Modification of butylated hydroxytoluene-induced pulmonary toxicity in mice by diethyl maleate, buthionine sulfoximine, and cysteine

doi:10.1016/0378-4274(84)90029-8

Toxicology Letters

Volume 23, Issue 3, December 1984, Pages 327-331

https://doi.org/10.1016/0378-4274(84)90029-8 Get rights and content

Abstract

Treatment of mice with diethyl maleate (DEM) or buthionine sulfoximine (BSO) significantly enhanced the lung injury caused by butylated hydroxytoluene (BHT). Conversely, cysteine protected mice from the lung toxicity of BHT. BHT administration to mice produced a time-dependent reduction of glutathione (GSH) content in the lung, but not in the liver. These results support the concept that conjugation of 2,6-di-tert-butyl-4-methylene-2,5-cyclohexadienone (BHT-quinone methide), a proposed reactive metabolite of BHT, with GSH is involved in the detoxification of BHT in mice.

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Cited by (26)

Protective effects of Ligustrum lucidum fruit extract on acute butylated hydroxytoluene-induced oxidative stress in rats
2007, Journal of Ethnopharmacology
Nuzhenzi, the fruit of Ligustrum lucidum Ait. (Oleaceae), is commonly used as tonic for kidney and liver in the traditional Chinese medicine prescription. The present study aimed to investigate the antioxidant activities of ethanol extract of Ligustrum lucidum fruits (ELL) and its effects on butylated hydroxytoluene (BHT)-induced oxidative stress in rats. Results showed that ELL possesses weak antioxidant activities. Compared to the BHT (1000 mg/kg)-treated group, results showed that ELL at 250, 500 and 1000 mg/kg significantly reduced the levels of blood urea nitrogen (BUN), serum glutamic pyruvic transaminase (sGPT), glutamic oxaloacetic transaminase (sGOT), alkaline phosphatase (sALP), lactate dehydrogenase (LDH), triglyceride (TG) and creatinine (Cr), as well as LDH in bronchoalveolar lavage fluid (BALF). It also significantly decreased the level of lipid peroxides in liver and lung. In addition, ELL significantly enhanced the levels of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) in these organs. Histopathological evaluation of the tissues revealed that ELL reduced the incidence of lung lesions, while the liver and kidney tissues were not affected by BHT administration. Taken together, the protective effect of ELL against acute BHT-induced oxidative stress in rats could be through the upregulation of antioxidant enzymes.
Responses of tumorigenic and non-tumorigenic mouse lung epithelial cell lines to electrophilic metabolites of the tumor promoter butylated hydroxytoluene
2003, Chemico-Biological Interactions
Citation Excerpt :
Greater resistance of initiated cells to cytotoxic promoters has been reported previously, although no electrophilic agents were utilized in that work [32]. With quinone methides, trapping by GSH occurs very rapidly and conjugate formation should be the main pathway for BHT-QM detoxification [8,13]. As expected, depletion of GSH by BSO treatment enhanced BHT-QM cytotoxicity (Table 1).
A model system to investigate the promotion phase of pulmonary carcinogenesis involves chronic exposure of carcinogen-initiated mice to the food additive, butylated hydroxytoluene (BHT). Previous studies strongly suggested that this activity is due to the cytochrome P450-catalyzed formation of quinone methides 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dienone (BHT-QM) and 6-tert-butyl-2-(1′,1′-dimethyl-2′-hydroxy)ethyl-4-methylenecyclohexa-2,5-dienone (BHTOH-QM). The effects of these electrophiles on non-tumorigenic C10 and E10 epithelial cell lines derived from a normal mouse lung explant were compared with effects on their corresponding neoplastic siblings, the A5 and E9 spontaneous transformants, respectively. The tumorigenic cells were more resistant to cell killing, with LC₅₀ values of 165–180 μM for BHT-QM and 12–22 μM for BHTOH-QM, versus LC₅₀ values in the non-tumorigenic cells of 105–118 μM and 5.0-6.0 μM, respectively. Constitutive glutathione (GSH) concentrations were 12–20 nmol/10⁶ cells, and BHT-QM toxicity was enhanced >2-fold by depleting GSH with buthionine sulfoximine (BSO). Formation of the GSH conjugate of BHT-QM accounted for a substantial fraction of the cellular GSH lost by quinone methide exposure. Enhanced lipid peroxidation and superoxide formation occurred in all cell lines treated with BHT-QM, but both tumorigenic lines contained higher levels of GSH S-transferase and superoxide dismutase (SOD) activities. These data suggest the possibility that BHT-derived quinone methides may exert their promoting effects by inducing oxidative stress; such stress is better tolerated by tumorigenic cells, which have higher levels of antioxidant enzymes. Normal cells are destroyed more readily which allows neoplastic cells to expand their proliferation.
Glutathione reduces the toxicity associated with antitumor therapy of ascites fluid adsorbed over Staphylococcus aureus Cowan I in tumor bearing mice
1999, Toxicology Letters
