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Yu N, Ye Q, Nie X, Xia C, Meng X. Distribution of 2-tert-butyl-1,4-benzoquinone and its precursor, tert-butylhydroquinone, in typical edible oils and oleaginous foods marketed in Hangzhou City, China. Food Chem 2021; 361:130039. [PMID: 34022482 DOI: 10.1016/j.foodchem.2021.130039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/08/2021] [Accepted: 05/03/2021] [Indexed: 01/22/2023]
Abstract
This study aimed to obtain a reliable evaluation about addition of tert-butylhydroquinone (TBHQ), and distribution of TBHQ and 2-tert-butyl-1,4-benzoquinone (TBBQ) contents in typical edible oils and oleaginous foods marketed in Hangzhou City. Briefly, the probability of labeled with addition of TBHQ in foods decreased from 36.45 ± 2.6% to 28.78 ± 3.7% in the period from 2018 to 2020. In the 135 analyzed samples, TBHQ contents were far less than the maximum legal additive amount, and TBBQ contents ranged from below its limit of quantification (LOQ) to 13.54 ± 1.15 mg/kg. The conversion rate from TBHQ to TBBQ in edible oils was 2.94 ± 1.17%, much lower than that in other food categories. Further research determined that the process method and food composition were the main factors for different conversion rates from TBHQ to TBBQ in various food categories. In addition, oil consumption was found to be the primary source of dietary intake of TBHQ and TBBQ.
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Affiliation(s)
- Ningxiang Yu
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
| | - Qin Ye
- Institute of Food Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou 310014, China
| | - Xiaohua Nie
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
| | - Chaosheng Xia
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
| | - Xianghe Meng
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China.
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2
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Meng X, Xia C, Ye Q, Nie X. tert-Butyl-p-benzoquinone induces autophagy by inhibiting the Akt/mTOR signaling pathway in RAW 264.7 cells. Food Funct 2020; 11:4193-4201. [PMID: 32352125 DOI: 10.1039/d0fo00281j] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
tert-Butyl-p-benzoquinone (TBBQ), a metabolite of tert-butylhydroquinone from food, has cytotoxicity, the underlying mechanism of which is not clear. In this study, the viability of RAW 264.7 cells exposed to TBBQ at concentrations of 0.5-10 μg mL-1 was assayed by MTT. Results suggest that TBBQ decreased the viability in a dose-dependent manner. Monodansylcadaverine (MDC) staining results indicate the occurrence of autophagy induced by TBBQ, which was manifested by activation of LC3-II concurrent with the increased levels of Beclin1 and reduced levels of p62. Elevated lipid peroxide and decreased SOD activity by TBBQ exposure suggest the overproduction of ROS, which may account for the increase in the genotoxic stress protein p53. Both upregulation of p53 and reduction of Akt levels inhibited mTOR, which activated autophagy. Addition of 3-MA counteracted the impact of TBBQ on ATG proteins and cell viability. All of these results suggest that TBBQ induces autophagy of RAW 264.7 cells principally by inhibition of the Akt/mTOR signaling pathway, and they implicate ROS in this regulation.
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Affiliation(s)
- Xianghe Meng
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou, 310014, People's Republic of China.
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3
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The Microbiota-Gut-Brain Axis Heart Shunt Part I: The French Paradox, Heart Disease and the Microbiota. Microorganisms 2020; 8:microorganisms8040490. [PMID: 32235574 PMCID: PMC7232195 DOI: 10.3390/microorganisms8040490] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/04/2020] [Accepted: 03/09/2020] [Indexed: 12/16/2022] Open
Abstract
It has been well established that a vegetarian and polyphenol-rich diet, including fruits, vegetables, teas, juices, wine, indigestible fiber and whole grains, provide health-promoting phytochemicals and phytonutrients that are beneficial for the heart and brain. What is not well-characterized is the affect these foods have when co-metabolized within our dynamic gut and its colonizing flora. The concept of a heart shunt within the microbiota-gut-brain axis underscores the close association between brain and heart health and the so-called “French paradox” offers clues for understanding neurodegenerative and cerebrovascular diseases. Moreover, oxidation-redox reactions and redox properties of so-called brain and heart-protective foods are underappreciated as to their enhanced or deleterious mechanisms of action. Focusing on prodromal stages, and common mechanisms underlying heart, cerebrovascular and neurodegenerative diseases, we may unmask and understanding the means to better treat these related diseases.
