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Dalmizrak O, Teralı K, Asuquo EB, Ogus IH, Ozer N. The Relevance of Glutathione Reductase Inhibition by Fluoxetine to Human Health and Disease: Insights Derived from a Combined Kinetic and Docking Study. Protein J 2020; 38:515-524. [PMID: 31004256 DOI: 10.1007/s10930-019-09834-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Glutathione reductase (GR) is a homodimeric enzyme playing an important role in the regeneration of the central antioxidant molecule reduced glutathione (GSH) from oxidized glutathione (GSSG) at the expense of a molecule of NADPH. GSH scavenges and eliminates superoxide and hydroxyl radicals non-enzymatically or serves as an electron donor for several enzymes. Fluoxetine (FLU), a selective serotonin reuptake inhibitor, is widely prescribed in the treatment of major depressive disorder. Here, using enzyme kinetic studies and molecular docking simulations, we aimed at disclosing the mechanistic and structural aspects of the interaction between GR and FLU. Affecting enzyme activity in a dose-dependent manner, FLU was shown to be a moderately potent (IC50 = 0.88 mM) inhibitor of GR. When the variable substrate was GSSG, the type of inhibition was linear mixed-type competitive (Ki = 279 ± 32 μM; α = 5.48 ± 1.29). When the variable substrate was NADPH, however, the type of inhibition was non-competitive (Ki = 879 ± 82 μM). The observed difference in inhibition types was attributed to the binding of FLU in the large intermonomer cavity of GR, where it hampered catalysis and interfered with substrate binding. Overall, although it is anticipated that long-term use of FLU leads to acquired GR deficiency, the inhibitory action of FLU on GR may be therapeutically exploited in anti-cancer research.
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Affiliation(s)
- Ozlem Dalmizrak
- Department of Medical Biochemistry, Faculty of Medicine, Near East University, Near East Boulevard, Nicosia/TRNC, Mersin 10, 99138, Turkey
| | - Kerem Teralı
- Department of Medical Biochemistry, Faculty of Medicine, Near East University, Near East Boulevard, Nicosia/TRNC, Mersin 10, 99138, Turkey
| | - Evelyn Bright Asuquo
- Department of Medical Biochemistry, Faculty of Medicine, Near East University, Near East Boulevard, Nicosia/TRNC, Mersin 10, 99138, Turkey
| | - Izzet Hamdi Ogus
- Department of Medical Biochemistry, Faculty of Medicine, Near East University, Near East Boulevard, Nicosia/TRNC, Mersin 10, 99138, Turkey
| | - Nazmi Ozer
- Department of Medical Biochemistry, Faculty of Medicine, Near East University, Near East Boulevard, Nicosia/TRNC, Mersin 10, 99138, Turkey.
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Abstract
The potential of flavoproteins as targets of pharmacological treatments is immense. In this review we present an overview of the current research progress on medical interventions based on flavoproteins with a special emphasis on cancer, infectious diseases, and neurological disorders.
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Affiliation(s)
- Esther Jortzik
- Interdisciplinary Research Center, Justus Liebig University, Giessen, Germany
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3
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Pedrolli DB, Jankowitsch F, Schwarz J, Langer S, Nakanishi S, Mack M. Natural riboflavin analogs. Methods Mol Biol 2014; 1146:41-63. [PMID: 24764087 DOI: 10.1007/978-1-4939-0452-5_3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Riboflavin analogs have a good potential to serve as basic structures for the development of novel anti-infectives. Riboflavin analogs have multiple cellular targets, since riboflavin (as a precursor to flavin cofactors) is active at more than one site in the cell. As a result, the frequency of developing resistance to antimicrobials based on riboflavin analogs is expected to be significantly lower. The only known natural riboflavin analog with antibiotic function is roseoflavin from the bacterium Streptomyces davawensis. This antibiotic negatively affects flavoenzymes and FMN riboswitches. Another roseoflavin producer, Streptomyces cinnabarinus, was recently identified. Possibly, flavin analogs with antibiotic activity are more widespread than anticipated. The same could be true for flavin analogs yet to be discovered, which could constitute tools for cellular chemistry, thus allowing a further extension of the catalytic spectrum of flavoenzymes.
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Affiliation(s)
- Danielle Biscaro Pedrolli
- Institute for Technical Microbiology, Mannheim University of Applied Sciences, Paul-Wittsack-Str. 10, 68163, Mannheim, Germany
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Munigunti R, Gathiaka S, Acevedo O, Sahu R, Tekwani B, Calderón AI. Characterization of PfTrxR inhibitors using antimalarial assays and in silico techniques. Chem Cent J 2013; 7:175. [PMID: 24209891 PMCID: PMC3828397 DOI: 10.1186/1752-153x-7-175] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 11/05/2013] [Indexed: 02/02/2023] Open
Abstract
Background The compounds 1,4-napthoquinone (1,4-NQ), bis-(2,4-dinitrophenyl)sulfide (2,4-DNPS), 4-nitrobenzothiadiazole (4-NBT), 3-dimethylaminopropiophenone (3-DAP) and menadione (MD) were tested for antimalarial activity against both chloroquine (CQ)-sensitive (D6) and chloroquine (CQ)-resistant (W2) strains of Plasmodium falciparum through an in vitro assay and also for analysis of non-covalent interactions with P. falciparum thioredoxin reductase (PfTrxR) through in silico docking studies. Results The inhibitors of PfTrxR namely, 1,4-NQ, 4-NBT and MD displayed significant antimalarial activity with IC50 values of < 20 μM and toxicity against 3T3 cell line. 2,4-DNPS was only moderately active. In silico docking analysis of these compounds with PfTrxR revealed that 2,4-DNPS, 4-NBT and MD interact non-covalently with the intersubunit region of the enzyme. Conclusions In this study, tools for the identification of PfTrxR inhibitors using phenotyphic screening and docking studies have been validated for their potential use for antimalarial drug discovery project.
