Menadione kills trophozoites and cysts of Giardia intestinalis

Paget, Timothy A.; Maroulis, Sarah; Mitchell, Andrew J.; Edwards, Michael R.; Jarroll, Edward L.; Lloyd, David

doi:10.1099/mic.0.26836-0

Cited by 15 publications

(10 citation statements)

References 41 publications

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“…To further investigate whether intracellular consumption of G6P correlates with the redox status of the oxidants, we monitored plumbagin and menadione reduction in extracellular medium. Spectral and redox characteristics of plumbagin and menadione, reported earlier (35,36), were verified in this study by NaBH 4 reduction. Oxidized plumbagin and menadione give well resolved peaks at 419 and 337 nm, respectively, and the absorbance at these wavelengths decreases markedly upon reduction (data not shown).…”

Section: Smegmatis Consumes G6p and Reduces Extracellular Plumbagisupporting

confidence: 87%

Glucose 6-Phosphate Accumulation in Mycobacteria

Hasan¹,

Rahman²,

Jaques³

et al. 2010

Journal of Biological Chemistry

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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 (ϳ17-130-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 mycobacteriaspecific Fgd-F 420 system, plays a protective role against oxidative stress.

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Section: Smegmatis Consumes G6p and Reduces Extracellular Plumbagisupporting

confidence: 87%

Glucose 6-Phosphate Accumulation in Mycobacteria

Hasan¹,

Rahman²,

Jaques³

et al. 2010

Journal of Biological Chemistry

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“…Moreover, disulfiram has also shown toxicity toward the malaria parasite [ 43 ] and efficacy against Giardia lamblia [ 44 ], Trichomonas vaginalis and Trichomonas foetus [ 45 ] infections. Finally, menadione had highly toxic effects on trophozoites and cysts of Giardia intestinalis [ 46 ].…”

Section: Discussionmentioning

confidence: 99%

Development and Validation of a Luminescence-based, Medium-Throughput Assay for Drug Screening in Schistosoma mansoni

et al. 2015

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BackgroundSchistosomiasis, 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 FindingsThe 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.ConclusionsThe 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.

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“…During redox-cycling, NBF-SPh rapidly converts O 2 to ROS at an higher rate than that of the most toxic redox-cycling quinones and the nitrocompound MTZ. Bio-reduction of the redox cycling naphthoquinone menadione by flavoprotein/iron–sulphur-mediated electron transfer in both G. duodenalis trophozoites and cysts has been proven to be a potent generator of ROS, even in the presence of low levels of oxygen, thus leading to parasite killing ( Paget et al, 2004 ). Therefore, we propose that the cytotoxicity exerted by NBDHEX against G. duodenalis could be due to its nitroreduction and to ROS generation during the reductive process, likely involving gG3PD.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2015

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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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Menadione kills trophozoites and cysts of Giardia intestinalis

Cited by 15 publications

References 41 publications

Glucose 6-Phosphate Accumulation in Mycobacteria

Glucose 6-Phosphate Accumulation in Mycobacteria

Development and Validation of a Luminescence-based, Medium-Throughput Assay for Drug Screening in Schistosoma mansoni

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

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