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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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2
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Kapadia GJ, Soares IAO, Rao GS, Badoco FR, Furtado RA, Correa MB, Tavares DC, Cunha WR, Magalhães LG. Antiparasitic activity of menadione (vitamin K 3) against Schistosoma mansoni in BABL/c mice. Acta Trop 2017; 167:163-173. [PMID: 28017859 DOI: 10.1016/j.actatropica.2016.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 11/03/2016] [Accepted: 12/01/2016] [Indexed: 12/25/2022]
Abstract
Schistosomiasis is one of the neglected tropical diseases affecting nearly quarter of a billion people in economically challenged tropical and subtropical countries of the world. Praziquantel (PZQ) is the only drug currently available to treat this parasitic disease in spite being ineffective against juvenile worms and concerns about developing resistance to treat reinfections. Our earlier in vitro viability studies demonstrated significant antiparasitic activity of menadione (MEN) (vitamin K3) against Schistosoma mansoni adult worms. To gain insight into plausible mechanism of antischistosomal activity of MEN, its effect on superoxide anion levels in adult worms were studied in vitro which showed significant increases in both female and male worms. Further confirmation of the deleterious morphological changes in their teguments and organelles were obtained by ultrastructural analysis. Genotoxic and cytotoxic studies in male Swiss mice indicated that MEN was well tolerated at the oral dose of 500mg/kg using the criteria of MNPCE frequency and PCE/RBC ratio in the bone marrow of infected animals. The in vivo antiparasitic activity of MEN was conducted in female BALB/c mice infected with S. mansoni and significant reductions (P<0.001) in total worm burden were observed at single oral doses of 40 and 400mg/kg (48.57 and 61.90%, respectively). Additionally, MEN significantly reduced (P<0.001) the number of eggs in the liver of infected mice by 53.57 and 58.76%, respectively. Similarly, histological analysis of the livers showed a significant reduction (P<0.001) in the diameter of the granulomas. Since MEN is already in use globally as an over-the-counter drug for a variety of common ailments and a dietary supplement with a safety record in par with similar products when used in recommended doses, the above antiparasitic results which compare reasonably well with PZQ, make a compelling case for considering MEN to treat S. mansoni infection in humans.
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Affiliation(s)
- Govind J Kapadia
- Department of Pharmaceutical Sciences, College of Pharmacy, Howard University, Washington, DC 20059, USA
| | - Ingrid A O Soares
- Research Group on Natural Products, Center for Research in Sciences and Technology, University of Franca, Franca, Brazil
| | - G Subba Rao
- Global Biotechnology Resource Center, 145 Rosewood Drive, Streamwood, IL 60107, USA
| | - Fernanda R Badoco
- Research Group on Natural Products, Center for Research in Sciences and Technology, University of Franca, Franca, Brazil
| | - Ricardo A Furtado
- Research Group on Natural Products, Center for Research in Sciences and Technology, University of Franca, Franca, Brazil
| | - Mariana B Correa
- Research Group on Natural Products, Center for Research in Sciences and Technology, University of Franca, Franca, Brazil
| | - Denise C Tavares
- Research Group on Natural Products, Center for Research in Sciences and Technology, University of Franca, Franca, Brazil
| | - Wilson R Cunha
- Research Group on Natural Products, Center for Research in Sciences and Technology, University of Franca, Franca, Brazil
| | - Lizandra G Magalhães
- Research Group on Natural Products, Center for Research in Sciences and Technology, University of Franca, Franca, Brazil.