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Affiliation(s)
| | | | | | | | | | - Angela I Calderón
- Department of Pharmacal Sciences, 4306 Walker Building, Auburn University, Auburn, AL, USA.
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5
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Conroy T, Guo JT, Hunt NH, Payne RJ. Total Synthesis and Antimalarial Activity of Symplostatin 4. Org Lett 2010; 12:5576-9. [DOI: 10.1021/ol1024663] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Trent Conroy
- School of Chemistry, The University of Sydney, NSW 2006, Australia, and School of Medical Sciences, Sydney Medical School, The University of Sydney, NSW 2006, Australia
| | - Jin T. Guo
- School of Chemistry, The University of Sydney, NSW 2006, Australia, and School of Medical Sciences, Sydney Medical School, The University of Sydney, NSW 2006, Australia
| | - Nicholas H. Hunt
- School of Chemistry, The University of Sydney, NSW 2006, Australia, and School of Medical Sciences, Sydney Medical School, The University of Sydney, NSW 2006, Australia
| | - Richard J. Payne
- School of Chemistry, The University of Sydney, NSW 2006, Australia, and School of Medical Sciences, Sydney Medical School, The University of Sydney, NSW 2006, Australia
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6
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In vitro inhibition of human erythrocyte glutathione reductase by some new organic nitrates. Bioorg Med Chem Lett 2009; 19:3661-3. [DOI: 10.1016/j.bmcl.2009.04.087] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 04/14/2009] [Accepted: 04/17/2009] [Indexed: 11/21/2022]
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7
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Seefeldt T, Zhao Y, Chen W, Raza AS, Carlson L, Herman J, Stoebner A, Hanson S, Foll R, Guan X. Characterization of a novel dithiocarbamate glutathione reductase inhibitor and its use as a tool to modulate intracellular glutathione. J Biol Chem 2008; 284:2729-2737. [PMID: 19049979 DOI: 10.1074/jbc.m802683200] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thiol redox state (TRS) is an important parameter to reflect intracellular oxidative stress and is associated with various normal and abnormal biochemical processes. Agents that can be used to increase intracellular TRS will be valuable tools in TRS-related research. Glutathione reductase (GR) is a critical enzyme in the homeostasis of TRS. The enzyme catalyzes the reduction of GSSG to GSH to maintain a high GSH:GSSG ratio. Inhibition of the enzyme can be used to increase TRS. Despite the reports of various GR inhibitors, N,N-bis(2-chloroethyl)-N-nitrosourea, an anticancer drug with IC(50) = 647 microm against yeast GR, remains the most commonly used GR inhibitor in the literature. However, the toxicity caused by nonspecific interactions, as well as inhibition of DNA synthesis, complicates the use of N,N-bis(2-chloroethyl)-N-nitrosourea as a GR inhibitor. We report 2-acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylthiocarbonylamino)phenylthiocarbamoylsulfanyl]propionic acid (2-AAPA) as a novel irreversible GR inhibitor. 2-AAPA was prepared by one-step synthesis from commercially available reagents. The K(i) and k(inact) of 2-AAPA against yeast GR were determined to be 56 microm and 0.1 min(-1), respectively. At the concentration that produced >80% yeast GR inhibition, 2-AAPA showed no inhibition against glutamylcysteine synthetase, glutathione synthetase, catalase, and superoxide dismutase, but minimal inhibition against glutathione S-transferase and glutathione peroxidase. In CV-1 cells, 2-AAPA (0.1 mm) produced 97% GR inhibition, 25% GSH reduction, and a 5-fold increase in GSSG in 20 min. The compound can be a useful tool in TRS-related research.
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Affiliation(s)
- Teresa Seefeldt
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007
| | - Yong Zhao
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007
| | - Wei Chen
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007
| | - Ashraf S Raza
- Covance Bioanalytical Services LLC, Indianapolis, Indiana 46214
| | - Laura Carlson
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007
| | - Jocqueline Herman
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007
| | - Adam Stoebner
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007
| | - Sarah Hanson
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007
| | - Ryan Foll
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007
| | - Xiangming Guan
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007.
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8
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Sherman IW. References. ADVANCES IN PARASITOLOGY 2008. [DOI: 10.1016/s0065-308x(08)00430-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Nmoris OPG, Ukwandu NCD, Isaac C, Egwunyenga AO, Alawode PO, Anyanwu ALC. Riboflavin and thiamin status of Nigerian children with Plasmodium falciparum malaria. Trop Med Health 2008. [DOI: 10.2149/tmh.2007-57] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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10
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Seefeldt T, Dwivedi C, Peitz G, Herman J, Carlson L, Zhang Z, Guan X. 2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino)- phenylcarbamoylsulfanyl]propionic acid and its derivatives as a novel class of glutathione reductase inhibitors. J Med Chem 2005; 48:5224-31. [PMID: 16078841 DOI: 10.1021/jm050030i] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glutathione reductase (GR) catalyzes the reduction of oxidized glutathione to reduced glutathione. The enzyme is an attractive target for the development of antimalarial agents, agents to decrease malarial drug resistance and anticancer agents. In addition, inhibition of the enzyme has been employed as a tool in research for various purposes. In this paper, we present a rational design of 2-acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino)phenylcarbamoylsulfanyl]propionic acid and its derivatives as irreversible GR inhibitors. The K(i) and k(inact) values of 2-acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino)phenylcarbamoylsulfanyl]propionic acid, the most potent derivative of the series, are 88 muM and 0.1 min(-1), respectively. Although the K(i) value of the inhibitor is in the micromolar range, it is more potent than N,N-bis(2-chloroethyl)-N-nitrosourea, which is currently the most commonly employed irreversible GR inhibitor with a reported IC(50) value of 646 microM. Additional attractive features of the inhibitor include its ready availability through a one-step synthesis and good solubility in both organic and aqueous solutions.
