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At least 19 recordsLinked to original sources
PubMed1990

Synthesis and properties of vinyl carbamate epoxide, a possible ultimate electrophilic and carcinogenic metabolite of vinyl carbamate and ethyl carbamate.

Vinyl carbamate reacted with dimethyldioxirane in dry acetone to give a high yield of pure crystalline vinyl carbamate epoxide. This epoxide was characterized by its NMR and MS spectra and elementary analysis. It is unstable at room temperature and has a half-life in water solution of approximately 32 minutes. It reacts with adenosine to form 1,N6-ethenoadenosine and more of this etheno nucleoside was found in hydrolysates of hepatic RNA of male mice injected i.p. with the epoxide than with vinyl carbamate. Tests with Salmonella typhimurium TA1535 showed that this epoxide is a strong direct mutagen. It is also more toxic in the mouse than vinyl carbamate. Studies on the carcinogenicity of this epoxide are in progress.

Animals↗
PubMed1993

Vinyl carbamate epoxide, a major strong electrophilic, mutagenic and carcinogenic metabolite of vinyl carbamate and ethyl carbamate (urethane).

Vinyl carbamate epoxide (VCO) was found to possess strong electrophilic, mutagenic and carcinogenic activities. It reacted with water at 37 degrees C and pH 7.4 (phosphate buffer) to form glycolaldehyde and several related reducing compounds; none of these products were mutagenic for Salmonella typhimurium TA1535. Under these conditions VCO had a half-life (determined chemically and mutagenically) of approximately 10.5 min. This half-life was progressively lowered by increasing concentrations of chloride ion (liver, serum and isotonic levels). This ion reacted with VCO to form chloroacetaldehyde. VCO also reacted with other nucleophiles such as glutathione, DNA and its constituent guanine and adenine bases. The purine adducts formed by VCO in DNA in vitro and in vivo were released by weak acid treatment and consisted of 7-(2'-oxoethyl)guanine and N2,3-ethenoguanine as major products with 1,N6-ethenoadenine as a minor product. VCO was a strong direct mutagen in Salmonella typhimurium TA1535 and TA100 but was only weakly active in the TA98 mutant. VCO was a stronger initiator of carcinogenesis in the skin of CD-1 mice and in the liver of infant male B6C3F1 mice than its metabolic precursors vinyl carbamate (VC) and ethyl carbamate (EC). Unlike VC and EC, VCO was a strong complete carcinogen in the skin of CD-1 mice and induced papillomas and carcinomas following repetitive administration of sub-ulcerogenic doses. VCO also exhibited some carcinogenic activity in the lungs of mice and in the s.c. and mammary tissue of female Sprague-Dawley rats. These data and those from other recent studies support the conclusion that VCO is a major strong electrophilic, mutagenic and carcinogenic metabolite of EC and VC in the mouse.

Animals↗
PubMed2000

The 1.5 A resolution crystal structure of the carbamate kinase-like carbamoyl phosphate synthetase from the hyperthermophilic Archaeon pyrococcus furiosus, bound to ADP, confirms that this thermostable enzyme is a carbamate kinase, and provides insight into substrate binding and stability in carbamate kinases.

Carbamoyl phosphate (CP), an essential precursor of arginine and the pyrimidine bases, is synthesized by CP synthetase (CPS) in three steps. The last step, the phosphorylation of carbamate, is also catalyzed by carbamate kinase (CK), an enzyme used by microorganisms to produce ATP from ADP and CP. Although the recently determined structures of CPS and CK show no obvious mutual similarities, a CK-like CPS reported in hyperthermophilic archaea was postulated to be a missing link in the evolution of CP biosynthesis. The 1.5 A resolution structure of this enzyme from Pyrococcus furiosus shows both a subunit topology and a homodimeric molecular organization, with a 16-stranded open beta-sheet core surrounded by alpha-helices, similar to those in CK. However, the pyrococcal enzyme exhibits many solvent-accessible ion-pairs, an extensive, strongly hydrophobic, intersubunit surface, and presents a bound ADP molecule, which does not dissociate at 22 degrees C from the enzyme. The ADP nucleotide is sequestered in a ridge formed over the C-edge of the core sheet, at the bottom of a large cavity, with the purine ring enclosed in a pocket specific for adenine. Overall, the enzyme structure is ill-suited for catalyzing the characteristic three-step reaction of CPS and supports the view that the CK-like CPS is in fact a highly thermostable and very slow (at 37 degrees C) CK that, in the extreme environment of P. furiosus, may have the new function of making, rather than using, CP. The thermostability of the enzyme may result from the extension of the hydrophobic intersubunit contacts and from the large number of exposed ion-pairs, some of which form ion-pair networks across several secondary structure elements in each enzyme subunit. The structure provides the first information on substrate binding and catalysis in CKs, and suggests that the slow rate at 37 degrees C is possibly a consequence of slow product dissociation.