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Hart CJS, Munro T, Andrews KT, Ryan JH, Riches AG, Skinner-Adams TS. A novel in vitro image-based assay identifies new drug leads for giardiasis. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 7:83-89. [PMID: 28171818 PMCID: PMC5295624 DOI: 10.1016/j.ijpddr.2017.01.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/12/2017] [Accepted: 01/13/2017] [Indexed: 12/26/2022]
Abstract
Giardia duodenalis is an intestinal parasite that causes giardiasis, a widespread human gastrointestinal disease. Treatment of giardiasis relies on a small arsenal of compounds that can suffer from limitations including side-effects, variable treatment efficacy and parasite drug resistance. Thus new anti-Giardia drug leads are required. The search for new compounds with anti-Giardia activity currently depends on assays that can be labour-intensive, expensive and restricted to measuring activity at a single time-point. Here we describe a new in vitro assay to assess anti-Giardia activity. This image-based assay utilizes the Perkin-Elmer Operetta® and permits automated assessment of parasite growth at multiple time points without cell-staining. Using this new approach, we assessed the "Malaria Box" compound set for anti-Giardia activity. Three compounds with sub-μM activity (IC50 0.6-0.9 μM) were identified as potential starting points for giardiasis drug discovery.
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Affiliation(s)
- Christopher J S Hart
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland 4111, Australia
| | - Taylah Munro
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland 4111, Australia
| | - Katherine T Andrews
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland 4111, Australia
| | - John H Ryan
- Commonwealth Scientific and Industrial Research Organization, Biomedical Manufacturing, Clayton, Victoria 3168, Australia
| | - Andrew G Riches
- Commonwealth Scientific and Industrial Research Organization, Biomedical Manufacturing, Clayton, Victoria 3168, Australia
| | - Tina S Skinner-Adams
- Griffith Institute for Drug Discovery, Griffith University, Nathan, Queensland 4111, Australia.
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Travers MA, Sow C, Zirah S, Deregnaucourt C, Chaouch S, Queiroz RML, Charneau S, Allain T, Florent I, Grellier P. Deconjugated Bile Salts Produced by Extracellular Bile-Salt Hydrolase-Like Activities from the Probiotic Lactobacillus johnsonii La1 Inhibit Giardia duodenalis In vitro Growth. Front Microbiol 2016; 7:1453. [PMID: 27729900 PMCID: PMC5037171 DOI: 10.3389/fmicb.2016.01453] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 08/31/2016] [Indexed: 12/15/2022] Open
Abstract
Giardiasis, currently considered a neglected disease, is caused by the intestinal protozoan parasite Giardia duodenalis and is widely spread in human as well as domestic and wild animals. The lack of appropriate medications and the spread of resistant parasite strains urgently call for the development of novel therapeutic strategies. Host microbiota or certain probiotic strains have the capacity to provide some protection against giardiasis. By combining biological and biochemical approaches, we have been able to decipher a molecular mechanism used by the probiotic strain Lactobacillus johnsonii La1 to prevent Giardia growth in vitro. We provide evidence that the supernatant of this strain contains active principle(s) not directly toxic to Giardia but able to convert non-toxic components of bile into components highly toxic to Giardia. By using bile acid profiling, these components were identified as deconjugated bile-salts. A bacterial bile-salt-hydrolase of commercial origin was able to mimic the properties of the supernatant. Mass spectrometric analysis of the bacterial supernatant identified two of the three bile-salt-hydrolases encoded in the genome of this probiotic strain. These observations document a possible mechanism by which L. johnsonii La1, by secreting, or releasing BSH-like activity(ies) in the vicinity of replicating Giardia in an environment where bile is present and abundant, can fight this parasite. This discovery has both fundamental and applied outcomes to fight giardiasis, based on local delivery of deconjugated bile salts, enzyme deconjugation of bile components, or natural or recombinant probiotic strains that secrete or release such deconjugating activities in a compartment where both bile salts and Giardia are present.
