization via dihydroorotate dehydrogenase and coenzyme Q. Complete sets of genes encoding enzymes of the tricarboxylic acid cycle and the ATP synthase complex are predicted fromP. falciparumgenomics information. Other metabolic roles of this organelle include membrane potential maintenance, haem and coenzyme Q biosynthesis, and oxidative phosphorylation. Furthermore, the mitochondrion may be a chemotherapeutic target for antimalarial drug development. The antimalarial drug atovaquone targets the mitochondrion.
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Affiliation(s)
- J Krungkrai
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
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22
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Biagini GA, O'Neill PM, Nzila A, Ward SA, Bray PG. Antimalarial chemotherapy: young guns or back to the future? Trends Parasitol 2003; 19:479-87. [PMID: 14580958 DOI: 10.1016/j.pt.2003.09.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Giancarlo A Biagini
- Division of Molecular and Biochemical Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
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23
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Mi-Ichi F, Takeo S, Takashima E, Kobayashi T, Kim HS, Wataya Y, Matsuda A, Torrii M, Tsuboi T, Kita K. Unique properties of respiratory chain in Plasmodium falciparum mitochondria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 531:117-33. [PMID: 12916785 DOI: 10.1007/978-1-4615-0059-9_9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- Fumika Mi-Ichi
- Dept. of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Hongo Bunkyo-ku, Tokyo 113-0033, Japan
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24
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de Macedo CS, Uhrig ML, Kimura EA, Katzin AM. Characterization of the isoprenoid chain of coenzyme Q in Plasmodium falciparum. FEMS Microbiol Lett 2002; 207:13-20. [PMID: 11886744 DOI: 10.1111/j.1574-6968.2002.tb11021.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Little is known about isoprenoid biosynthesis in parasitic protozoa. The presence of dolichol and isoprenylated proteins has been detected in Plasmodium falciparum, but no studies are available about the biosynthesis of the isoprenic side chain attached to the benzoquinone ring of coenzyme Q. In the present study, using metabolic labelling with different intermediates, we demonstrated the presence of an active isoprenoid pathway for the biosynthesis of the isoprenic chain of coenzyme Q. Our results show that P. falciparum is able to synthesize different homologs (coenzyme Q(8) and coenzyme Q(9)), depending on the given intermediate. Parasites treated with nerolidol at doses 2.2 times below the IC(50) showed a decreased ability to synthesize the isoprenic chain attached to coenzyme Q at all intraerythrocytic stages. Treatment with nerolidol arrested development of the intraerythrocytic stages of the parasites, indicating that the drug may have an antimalarial potential.
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Affiliation(s)
- Cristiana Santos de Macedo
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, CEP 05508-900, SP, Brazil
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25
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Kita K, Hirawake H, Miyadera H, Amino H, Takeo S. Role of complex II in anaerobic respiration of the parasite mitochondria from Ascaris suum and Plasmodium falciparum. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1553:123-39. [PMID: 11803022 DOI: 10.1016/s0005-2728(01)00237-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Parasites have developed a variety of physiological functions necessary for existence within the specialized environment of the host. Regarding energy metabolism, which is an essential factor for survival, parasites adapt to low oxygen tension in host mammals using metabolic systems that are very different from that of the host. The majority of parasites do not use the oxygen available within the host, but employ systems other than oxidative phosphorylation for ATP synthesis. In addition, all parasites have a life cycle. In many cases, the parasite employs aerobic metabolism during their free-living stage outside the host. In such systems, parasite mitochondria play diverse roles. In particular, marked changes in the morphology and components of the mitochondria during the life cycle are very interesting elements of biological processes such as developmental control and environmental adaptation. Recent research has shown that the mitochondrial complex II plays an important role in the anaerobic energy metabolism of parasites inhabiting hosts, by acting as quinol-fumarate reductase.
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Affiliation(s)
- Kiyoshi Kita
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033, Tokyo, Japan.