Adenosine Diphosphate↗
PubMedDate not supplied

Enzymatic oxidation of ethyl carbamate to vinyl carbamate and its role as an intermediate in the formation of 1,N6-ethenoadenosine.

The carcinogen ethyl carbamate has been postulated to be activated by oxidation to vinyl carbamate and then to an epoxide which can react with nucleic acids [Dahl, G.A., Miller, J. A., and Miller, E. C. (1978) Cancer Res. 38, 3793-3804]. To date, the enzymatic conversion of ethyl carbamate to vinyl carbamate had not been demonstrated. Recently, we obtained evidence that the same cytochrome P-450 enzyme (P-450 2E1) is involved in the oxidation of both ethyl carbamate and vinyl carbamate [Guengerich, F. P., Kim, D.-H., and Iwasaki, M. (1991) Chem. Res. Toxicol. 4, 168-179]. When human liver microsomes were incubated with NADPH and ethyl carbamate, the products vinyl carbamate, 2-hydroxyethyl carbamate, and ethyl N-hydroxycarbamate were detected by use of (a) combined capillary gas chromatography/chemical ionization mass spectrometry or (b) high-performance liquid chromatography of radioactive materials. A Km of approximately 54 microM was estimated for the conversion of vinyl carbamate to 1,N6-ethenoadenosine (in the presence of adenosine), but when the reaction was done with ethyl carbamate as the substrate, the rate of product formation was nearly first order in ethyl carbamate concentration (Km greater than 2 mM) and the rate was considerably slower than in the case of vinyl carbamate. The model derived with these parameters predicts a steady-state level of 0.22 microM vinyl carbamate, consonant with the value of approximately 0.2 microM estimated experimentally. A large kinetic deuterium isotope effect (greater than 7) was observed for the formation of 1,N6-ethenoadenosine from ethyl carbamate, and high isotope effects (6-8) were also noted for the formation of vinyl carbamate and 2-hydroxyethyl carbamate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1978

Vinyl carbamate as a promutagen and a more carcinogenic analog of ethyl carbamate.

Vinyl carbamate was much more active (10 to 50 times) than ethyl carbamate for the initiation of skin tumors and for the induction of lung adenomas in mice. Vinyl carbamate was also mutagenic to Salmonella typhimurium TA 1535 and TA 100 in the presence of reduced nicotinamide adenine dinucleotide phosphate-fortified rat or mouse liver mitochondrial supernatant fractions. This mutagenic activity was inhibited strongly by cytochrome P-450 inhibitors. No mutagenic activity was observed for vinyl carbamate in the absence of added liver preparations or for ethyl carbamate in the presence or absence of liver fractions. Extensive tests with sensitive methods failed to detect vinyl carbamate as a metabolite of ethyl carbamate in the mouse in vivo. However, on administration of [ethyl-1-14C;1,2-3H]ethyl carbamate to adult mice the 3H/14C ratios of the hepatic DNA-, rRNA-, and protein-adducts were similar to each other and much lower than the ratio of the administered ethyl carbamate. These data are consistent with the presence of desaturated and/or oxidized ethyl groups in the macromolecular adducts. The qualitatively similar, but much stronger, carcinogenic activity of vinyl carbamate as compared to that of ethyl carbamate suggests that the metabolic pathways of these two carbamates may converge in the formation of similar or identical electrophilic reactants that bind covalently to macromolecules in vivo and initiate carcinogenesis.

Adenoma↗
PubMed1982

Comparative genotoxicity studies of ethyl carbamate and related chemicals: further support for vinyl carbamate as a proximate carcinogenic metabolite.