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Affiliation(s)
- Marie-Agnès Travers
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Unité SG2M, IFREMER La Tremblade, France
| | - Cissé Sow
- MCAM UMR 7245, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Universités Paris, France
| | - Séverine Zirah
- MCAM UMR 7245, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Universités Paris, France
| | - Christiane Deregnaucourt
- MCAM UMR 7245, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Universités Paris, France
| | - Soraya Chaouch
- MCAM UMR 7245, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Universités Paris, France
| | - Rayner M L Queiroz
- Department of Cell Biology, Institute of Biology, University of Brasilia Brasília, Brazil
| | - Sébastien Charneau
- Department of Cell Biology, Institute of Biology, University of Brasilia Brasília, Brazil
| | - Thibault Allain
- MCAM UMR 7245, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne UniversitésParis, France; UMR 1319, Commensal and Probiotics-Host Interactions Laboratory, INRA, AgroParisTechJouy en Josas, France
| | - Isabelle Florent
- MCAM UMR 7245, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Universités Paris, France
| | - Philippe Grellier
- MCAM UMR 7245, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Universités Paris, France
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Transcriptional profiling of Giardia intestinalis in response to oxidative stress. Int J Parasitol 2015; 45:925-38. [DOI: 10.1016/j.ijpara.2015.07.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/17/2015] [Accepted: 07/24/2015] [Indexed: 12/20/2022]
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Lalle M, Camerini S, Cecchetti S, Finelli R, Sferra G, Müller J, Ricci G, Pozio E. The FAD-dependent glycerol-3-phosphate dehydrogenase of Giardia duodenalis: an unconventional enzyme that interacts with the g14-3-3 and it is a target of the antitumoral compound NBDHEX. Front Microbiol 2015; 6:544. [PMID: 26082764 PMCID: PMC4450592 DOI: 10.3389/fmicb.2015.00544] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/17/2015] [Indexed: 12/18/2022] Open
Abstract
The flagellated protozoan Giardia duodenalis is a worldwide parasite causing giardiasis, an acute and chronic diarrheal disease. Metabolism in G. duodenalis has a limited complexity thus making metabolic enzymes ideal targets for drug development. However, only few metabolic pathways (i.e., carbohydrates) have been described so far. Recently, the parasite homolog of the mitochondrial-like glycerol-3-phosphate dehydrogenase (gG3PD) has been identified among the interactors of the g14-3-3 protein. G3PD is involved in glycolysis, electron transport, glycerophospholipids metabolism, and hyperosmotic stress response, and is emerging as promising target in tumor treatment. In this work, we demonstrate that gG3PD is a functional flavoenzyme able to convert glycerol-3-phosphate into dihydroxyacetone phosphate and that its activity and the intracellular glycerol level increase during encystation. Taking advantage of co-immunoprecipitation assays and deletion mutants, we provide evidence that gG3PD and g14-3-3 interact at the trophozoite stage, the intracellular localization of gG3PD is stage dependent and it partially co-localizes with mitosomes during cyst development. Finally, we demonstrate that the gG3PD activity is affected by the antitumoral compound 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol, that results more effective in vitro at killing G. duodenalis trophozoites than the reference drug metronidazole. Overall, our results highlight the involvement of gG3PD in processes crucial for the parasite survival thus proposing this enzyme as target for novel antigiardial interventions.
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Affiliation(s)
- Marco Lalle
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità Rome, Italy
| | - Serena Camerini
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità Rome, Italy
| | - Serena Cecchetti
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità Rome, Italy
| | - Renata Finelli
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità Rome, Italy
| | - Gabriella Sferra
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità Rome, Italy
| | - Joachim Müller
- Institute of Parasitology, Vetsuisse Faculty, University of Bern Bern, Switzerland
| | - Giorgio Ricci
- Department of Sciences and Chemical Technologies, University of Rome "Tor Vergata" Rome, Italy
| | - Edoardo Pozio
- Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità Rome, Italy
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Ansell BRE, McConville MJ, Ma'ayeh SY, Dagley MJ, Gasser RB, Svärd SG, Jex AR. Drug resistance in Giardia duodenalis. Biotechnol Adv 2015; 33:888-901. [PMID: 25922317 DOI: 10.1016/j.biotechadv.2015.04.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 04/21/2015] [Accepted: 04/21/2015] [Indexed: 02/07/2023]
Abstract
Giardia duodenalis is a microaerophilic parasite of the human gastrointestinal tract and a major contributor to diarrheal and post-infectious chronic gastrointestinal disease world-wide. Treatment of G. duodenalis infection currently relies on a small number of drug classes. Nitroheterocyclics, in particular metronidazole, have represented the front line treatment for the last 40 years. Nitroheterocyclic-resistant G. duodenalis have been isolated from patients and created in vitro, prompting considerable research into the biomolecular mechanisms of resistance. These compounds are redox-active and are believed to damage proteins and DNA after being activated by oxidoreductase enzymes in metabolically active cells. In this review, we explore the molecular phenotypes of nitroheterocyclic-resistant G. duodenalis described to date in the context of the protist's unusual glycolytic and antioxidant systems. We propose that resistance mechanisms are likely to extend well beyond currently described resistance-associated enzymes (i.e., pyruvate ferredoxin oxidoreductases and nitroreductases), to include NAD(P)H- and flavin-generating pathways, and possibly redox-sensitive epigenetic regulation. Mechanisms that allow G. duodenalis to tolerate oxidative stress may lead to resistance against both oxygen and nitroheterocyclics, with implications for clinical control. The present review highlights the potential for systems biology tools and advanced bioinformatics to further investigate the multifaceted mechanisms of nitroheterocyclic resistance in this important pathogen.
