Correlation of metabolism, covalent binding and toxicity for a series of bromobenzene derivatives using rat liver slices in vitro

Fisher, Ron; Brendel, Klaus; Hanzlik, Robert P.

doi:10.1016/0009-2797(93)90091-c

Cited by 34 publications

(12 citation statements)

References 39 publications

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“…The epoxide intermediate may also undergo nonenzymatic isomerisation to 4-bromophenol (Selander et al 1975), which can be further metabolized to yield catechols and quinones, some of which have been associated with hepatotoxicity via redox cycling and oxidative stress (Mizutani and Miyamoto 1999). The postulated mechanisms of bromobenzene-induced hepatotoxicity include GSH depletion, lipid peroxidation, covalent modification of critical cellular proteins, and mitochondrial dysfunction (Casini et al 1985;Fisher et al 1993;Koen et al 2007;Maellaro et al 1990). Modification of rat hepatic proteins by bromobenzene's reactive metabolites has been analyzed in some detail and undoubtedly appears to be a highly selective process at both the molecular (Koen et al 2006) and cellular levels ), although there is partial commonality with the proteins modified by other bioactivated hepatotoxins such as APAP ).…”

Section: Bromobenzenementioning

confidence: 97%

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Role of Reactive Metabolites in Drug-Induced Hepatotoxicity

Srivastava¹,

Maggs²,

Antoine³

et al. 2009

Handbook of Experimental Pharmacology

133

117

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Drugs are generally converted to biologically inactive forms and eliminated from the body, principally by hepatic metabolism. However, certain drugs undergo biotransformation to metabolites that can interfere with cellular functions through their intrinsic chemical reactivity towards glutathione, leading to thiol depletion, and functionally critical macromolecules, resulting in reversible modification, irreversible adduct formation, and irreversible loss of activity. There is now a great deal of evidence which shows that reactive metabolites are formed from drugs known to cause hepatotoxicity, such as acetaminophen, tamoxifen, isoniazid, and amodiaquine. The main theme of this article is to review the evidence for chemically reactive metabolites being initiating factors for the multiple downstream biological events culminating in toxicity. The major objectives are to understand those idiosyncratic hepatotoxicities thought to be caused by chemically reactive metabolites and to define the role of toxic metabolites.

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Section: Bromobenzenementioning

confidence: 97%

“…The hepatic damage is generally believed to be mediated through P450-generated reactive intermediates (Fisher et al 1993), especially bromobenzene 3,4-epoxide, although alkylation of protein sulfur nucleophiles in vivo by quinone metabolites is 10-15 times more extensive than alkylation by epoxides (Slaughter and Hanzlik 1991) (Fig. 3).…”

Section: Bromobenzenementioning

confidence: 99%

Role of Reactive Metabolites in Drug-Induced Hepatotoxicity

Srivastava¹,

Maggs²,

Antoine³

et al. 2009

Handbook of Experimental Pharmacology

133

117

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“…For analysis of CVB in incubated hepatocytes we applied the principle of protein precipitation on filter paper. 26, 27 Aliquots (100 μL) of quenched incubations were applied on 12 × 80 mm strips of absorbent paper 3MM. After drying briefly in air the strips were washed by immersion for 10–15 min in each of a series of four baths (ca.…”

Section: Methodsmentioning

confidence: 99%

Liver Protein Targets of Hepatotoxic 4-Bromophenol Metabolites

Koen

Hajovsky

Liu

et al. 2012

Chem. Res. Toxicol.

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The hepatotoxicity of bromobenzene (BB) is directly related to the covalent binding of both initially formed epoxide and secondary quinone metabolites to at least 45 different liver proteins. 4-Bromophenol (4BP) is a significant BB metabolite and a precursor to reactive quinone metabolites; yet, when administered exogenously, it has negligible hepatotoxicity as compared to BB. The protein adducts of 4BP were thus labeled as nontoxic [Monks, T. J., Hinson, J. A., and Gillette, J. R. (1982) Life Sci. 30, 841−848]. To help identify which BB-derived adducts might be related to its cytotoxicity, we sought to identify the supposedly nontoxic adducts of 4BP and eliminate them from the BB target protein list. Administration of [ 14 C]-4BP to phenobarbital-induced rats resulted in covalent binding of 0.25, 0.33, and 0.42 nmol equiv 4BP/mg protein in the mitochondrial, microsomal, and cytosolic fractions, respectively. These values may be compared to published values of 3−6 nmol/mg protein from a comparable dose of [ 14 C]-BB. After subcellular fractionation and 2D electrophoresis, 47 radioactive spots on 2D gels of the mitochondrial, microsomal, and cytosolic fractions were excised, digested, and analyzed by LC-MS/MS. Twenty-nine of these spots contained apparently single proteins, of which 14 were nonredundant. Nine of the 14 are known BB targets. Incubating freshly isolated rat hepatocytes with 4BP (0.1−0.5 mM) produced time-and concentration-dependent increases in lactate dehydrogenase release and changes in cellular morphology. LC-MS/MS analysis of the cell culture medium revealed rapid and extensive sulfation and glucuronidation of 4BP as well as formation of a quinone-derived glutathione conjugate. Studies with 7-hydroxycoumarin, (−)-borneol, or D-(+)-galactosamine showed that inhibiting the glucuronidation/ sulfation of 4BP increased the formation of a GSH-bromoquinone adduct, increased covalent binding of 4BP to hepatocyte proteins, and potentiated its cytotoxicity. Taken together, our data demonstrate that protein adduction by 4BP metabolites can be toxicologically consequential and provide a mechanistic explanation for the failure of exogenously administered 4BP to cause hepatotoxicity. Thus, the probable reason for the low toxicity of 4BP in vivo is that rapid conjugation limits its oxidation and covalent binding and thus its toxicity.

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“…In some cases a pretreatment of the animals has yielded 'liver-specific' in vitro results (e.g, with LPS [15], aroclor 1254 [16], phenobarbital [17] or adrenalectomy [18]). These approaches do not provide an alternative for studies requiring large numbers of laboratory animals.…”

Section: Introductionmentioning

confidence: 99%

Hormone‐ and endotoxin‐modulated gene expression of a long‐term organ culture system of adult rat liver

Sultan¹,

Hartung²,

Bade³

1996

FEBS Letters

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Precision-cut slices of normal adult rat liver maintained in serum-free medium remain hormone-and endotoxinresponsive for at least 48 h. They respond to glucocorticoid (dexamethasone) with the induction of the ghiconeogenic enzyme tyrosine aminotransferase (TAT), as determined by enzymatic activity and by the increase in enzyme protein. Furthermore, endotoxin (LPS) induced nitric oxide synthase II (i-NOS), and this induction is repressed, similarly to the in vivo situation, by dexamethasone (DEX). All increases are inhibited by cycloheximide (CHX). The length of the period of responsiveness suggests that this organ culture system might be generally useful for studying the modulation of liver gene expression by physiological and pathological influences.

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Correlation of metabolism, covalent binding and toxicity for a series of bromobenzene derivatives using rat liver slices in vitro

Cited by 34 publications

References 39 publications

Role of Reactive Metabolites in Drug-Induced Hepatotoxicity

Role of Reactive Metabolites in Drug-Induced Hepatotoxicity

Liver Protein Targets of Hepatotoxic 4-Bromophenol Metabolites

Hormone‐ and endotoxin‐modulated gene expression of a long‐term organ culture system of adult rat liver

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