In vivo and/or in vitro mammalian cell systems were used to evaluate sister chromatid exchange (SCE) induction and gene mutagenesis effects following exposure to ethyl carbamate (urethane), vinyl carbamate, ethyl N-hydroxycarbamate, and 2-hydroxyethyl carbamate. Although ethyl carbamate caused dose-dependent increases in SCE when injected into mice, it was ineffective for inducing SCE and gene mutation (6-thio-guanine resistance) in Chinese hamster V-79 cells cultured with or without the addition of S9 enzyme mix during treatment. Chemical-specific patterns of genotoxicity were evident for the known or suspect metabolites under test: only vinyl carbamate consistently (in vivo and in vitro) revealed strong activity for the genetic endpoints. SCE induction levels of 5-8 times baseline were observed after animal or cell culture exposures to vinyl carbamate. Doses required to produce this effect in V-79 cells in the presence of S9 mix were approximately 100 times lower than those needed when S9 was absent. The extensive gene mutagenesis (approaching 600 mutants/10(6) survivors) noted was completely dependent upon the presence of S9 mix. These observations are consistent with current theory holding that vinyl carbamate is a metabolic intermediate of ethyl carbamate, and is converted to the ultimately reactive species (presumably, vinyl carbamate epoxide) which is responsible for ethyl carbamate carcinogenesis.

Animals↗
PubMed1986

Induction of sister chromatid exchange by ethyl carbamate and vinyl carbamate.

High levels of sister chromatid exchanges (SCEs) can be induced in murine bone marrow, alveolar macrophages and regenerating liver cells by carcinogenic carbamate esters; however, the frequencies observed in the latter two tissues, which are also common tissues for carbamate-induced tumours, are relatively enhanced compared to the frequency in bone marrow. Relative to these tissues, peripheral blood lymphocytes, which do not divide during in-vivo exposure but which can be cultured in vitro, exhibit considerably lower levels of ethyl-carbamate-induced SCEs. Lymphocytes, however, are uniquely able to accumulate SCE-inducing lesions produced by multiple treatments with ethyl carbamate. In the present study, significantly elevated levels of SCEs were still apparent in lymphocytes of BDF1 mice eight weeks after a series of 12 multiple injections (2.2 mmol/kg; 3 times weekly) of ethyl carbamate. Long-term persistence of genetic damage produced by ethyl carbamate in murine lymphocytes is in agreement with our previous findings of highly persistent SCE-inducing damage in murine bone marrow and alveolar macrophage cells. The highly persistent nature of ethyl-carbamate-induced DNA damage and/or its continued ability to induce SCEs is undoubtedly relevant to its tumourigenic activity.

Animals↗
PubMed1990

1,N6-ethenoadenosine formation, mutagenicity and murine tumor induction as indicators of the generation of an electrophilic epoxide metabolite of the closely related carcinogens ethyl carbamate (urethane) and vinyl carbamate.

Previous studies from this laboratory showed that (i) vinyl carbamate (VC) was much more carcinogenic than ethyl carbamate (EC) and that both carbamates induced the same spectrum of tumors in mice and rats, (ii) adducts of [14C]- or [3H]1,N6-ethenoadenosine and [14C]- or [3H]3,N4-ethenocytidine e were formed in the hepatic RNA of infant male B6C3F1 mice administered [1-14C]ethyl or [1,2-3H]ethyl EC and (iii) VC formed much more of the 1,N6-ethenoadenosine (epsilon Ado) adduct in the hepatic RNA and the 7-(2-oxoethyl)-guanine adduct in the hepatic DNA of mice than did EC. By analogy to the similar results of earlier studies by other investigators on the related carcinogen vinyl chloride, the above data suggested that VC epoxide was a reactive electrophilic metabolite of these carbamates. In the present studies, VC, but not EC, was found to be oxidized by 3-chloroperbenzoic acid to a derivative that reacted with adenosine to form epsilon Ado. Far more of this etheno nucleoside was formed from VC than from EC when these carbamates were metabolized by cofactor-fortified mouse liver microsomes in the presence of adenosine. Sodium diethyldithiocarbamate strongly inhibited these microsomal reactions and the formation of epsilon Ado in the hepatic RNA of mice administered either carbamate. Likewise, the i.p. preadministration of deithyldithiocarbamate markedly inhibited the induction of tumors by single i.p. doses of EC or VC in the livers of infant male B6C3F1 mice and in the livers, lungs and Harderian glands of infant female B6C3F1 mice. This inhibitor also considerably reduced lung tumor induction by VC in adult female A/Jax mice. 2-(2,4-Dichloro-6-phenyl) phenoxyethyl amine, a cytochrome P450 inhibitor, reduced the carcinogenicity of low doses of EC but appeared to increase the carcinogenicity of low doses of VC. The mutagenicity of VC for Salmonella typhimurium TA1535 in the presence of a hepatic activating system was greatly reduced by these inhibitors. The data from all these studies are consistent with the proposal that VC epoxide is an ultimate electrophilic and carcinogenic metabolite of EC and VC in the mouse.