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Affiliation(s)
- Teresa Seefeldt
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007, USA
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11
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Becker K, Tilley L, Vennerstrom JL, Roberts D, Rogerson S, Ginsburg H. Oxidative stress in malaria parasite-infected erythrocytes: host–parasite interactions. Int J Parasitol 2004; 34:163-89. [PMID: 15037104 DOI: 10.1016/j.ijpara.2003.09.011] [Citation(s) in RCA: 420] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2003] [Revised: 09/18/2003] [Accepted: 09/18/2003] [Indexed: 01/09/2023]
Abstract
Experimenta naturae, like the glucose-6-phosphate dehydrogenase deficiency, indicate that malaria parasites are highly susceptible to alterations in the redox equilibrium. This offers a great potential for the development of urgently required novel chemotherapeutic strategies. However, the relationship between the redox status of malarial parasites and that of their host is complex. In this review article we summarise the presently available knowledge on sources and detoxification pathways of reactive oxygen species in malaria parasite-infected red cells, on clinical aspects of redox metabolism and redox-related mechanisms of drug action as well as future prospects for drug development. As delineated below, alterations in redox status contribute to disease manifestation including sequestration, cerebral pathology, anaemia, respiratory distress, and placental malaria. Studying haemoglobinopathies, like thalassemias and sickle cell disease, and other red cell defects that provide protection against malaria allows insights into this fine balance of redox interactions. The host immune response to malaria involves phagocytosis as well as the production of nitric oxide and oxygen radicals that form part of the host defence system and also contribute to the pathology of the disease. Haemoglobin degradation by the malarial parasite produces the redox active by-products, free haem and H(2)O(2), conferring oxidative insult on the host cell. However, the parasite also supplies antioxidant moieties to the host and possesses an efficient enzymatic antioxidant defence system including glutathione- and thioredoxin-dependent proteins. Mechanistic and structural work on these enzymes might provide a basis for targeting the parasite. Indeed, a number of currently used drugs, especially the endoperoxide antimalarials, appear to act by increasing oxidant stress, and novel drugs such as peroxidic compounds and anthroquinones are being developed.
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Affiliation(s)
- Katja Becker
- Interdisciplinary Research Center, Heinrich-Buff-Ring 26-32, Justus-Liebig University, D-35392 Giessen, Germany.
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12
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Sarma GN, Savvides SN, Becker K, Schirmer M, Schirmer RH, Karplus PA. Glutathione reductase of the malarial parasite Plasmodium falciparum: crystal structure and inhibitor development. J Mol Biol 2003; 328:893-907. [PMID: 12729762 DOI: 10.1016/s0022-2836(03)00347-4] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The malarial parasite Plasmodium falciparum is known to be sensitive to oxidative stress, and thus the antioxidant enzyme glutathione reductase (GR; NADPH+GSSG+H(+) <==> NADP(+)+2 GSH) has become an attractive drug target for antimalarial drug development. Here, we report the 2.6A resolution crystal structure of P.falciparum GR. The homodimeric flavoenzyme is compared to the related human GR with focus on structural aspects relevant for drug design. The most pronounced differences between the two enzymes concern the shape and electrostatics of a large (450A(3)) cavity at the dimer interface. This cavity binds numerous non-competitive inhibitors and is a target for selective drug design. A 34-residue insertion specific for the GRs of malarial parasites shows no density, implying that it is disordered. The precise location of this insertion along the sequence allows us to explain the deleterious effects of a mutant in this region and suggests new functional studies. To complement the structural comparisons, we report the relative susceptibility of human and plasmodial GRs to a series of tricyclic inhibitors as well as to peptides designed to interfere with protein folding and dimerization. Enzyme-kinetic studies on GRs from chloroquine-resistant and chloroquine-sensitive parasite strains were performed and indicate that the structure reported here represents GR of P.falciparum strains in general and thus is a highly relevant target for drug development.
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Affiliation(s)
- G N Sarma
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7305, USA
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13
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Becker K, Rahlfs S, Nickel C, Schirmer RH. Glutathione--functions and metabolism in the malarial parasite Plasmodium falciparum. Biol Chem 2003; 384:551-66. [PMID: 12751785 DOI: 10.1515/bc.2003.063] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
When present as a trophozoite in human erythrocytes, the malarial parasite Plasmodium falciparum exhibits an intense glutathione metabolism. Glutathione plays a role not only in antioxidative defense and in maintaining the reducing environment of the cytosol. Many of the known glutathione-dependent processes are directly related to the specific lifestyle of the parasite. Reduced glutathione (GSH) supports rapid cell growth by providing electrons for deoxyribonucleotide synthesis and it takes part in detoxifying heme, a product of hemoglobin digestion. Free radicals generated in the parasite can be scavenged in reaction sequences involving the thiyl radical GS* as well as the thiolate GS-. As a substrate of glutathione S-transferase, glutathione is conjugated to non-degradable compounds including antimalarial drugs. Furthermore, it is the coenzyme of the glyoxalase system which detoxifies methylglyoxal, a byproduct of the intense glycolysis taking place in the trophozoite. Proteins involved in GSH-dependent processes include glutathione reductase, glutaredoxins, glyoxalase I and II, glutathione S-transferases, and thioredoxins. These proteins, as well as the ATP-dependent enzymes of glutathione synthesis, are studied as factors in the pathophysiology of malaria but also as potential drug targets. Methylene blue, an inhibitor of the structurally known P. falciparum glutathione reductase, appears to be a promising antimalarial medication when given in combination with chloroquine.