It has been well documented in the literature that the removal of circulatory immune complexes (CICs) from the host circulation leads to the immunopotentiation as well as generation of antitumor responses in a variety of tumors in rats, cats, dogs and human patients. CICs are the major immunosuppressive factors in tumor bearing host. Protein A (PA) has been extensively used for the removal of these CICs from the sera/plasma of tumor bearers, because PA has the ability to bind with the Fc portion of mammalian immunoglobulins. Previously, we reported for the first time a potent antitumor response by the inoculation of cell free Ehrlich’s ascites fluid adsorbed in vitro over PA containing Staphylococcus aureus Cowan I (SAC) in Ehrlich’s ascites tumor model. However, there was toxicity associated with this form of therapy in terms of early death of treated animals and the depletion of hepatic glutathione pool as well as phase I biotransformation enzyme and increase in glutathione-S-transferase (GST) activities. In the present investigation, tumor bearing animals were treated intraperitoneally (i.p.) on alternate days for 15 days with adsorbed ascites fluid (ad-ASF) (0.1 ml) and glutathione (GSH) (250 mg/kg body weight) separately. We found that GSH supplementation increases mean survival time of GSH and ad-ASF treated mice up to 37.2 days in comparison with 19.9 days for only ad-ASF treated animals, while percent increase in body weight was found to be not affected by the GSH substitution, which remains significantly lower (P<0.01) in comparison to the tumor control animals. GSH supplementation causes a significant decrease (P<0.05) of glutathione-S-transferase and restoration of aniline hydroxylase activity (P<0.05) and aminopyrine-N-demethylase activity. We have also observed that GSH supplementation does not alter the tumor cell viability and tumor cell counts in ad-ASF treated animals in comparison to only ad-ASF treated animals, which indicates that GSH supplementation does not alter the antitumor effect of the therapy. Treatment of Ehrlich’s ascites tumor bearing mice with ad-ASF and glutathione increased their survival, but did not reduce the mortality of animals because of tumor.
Metabolic activation of butylated hydroxytoluene by mouse bronchiolar clara cells
1993, Toxicology and Applied Pharmacology
Metabolism of BHT (2,6-di-tert-butyl-4-methylphenol) is requisite for its pneumotoxic activities. Previous evidence using microsomal preparations from livers and lungs of mice indicated that cvtochrome P450-catalyzed hydroxylation of a tert-butyl group to form 6-tert-butyl-2-(hydroxy-tert-butyl)-4-methylphenol (BHTOH) is the first step in the bioactivation of this compound. Subsequent oxidation of BHTOH produces the quinone methide 6-tert-butyl-2-(hydroxy-tert-butyl)-4-methylene-2,5-cyclohexadienone (BHTOH-QM), and this highly reactive electrophile may be directly responsible for the pulmonary effects of BHT. The present study assessed the ability of intact bronchiolar Clara cells isolated from mice, a major site of pulmonary xenobiotic metabolism, to convert BHT to BHTOH-QM. The data demonstrate that BHTOH is, in fact, the principal oxidation product in these cells, and that a substantial portion of this metabolite is oxidized further to the quinone methide. BHTOH was found to be considerably more toxic to Clara cells than BHT, and both toxicity and metabolism were simultaneously depressed by the cytochrome P450 inhibitor SKF 525-A. These results strongly support the hypothesis that BHTOH-QM is the active metabolite that generates acute pneumotoxicity and modulates lung tumor formation.
Biological and toxicological consequences of quinone methide formation
1993, Chemico-Biological Interactions
Quinone methides are a class of reactive, electrophilic compounds which are capable of alkylating cellular macromolecules. They are formed during xenobiotic biotransformation reactions and are hypothesized to mediate the toxicity of a large number of quinone antitumor drugs as well as several alkylphenols. In addition, oxidation of specific endogenous alkylphenols (e.g. coniferyl alcohol) and alkylcatechols (e.g. N-acetyldopamine, dopa) to quinone methides plays an important role in the synthesis of several complex plant and animal polymers, including lignin, cuticle and melanin. The role of quinone methides in these various processes is reviewed.
The site specificity and sensitivity of the rat liver to butylated hydroxytoluene-induced damage
1991, Toxicology and Applied Pharmacology
The food additive butylated hydroxytoluene (BHT) is capable of damaging centrilobular or periportal cells in the liver according to the dose and duration of treatment. The effect of two hepatotoxicity potentiating agents on the site specificity of acute cell damage was investigated in Sprague-Dawley rats. A 500 mg/kg oral dose of BHT did not cause overt hepaticnecrosis or alter the cytochrome P450 concentration, but increased ethoxycoumarin-O-deethylation, implying an alteration in the ratio of P450 isoenzymes. Pretreatment with either phenobarbitone (3 × 80 mg/kg, ip) or the glutathione depleting agent buthionine sulfoximine (900 mg/kg, ip) produced liver necrosis in approximately 50% of animals: mainly in centrilobular areas, but with some necrosis in midzonal or periportal areas. Phenobarbitone and BHT did not significantly change the cytochrome P450 concentration, but did alter the ratio of P450 isoenzymes. In phenobarbitone-pretreated rats centrilobular hepatocyte damage was clearly localized in cells with high immunocytochemical staining for the cytochrome P450_IIB subfamily. Buthionine sulfoximine and BHT reduced the cytochrome P450 concentration without reducing ethoxycoumarin-O-deethylase activity, implying a different alteration in the ratio of P450 isoenzymes. These results indicate that phenobarbitone-inducible enzymes are capable of activating high doses of BHT to reactive oxidizing intermediates, which in the absence of adequate glutathione can cause cell death. Enzymes of the P450_IIB subfamily are implicated in this mechanism.

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Modification of butylated hydroxytoluene-induced pulmonary toxicity in mice by diethyl maleate, buthionine sulfoximine, and cysteine

Abstract

Toxicol. Appl. Pharmacol.

Toxicol. Appl. Pharmacol.

Toxicol. Appl. Pharmacol.

Methods Enzymol.

J. Biol. Chem.

Anal. Biochem.