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26
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Takashima E, Takamiya S, Takeo S, Mi-ichi F, Amino H, Kita K. Isolation of mitochondria from Plasmodium falciparum showing dihydroorotate dependent respiration. Parasitol Int 2001; 50:273-8. [PMID: 11719114 DOI: 10.1016/s1383-5769(01)00085-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Using N2 cavitation, we established a protocol to prepare the active mitochondria from Plasmodium falciparum showing a higher succinate dehydrogenase activity than previously reported and a dihydroorotate-dependent respiration. The fact that fumarate partially inhibited the dihydroorotate dependent respiration suggests that complex II (succinate-ubiquinone reductase/quinol-fumarate reductase) in the erythrocytic stage cells of P. falciparum functions as a quinol-fumarate reductase.
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Affiliation(s)
- E Takashima
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, 113-0033, Tokyo, Japan
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27
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Kaneshiro ES. Are cytochrome b gene mutations the only cause of atovaquone resistance in Pneumocystis? Drug Resist Updat 2001; 4:322-9. [PMID: 11991686 DOI: 10.1054/drup.2001.0221] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
There is evidence that exposure of the opportunistic pathogen Pneumocystis to atovaquone enhances the development of resistance to the drug. Atovaquone is a structural analog of ubiquinone, which binds to the mitochondrial cytochrome bc(1) complex and inhibits electron transport. Like the parasites Plasmodium and Toxoplasma, atovaquone resistance can result from mutations in the cytochrome b gene of Pneumocystis. However, atovaquone resistance cannot be explained by cytochrome b gene mutations in all cases. The discovery that atovaquone also inhibits biosynthesis of ubiquinone in P. carinii may unfold other mechanisms by which drug resistance develops.
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Affiliation(s)
- E S Kaneshiro
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
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28
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Lindegårth N, Funding L, Bergqvist Y. Automated solid-phase extraction method for the determination of atovaquone in capillary blood applied onto sampling paper by rapid high-performance liquid chromatography. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 758:137-44. [PMID: 11486822 DOI: 10.1016/s0378-4347(01)00160-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A bioanalytical method for the determination of atovaquone in 100 microl blood-spots by solid-phase extraction and high-performance liquid chromatography has been developed and validated. Atovaquone was extracted from the sampling paper in 0.2 M phosphoric acid and a structurally similar internal standard was added with acetonitrile before being loaded onto a C8 end-capped solid-phase extraction column. Atovaquone and internal standard were analysed by high-performance liquid chromatography on a C18 J'Sphere ODS-M80 (150 x 4.0 mm) column with mobile phase acetonitrile-phosphate buffer, 0.01 M, pH 7.0 (65:35, v/v) and UV detection at 277 nm. The intra-assay precision was 2.7% at 12.00 microM and 13.5% at 1.00 microM. The inter-assay precision was 3.3% at 12.00 microM and 15.6% at 1.00 microM. The lower limit of quantification was 1.00 microM. The limit of detection was 0.50 microM.
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29
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Sul D, Kaneshiro ES. Pneumocystis carinii f. sp. carinii synthesizes de novo four homologs of ubiquinone. J Eukaryot Microbiol 2001; 48:182-7. [PMID: 12095106 DOI: 10.1111/j.1550-7408.2001.tb00301.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ubiquinone, coenzyme Q, plays a pivotal role in electron transport and is a target for chemotherapy against a number of eukaryotic infectious agents, including Pneumocystis carinii. Coenzyme Q10 was previously identified as the major ubiquinone homolog in P. carinii isolated and purified from rat lungs; CoQ9 was also present. In contrast, CoQ9 and CoQ8 (but not CoQ10) were detected in the lungs of uninfected rat controls. These observations suggested that the pathogen synthesizes CoQ10, and perhaps CoQ9 as well. In the present study, CoQ biosynthesis in P. carinii was examined in greater detail. Radiolabeled mevalonate, a precursor of the CoQ polyprenyl chain, was incorporated in vitro into P. carinii ubiquinones. Incorporation of radiolabeled mevalonate into P. carinii CoQ was not enhanced by treating cells with lovastatin, suggesting that the cells did not transport the drug, or that a lovastatin-insensitive pathway for de novo synthesis of isoprenoids may also function in this organism. Radiolabeled precursors of the ring moiety, including shikimic acid, p-hydroxybenzoic acid, and tyrosine were also incorporated into P. carinii CoQ. Unexpectedly, it was found that not only CoQ9 and CoQ10, but also CoQ7, and CoQ8, were metabolically radiolabeled by all the precursors tested, indicating that the organism synthesizes CoQ7, CoQ8, CoQ9, and CoQ10. Metabolic radiolabeling of ubiquinones in rat lung controls was not detected in experiments using either radioactive mevalonate or p-hydroxybenzoate. Thus the incorporations measured using purified P. carinii preparations were due to the enzymes of the organism.