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Affiliation(s)
- Katja Becker
- Interdisciplinary Research Center, Justus-Liebig-University, D-35392 Giessen, Germany
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14
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Davioud-Charvet E, Delarue S, Biot C, Schwöbel B, Boehme CC, Müssigbrodt A, Maes L, Sergheraert C, Grellier P, Schirmer RH, Becker K. A prodrug form of a Plasmodium falciparum glutathione reductase inhibitor conjugated with a 4-anilinoquinoline. J Med Chem 2001; 44:4268-76. [PMID: 11708927 DOI: 10.1021/jm010268g] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glutathione (GSH), which is known to guard Plasmodium falciparum from oxidative damage, may have an additional protective role by promoting heme catabolism. An elevation of GSH content in parasites leads to increased resistance to chloroquine (CQ), while GSH depletion in resistant P. falciparum strains is expected to restore the sensitivity to CQ. High intracellular GSH levels depend inter alia on the efficient reduction of GSSG by glutathione reductase (GR). On the basis of this hypothesis, we have developed a new strategy for overcoming glutathione-dependent 4-aminoquinoline resistance. To direct both a 4-aminoquinoline and a GR inhibitor to the parasite, double-drugs were designed and synthesized. Quinoline-based alcohols (with known antimalarial activity) were combined with a GR inhibitor via a metabolically labile ester bond to give double-headed prodrugs. The biochemically most active double-drug 7 of this series was then evaluated as a growth inhibitor against six Plasmodium falciparum strains that differed in their degree of resistance to CQ; the ED(50) values for CQ ranged from 14 to 183 nM. While the inhibitory activity of the original 4-aminoquinoline-based alcohol followed that of CQ in these tests, the double-drug exhibited similar efficiency against all strains, the ED(50) being as low as 28 nM. For the ester 7, a dose-dependent decrease in glutathione content and GR activity and an increase in glutathione-S-transferase activity were determined in treated parasites. The drug was subsequently tested for its antimalarial action in vivo using murine malaria models infected with P. berghei. A 178% excess mean survival time was determined for the animals treated with 40 mg/kg 7 for 4 days. No cytotoxicity due to this compound was observed. Work is in progress to extend and validate the strategy outlined here.
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Affiliation(s)
- E Davioud-Charvet
- UMR 8525 CNRS-Université Lille II-Institut Pasteur de Lille, Institut de Biologie de Lille, 1 rue du Professeur Calmette, BP447 59021 Lille Cedex, France.
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15
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Grellier P, Sarlauskas J, Anusevicius Z, Maroziene A, Houee-Levin C, Schrevel J, Cenas N. Antiplasmodial activity of nitroaromatic and quinoidal compounds: redox potential vs. inhibition of erythrocyte glutathione reductase. Arch Biochem Biophys 2001; 393:199-206. [PMID: 11556806 DOI: 10.1006/abbi.2001.2487] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prooxidant nitroaromatic and quinoidal compounds possess antimalarial activity, which might be attributed either to their formation of reactive oxygen species or to their inhibition of antioxidant enzyme glutathione reductase (GR, EC 1.6.4.2). We have examined the activity in vitro against Plasmodium falciparum of 24 prooxidant compounds of different structure (nitrobenzenes, nitrofurans, quinones, 1,1'-dibenzyl-4,4'-bipyridinium, and methylene blue), which possess a broad range of single-electron reduction potentials (E(1)(7)) and erythrocyte glutathione reductase inhibition constants (K(i(GR))). For a series of homologous derivatives of 2-(5'-nitrofurylvinyl)quinoline-4-carbonic acid, the relationship between compound K(i(GR)) and concentration causing 50% parasite growth inhibition (IC(50)) was absent. For all the compounds examined in this study, the dependence of IC(50) on their K(i(GR)) was insignificant. In contrast, IC(50) decreased with an increase in E(1)(7) and positive electrostatic charge of aromatic part of molecule (Z): log IC(50) (microM) = -(0.9846 +/- 0.3525) - (7.2850 +/- 1.2340) E(1)(7) (V) - (1.1034 +/- 0.1832) Z (r(2) = 0.8015). The redox cycling activity of nitroaromatic and quinoidal compounds in ferredoxin:NADP(+) reductase-catalyzed reaction and the rate of oxyhemoglobin oxidation in lysed erythrocytes increased with an increase in their E(1)(7) value. Our findings imply that the antiplasmodial activity of nitroaromatic and quinoidal compounds is mainly influenced by their ability to form reactive oxygen species, and much less significantly by the GR inhibition.
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Affiliation(s)
- P Grellier
- Laboratoire de Biologie Parasitaire et Chimiothérapie, Muséum National d'Histoire Naturelle, IFR 63, 61 rue Buffon, 75231 Paris Cedex 05, France
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Müller S, Gilberger TW, Krnajski Z, Lüersen K, Meierjohann S, Walter RD. Thioredoxin and glutathione system of malaria parasite Plasmodium falciparum. PROTOPLASMA 2001; 217:43-49. [PMID: 11732337 DOI: 10.1007/bf01289412] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Plasmodium falciparum is the causative agent of malaria tropica. Due to the increasing resistance towards the commonly used plasmodicidal drugs there is an urgent need to identify and assess new targets for the chemotherapeutic intervention of parasite development in the human host. It is established that P. falciparum-infected erythrocytes are vulnerable to oxidative stress, and therefore efficient antioxidative systems are required to ensure parasite development within the host cell. The thioredoxin and glutathione redox systems represent two powerful means to detoxify reactive oxygen species and this article summarizes some of the recent work which has led to a better understanding of these systems in the parasite and will help to assess them as potential targets for the development of new chemotherapeutics of malaria.
