Drug residue formation from ronidazole, a 5-nitroimidazole. V. Cysteine adducts formed upon reduction of ronidazole by dithionite or rat liver enzymes in the presence of cysteine

Wislocki, Peter G.; Bagan, Edward S.; Vandenheuvel, W.J.A.; Walker, Robert; Alvaro, Raul; Arison, Byron H.; Lu, Anthony Y. H.; Wolf, Frank J.

doi:10.1016/0009-2797(84)90049-8

Cited by 33 publications

(15 citation statements)

References 23 publications

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“…The shift in the deconvoluted spectra of both recEh Trx and recEh TrxR (but here only illustrated with recEh Trx), corresponded to a mass gain of 141 Da. This is in good agreement with the in vitro reaction scheme for 5-nitroimidazoles as proposed by Wislocki and colleagues [33] (Figure 4B). In this scheme, the activated 5-nitroimidazole is first reduced to an electrophilic nitrosoimidazole, which is subsequently attacked at its C4 atom by a sulfhydryl group.…”

Section: Resultssupporting

confidence: 92%

“…When BL21 (DE3) cells were exposed to metronidazole or tinidazole during recombinant protein expression, recEh Trx modified with metronidazole or tinidazole eluted slightly earlier on the LC than unmodified recEh Trx. The determined mass increments, i.e., 141 Da with metronidazole treatment and 217 Da with tinidazole, support the reaction scheme for 5-nitroimidazoles as proposed by Wislocki and colleagues [33]. Additional peaks in the spectra of modified recEh Trx correspond to mass increments of approximately 16 Da or 32 Da, and can be attributed to bound oxygen (a single oxygen or two).…”

Section: Resultssupporting

confidence: 80%

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Nitroimidazole Action in Entamoeba histolytica: A Central Role for Thioredoxin Reductase

et al. 2007

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Metronidazole, a 5-nitroimidazole drug, has been the gold standard for several decades in the treatment of infections with microaerophilic protist parasites, including Entamoeba histolytica. For activation, the drug must be chemically reduced, but little is known about the targets of the active metabolites. Applying two-dimensional gel electrophoresis and mass spectrometry, we searched for protein targets in E. histolytica. Of all proteins visualized, only five were found to form adducts with metronidazole metabolites: thioredoxin, thioredoxin reductase, superoxide dismutase, purine nucleoside phosphorylase, and a previously unknown protein. Recombinant thioredoxin reductase carrying the modification displayed reduced enzymatic activity. In treated cells, essential non-protein thiols such as free cysteine were also affected by covalent adduct formation, their levels being drastically reduced. Accordingly, addition of cysteine allowed E. histolytica to survive in the presence of otherwise lethal metronidazole concentrations and reduced protein adduct formation. Finally, we discovered that thioredoxin reductase reduces metronidazole and other nitro compounds, suggesting a new model of metronidazole activation in E. histolytica with a central role for thioredoxin reductase. By reducing metronidazole, the enzyme renders itself and associated thiol-containing proteins vulnerable to adduct formation. Because thioredoxin reductase is a ubiquitous enzyme, similar processes could occur in other eukaryotic or prokaryotic organisms.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 80%

Nitroimidazole Action in Entamoeba histolytica: A Central Role for Thioredoxin Reductase

et al. 2007

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“…2) have shown that small ~, , amounts of these drugs are retained in tissues as nonextractable protein-bound adducts of unknown toxicity. While the nature of these adducts remains unknown, a general structure has been proposed, based on the widely accepted mechanism of activation for these nitroimidazoles (2) involving formation of reduced 4-thiosubstituted imidazoles. T o gain further insight into the structure of these biomolecular adducts, the reactivity of ronidazole and dimetridazole towards thiol-containing substrates has been studied.…”

Section: Introductionmentioning

confidence: 99%

5-Nitroimidazoles. II: Unexpected reactivity of ronidazole and dimetridazole with thiols

Girard¹,

Clairmont²,

Maneckjee³

et al. 1993

Can. J. Chem.