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Affiliation(s)
- Brendan R E Ansell
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Cnr Park Dr and Flemington Rd, Parkville, VIC 3010, Australia.
| | - Malcolm J McConville
- Bio21 Institute, University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia
| | - Showgy Y Ma'ayeh
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Box 596, SE-751 24 Uppsala, Sweden
| | - Michael J Dagley
- Bio21 Institute, University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia
| | - Robin B Gasser
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Cnr Park Dr and Flemington Rd, Parkville, VIC 3010, Australia
| | - Staffan G Svärd
- Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Box 596, SE-751 24 Uppsala, Sweden
| | - Aaron R Jex
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Cnr Park Dr and Flemington Rd, Parkville, VIC 3010, Australia
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Comparative characterisation of two nitroreductases from Giardia lamblia as potential activators of nitro compounds. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2015; 5:37-43. [PMID: 27099829 PMCID: PMC4813764 DOI: 10.1016/j.ijpddr.2015.03.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/12/2015] [Accepted: 03/16/2015] [Indexed: 11/23/2022]
Abstract
G. lamblia has two nitroreductases with substrate specificities not only for nitro compounds, but also for quinones. GlNR1 rather activates nitro drugs by forming toxic intermediates, GlNR2 rather inactivates them.
Giardia lamblia is a protozoan parasite that causes giardiasis, a diarrhoeal disease affecting humans and various animal species. Nitro drugs such as the nitroimidazole metronidazole and the nitrothiazolide nitazoxanide are used for treatment of giardiasis. Nitroreductases such as GlNR1 and GlNR2 may play a role in activation or inactivation of these drugs. The aim of this work is to characterise these two enyzmes using functional assays. For respective analyses recombinant analogues from GlNR1 and GlNR2 were produced in Escherichia coli. E. coli expressing GlNR1 and GlNR2 alone or together were grown in the presence of nitro compounds. Furthermore, pull-down assays were performed using HA-tagged GlNR1 and GlNR2 as baits. As expected, E. coli expressing GlNR1 were more susceptible to metronidazole under aerobic and semi-aerobic and to nitazoxanide under semi-aerobic growth conditions whereas E. coli expressing GlNR2 were susceptible to neither drug. Interestingly, expression of both nitroreductases gave the same results as expression of GlNR2 alone. In functional assays, both nitroreductases had their strongest activities on the quinone menadione (vitamin K3) and FAD, but reduction of nitro compounds including the nitro drugs metronidazole and nitazoxanide was clearly detected. Full reduction of 7-nitrocoumarin to 7-aminocoumarin was preferentially achieved with GlNR2. Pull-down assays revealed that GlNR1 and GlNR2 interacted in vivo forming a multienzyme complex. These findings suggest that both nitroreductases are multifunctional. Their main biological role may reside in the reduction of vitamin K analogues and FAD. Activation by GlNR1 or inactivation by GlNR2 of nitro drugs may be the consequence of a secondary enzymatic activity either yielding (GlNR1) or eliminating (GlNR2) toxic intermediates after reduction of these compounds.