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Affiliation(s)
- S Müller
- Department of Parasite Biochemistry, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Federal Republic of Germany
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Akompong T, Ghori N, Haldar K. In vitro activity of riboflavin against the human malaria parasite Plasmodium falciparum. Antimicrob Agents Chemother 2000; 44:88-96. [PMID: 10602728 PMCID: PMC89633 DOI: 10.1128/aac.44.1.88-96.2000] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human malaria parasite Plasmodium falciparum digests hemoglobin and polymerizes the released free heme into hemozoin. This activity occurs in an acidic organelle called the food vacuole and is essential for survival of the parasite in erythrocytes. Since acidic conditions are known to enhance the auto-oxidation of hemoglobin, we investigated whether hemoglobin ingested by the parasite was oxidized and whether the oxidation process could be a target for chemotherapy against malaria. We released parasites from their host cells and separately analyzed hemoglobin ingested by the parasites from that remaining in the erythrocytes. Isolated parasites contained elevated amounts (38.5% +/- 3.5%) of oxidized hemoglobin (methemoglobin) compared to levels (0.8% +/- 0.2%) found in normal, uninfected erythrocytes. Further, treatment of infected cells with the reducing agent riboflavin for 24 h decreased the parasite methemoglobin level by 55%. It also inhibited hemozoin production by 50% and decreased the average size of the food vacuole by 47%. Administration of riboflavin for 48 h resulted in a 65% decrease in food vacuole size and inhibited asexual parasite growth in cultures. High doses of riboflavin are used clinically to treat congenital methemoglobinemia without any adverse side effects. This activity, in conjunction with its impressive antimalarial activity, makes riboflavin attractive as a safe and inexpensive drug for treating malaria caused by P. falciparum.
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Affiliation(s)
- T Akompong
- Departments of Pathology and Microbiology-Immunology, Northwestern University Medical School, Chicago, Illinois 60611-3008, USA.
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Bonse S, Santelli-Rouvier C, Barbe J, Krauth-Siegel RL. Inhibition of Trypanosoma cruzi trypanothione reductase by acridines: kinetic studies and structure-activity relationships. J Med Chem 1999; 42:5448-54. [PMID: 10639286 DOI: 10.1021/jm990386s] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Series of 9-amino and 9-thioacridines have been synthesized and studied as inhibitors of trypanothione reductase (TR) from Trypanosoma cruzi, the causative agent of Chagas' disease. The compounds are structural analogues of the acridine drug mepacrine (quinacrine), which is a competitive inhibitor of the parasite enzyme, but not of human glutathione reductase, the closest related host enzyme. The 9-aminoacridines yielded apparent K(i) values for competitive inhibition between 5 and 43 microM. The most effective inhibitors were those with the methoxy and chlorine substituents of mepacrine and NH(2) or NHCH(CH(3))(CH(2))(4)N(Et)(2) at C9. Detailed kinetic analyses revealed that in the case of 9-aminoacridines more than one inhibitor molecule can bind to the enzyme. In contrast, the 9-thioacridine derivatives inhibit TR with mixed-type kinetics. The kinetic data are discussed in light of the three-dimensional structure of the TR-mepacrine complex. The conclusion that structurally very similar acridine compounds can give rise to completely different inhibition patterns renders modelling studies and quantitative structure-activity relationships difficult.
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Affiliation(s)
- S Bonse
- Biochemie-Zentrum Heidelberg, Heidelberg University, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
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19
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Lüönd RM, McKie JH, Douglas KT, Dascombe MJ, Vale J. Inhibitors of glutathione reductase as potential antimalarial drugs. Kinetic cooperativity and effect of dimethyl sulphoxide on inhibition kinetics. JOURNAL OF ENZYME INHIBITION 1998; 13:327-45. [PMID: 9793837 DOI: 10.3109/14756369809021479] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We have developed inhibitors of glutathione reductase that improve on the inhibition of literature lead compounds by up to three orders of magnitude. Thus, analogues of Safranine O and menadione were found to be strong, reversible inhibitors of yeast glutathione reductase. Safranine O exhibited partial, uncompetitive inhibition with Ki and alpha values of 0.5 mM and 0.15, respectively. Thionine O was a partial (hyperbolic) uncompetitive inhibitor with Ki and alpha values of 0.4 microM and 0.15, respectively. LY83583 and 2-anilino-1,4-naphthoquinone also showed (hyperbolic) partial, uncompetitive inhibition with micromolar Ki values. For Nile Blue A a model for two-site binding with (parabolic) uncompetitive inhibition fitted the data with a Ki value of 11 microM and a kinetic cooperativity between the sites of 0.12, increased to 0.46 by preincubation of the enzyme and Nile Blue A in the presence of glutathione disulphide. Analysis of the effects of preincubation on the kinetics and cooperativity indicated the possibility of a slow conformational change in the homodimeric enzyme, the first such indication of kinetic cooperativity in the native enzyme to our knowledge. Further evidence of conformational changes for this enzyme came from studies of the effects of dimethyl sulphoxide which indicated that this co-solvent, which at low concentrations has no apparent effect on initial velocities under normal assay conditions, induced a slow conformational change in the enzyme. Thionine O, Nile Blue A and LY83583 were redox-cycling substrates producing superoxide ion, detectable by means of cytochrome c reduction, but leading to no loss of glutathione reductase activity, under aerobic or anaerobic conditions. The water-soluble Safranine analogues Methylene Blue, Methylene Green, Nile Blue A and Thionine O (5 mg/kg i.p. x 5) were effective antimalarial agents in vivo against P. berghei, but their effect was small and a higher dose (50 mg/kg i.p. x 1) was toxic in mice. Comparison was made with human glutathione reductase and its literature-reported interactions with several tricyclic inhibitors as studied by X-ray diffraction. It is possible that the conformational changes detected in the present study from alterations in detailed kinetic inhibition mechanisms may shed light on information transfer through the glutathione reductase molecule from the dimer interface ligand pocket to the active-site.