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Đorđević J, Kolarević S, Jovanović J, Kostić-Vuković J, Novaković I, Jeremić M, Sladić D, Vuković-Gačić B. Evaluation of genotoxic potential of tert-butylquinone and its derivatives in prokaryotic and eukaryotic test models. Drug Chem Toxicol 2018; 43:522-530. [PMID: 30257571 DOI: 10.1080/01480545.2018.1514043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Tert-butylquinone (TBQ) and its alkylamino and aralkylamino derivatives are of high interest as a potential antitumor agent. Therefore, it was necessary to investigate if the compounds exert undesirable activities such as interaction with DNA molecule which could result in negative side effects in the case of their use in the diseases treatment. The major aim of this study was to investigate genotoxic potential of TBQ and selected derivatives in an acellular model by using plasmid DNA, in the prokaryotic model by the SOS/umuC assay in Salmonella typhimurium TA1535/pSK1002 and in eukaryotic models by using comet assay in human fetal lung cell line (MRC-5) and human liver cancer cell line (HepG2). Results indicated that in the acellular model TBQ and its derivatives do not interact with plasmid pUC19. In the prokaryotic model, only TBQ exerted weak genotoxic potential and only at highly cytotoxic concentrations. In eukaryotic models, genotoxic potential was detected mainly at the highest concentrations of the tested substances but the effect was lower in both cell lines in comparison with benzo[a]pyrene and etoposide which were used as positive controls. Weak genotoxic potential of tested compounds recommends them as good candidates for further testing in development of new antitumor agents.
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Affiliation(s)
- Jelena Đorđević
- Faculty of Biology, Center for Genotoxicology and Ecogenotoxicology, University of Belgrade, Belgrade, Serbia
| | - Stoimir Kolarević
- Faculty of Biology, Center for Genotoxicology and Ecogenotoxicology, University of Belgrade, Belgrade, Serbia
| | - Jovana Jovanović
- Institute for Biological Research "Siniša Stanković", University of Belgrade, Belgrade, Serbia
| | - Jovana Kostić-Vuković
- Faculty of Biology, Center for Genotoxicology and Ecogenotoxicology, University of Belgrade, Belgrade, Serbia.,Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia
| | - Irena Novaković
- Center for Chemistry, Institute for Chemistry, Technology and Metallurgy, University of Belgrade, Belgrade, Serbia
| | - Marko Jeremić
- Innovation Center of Faculty of Chemistry, University of Belgrade, Belgrade, Serbia
| | - Dušan Sladić
- Faculty of Chemistry, University of Belgrade, Belgrade, Serbia
| | - Branka Vuković-Gačić
- Faculty of Biology, Center for Genotoxicology and Ecogenotoxicology, University of Belgrade, Belgrade, Serbia
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5
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Endo S, Nishiyama A, Suyama M, Takemura M, Soda M, Chen H, Tajima K, El-Kabbani O, Bunai Y, Hara A, Matsunaga T, Ikari A. Protective roles of aldo-keto reductase 1B10 and autophagy against toxicity induced by p-quinone metabolites of tert-butylhydroquinone in lung cancer A549 cells. Chem Biol Interact 2015; 234:282-9. [DOI: 10.1016/j.cbi.2014.09.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/20/2014] [Accepted: 09/24/2014] [Indexed: 12/31/2022]
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Matsunaga T, Endo S, Takemura M, Soda M, Yamamura K, Tajima K, Miura T, Terada T, El-Kabbani O, Hara A. Reduction of cytotoxic p-quinone metabolites of tert-butylhydroquinone by human aldo-keto reductase (AKR) 1B10. Drug Metab Pharmacokinet 2012; 27:553-8. [PMID: 22498646 DOI: 10.2133/dmpk.dmpk-12-nt-012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
2-tert-Butylhydroquinone (BHQ), an antioxidant used as a food additive, exhibits an anticancer effect, whereas it is carcinogenic in rodents at high doses. BHQ is metabolized into cytotoxic tert-butylquinone (BQ), which is further converted to 6-tert-butyl-2,3-epoxy-4-hydroxy-5-cyclohexen-1-one (TBEH) through 6-tert-butyl-2,3-epoxy-4-benzoquinone (TBE), which induces chromosomal aberration. The reductases for BQ and TBE may be protective against the toxicity of the two p-quinones, but the responsible human enzymes remain unidentified. In this study, we compared the ability of 12 human recombinant enzymes in the aldo-keto reductase (AKR) and short-chain dehydrogenase/reductase superfamilies to reduce BQ and TBE. Among them, AKR1B10 was the most efficient catalyst of the stoichiometric two-electron reduction of BQ and TBE into BHQ and TBEH, respectively. BQ and TBE are more cytotoxic towards endothelial cells than BHQ and TBEH, and their cytotoxicity was decreased by the overexpression of AKR1B10 in the cells. Additionally, AKR1B10 gene expression in human HCT116 cells was up-regulated by treatments with BHQ, BQ and TBE. These results suggest a role for the enzyme in protection at least against the toxicity of the two p-quinone metabolites of BHQ.
