Ultrastructural and biochemical changes in the liver of monkeys given butylated hydroxytoluene and butylated hydroxyanisole.
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When butylated hydroxytoluene (BHT) was administered to rats, the smallest subunit Ya (Mr 22,000) of rat liver GSH S-transferases was found to undergo maximum induction. It is suggested that the differential induction of GSH S-transferase activities by BHT towards different substrates may be due to the differences in the induction of the constituent subunits of GSH S-transferases.
Butylated hydroxytoluene has been previously shown to damage alveolar type-I cells followed by proliferation of type-II pneumocytes which then redifferentiate into intermediate and newly formed type-I epithelial cells. In relation to this transformation process, in vivo incorporation of H3-choline, a precursor of the main component of lung surfactant, was studied in type-II cells of BHT-treated mice by electron microscopic radioautography. The labeling density was reduced in some type-II cells at 2, 3 and 5 days after a single injection of BHT. Cellular compartment analysis indicated that the transformation of type-II cells is accompanied by a notable loss of their lamellar body component as well as a decreased radioautographic labeling associated with this cell type, possible in relation with modified synthesis of phospholipid material of surfactant.
Concentrations of synthetic antioxidants butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone were quantified using a high-performance liquid chromatograph with spectrofluorometric detector. The antioxidants were separated and eluted on a reversed-phase column by gradient of a mixture of H2O/acetonitrile/acetic acid (66.5: 28.5:5, by vol) and a mixture of acetonitrile/acetic acid (95:5, vol/vol). The eluants were monitored at emission and excitation wavelengths of 310 and 280 nm, respectively. Calibration curves obtained using peak areas against concentration showed high coefficients of multiple determination (R2 > 0.99) for all antioxidants. Known concentrations of added antioxidant standards were recoverable within 98-99% from oils and over 93% from mouse blood. This method requires minimum sample extraction and purification before analysis and provides a relatively high percentage recovery. The method has been applied successfully for the measurement of antioxidant concentrations in oils, dried foods, and biological fluids.
The study was conducted to establish the estimated daily intake (EDI) of antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) in Korea. The EDIs were obtained from two sources. One of the estimations was based on the analytical determination of BHA, BHT and TBHQ in 12 food categories (ten food categories for TBHQ) and on individual dietary intake data obtained from the National Health and Nutrition Survey in 1998 (n=11 525, age > 1 year). The other EDIs of BHA, BHT and TBHQ were based on the maximum permitted levels specified in national food standards in Korea and on individual dietary intake data obtained from the National Health and Nutrition Survey in 1998 (n=11 525, age > 1 year). To establish the EDIs based on the analytical determination and on individual dietary intake data, 133 food samples in 12 food categories were selected from the foods considered to be representative sources of BHA, BHT and TBHQ in the Korean diet. Selected samples were analysed by GC with FID. BHA was not detected in any of the samples analysed. BHT and TBHQ were detected in the samples, but the levels were significantly lower than their maximum limits. The EDIs1 of BHT, and TBHQ for average consumers were 0.0156(-3), and 0.0012(-3) mg kg(-1) body weight bw day(-1) and as a proportion of the ADI were 0.0052 and 0.0002%, respectively. For 95th percentile consumers, the EDIs of BHT and TBHQ were 0.0080 and 0.0006 mg kg(-1) bw day(-1), and as a proportion of the ADI were 2.67 and 0.09%, respectively. EDIs for BHA, BHT and TBHQ based on the maximum permitted levels and on individual dietary intake data were 0.04, 0.04 and 0.04 mg kg(-1) bw day(-1), respectively. The EDIs of BHA, BHT and TBHQ for average consumers ranged from 6.00 to 14.42% of the ADI of each antioxidant. According to these results, the EDIs of BHA, BHT and TBHQ in Korea were significantly lower than ADI of these antioxidants established by the JECFA.
The nature of the skin tumor promotion response to a hydroperoxide metabolite of butylated hydroxytoluene, 2,6-di-tert-butyl-4-hydroperoxyl-2,5-cyclohexadienone (BHTOOH), was examined in SENCAR mice. BHTOOH was an effective inducer of epidermal ornithine decarboxylase (ODC) activity. Maximal induction of ODC activity was observed 12 hours after a single application of BHTOOH. Dose-dependent increases were seen between 2 and 20 mumol while higher amounts were less effective. A similar dose-response relationship for papilloma and carcinoma formation was observed when BHTOOH was applied twice weekly for 50 weeks to mice previously initiated with 7,12-dimethylbenz[a]anthracene. Doses of 2, 8, and 20 mumol BHTOOH gave maximal papilloma responses of 0.1, 0.6, and 3.6 papillomas/mouse, respectively. The progression of papillomas to carcinomas was examined and at 60 weeks the incidence of carcinomas was 0, 17, and 28% for the three treatment groups. The carcinoma:papilloma ratios were 0.08 and 0.40 for the high and intermediate BHTOOH dose groups. The data suggest that BHTOOH, unlike butylated hydroxytoluene, is an effective tumor promoter in mouse skin. Additionally, BHTOOH may enhance the conversion of papillomas to carcinomas. However, BHTOOH is not a complete carcinogen in that no papillomas or carcinomas were observed in uninitiated mice treated with BHTOOH only.