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Affiliation(s)
- R M Lüönd
- School of Pharmacy and Pharmaceutical Sciences, University of Manchester, UK
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Faust R, Weber C, Fiandanese V, Marchese G, Punzi A. One-step synthesis of dialkynyl-1,2-diones and their conversion to fused pyrazines bearing enediyne units. Tetrahedron 1997. [DOI: 10.1016/s0040-4020(97)01007-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Müller S, Gilberger TW, Fairlamb AH, Walter RD. Molecular characterization and expression of Onchocerca volvulus glutathione reductase. Biochem J 1997; 325 ( Pt 3):645-51. [PMID: 9271084 PMCID: PMC1218607 DOI: 10.1042/bj3250645] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Glutathione metabolism represents a potential target for anti-parasite drug design. The central role of glutathione reductase (GR) in maintenance of the thiol redox state and in anti-oxidative defence has to be evaluated in more detail in order to establish the essential function of this enzyme for the survival of the filarial parasite Onchocerca volvulus. The O. volvulus GR (OvGR) gene was cloned and sequenced. The gene is composed of 13 exons and 12 introns and spans 4065 bp. The first intron is located within the 5'-untranslated region of the gene, 16 nucleotides upstream of the translation initiation codon. Southern-blot analysis and structural characterization of the genomic sequence indicate that OvGR is encoded by a single-copy gene. Isolation of various cDNA clones revealed a polymorphism of polyadenylation initiation with no consensus polyadenylation sites in any of the cDNAs analysed. The entire cDNA is 1977 bp long and carries the nematode-specific spliced leader sequence SL1 at its 5' end, 236 nucleotides upstream of the first in-frame methionine. The cDNA codes for a polypeptide of 462 amino acids with 53.5% sequence identity with human GR (HsGR). A total of 18 out of 19 residues contributing to glutathione binding are identical in OvGR and HsGR. However, one of the arginine residues (Arg-224 in HsGR) involved in discrimination between NADPH and NADH in all known GRs is substituted by tryptophan (Trp-207 in OvGR). The coding region of OvGR was expressed in Escherichia coli as a histidine-fusion protein, and it was established that the parasite protein still favours the binding of NADPH (Km 10.9 microM) over NADH (Km 108 microM). The histidine-fusion protein has a subunit size of 54 kDa and is active as a homodimer of 110 kDa.
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Affiliation(s)
- S Müller
- Bernhard Nocht Institute of Tropical Medicine, Department of Biochemistry, D-20359 Hamburg, Germany
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Savvides SN, Karplus PA. Kinetics and crystallographic analysis of human glutathione reductase in complex with a xanthene inhibitor. J Biol Chem 1996; 271:8101-7. [PMID: 8626496 DOI: 10.1074/jbc.271.14.8101] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have determined the crystal structure of a complex between the noncompetitive inhibitor (Kis = 27 microM, Kii = 48 microM with respect to oxidized glutathione (GSSG) and Kis = 144 microM, Kii = 176 microM with respect to NADPH) 6-hydroxy-3-oxo-3H-xanthene-9-propionic acid (XAN) and human glutathione reductase (hGR). The structure, refined to an R-factor of 0.158 at 2.0 A resolution, reveals XAN bound in the large cavity present at the hGR dimer interface where it does not overlap the glutathione binding site. The inhibitor binding causes extensive local structural changes that primarily involve amino acid residues from a 30-residue alpha-helix that lines the cavity and contributes to the active site of hGR. Despite the lack of physical overlap of XAN with the GSSG binding site, no GSSG binding is seen in soaks carried out with high XAN and GSSG concentrations, suggesting that some subtle interaction between the sites exists. An earlier crystallographic analysis on the complex between hGR and 3,7-diamino-2,8-dimethyl-5-phenyl-phenazinium chloride (safranin) showed that safranin bound at this same site. We have found that safranin also inhibits hGR in a noncompetitive fashion, but it binds about 16 times less tightly (Kis = 453 microM, Kii = 586 microM with respect to GSSG) than XAN and does not preclude the binding of GSSG in the crystal. Although in structure-based drug design competitive inhibitors are usually targetted, XAN's binding to a well defined site that is unique to glutathione reductase suggests that noncompetitive inhibitors could also serve as lead compounds for structure-based drug design, in particular as components of chimeric inhibitors.
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Affiliation(s)
- S N Savvides
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853, USA
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Schönleben-Janas A, Kirsch P, Mittl PR, Schirmer RH, Krauth-Siegel RL. Inhibition of human glutathione reductase by 10-arylisoalloxazines: crystalline, kinetic, and electrochemical studies. J Med Chem 1996; 39:1549-54. [PMID: 8691487 DOI: 10.1021/jm950511+] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A series of newly synthesized N(10)-arylisoalloxazines--some of which are known to be antimalarial agents--were studied as inhibitors of human glutathione reductase (GR;NADPH + GSSG + H(+) <==> NADP(+) + 2GSH). The flavoenzyme was inhibited with IC(50) values between </- 1 and 100 microM in the presence of 100 microM NADPH. The isoalloxazines and N(3)-methylisoalloxazines with a 4'-chlorophenyl or a 3',5'-dichlorophenyl group at N10 were found to be the most promising inhibitors of GR, although even the bulkier 10-naphthyl and -anthryl derivatives were also effective inhibitors. In contrast, at position N3 of the isoalloxazine ring, the size of the substituent was found to strongly influence the inhibitory effect. Introduction of a carboxymethyl group at N3--which markedly increased the solubility of the derivative in aqueous solutions-- caused a rise in the IC(50) values by 1 order of magnitude. 8-Fluoro- and 8-azido-10-arylisoalloxazines were potent inhibitors of GR; consequently position C8 of the benzenoid subnucleus instead of N3 should be considered for introducing substituents. No correlation was observed between the inhibitory strength of several isoalloxazines and their redox potential as measured by cyclovoltammetry. The crystallographic analysis of GR complexed with 10-(4'-chlorophenyl)-3-(carboxymethyl)isoalloxazine and 10-(3',5'-dichlorophenyl)-3-(carboxymethyl)isoalloxazine, respectively, revealed the presence of one inhibitor molecule bound at the 2-fold axis of the homodimeric protein. This location is consistent with fluorescence titration measurements and enzyme kinetic studies in solution which gave no indication for binding at the substrate sites.