Adenosine↗
PubMed1976

High-pressure liquid chromatographic determination of chlorphenesin carbamate and the beta-isomeric carbamate.

A high-pressure liquid chromatographic assay was developed for the determination of chlorphenesin carbamate and its beta-isomeric carbamate. A single 4-mm i.d. X 30-cm column, prepacked with 10 micrometer fully porous silica gel particles, is used with 3% methanol in 50% water-saturated butyl chloride as the mobile phase. The procedure separates chlorphenesin carbamate from several possible impurities in addition to the beta-isomeric carbamate. The assay was applied to bulk drug and compressed tablets. The relative standard deviations for the assays of chlorphenesin carbamate and the beta-isomer are approximately 1 and 2%, respectively.

Carbamates↗
PubMedDate not supplied

19F nuclear magnetic resonance analysis of the carbamate reaction of alpha-fluoro-beta-alanine (FBAL), the major catabolite of fluoropyrimidines. Application to FBAL carbamate determination in body fluids of patients treated with 5'-deoxy-5-fluorouridine.

alpha-Fluoro-beta-alanine (FBAL), the major catabolite of the antineoplastic fluoropyrimidines, is an amino acid which is in equilibrium with its carbamate derivative in weakly alkaline aqueous solutions containing carbonate. In both water and control biological fluids (urine, plasma) spiked with FBAL (and sodium bicarbonate, in some cases), 19F NMR was used: (i) to determine the pH range over which FBAL carbamate is present (pH greater than or equal to 7), the maximum concentration formed occurring around pH 9, (ii) to show that the amino group of FBAL interacts very slowly with a non-protein plasma component to form a compound X, unstable in acid medium. The presumed structure of X is RCONHCH2CHFCOOH, with R different from an alkyl group but still unidentified. The behavior of FBAL in urine and plasma of rats treated with FBAL or 5'-deoxy-5-fluorouridine (5'-dFUrd), a prodrug of 5-fluorouracil, and from patients treated with 5'-dFUrd was investigated. FBAL carbamate was not present in acid medium and was therefore absent in acidic human urine. However, it was found in alkaline rat urine. FBAL carbamate was found in plasma along with the compound X. The 19F NMR spectra of FBAL and derivatives are complex since alpha-fluoro-beta-ureido-propionic acid, the precursor of FBAL in the catabolic pathway of antineoplastic fluoropyrimidines, produces a signal overlapping that of FBAL carbamate, and very close to that of compound X.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine↗
PubMed1994

Weak carcinogenicity of 2-hydroxyethyl carbamate in strain A mice: indication that this is not a proximal metabolite of ethyl carbamate.

Ethyl carbamate (EC, urethan) is carcinogenic probably because it is converted in vivo to vinyl carbamate and then to vinyl carbamate epoxide, which reacts with DNA bases. We hypothesized that vinyl carbamate arises from EC by oxidation to 2-hydroxy-EC (HEC) and dehydration of the HEC, rather than by direct dehydrogenation of EC. In that case, HEC should be more carcinogenic than EC. In a previous test, HEC showed only borderline initiating activity for mouse skin, but its synthesis was poorly described. In the present study, HEC was synthesized by reacting ethylene carbonate with ammonia and was characterized. A single dose of HEC or EC in saline was injected i.p. into adult male strain A mice, which were maintained for 16 weeks. HEC doses of 1.12, 4.6 and 11.2 mmol/kg induced 0.16, 0.32 and 0.32 lung adenomas/mouse, respectively. The 28% tumor incidence for the two highest doses was significantly (P < 0.05) greater than that in controls injected with saline alone. The number of tumors/mouse with 4.6 mmol HEC/kg was one-fortieth of that for an equimolar dose of EC. The weak activity of HEC supports the view that HEC is not a proximal carcinogenic metabolite of EC, i.e. that vinyl carbamate is produced directly from EC.

Animals↗
PubMed1993

Synthesis of 2,4-disubstituted thiazoles and selenazoles as potential antitumor and antifilarial agents: 1. Methyl 4-(isothiocyanatomethyl)thiazole-2-carbamates, -selenazole-2- carbamates, and related derivatives.