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Affiliation(s)
- D Sul
- Department of Biological Sciences, University of Cincinnati, Ohio 45221, USA
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30
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Kayser O, Kiderlen AF, Laatsch H, Croft SL. In vitro leishmanicidal activity of monomeric and dimeric naphthoquinones. Acta Trop 2000; 77:307-14. [PMID: 11114393 DOI: 10.1016/s0001-706x(00)00161-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A series of monomeric and dimeric naphthoquinones with potential for treatment of Leishmania infections was identified in vitro using both a direct cytotoxicity assay against extracellular promastigotes of Leishmania donovani, L. infantum, L. enriettii, and L. major and a test against intracellular amastigote L. donovani residing within murine macrophages. Several naphthoquinones proved to be active at concentrations in the microgram range (EC(50) 0.9-17.0 microg/ml). When tested against a panel of human cancer cell lines (KB, SKMel, A549, MDA) and murine bone marrow culture-derived macrophages (BMMPhi) as mammalian host cell controls, compounds with anti-Leishmania-activity showed moderate (EC(50)>25 microg/ml) to pronounced (EC(50)<10 microg/ml) toxic effects.
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Affiliation(s)
- O Kayser
- Institute of Pharmacy, Pharmaceutical Technology, Biopharmacy and Biotechnology, Freie Universität Berlin, Kelchstrasse 31, D-12169, Berlin, Germany.
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31
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Kayser O, Kiderlen AF, Laatsch H, Croft SL. In vitro leishmanicidal activity of monomeric and dimeric naphthoquinones. Acta Trop 2000; 76:131-8. [PMID: 10936572 DOI: 10.1016/s0001-706x(00)00078-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A series of monomeric and dimeric naphthoquinones with potential for treatment of Leishmania infections was identified in vitro using both a direct cytotoxicity assay against extracellular promastigotes of Leishmania donovani, Leishmania infanturn, Leishmania enriettii, and Leishmania major and a test against intracellular amastigote L. donovani residing within murine macrophages. Several naphthoquinones proved to be active at concentrations in the microgram range (EC(50) 0.9-17.0 microg/ml). When tested against a panel of human cancer cell lines (KB, SKMel, A549, MDA) and murine bone marrow culture-derived macrophages (BMMPhi) as mammalian host cell controls, compounds with anti-Leishmania-activity showed moderate (EC(50)>25 microg/ml) to pronounced (EC(50)<10 microg/ml) toxic effects.
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Affiliation(s)
- O Kayser
- Institute of Pharmacy, Pharmazeutische Technologie, Biopharmazie und Biotechnologie, Freie Universität Berlin, Germany.