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Lalli C, Guidi A, Gennari N, Altamura S, Bresciani A, Ruberti G. Development and validation of a luminescence-based, medium-throughput assay for drug screening in Schistosoma mansoni. PLoS Negl Trop Dis 2015; 9:e0003484. [PMID: 25635836 PMCID: PMC4312041 DOI: 10.1371/journal.pntd.0003484] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 12/16/2014] [Indexed: 01/21/2023] Open
Abstract
Background Schistosomiasis, one of the world’s greatest neglected tropical diseases, is responsible for over 280,000 human deaths per annum. Praziquantel, developed in the 1970s, has high efficacy, excellent tolerability, few and transient side effects, simple administration procedures and competitive cost and it is currently the only recommended drug for treatment of human schistosomiasis. The use of a single drug to treat a population of over 200 million infected people appears particularly alarming when considering the threat of drug resistance. Quantitative, objective and validated methods for the screening of compound collections are needed for the discovery of novel anti-schistosomal drugs. Methodology/Principal Findings The present work describes the development and validation of a luminescence-based, medium-throughput assay for the detection of schistosomula viability through quantitation of ATP, a good indicator of metabolically active cells in culture. This validated method is demonstrated to be fast, highly reliable, sensitive and automation-friendly. The optimized assay was used for the screening of a small compound library on S. mansoni schistosomula, showing that the proposed method is suitable for a medium-throughput semi-automated screening. Interestingly, the pilot screening identified hits previously reported to have some anti-parasitic activity, further supporting the validity of this assay for anthelminthic drug discovery. Conclusions The developed and validated schistosomula viability luminescence-based assay was shown to be successful and suitable for the identification of novel compounds potentially exploitable in future schistosomiasis therapies. Schistosomiasis, one of the world’s greatest human neglected tropical diseases, is caused by a parasitic flatworm trematode of the genus Schistosoma. Among human parasitic diseases, schistosomiasis ranks second behind malaria in terms of socio-economic and public health importance in tropical and subtropical areas. More than 200 million people are currently infected in 77 countries, 85% of whom live in sub-Saharian Africa. To date no vaccine is available against schistosomiasis. As chemotherapy relies on a single drug, praziquantel, many initiatives have been promoted aiming to search for novel anti-schistosomal drugs that can represent a valid alternative to the current treatment or could be used in case of emerging resistance. Quantitative, objective and validated methods for compound collections screening are needed for the discovery of novel anti-schistosomal drugs. Here, we report the development and validation of a medium-throughput, luminescence-based assay for assessing viability at the schistosomulum stage of the human parasite S. mansoni. Our methodology enables a simple, reproducible, highly sensitive and objective quantitation of parasite viability. It is also automation compatible and enables the screening of compound collections thus hopefully contributing to the discovery of novel therapeutic strategies against schistosomiasis.
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Affiliation(s)
- Cristiana Lalli
- Institute of Cell Biology and Neurobiology, Campus A. Buzzati-Traverso, National Research Council, Monterotondo, Rome, Italy
| | - Alessandra Guidi
- Institute of Cell Biology and Neurobiology, Campus A. Buzzati-Traverso, National Research Council, Monterotondo, Rome, Italy
| | - Nadia Gennari
- Department of Biology, IRBM Science Park xSpA, Pomezia, Rome, Italy
| | - Sergio Altamura
- Department of Biology, IRBM Science Park xSpA, Pomezia, Rome, Italy
| | - Alberto Bresciani
- Department of Biology, IRBM Science Park xSpA, Pomezia, Rome, Italy
- * E-mail: (AB); (GR)
| | - Giovina Ruberti
- Institute of Cell Biology and Neurobiology, Campus A. Buzzati-Traverso, National Research Council, Monterotondo, Rome, Italy
- * E-mail: (AB); (GR)