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Affiliation(s)
- A Schönleben-Janas
- Institut für Biochemie II der Universität, Im Neuenheimer Feld, Heidelberg, Germany
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Krauth-Siegel RL, Müller JG, Lottspeich F, Schirmer RH. Glutathione reductase and glutamate dehydrogenase of Plasmodium falciparum, the causative agent of tropical malaria. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 235:345-50. [PMID: 8631352 DOI: 10.1111/j.1432-1033.1996.00345.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The use of glutathione reductase inhibitors in chemotherapy is the raison d'être for this study. Two enzymes were purified to homogeneity from the intraerythrocytic malarial parasite Plasmodium falciparum: glutathione disulfide reductase, an antioxidative enzyme, which appears to play an essential role for parasite growth and differentiation, and glutamate dehydrogenase, an enzyme not occurring in the host erythrocyte. The two proteins were copurified and separated by gel electrophoresis with yields of approximately 20%. Malarial glutathione reductase, a homodimer of 110 kDa with a pH optimum of 6.8 and a high preference for NADPH over NADH, was shown to contain FAD as its prosthetic group. The N-terminal sequence, VYDLIVIGGGSGGMA, which can be aligned with residues 20-34 of human glutathione reductase, represents the first beta strand and the diphosphate-fixing helix of the FAD domain. Glutamate dehydrogenase was confirmed as a hexamer with blocked N-termini; it is an enzyme that is highly specific for NADP and NADPH. The copurification of the proteins and the potential of P.falciparum glutathione reductase as a drug target are discussed.
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Elskens MT, Penninckx MJ. In vitro inactivation of yeast glutathione reductase by tetramethylthiuram disulphide. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 231:667-72. [PMID: 7649166 DOI: 10.1111/j.1432-1033.1995.tb20746.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Previous in vivo investigations have shown that glutathione reductase is one of the sites of action of the dithiocarbamate fungicide tetramethylthiuram disulphide (thiram) in the yeast Saccharomyces cerevisiae. The inactivation of glutathione reductase by thiram has now been demonstrated in vitro. This inactivation was time-dependent and occurred only with the enzyme in the reduced state and in the absence of glutathione. Since the turnover rate of the enzyme with thiram as a substrate was significantly higher than the rate of enzyme inactivation, it was suggested that more than one enzyme-inhibitor complex was involved in the reaction. Arguments supporting a covalent modification of glutathione reductase were further obtained by experiments carried out with [14C]thiram and gel filtration. A kinetic scheme for the inactivation is proposed and the relevance of the in vitro data to previous in vivo studies is discussed taking into consideration current concepts of glutathione reductase inactivation by affinity reagents.
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Affiliation(s)
- M T Elskens
- Laboratoire de Microbiologie de l'Université Libre de Bruxelles, Institut Pasteur, Belgium
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Kirsch P, Schönleben-Janas A, Schirmer RH. Synthesis and characterization of water-soluble and photolabile 10-arylisoalloxazines: Tools for studying the mechanism of action of flavin-type antimalarials. ACTA ACUST UNITED AC 1995. [DOI: 10.1002/jlac.1995199507169] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Schirmer RH, Müller JG, Krauth-Siegel RL. Inhibitoren von Disulfid-Reduktasen als Chemotherapeutica – Design von Wirkstoffen gegen die Chagas-Krankheit und gegen die Malaria. Angew Chem Int Ed Engl 1995. [DOI: 10.1002/ange.19951070204] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Becker K, Gui M, Traxler A, Kirsten C, Schirmer RH. Redox processes in malaria and other parasitic diseases. Determination of intracellular glutathione. HISTOCHEMISTRY 1994; 102:389-95. [PMID: 7868369 DOI: 10.1007/bf00268910] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The role of oxidative stress resulting from production of reactive oxygen species and/or from suppression of the cellular antioxidant capacity in parasitic infections is shortly reviewed. The experimental part of the paper deals with the glutathione (GSH)--glutathione reductase (GR) system, a cornerstone of intracellular antioxidant defence mechanisms. For studying this system in parasitic diseases such as malaria new or modified methods are required. Total glutathione comprising GSH and glutathione disulphide (GSSG) in blood samples was assayed as follows. One volume of blood (> or = 10 microliters) is mixed with two volumes of 5% sulphosalicylic acid; after centrifugation (5 min, 10000 g), 10 microliters of supernatant is taken for spectrophotometric analysis using the 5,5'-dithiobis(2-nitrobenzoate) (DTNB)-glutathione recycling assay. When compared with the original method, the procedure reported here is more sensitive, less time-consuming, avoids unfavourable pH-values and leads to a sample which when frozen is stable for months. In a pilot study, the method was applied to 14 patients suffering from malaria caused by Plasmodium falciparum. The concentrations of erythrocyte glutathione were significantly decreased in the patients (1.42 +/- 0.47 mM, mean +/- SD) when compared to age- and sex-matched controls (2.11 +/- 0.45 mM, P < 0.01). The findings are contrasted with P. falciparum cultures in vitro where glutathione levels are known to be elevated. Based on the characteristics of GR a concept of determining the redox state of single cells is introduced.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K Becker
- Institute of Biochemistry II, University of Heidelberg, Germany
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Nordhoff A, Schirmer RH, Mayatepek E, Becker K. No evidence for inhibition of human glutathione reductase by valproic acid. Biochem Pharmacol 1994; 47:1453-6. [PMID: 8185653 DOI: 10.1016/0006-2952(94)90347-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The human red blood cell enzyme glutathione reductase (GR) was reported to be inhibited by the anticonvulsant drug valproic acid (VPA) [Cotariu et al., Biochem Pharmacol 43: 425-429, 1992]. When attempting to reproduce and extend these experiments, we could not detect any significant effect of VPA on glutathione reductase in haemolysates from 20 healthy children and 10 children under VPA therapy, no matter which concentration of the drug (0.9 or 1.8 mM in a haemolysate diluted by a factor of 50 or 1.8 mM directly in the assay), which incubation time (0-60 min) and which assay system were chosen. An influence of VPA on FAD-free apoglutathione reductase was also excluded. GR-activities of 10 children under VPA therapy (1.08 +/- 0.14 U/mL blood or 7.57 +/- 0.94 U/g Hb) were almost identical with the activities of age- and sex-matched controls (1.04 +/- 0.17 U/mL or 7.79 +/- 1.32 U/g Hb). No correlation between erythrocyte GR activity and serum levels of VPA was observed. Finally, incubation of crystalline human GR with VPA did not lead to enzyme inhibition; rather, in most experiments the enzyme was stabilized by incubation with VPA. Possible explanations for the discrepancies between the results of Cotariu et al. and our data are discussed.