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32
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McFadden DC, Tomavo S, Berry EA, Boothroyd JC. Characterization of cytochrome b from Toxoplasma gondii and Q(o) domain mutations as a mechanism of atovaquone-resistance. Mol Biochem Parasitol 2000; 108:1-12. [PMID: 10802314 DOI: 10.1016/s0166-6851(00)00184-5] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Atovaquone is active in vitro against the tachyzoites of Toxoplasma gondii at nanomolar concentrations and is used clinically to treat acute cases of human toxoplasmosis. In pursuit of the mechanism of action of atovaquone against T. gondii and to understand how resistance might arise, drug-resistant mutants were generated and examined. The previously uncloned cytochrome b gene of T. gondii was cloned and sequenced from wild type and resistant strains as this was a likely candidate for the target of the drug and thus a source of resistance. Mutations are present within the cytochrome b gene of atovaquone-resistant parasites (M129L and I254L) and represent alterations in two different regions of the ubiquinol-binding pocket (Q(o) domain) of cytochrome b, suggesting that atovaquone interferes with electron transport at the cytochrome bc(1) complex in T. gondii. A structural model for how this hydroxynaphthoquinone is binding within the Q(o) domain is presented. Further analysis of the cytochrome b gene suggested that the protein may differ from other homologues by terminating within the mitochondrial membrane. Cytochrome b becomes the first complete mitochondrial gene and cognate protein to be described for T. gondii.
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Affiliation(s)
- D C McFadden
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
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33
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Cushion MT, Collins M, Hazra B, Kaneshiro ES. Effects of atovaquone and diospyrin-based drugs on the cellular ATP of Pneumocystis carinii f. sp. carinii. Antimicrob Agents Chemother 2000; 44:713-9. [PMID: 10681344 PMCID: PMC89752 DOI: 10.1128/aac.44.3.713-719.2000] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Atovaquone (also called Mepron, or 566C80) is a napthoquinone used for the treatment of infections caused by pathogens such as Plasmodium spp. and Pneumocystis carinii. The mechanism of action against the malarial parasite is the inhibition of dihydroorotate dehydrogenase (DHOD), a consequence of blocking electron transport by the drug. As an analog of ubiquinone (coenzyme Q [CoQ]), atovaquone irreversibly binds to the mitochondrial cytochrome bc(1) complex; thus, electrons are not able to pass from dehydrogenase enzymes via CoQ to cytochrome c. Since DHOD is a critical enzyme in pyrimidine biosynthesis, and because the parasite cannot scavenge host pyrimidines, the drug is lethal to the organism. Oxygen consumption in P. carinii is inhibited by the drug; thus, electron transport has also been identified as the drug target in P. carinii. However, unlike Plasmodium DHOD, P. carinii DHOD is inhibited only at high atovaquone concentrations, suggesting that the organism may salvage host pyrimidines and that atovaquone exerts its primary effects on ATP biosynthesis. In the present study, the effect of atovaquone on ATP levels in P. carinii was measured directly from 1 to 6 h and then after 24, 48, and 72 h of exposure. The average 50% inhibitory concentration after 24 to 72 h of exposure was 1.5 microgram/ml (4.2 microM). The kinetics of ATP depletion were in contrast to those of another family of naphthoquinone compounds, diospyrin and two of its derivatives. Whereas atovaquone reduced ATP levels within 1 h of exposure, the diospyrins required at least 48 h. After 72 h, the diospyrins were able to decrease ATP levels of P. carinii at nanomolar concentrations. These data indicate that although naphthoquinones inhibit the electron transport chain, the molecular targets in a given organism are likely to be distinct among members of this class of compounds.
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Affiliation(s)
- M T Cushion
- Department of Internal Medicine, University of Cincinnati College of Medicine, and Veterans Affairs Medical Center, Ohio, USA.