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7
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Paradoxical cytotoxicity of tert-butylhydroquinone in vitro: what kills the untreated cells? Arch Toxicol 2012; 86:1481-7. [DOI: 10.1007/s00204-012-0841-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 03/06/2012] [Indexed: 10/28/2022]
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Bekdeser B, Ozyürek M, Güçlü K, Apak R. tert-Butylhydroquinone as a spectroscopic probe for the superoxide radical scavenging activity assay of biological samples. Anal Chem 2011; 83:5652-60. [PMID: 21630637 DOI: 10.1021/ac200788m] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As a more convenient and less costly alternative to electron spin resonance (ESR) and nonspecific nitroblue tetrazolium (NBT) and cytochrome c assays of superoxide radical (SR, O(2)(•-)) detection, a novel probe, tert-butylhydroquinone (TBHQ), is introduced for SR nonenzymatically generated in the phenazine methosulfate-β-nicotinamide adenine dinucleotide (PMS-NADH) system. SR attacks both TBHQ and SR scavengers incubated in solution for 30 min where scavengers compete with TBHQ for the O(2)(•-) produced. TBHQ, but not its O(2)(•-) oxidation product, tert-butyl-1,4-benzoquinone (TBBQ), is responsive to the CUPRAC (cupric reducing antioxidant capacity) spectrophotometric assay. The CUPRAC absorbance of the ethyl acetate extract of the incubation solution arising from the reduction of Cu(II)-neocuproine reagent by the remaining TBHQ was higher in the presence of O(2)(•-) scavengers (due to less conversion to TBBQ), the difference being correlated to the SR scavenging activity (SRSA) of the analytes. With the use of this reaction, a kinetic approach was adopted to assess the SRSA of amino acids, vitamins, and plasma and thiol antioxidants. This assay, applicable to small-molecule antioxidants and tissue homogenates, proved to be efficient for cysteine, uric acid, and bilirubin, for which the widely used NBT test is nonresponsive. Thus, conventional problems of NBT assay arising from formazan insolubility and direct reduction of NBT by tested scavengers were overcome.
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Affiliation(s)
- Burcu Bekdeser
- Department of Chemistry, Faculty of Engineering, Istanbul University, Istanbul, Turkey
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9
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Birrell L, Cahill P, Hughes C, Tate M, Walmsley RM. GADD45a-GFP GreenScreen HC assay results for the ECVAM recommended lists of genotoxic and non-genotoxic chemicals for assessment of new genotoxicity tests. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2010; 695:87-95. [DOI: 10.1016/j.mrgentox.2009.12.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 09/10/2009] [Accepted: 11/14/2009] [Indexed: 01/29/2023]
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10
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Opinion of the Scientific Panel on food additives, flavourings, processing aids and materials in contact with food (AFC) on a request from the Commission related to tertiary-Butylhydroquinone (TBHQ). EFSA J 2004. [DOI: 10.2903/j.efsa.2004.84] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Okubo T, Yokoyama Y, Kano K, Kano I. Cell death induced by the phenolic antioxidant tert-butylhydroquinone and its metabolite tert-butylquinone in human monocytic leukemia U937 cells. Food Chem Toxicol 2003; 41:679-88. [PMID: 12659721 DOI: 10.1016/s0278-6915(03)00002-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
2-tert-Butyl-4-hydroquinone (TBHQ), a phenolic antioxidant used as a food additive, and its metabolite 2-tert-butyl-1,4-benzoquinone (TBQ) were both cytotoxic in human monocytic leukemia U937 cells, TBQ being the more strongly cytotoxic. Both compounds induced caspase activity towards DEVD-MCA as a substrate and the cleavage of poly(ADP-ribose) polymerase in cells. Enzyme activities of caspase-3,-7,-6 and -9 seemed to be induced, and procaspases-3 and-7 were processed to active forms in cells treated with TBHQ and TBQ. They induced nuclear condensation and fragmentation in some cells. Electron microscopic examination revealed severe disruption of mitochondrial structure and the formation of intracellular vacuoles. Morphological changes were more marked in the cells treated with TBHQ than TBQ. Mitochondrial transmembrane potential was disrupted. Cytochrome c was released from mitochondria to cytosol and ATP level was moderately decreased by the treatment of cells with these chemicals. Cellular glutathione (GSH) appeared to contribute to defense against cell death induced by TBQ, but its contribution was not marked in the case of TBHQ. TBHQ and TBQ exhibited the apoptotic features in various assays, but the mode of cell death may not be defined as a typical apoptosis or necrosis.