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Affiliation(s)
- A Nordhoff
- Institute of Biochemistry II, Heidelberg University, Germany
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30
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Affiliation(s)
- M J Penninckx
- Unité de Physiologie et Ecologie Microbiennes, Faculté des Sciences, Université libre de Bruxelles, Instut Pasteur Brabant, Belgium
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Abstract
Susceptibility to oxidative stress is a well-established feature of the malarial parasite. Pharmacologists have taken advantage of this property to design highly effective pro-oxidant antimalarial drugs. Less well appreciated is the fact that nutritional manipulation of host oxidative stress status by dietary means can have a profound effect on the growth of the parasite. In particular, rapid induction of vitamin E deficiency in mice by feeding highly unsaturated fatty acids (fish oil) strongly suppresses plasmodial growth. Likewise, the status of other antioxidant nutrients (e.g., riboflavin or vitamin C) may also influence the course of malarial infection under certain conditions. A combined nutritional pharmacology approach may offer some promise in controlling malaria.
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Affiliation(s)
- O A Levander
- Vitamin and Mineral Nutrition Laboratory, Beltsville Human Nutrition Research Center, U.S. Department of Agriculture, Maryland 20705-2350
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32
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Dutta P. Enhanced uptake and metabolism of riboflavin in erythrocytes infected with Plasmodium falciparum. THE JOURNAL OF PROTOZOOLOGY 1991; 38:479-83. [PMID: 1920146 DOI: 10.1111/j.1550-7408.1991.tb04820.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Riboflavin deficiency inhibits the growth of malaria parasites both in vitro and in vivo in infected animals and humans. Although the precise mechanisms underlying this inhibition are unknown, they may involve enhanced requirements for riboflavin by parasites. To investigate this possibility, the rate of uptake of [14C]riboflavin and the biosynthesis of FMN and FAD from riboflavin were studied in infected (5-8% parasitemia) and uninfected human erythrocytes. All cells were incubated for 0-3 h at 37 degrees C in phosphate buffered saline containing MgCl2, glucose, and [14C]riboflavin (2.5-7.5 microM). At hourly intervals, samples were removed, centrifuged, washed twice with cold buffer, and lysed before counting the radioactivity. The rate of in vitro biosynthesis of FMN and FAD from riboflavin in erythrocytes was measured by ion exchange chromatography and reverse isotope dilution techniques. Results showed that the rate of riboflavin uptake and the biosynthesis of FMN and FAD were enhanced in erythrocytes with parasitemia as compared with results in unparasitized erythrocytes. Riboflavin uptake in erythrocytes was proportional to the extent of parasitemia and especially to percent of schizonts present in erythrocytes. These studies indicate that the requirement for riboflavin may be greater in the parasite than in the host erythrocyte. This increased riboflavin requirement may be due to rapid multiplication, higher metabolic rate, and extreme vulnerability to oxidative stress of malaria parasites compared with that of host erythrocytes. The differential requirement of riboflavin by the host and the malaria parasite may hold important potential for developing new strategies for malaria chemotherapy.
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Affiliation(s)
- P Dutta
- Memorial Sloan-Kettering Cancer Center, Cornell University Medical Center, New York, New York 10021
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Halladay PK, Hunt NH, Butcher GA, Cowden WB. Antimalarial action of flavin analogues seems not be due to inhibition of glutathione reductase of host erythrocytes. Biochem Pharmacol 1990; 39:1063-5. [PMID: 2182031 DOI: 10.1016/0006-2952(90)90285-s] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A series of 10-(4'-chlorophenyl)-3-substituted flavins (1a-f) were examined with respect to their antimalarial properties. They were tested against Plasmodium falciparum in vitro and Plasmodium vinckei vinckei in vivo. The proposition that they might act through glutathione reductase (GR) (EC 1.6.4.2) inhibition has been studied. Inhibition of P. falciparum in vitro by these compounds shows only slight variation between analogues; in contrast, inhibition of human erythrocyte GR by members of the same series is highly variable, indicating that this is probably not their primary mode of antimalarial action. Results of the P. vinckei vinckei screen showed that 10-(4'-chlorophenyl)-3-methyl,3-ethyl and 3-propyl substituted flavins are active in vivo over the dose range screened (10-70 mg/kg).
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Affiliation(s)
- P K Halladay
- Division of Cell Biology, John Curtin School of Medical Research, Canberra, A.C.T, Australia
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