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34
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Kaneshiro ES, Sul D, Hazra B. Effects of atovaquone and diospyrin-based drugs on ubiquinone biosynthesis in Pneumocystis carinii organisms. Antimicrob Agents Chemother 2000; 44:14-8. [PMID: 10602716 PMCID: PMC89621 DOI: 10.1128/aac.44.1.14-18.2000] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The naphthoquinone atovaquone is effective against Plasmodium and Pneumocystis carinii carinii. In Plasmodium, the primary mechanism of drug action is an irreversible binding to the mitochondrial cytochrome bc(1) complex as an analog of ubiquinone. Blockage of the electron transport chain ultimately inhibits de novo pyrimidine biosynthesis since dihydroorotate dehydrogenase, a key enzyme in pyrimidine biosynthesis, is unable to transfer electrons to ubiquinone. In the present study, the effect of atovaquone was examined on Pneumocystis carinii carinii coenzyme Q biosynthesis (rather than electron transport and respiration) by measuring its effect on the incorporation of radiolabeled p-hydroxybenzoate into ubiquinone in vitro. A triphasic dose-response was observed, with inhibition at 10 nM and then stimulation up to 0.2 microM, followed by inhibition at 1 microM. Since other naphthoquinone drugs may also act as analogs of ubiquinone, diospyrin and two of its derivatives were also tested for their effects on ubiquinone biosynthesis in P. carinii carinii. In contrast to atovaquone, these drugs did not inhibit the incorporation of p-hydroxybenzoate into P. carinii carinii ubiquinone.
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Affiliation(s)
- E S Kaneshiro
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio 45221, USA.
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Syafruddin D, Siregar JE, Marzuki S. Mutations in the cytochrome b gene of Plasmodium berghei conferring resistance to atovaquone. Mol Biochem Parasitol 1999; 104:185-94. [PMID: 10593174 DOI: 10.1016/s0166-6851(99)00148-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The molecular lesions which underlie the resistance of the malaria parasites to atovaquone, a coenzyme Q analogue, were investigated. Resistant clones of Plasmodium berghei ANKA strain were isolated following prolonged propagation in mice in the presence of increasing doses of the drug, and their cytochrome b gene sequenced. Three mutations were detected, T-C substitution at nt 431, G-A at nt 399 and G-T at nt 850, resulting in amino acid changes in the putative cytochrome b product at residues 133, 144 and 284. The V284F amino acid change is in the sixth transmembrane helix of the protein and was observed in all resistant clones. An additional M133I or L144S amino acid change within the Qo site at an extramembranous amphipathic helix significantly increases the resistance to atovaquone. Our results (a) provide evidence that the antimalarial activity of atovaquone indeed involves an interaction with the cytochrome b; (b) define atovaquone as an inhibitor of the ubiquinol oxidase activity of the cytochrome bc1 complex; and (c) define amino acid residues in the mammalian cytochrome b which might be critical in determining its relative resistance to atovaquone.
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Affiliation(s)
- D Syafruddin
- Eijkman Institute for Molecular Biology, Jakarta, Indonesia
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Kaneshiro ES. Lipid metabolism of Pneumocystis: toward the definition of new molecular targets. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 1998; 22:135-43. [PMID: 9792072 DOI: 10.1111/j.1574-695x.1998.tb01198.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- E S Kaneshiro
- Department of Biological Sciences, University of Cincinnati, OH 45221-0006, USA.
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Abstract
Information about a number of Pneumocystis carinii lipids obtained by the analyses of organisms isolated and purified from infected lungs of corticosteroid-immunosuppressed rats has been reported in recent years. Of the common opportunistic protists associated with AIDS (Cryptosporidium, Toxoplasma, and the microsporidia), more is currently known about the lipids of P. carinii than the others. Lipids that are synthesized by the organism but not by humans are attractive targets for drug development. Thus, the elucidation of delta 7C-24-alykylated sterol and cis-9,10-epoxystearic acid biosyntheses in P. carinii is currently being examined in detail, since these have been identified as P. carinii-specific lipids. The development of low-toxicity drugs that prevent sterol C-24 alkylation and the specific inhibition of the lipoxygenase that forms cis-9,10-epoxystearic acid might prove fruitful. Although humans can synthesize coenzyme Q10, the anti-P. carinii activity and low toxicity of ubiquinone analogs such as atovaquone suggest that the electron transport chain in the pathogen may differ importantly from that in the host. Although resistance to atovaquone has been observed, development of other naphthoquinone drugs would provide a broader armamentarium of drugs to treat patients with P. carinii pneumonia. Studies of bronchoalveolar lavage fluid and of infected lungs have demonstrated that the infection causes a number of chemical abnormalities. Bronchoalveolar lavage fluid obtained after the removal of lung cellular material and the organisms has been shown to contain larger amounts of surfactant proteins and smaller amounts of phospholipids than do comparable samples from P. carinii-free lungs. Increased phospholipase activity, inhibition of surfactant secretion by type II cells, and uptake and catabolism of lipids by the pathogen may explain this phenomenon related to P. carinii pneumonia. Although not yet thoroughly examined, initial studies on the uptake and metabolism of lipids by P. carinii suggest that the organism relies heavily on exogenous lipid nutrients.