Methyl 4-(isothiocyanatomethyl)thiazole-2-carbamate and methyl 4-(isothiocyanatomethyl)selenazole-2-carbamate have been prepared via chemical transformations involving 2-amino-4-(chloromethyl)thiazole (1) and 2-amino-4-(chloromethyl)selenazole (2), respectively, as starting materials. The homoanalog, methyl 4-(2-isothiocyanatoethyl)thiazole-2-carbamate, was prepared from (2-aminothiazol-4-yl)acetic acid. All compounds prepared were evaluated for their ability to inhibit leukemia L1210 cell proliferation. Methyl 4-(isothiocyanatomethyl)thiazole-2-carbamate (7) was the most active compound in this screen, inhibiting the growth of L1210 leukemic cells with an IC50 = 3.2 microM. Mitotic blocking appears to be its primary mechanism of cytotoxic activity. Compound 7 also was the only compound which demonstrated significant in vivo antifilarial activity against the adult worms of Acanthocheilonema viteae in experimentally infected jirds. This compound was inactive against Brugia pahangi at a dosage of 100 mg/kg x 5 days.

Animals↗
PubMed1985

Comparison of the effects of imidazo[1,2-a]pyridine-2-carbamates and benzimidazole-2-carbamates on the development of Hymenolepis nana in Tribolium confusum.

The anthelmintic properties of several imidazo[1,2-a]pyridine carbamates and benzimidazole carbamates against Hymenolepis nana are compared. The results of this study, coupled with previous work, indicate that methyl 6-(trichloroethenyl)-imidazo[1,2-a]pyridine-2-carbamate has the potential of being a broad spectrum anthelmintic effective against both nematodes and cestodes.

Animals↗
PubMed1984

Rodent species and strain specificities for sister-chromatid exchange induction and gene mutagenesis effects from ethyl carbamate, ethyl N-hydroxycarbamate, and vinyl carbamate.

Ethyl carbamate (EC) and two related carcinogens, ethyl N-hydroxycarbamate (ENHC) and vinyl carbamate (VC), caused species-specific increases in sister-chromatid exchange (SCE) formation in the bone marrow cells of rodents. Mice exposed to 400 mg/kg of EC had SCE increases of 6-times-baseline, while rats, Chinese hamsters, and golden hamsters showed 3- to 4-times-baseline increases in response to this dose. Lesser, but still significant, differences were found for ENHC and VC; the severest effects consistently occurred in mice. Control bone marrow cell-cycle kinetics among the rodent species were similar. Mouse strains A and C57BL/6, which have high and low susceptibilities to EC induction of lung adenomas, respectively, showed nearly identical levels of SCE induction after in vivo exposure to these carbamates. However, testing of VC, a possible metabolite of EC, in vitro revealed strain-dependent liver enzyme (Aroclor-induced S-9 fraction) capabilities to convert VC to genotoxic products. SCE induction, gene mutation for 6-thioguanine and ouabain resistance, and cytotoxicity in Chinese hamster V79 cells were significantly greater when A strain S-9 enzymes were used as compared with C57BL/6 strain S-9 enzyme preparations. No effect on SCE of reseeding, compared with no reseeding, of VC-treated V79 cells was observed. At a concentration of 25 micrograms/ml, VC caused 6-times-baseline induction of SCE in the presence of A strain S-9 mix and 4-times-baseline induction in the presence of C57BL/6 strain S-9 mix. These in vitro strain-dependent patterns of response are relevant to the current theory that VC may be a proximate carcinogenic metabolite of EC.

Animals↗
PubMed1999

Unique analogues of anandamide: arachidonyl ethers and carbamates and norarachidonyl carbamates and ureas.