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Affiliation(s)
- T Okubo
- Department of Toxicology, The Tokyo Metropolitan Research Laboratory of Public Health, 3-24-1 Hyakunin-cho, Shinjuku-ku, Japan.
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12
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Abstract
The metallothioneins (MT) are small, cysteine-rich heavy metal-binding proteins which participate in an array of protective stress responses. Although a single essential function of MT has not been demonstrated, MT of higher eukaryotes evolved as a mechanism to regulate zinc levels and distribution within cells and organisms. These proteins can also protect against some toxic metals and oxidative stress-inducing agents. In mice, among the four known MT genes, the MT-I and -II genes are most widely expressed. Transcription of these genes is rapidly and dramatically up-regulated in response to zinc and cadmium, as well as in response to agents which cause oxidative stress and/or inflammation. The six zinc-finger metal-responsive transcription factor MTF-1 plays a central role in transcriptional activation of the MT-I gene in response to metals and oxidative stress. Mutation of the MTF-1 gene abolishes these responses, and MTF-1 is induced to bind to the metal response elements in proximal MT promoter in cells treated with zinc or during oxidative stress. The exact molecular mechanisms of action of MTF-1 are not fully understood. Our studies suggest that the DNA-binding activity of MTF-1 in vivo and in vitro is reversibly activated by zinc interactions with the zinc-finger domain. This reflects heterogeneity in the structure and function of the six zinc fingers. We hypothesize that MTF-1 functions as a sensor of free zinc pools in the cell. Changes in free zinc may occur in response to chemically diverse inducers. MTF-1 also exerts effects on MT-I gene transcription which are independent of a large increase in MTF-1 DNA-binding activity. For example, cadmium, which has little effect on the DNA-binding activity of MTF-1 in vivo or in vitro, is a more potent inducer of MT gene expression than is zinc. The basic helix-loop-helix-leucine zipper protein, USF (upstream stimulatory factor family), also plays a role in regulating transcription of the mouse MT-I gene in response to cadmium or H2O2. Expression of dominant negative USF-1 or deletion of its binding site from the proximal promoter attenuates induction of the mouse MT-I gene. USF apparently functions in this context by interacting with as yet unidentified proteins which bind to an antioxidant response element which overlaps the USF-binding site (USF/ARE). Interestingly, this composite element does not participate in the induction of MT-I gene transcription by zinc or redox-cycling quinones. Thus, regulation of the mouse MT-I gene by metals and oxidative stress involves multiple signaling pathways which depend on the species of metal ion and the nature of the oxidative stress.
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Affiliation(s)
- G K Andrews
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City 66160-7421, USA.
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13
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Dalton TP, Li Q, Bittel D, Liang L, Andrews GK. Oxidative stress activates metal-responsive transcription factor-1 binding activity. Occupancy in vivo of metal response elements in the metallothionein-I gene promoter. J Biol Chem 1996; 271:26233-41. [PMID: 8824273 DOI: 10.1074/jbc.271.42.26233] [Citation(s) in RCA: 185] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Oxidative stress (tert-butylhydroquinone) rapidly induced metallothionein-I gene expression in mouse Hepa cells, and this effect was mediated predominantly through metal response promoter elements in transient transfection assays. In vivo genomic footprinting of the mouse metallothionein-I promoter after treatment of Hepa cells with hydrogen peroxide, tert-butylhydroquinone, or zinc suggested a rapid increase in occupancy of the metal response elements. More subtle changes also occurred in the constitutive genomic footprint at the composite major late transcription factor/antioxidant response element. This element may, in part, mediate induction by hydrogen peroxide. Electrophoretic mobility shift assays demonstrated a rapid (30 min) increase in the DNA binding activity of metal-responsive transcription factor-1 in Hepa cells treated with any of these inducers. In control cells, upstream stimulatory factor binding with the major late transcription factor site, and a nuclear protein complex distinct from AP-1, but specific for the antioxidant response element, were detected. The amounts of these complexes were not altered after these treatments. These studies indicate that metal-responsive transcription factor-1 plays a role in activating mouse metallothionein-I gene transcription in response to reactive oxygen species.