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Affiliation(s)
- E S Kaneshiro
- Department of Biological Sciences, University of Cincinnati, Ohio 45221, USA.
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Minagawa N, Yabu Y, Kita K, Nagai K, Ohta N, Meguro K, Sakajo S, Yoshimoto A. An antibiotic, ascofuranone, specifically inhibits respiration and in vitro growth of long slender bloodstream forms of Trypanosoma brucei brucei. Mol Biochem Parasitol 1997; 84:271-80. [PMID: 9084049 DOI: 10.1016/s0166-6851(96)02797-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ascofuranone, a prenylphenol antibiotic isolated from a phytopathogenic fungus, Ascochyta visiae, strongly inhibited both glucose-dependent cellular respiration and glycerol-3-phosphate-dependent mitochondrial O2 consumption of long slender bloodstream forms of Trypanosoma brucei brucei. This inhibition was suggested to be due to inhibition of the mitochondrial electron-transport system, composed of glycerol-3-phosphate dehydrogenase (EC 1.1.99.5) and plant-like alternative oxidase. Ascofuranone noncompetitively inhibited the reduced coenzyme Q1-dependent O2 uptake of the mitochondria with respect to ubiquinol (Ki = 2.38 nM). Therefore, the susceptible site is deduced to be the ubiquinone redox machinery which links the two enzyme activities. Further, ascofuranone in combination with glycerol completely blocked energy production, and potently inhibited the in vitro growth of the parasite. Our findings suggest that ascofuranone might be a promising candidate for the chemotherapeutic agents of African trypanosomiasis.
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Affiliation(s)
- N Minagawa
- Department of Biochemistry, Niigata College of Pharmacy, Japan.
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39
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Minagawa N, Yabu Y, Kita K, Nagai K, Ohta N, Meguro K, Sakajo S, Yoshimoto A. An antibiotic, ascofuranone, specifically inhibits respiration and in vitro growth of long slender bloodstream forms of Trypanosoma brucei brucei. Mol Biochem Parasitol 1996; 81:127-36. [PMID: 8898329 DOI: 10.1016/0166-6851(96)02665-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Ascofuranone, a prenylphenol antibiotic isolated from a phytopathogenic fungus, Ascochyta visiae, strongly inhibited both glucose-dependent cellular respiration and glycerol-3-phosphate-dependent mitochondrial O2 consumption of long slender bloodstream forms of Trypanosoma brucei brucei. This inhibition was suggested to be due to inhibition of the mitochondriai electron-transport system, composed of glycerol-3-phosphate dehydrogenase (EC 1.1.99.5) and plant-like alternative oxidase. Ascofuranone noncompetitively inhibited the reduced coenzyme Q1-dependent O2 uptake of the mitochondria with respect to ubiquinol (Ki = 2.38 nM). Therefore, the susceptible site is deduced to be the ubiquinone redox machinery which links the two enzyme activities. Further, ascofuranone in combination with glycerol completely blocked energy production, and potently inhibited the in vitro growth of the parasite. Our findings suggest that ascofuranone might be a promising candidate for the chemotherapeutic agents of African trypanosomiasis.