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. 71, 1349 (1993). Ronidazole and dimetridazole, two important veterinary drugs, were found to react readily in the presence of cysteine, under neutral aqueous conditions, leading to the formation of 5-S-cysteinyl-1-methylimidazole-2-methanol carbamate and 5-S-cysteinyl-l,2-dimethylimidazole respectively through nitro displacement. The reaction products were identified by spectroscopic techniques. The rate of reaction was accelerated by increasing the pH of the medium and was accompanied by a slight change in the product distribution. The reaction was also observed, albeit at a slower rate than that of cysteine, with glutathione, another ubiquitous thiol substrate found in biological systems. While this type of nucleophilic reaction has previously been observed for suitably substituted nitrobenzene derivatives, to the best of our knowledge its occurrence with nitro-heteroaromatics has never been reported. The ready reaction of the parent nitro drugs under such mild aqueous conditions suggests that this may be an alternative path for the formation of nonextractable bound residues in tissues. On dkmontre que le ronidazole et le dimetridazole, deux medicaments vetkrinaires importants, reagissent facilement avec la cystkine, dans des conditions aqueuses neutres, pour former le carbamate du 5-S-cystkinyl-I -mCthylimidazole-2-methanol et le 5-S-cystkinyl-l,2-dimethylimidazole respectivement par dkplacement du groupe nitro. Les produits de la reaction ont CtC identifies l'aide de techniques spectroscopiques. L'augmentation du pH du milieu reactionnel a eu pour effet d'accklkrer la reaction ce qui, par ailleurs, conduit i une legere modification de la distribution des produits. La m&me type de reaction a kt6 observe avec le glutathion, un autre thiol retrouvk frkquemment dans les systemes biologiques. Cette rkaction de substitution nuclkophilique avait deja Ctk rapportke pour certains nitrobenzenes convenablement substituks, mais n'avait jamais encore Ct C decrite avec les nitro-hCtCroaromatiques. En considerant la facilite avec laquelle cette rkaction s'effectue partir des 5-nitroimidazoles, il apparait plausible de considkrer ce processus comme voie alternative pour la formation de rksidus entre ces medicaments et les macromolCcules tissulaires. IntroductionRonidazole (RNZ, 1-methyl-5-nitroimidazole-2-methano1 carbamate) (1) and dimetridazole (DMZ, 1,2-dimethyl-5-nitroimidazole) (2) are veterinary drugs widely used for

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“…The principal targets of protein alkylation were cysteine thiols (83). A ronidazole-cysteine adduct could be isolated (85) in in vitro incubations of rat liver microsomes, suggesting that this adduct may account for the observed binding of ronidazole to microsomal protein and for the presence of intractable drug residues in the tissues of the animals treated with this compound.…”

Section: Free-radical Metabolites Of Metronidazole and Other Nitroimimentioning

confidence: 98%

“…Under different experimental conditions leading to enzymatic reduction of this compound, reactive metabolites that bind covalently to protein were produced (81)(82)(83)(84)(85)(86). This covalent binding was effectively prevented by reduced glutathione and cysteine.…”

Section: Free-radical Metabolites Of Metronidazole and Other Nitroimimentioning

confidence: 99%

Mechanism of Toxicity of Nitro Compounds Used in the Chemotherapy of Trichomoniasis

Moreno¹,

Docampo²

1985

Environmental Health Perspectives

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The mechanism of the trichomonicidal activity of metronidazole and other 5-nitroimidazoles appears to depend on the ferredoxin-mediated reduction of their nitro group, with generation of a reactive metabolite or metabolites which interact with DNA leading to a subsequent inhibition of nucleic acid and protein synthesis. Redox cycling of these compounds under aerobic conditions appears to be a detoxification reaction by inhibiting net reduction of the drugs, thereby inhibiting their uptake. On the other hand, redox cycling of nitrofurans or other compounds with more positive reduction potential results in formation of high steady-state concentrations of oxygen-derived metabolites that might be of toxicological significance. It seems likely that reduced metabolites of nitroimidazoles (perhaps through covalent binding to tissue macromolecules and/or thiols depletion) are also involved in the nitroimidazoles' toxic effects to animal tissues and in their mutagenic and carcinogenic action.

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Drug residue formation from ronidazole, a 5-nitroimidazole. V. Cysteine adducts formed upon reduction of ronidazole by dithionite or rat liver enzymes in the presence of cysteine

Cited by 33 publications

References 23 publications

Nitroimidazole Action in Entamoeba histolytica: A Central Role for Thioredoxin Reductase

Nitroimidazole Action in Entamoeba histolytica: A Central Role for Thioredoxin Reductase

5-Nitroimidazoles. II: Unexpected reactivity of ronidazole and dimetridazole with thiols

Mechanism of Toxicity of Nitro Compounds Used in the Chemotherapy of Trichomoniasis

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