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The effect of butylated hydroxytoluene on the carcinogenicity to rats of concurrently administered N-2-fluorenylacetamide was determined. N-2-Fluorenylacetamide at 200 ppm alone in the diet produced liver neoplasms but no bladder neoplasms after 25 weeks. With simultaneous administration, 6000 ppm butylated hydroxytoluene inhibited the induction of liver neoplasms but resulted in production of bladder neoplasms. The finding that butylated hydroxytoluene inhibited hepatocarcinogenesis by N-2-fluorenylacetamide but enhanced bladder carcinogenesis demonstrates the complexity of potential effects on chemical carcinogenesis produced by modifying agents.
The antioxidant, butylated hydroxytoluene (BHT), causes lung toxicity in mice followed by regenerative repair, and can also modulate the development of carcinogen-induced lung adenomas. We are investigating changes in pulmonary biochemistry following BHT treatment in order to understand the mechanisms of BHT-induced pulmonary regenerative repair. BHT administration lowered cytosolic Ca2+-activated neutral protease (calpain) activity, increased the activity of the endogenous calpain inhibitor, calpastatin, increased the extent of photoincorporation of 8-N3-[32P]cAMP into a Mr 37,000 proteolytic product derived from cAMP-dependent protein kinase regulatory (R) subunits, and increased membrane-associated protease activity. All of these changes were dependent on the BHT dosage; the altered proteolytic activities occurred at a dose lower than that which caused observable lung toxicity as assessed by the lung weight/body weight ratio. Decreased cytosolic calpain activity was detectable within 1 day after BHT administration, was lowest at 4-7 days, and had not returned to control levels by Day 21, a time when normal lung morphology had been regained. The decrease in calpain activity cannot fully be accounted for by increased calpastatin activity; upon separation of these proteins by DEAE chromatography, the amount of calpain activity from BHT-treated mice remained lower than the corresponding peak from control mice. Increased photolabeling of the Mr 37,000 protein began at 1 day and continued to increase up to 4 days after BHT. All of the cytosolic changes preceded the increased particulate proteolytic activity by 1-2 days. R-subunits which have dissociated from their catalytic subunits are more susceptible to degradation by calpain, but BHT treatment did not enhance subunit dissociation as determined by the elution profile of 8-N3-[32P]cAMP-labeled R-subunits following DEAE chromatography. A large percentage of the particulate protease activity was inhibited by calpastatin, leupeptin, and E-64, all of which are known to inhibit calpain activity; this suggested that calpain accounted for most of this activity. Changes in the activities of proteases which catalyze limited proteolysis reactions may play an important role in the repair of acute lung injury.
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The ip coadministration of 200 mg/kg butylated hydroxyanisole (BHA) with a subtoxic dose (200 mg/kg) of butylated hydroxytoluene (BHT) enhanced the lung toxicity of BHT in mice. BHA coadministration significantly increased the radioactivity covalently bound to lung macromolecules at 4-8 hr after [14C]BHT. The area under the concentration versus time curve (AUC) for unchanged BHT in the lung for 24 hr after the coadministration was about 140% of that after the sole administration of BHT. At 2-8 hr after BHT, the coadministration produced a 40-85% increase in plasma concentration of unchanged BHT, but a 40-60% decrease in plasma concentration of total BHT (mainly consisted of BHT metabolites). The total metabolism of BHT by liver 9000 g supernatant was significantly reduced by in vitro addition of BHA. Pretreatment of mice with 200 mg/kg BHA also reduced the rate of 9000 g supernatant metabolism of BHT. These results support the suggestion that coadministration of BHA and BHT results in a decrease in the first-pass metabolism of BHT in the liver and thus the lung is exposed to a larger amount of BHT, developing enhanced toxic response.