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Affiliation(s)
- N Minagawa
- Department of Biochemistry, Niigata College of Pharmacy, Japan. minagawa@
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Ellis JE, Wyder MA, Zhou L, Gupta A, Rudney H, Kaneshiro ES. Composition of Pneumocystis carinii neutral lipids and identification of coenzyme Q10 as the major ubiquinone homolog. J Eukaryot Microbiol 1996; 43:165-70. [PMID: 8640186 DOI: 10.1111/j.1550-7408.1996.tb01385.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The lipids of purified preparations of Pneumocystis carinii carinii freshly isolated from infected rats were analyzed and compared with those of whole lungs from normal and methylprednisolone-immunosuppressed uninfected rats. In this study, the neutral lipid fraction was examined in detail; the relative concentrations of individual classes making up this fraction were quantified. Of particular interest was the nature of the organism's ubiquinone (coenzyme Q, CoQ) fraction because atovaquone, a hydroxynaphtho-quinone (566C80) analog of ubiquinone, is efficacious in the treatment of P. carinii pneumonia. The ubiquinone concentration in both P. carinii and lung tissues was relatively low compared to that present in rat heart and liver tissues. Two homologs were identified in the organism: CoQ10 was the predominant homolog with lesser amounts of CoQ9 present. In contrast, the lungs of normal and immunosuppressed uninfected rats had CoQ9 and lesser amounts of CoQ8, but no detectable CoQ10. Furthermore, radiolabeled mevalonic acid was incorporated in vitro into the ubiquinone fraction of P. carinii indicating that the organism has the de novo branch of the isoprenoid biosynthetic pathway leading to polyprenyl formation. Hence, it was concluded that CoQ10 (if not both CoQ10 and CoQ9) in P. carinii was not scavenged from the host but was synthesized by the organism. Although lung tissues contained substantial free fatty acids, the organism was enriched in these lipids. The high concentration of free fatty acids and relatively low level of triglycerides in P. carinii suggest that fatty acids may represent major carbon sources for ATP production by the organism.
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Affiliation(s)
- J E Ellis
- Department of Biological Sciences, University of Cincinnati, Ohio 45221, USA
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Pollakis G, Grady RW, Dieck HA, Clarkson AB. Competition between inhibitors of the trypanosome alternative oxidase (TAO) and reduced coenzyme Q9. Biochem Pharmacol 1995; 50:1207-10. [PMID: 7488235 DOI: 10.1016/0006-2952(95)00259-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The trypanosome alternative oxidase (TAO) is an attractive target for chemotherapy for the diseases caused by African trypanosomes because there is no equivalent enzyme in mammalian hosts. Many inhibitors of this enzyme have been described, but there have been no data on the mechanism of inhibition. In the present study, reduced 2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinone (decyl-CoQ-H2) was used as a substitute for the natural substrate CoQ9-H2 to allow direct measurements of the TAO in crude mitochondrial preparations from Trypanosoma brucei brucei. A Km value of 3.8 microM was obtained for this substrate. The following five compounds that have alkyl side chains from 1 to 4 carbons and belong to three classes of inhibitors showed a competitive inhibition pattern with respect to decyl-CoQ-H: p-methoxybenzhydroxamic acid, p-ethoxybenzhydroxamic acid,p-n-butyloxybenzhydroxamic acid, methyl 3,4-dihydroxybenzoate and N-n-butyl-3,4-dihydroxybenzamide. The following four compounds belonging to the same chemical classes but having alkyl side chains from 10 to 12 carbons showed uncompetitive inhibition patterns: p-n-dodecyloxybenzhydroxamic acid, n-decyl 3,4-dihydroxybenzoate, n-dodecyl 3,4-dihydroxybenzoate, and N-n-decyl-3,4-dihydroxybenzamide. Clearly, the first group of inhibitors compete with CoQ-H2 for the active site of the TAO. We propose that the uncompetitive patterns produced by the second group of inhibitors are due to the greater lipophilicity of these compounds and the resulting change in the interaction of the inhibitors and the membrane containing the TAO, thus affecting the local concentration of the inhibitors at the active site.
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Affiliation(s)
- G Pollakis
- Department of Medical and Molecular Parasitology, New York University Medical Center, NY 10016, USA
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