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O(2)-dependent efficacy of novel piperidine- and piperazine-based chalcones against the human parasite Giardia intestinalis. Antimicrob Agents Chemother 2013; 58:543-9. [PMID: 24217695 DOI: 10.1128/aac.00990-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Giardia intestinalis is the most frequent protozoan agent of intestinal diseases worldwide. Though commonly regarded as an anaerobic pathogen, it preferentially colonizes the fairly oxygen-rich mucosa of the proximal small intestine. Therefore, when testing new potential antigiardial drugs, O2 should be taken into account, since it also reduces the efficacy of metronidazole, the gold standard drug against giardiasis. In this study, 46 novel chalcones were synthesized by microwave-assisted Claisen-Schmidt condensation, purified, characterized by high-resolution mass spectrometry, (1)H and (13)C nuclear magnetic resonance, and infrared spectroscopy, and tested for their toxicity against G. intestinalis under standard anaerobic conditions. As a novel approach, compounds showing antigiardial activity under anaerobiosis were also assayed under microaerobic conditions, and their selectivity against parasitic cells was assessed in a counterscreen on human epithelial colorectal adenocarcinoma cells. Among the tested compounds, three [30(a), 31(e), and 33] were more effective in the presence of O2 than under anaerobic conditions and killed the parasite 2 to 4 times more efficiently than metronidazole under anaerobiosis. Two of them [30(a) and 31(e)] proved to be selective against parasitic cells, thus representing potential candidates for the design of novel antigiardial drugs. This study highlights the importance of testing new potential antigiardial agents not only under anaerobic conditions but also at low, more physiological O2 concentrations.
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Hasan MR, Rahman M, Jaques S, Purwantini E, Daniels L. Glucose 6-phosphate accumulation in mycobacteria: implications for a novel F420-dependent anti-oxidant defense system. J Biol Chem 2010; 285:19135-44. [PMID: 20075070 DOI: 10.1074/jbc.m109.074310] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Glucose 6-phosphate (G6P) is a metabolic intermediate with many possible cellular fates. In mycobacteria, G6P is a substrate for an enzyme, F(420)-dependent glucose-6-phosphate dehydrogenase (Fgd), found in few bacterial genera. Intracellular G6P levels in six Mycobacterium sp. were remarkably higher ( approximately 17-130-fold) than Escherichia coli and Bacillus megaterium. The high G6P level in Mycobacterium smegmatis may result from 10-25-fold higher activity of the gluconeogenic enzyme fructose-1,6-bisphosphatase when grown on glucose, glycerol, or acetate compared with B. megaterium and E. coli. In M. smegmatis this coincided with up-regulation of the first gluconeogenic enzyme, phosphoenolpyruvate carboxykinase, when acetate was the carbon source, suggesting a cellular program for maintaining high G6P levels. G6P was depleted in cells under oxidative stress induced by redox cycling agents plumbagin and menadione, whereas an fgd mutant of M. smegmatis used G6P less well under such conditions. The fgd mutant was more sensitive to these agents and, in contrast to wild type, was defective in its ability to reduce extracellular plumbagin and menadione. These data suggest that intracellular G6P in mycobacteria serves as a source of reducing power and, with the mycobacteria-specific Fgd-F(420) system, plays a protective role against oxidative stress.
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Affiliation(s)
- Mohammad Rubayet Hasan
- Department of Pharmaceutical Sciences, Irma Lerma Rangel College of Pharmacy, Texas A & M Health Science Center, Kingsville, Texas 78363, USA
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Abstract
Giardia lamblia, the cause of human giardiasis, is among the most common intestinal protozoa worldwide. Human infection may range from asymptomatic shedding of giardial cysts to symptomatic giardiasis, being responsible for abdominal cramps, nausea, acute or chronic diarrhoea, with malabsorption and failure of children to thrive. At present, treatment options include the nitroimidazoles derivatives; especially metronidazole, which has been the mainstay of treatment for decades and is still widely used. The increasing number of reports of refractory cases with this group of drugs and other antigiardial agents, has raised concern and led to a search for other compounds, some of which have arisen due to the introduction of drugs initially addressed to other diseases. The present article examines some of the most important points of antigiardial pharmacotherapy available at present and the future prospects of development of new agents.
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Affiliation(s)
- Angel A Escobedo
- Jefe del departamento de Microbiología y Parasitología, Hospital Pediatrico Universitario Pedro Borrás, Ciudad de La Habana, CP, Cuba.
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