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Affiliation(s)
- T P Dalton
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160-7421, USA
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Nakagawa Y. Effects of dicoumarol on cytotoxicity caused by tert-butylhydroquinone in isolated rat hepatocytes. Toxicol Lett 1996; 84:63-8. [PMID: 8614906 DOI: 10.1016/0378-4274(95)03608-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The effects of dicoumarol, an inhibitor of DT-diaphorase, on the cytotoxicity of tert-butylhydroquinone (tBHQ) were studied in freshly isolated rat hepatocytes. Addition of tBHQ (0.5 mM) to hepatocytes resulted in a time-dependent cell death accompanied by depletion of intracellular ATP, glutathione (GSH), and protein thiols. Pretreatment of hepatocytes with dicoumarol (30 microM) did not affect cell viability or cellular levels of ATP, GSH, or protein thiols during the incubation period; however, dicoumarol did promote the appearance of cell blebs and the depletion of ATP and protein thiols induced by tBHQ and ultimately enhanced the cytotoxicity of tBHQ.
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Affiliation(s)
- Y Nakagawa
- Department of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health, Japan
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Ahmad I, Krishnamurthi K, Arif JM, Ashquin M, Mahmood N, Athar M, Rahman Q. Augmentation of chrysotile-induced oxidative stress by BHA in mice lungs. Food Chem Toxicol 1995; 33:209-15. [PMID: 7896231 DOI: 10.1016/0278-6915(94)00137-d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Asbestos is known to induce oxidative stress in the lung. The consumption of butylated hydroxyanisole (BHA) in preserved food and soft drinks is increasing in the general population, which includes workers in asbestos factories. Because there is no information on the effect of co-exposure to chrysotile and BHA, the time-dependent effects of a single intratracheal dose of chrysotile (1 mg per mouse) and a single ip dose of BHA (350 mg/kg body weight) on various indices of oxidative stress such as lipid peroxidation, hydrogen peroxide generation, glutathione peroxidase (GPX), glutathione reductase (GR), catalase, glucose-6-phosphate dehydrogenase (G6PDH) and glutathione (GSH) were followed for up to 14 days. Microsomal lipid peroxidation (as well as that induced by NADPH) was significantly enhanced by BHA in the chrysotile-exposed group. GPX and GR activities in the same group were gradually decreased by BHA. Non-significant modulation of catalase activity by BHA was also noted. BHA induces GSH to a significant extent in lungs exposed with chrysotile. An increase in the G6PDH activity was maximal (19%; P < 0.05) at day 3. The results clearly demonstrate that BHA enhances chrysotile-induced oxidative stress in the lung.
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Affiliation(s)
- I Ahmad
- Industrial Toxicology Research Centre, Lucknow, India
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Nakagawa Y, Nakajima K, Moore G, Moldéus P. On the mechanisms of 3-tert-butyl-4-hydroxyanisole- and its metabolites-induced cytotoxicities in isolated rat hepatocytes. Eur J Pharmacol 1994; 270:341-8. [PMID: 7805783 DOI: 10.1016/0926-6917(94)90010-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The cytotoxic effects of 3-tert-butyl-4-hydroxyanisole (BHA) and its metabolites, 3-tert-butylhydroquinone (tBHQ) and 3-tert-butyl-4,5-dihydroxyanisole (BHA-OH), were investigated in freshly isolated rat hepatocytes. These compounds caused a time-dependent cell death accompanied by loss of intracellular ATP, glutathione (GSH) and protein thiols at concentration of 0.5 mM. Supplementation of the hepatocyte suspension with 5 mM N-acetylcysteine, a precursor of intracellular GSH, significantly delayed the onset of cytotoxicity induced by BHA-OH and tBHQ; the loss of intracellular ATP, GSH and protein thiols was also prevented. Although N-acetylcysteine did not affect BHA disappearance in the cell suspension, disappearance of tBHQ and formation of tBHQ-GSH conjugate were stimulated by N-acetylcysteine. In addition, N-acetylcysteine prevented BHA-OH disappearance and 3-tert-butyl-5-methoxy-1,2-benzoquinone (BHA-Q) formation. In isolated hepatic mitochondria, BHA, tBHQ and BHA-OH impaired respiration related to oxidative phosphorylation; tert-butylquinone (tBQ) and BHA-Q, quinones derived from tBHQ and BHA-OH, resulted in the significant inhibition of mitochondrial respiration. These results indicate that BHA-OH is the most cytotoxic followed by tBHQ and BHA and that protein thiols and mitochondrial respiratory system are important targets for BHA and its intermediates.
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Affiliation(s)
- Y Nakagawa
- Department of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health, Japan
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