To examine the effect of changing the amide bond of anandamide (5, AN) to a less hydrolyzable moiety, analogues 1a-1l, 2a-2c, 3a-3c, and 4a-4h were synthesized from commercially available arachidonyl alcohol or arachidonic acid and tested for their pharmacological activity. Arachidonyl ethers 1a-1k were obtained through the coupling of the arachidonyl mesylate (6) (generated from the mesylation of arachidonyl alcohol) with the appropriate alcohol in potassium hydroxide. Arachidonyl ether 1l was obtained through the phase-transfer coupling of arachidonyl alcohol with 2-(2-iodoethoxy)tetrahydropyran (which was generated from its bromide) followed by cleavage of the tetrahydropyran group with Dowex resin. Arachidonyl carbamates 2a-2c were obtained through the coupling of arachidonyl alcohol with the appropriate isocyanates. Norarachidonyl carbamates 3a-3c and ureas 4a-4h were obtained through the coupling of the norarachidonyl isocyanate (generated from arachidonic acid using diphenyl phosphorazidate and triethylamine upon heating) with the appropriate alcohols and amines, respectively. AN analogues 1-3 have shown poor binding affinities to the CB1 receptor and fail to produce significant pharmacological effect at doses up to 30 mg/kg. Several ether analogues 1 were also evaluated in the CB2 binding assay and were found to be of low affinity. However, norarachidonyl urea analogues 4 have shown generally good binding affinities to the CB1 receptor (Ki = 55-746 nM) and pharmacological activity with AN-like profiles. The most potent analogue of this series is the 2-fluoroethyl analogue 4f which binds 2 times better than AN and was more active in several mouse behavioral assays. It was also observed that urea analogues 4a and 4g, which have weak binding affinities to the CB1 receptor (Ki = 436 and 347 nM, respectively), produced surprisingly potent pharmacological activity. These urea analogues have also shown hydrolytic stability toward the amidase enzymes, responsible for the primary degradation pathway of anandamide, in binding affinity assays in the absence of the enzyme inhibitor PMSF.

Analgesics, Non-Narcotic↗
PubMedDate not supplied

A method for the determination of methyl carbamate and ethyl carbamate in wines.

A method is described for the simultaneous determination of methyl carbamate (MC) and ethyl carbamate (EC) in wines that is based on: (a) extraction of the sample with dichloromethane using an extraction tube or an alumina-Celite column, (b) concentration of the extract to a small volume, and (c) determination by gas-liquid chromatography-thermal energy analyser (N-mode). The method is highly sensitive (1-2 ng/ml), accurate (recoveries greater than 80%), and precise (CV, 5-10%). Nineteen of 27 samples of wines analysed contained traces (up to 2.7 ng/ml) of MC, and most contained EC (up to 70 ng/ml). Wines treated in the laboratory with 200 ppm dimethyl pyrocarbonate (DMPC)-a cold sterilant recently approved for use in wines-indicated that such a treatment may increase the MC contents of the wines to 10 ng/ml. Additional studies suggested that formation of MC in DMPC-treated wines is dependent on both pH and ammonia content of the wines. The identity of MC in a few selected samples was confirmed by gas-liquid chromatography-high resolution (10 K) mass spectrometry. The natural low levels of MC found in these wines are not considered to pose a risk to human health.

Ammonia↗
PubMed1995

Detoxification of vinyl carbamate epoxide by glutathione: evidence for participation of glutathione S-transferases in metabolism of ethyl carbamate.

Vinyl carbamate epoxide (VCO) is believed to be the metabolite of ethyl carbamate (EC) ultimately responsible for its carcinogenic effects. This study investigates the role of glutathione (GSH) in protection against VCO-mediated adduct formation, and the involvement of glutathione S-transferases (GSTs) in detoxification of VCO. Formation of 1,N6-ethenoadenosine from VCO and adenosine in vitro was employed as a measure of VCO toxicity. GSH inhibited formation of ethenoadenosine in a concentration-dependent manner at concentrations ranging from 1 to 8 mM. This effect was significantly enhanced by addition of rat liver GST. Mouse liver cytosol was also found to inhibit formation of ethenoadenosine in a concentration-dependent manner, and the inhibition was relieved by addition of S-octylglutathione, a competitive inhibitor of GST. Pretreatment of mice with 1% dietary (2(3)-tert-butyl-4-hydroxyanisole (BHA) caused parallel increases in cytosolic GST activity and cytosolic enhancement of detoxification of VCO by GSH. Furthermore, BHA increased hepatic steady-state concentrations of GSH greater than twofold. The effect of BHA on detoxification of EC in vivo was examined using formation of 2-oxoethylvaline (OEV) adducts of hemoglobin as a biomarker. Pretreatment with BHA decreased overall formation of OEV adducts 23%. The major conclusions of this study are (1) VCO can be detoxified by spontaneous conjugation with GSH, (2) conjugation of VCO with GST can be catalyzed by GST(s), (3) pretreatment with BHA protects against binding of active EC metabolites in vitro and in vivo, and (4) the protective effect of BHA against EC is mediated by increases in GST activity and GSH concentration.

Animals↗