The effect of butylated hydroxytoluene (BHT) and its metabolites on DNA cleavage in vitro was studied with supercoiled plasmid DNA, pUC18, by agarose gel electrophoresis. Among several BHT metabolites, 2,6-di-t-butyl-p-benzoquinone (BHT-quinone) caused cleavage of supercoiled DNA (form I) at a concentration as low as 1 x 10(-6) M. The relative amount of linear form (form III) was increased with increasing concentration of BHT-quinone. 2,6-Di-t-butyl-4-hydroperoxy-4-methyl-2,5-cyclohexadienone (BHT-peroxyquinol) and 3,5-di-t-butyl-4-hydroxybenzaldehyde (BHT-CHO) also cleaved DNA, but to a lesser extent than BHT-quinone. No DNA cleavage was detected by BHT, 2,6-di-t-butyl-4-hydroxymethyl phenol (BHT-OH), 3,5-di-t-butyl-4-hydroxybenzoic acid (BHT-COOH), 2,6-di-t-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone (BHT-quinol) or 2,6-di-t-butyl-4-methylene-2,5-cyclohexadienone (BHT-quinone methide). The DNA cleavage by BHT-quinone was inhibited by oxygen radical scavengers including superoxide dismutase (SOD), catalase, polyethylene glycol, t-butyl alcohol, dimethyl sulfoxide, sodium azide, sodium benzoate, bovine serum albumin and methionine, while it was enhanced by the addition of FeCl2. The production of superoxide radical in a solution of BHT-quinone was confirmed by cytochrome c reduction assay. Superoxide was not produced by BHT or other BHT metabolites except for BHT-quinone. These results suggest that BHT-quinone, one of the principal metabolites of BHT, cleaves DNA strands via its generation of oxygen radicals.(ABSTRACT TRUNCATED AT 250 WORDS)
Butylated hydroxytoluene is an antioxidant that has antiviral properties and sustains sperm viability during freezing and thawing. A field trial involving 11 bulls and 19,000 AI was conducted to determine whether addition of .5 mM butylated hydroxytoluene to whole milk extender during seminal processing affected bull fertility as estimated by nonreturn rates generated by cows bred to the bulls. Effects of bull, batch of semen nested within bull, treatment, and month of AI were studied. Nonreturn rates were recorded for each month for every bull, batch of semen (ejaculates pooled on a given day), and treatment combination. Because some bulls had < 6 batches of semen, the original experimental design was reduced to two smaller designs. Categorical data analysis with maximum likelihood estimation was used for analysis of nonreturn rates. The results from three models were used to interpret the data. The nonreturn rates were approximately 73.9% for the butylated hydroxytoluene treatment and 74.1% for the control. In all models, bull effect was significant, but batch, month of AI, and treatment had no effect on bull fertility. Addition of .5 mM butylated hydroxytoluene to whole milk extender during semen processing did not affect bull nonreturn rates.
The effect of butylated hydroxytoluene (BHT) on gamma-glutamyl transpeptidase (GGT) activity in F344 rat liver was investigated. GGT activity was significantly higher after the 1st week of BHT feeding than in control rats, and the high activity was maintained until BHT feeding was stopped. Four weeks after the cessation of an 8-week course of BHT feeding, there was no difference in liver GGT activity between control rats and BHT-treated rats. Histochemical analysis showed that GGT-positive hepatocytes appeared in periportal areas of the liver lobules in BHT-treated rats.
Butylated hydroxytoluene (BHT) is one of the antioxidants added to human and animal feed products in concentrations ranging from 50 to 200 ppm to delay degradation of the labile lipid components. BHT is known to be an inactivator of mammalian and bacterial viruses that contain lipid. Results of in vitro studies showed that 10 ppm of BHT in Mycoplasma medium prevented growth of each of the six Mycoplasma synoviae (Ms) isolates. BHT added at 100, 200, and 400 ppm in the feed did not have any significant in vivo effect on the Ms serological responses or show any chemoprophylactic effect on birds infected with Ms.
The effect of butylated hydroxytoluene (BHT) on doxorubicin (Adriamycin)-induced skin ulcers was investigated in mice. The skin lesions produced by a single intradermal (ID) injection of doxorubicin (0.05 mg; 1 mg/ml) reached maximum size between 5 and 10 days after injection of ADR. Different concentrations of BHT were administered by different routes and at different times in relation to the injection of doxorubicin. The most effective dose of BHT was 4 mg/animal. The topical application of BHT immediately following doxorubicin injection reduced the area of the ulcer by 57%; the immediate ID injection of BHT reduced the size of the ulcer by 84%. Additional studies are required to determine whether BHT will be a clinically useful modifier of the toxicity associated with doxorubicin extravasation in cancer patients.