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Ma J, Zhang C, He Y, Chen X, Lin G. Fasting augments pyrrolizidine alkaloid-induced hepatotoxicity. Arch Toxicol 2021; 96:639-651. [PMID: 34792613 DOI: 10.1007/s00204-021-03193-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 11/04/2021] [Indexed: 12/16/2022]
Abstract
Pyrrolizidine alkaloids (PAs) are phytotoxins widely present in various natural products and foodstuffs. The present study aims to investigate the effects of fasting on PA-induced hepatotoxicity and the underlying biochemical mechanisms. The results of hepatotoxic study showed that 15-h overnight fasting significantly exacerbated the hepatotoxicity of retrorsine (RTS, a representative toxic PA) in fasted rats compared to fed rats, as indicated by remarkably elevated plasma ALT and bilirubin levels and obvious liver histological changes. Further toxicokinetic studies revealed that fasting significantly enhanced cytochromes P450 enzymes (CYPs)-mediated metabolic activation of RTS leading to increased formation of pyrrole-protein adducts and thus decreased the in vivo exposure and excretion of both parent RTS and its N-oxide metabolite. Metabolic studies demonstrated that fasting induced enzyme activities of CYP1A2, CYP2B6 and CYP2E1 that participated in catalyzing RTS to its reactive pyrrolic metabolites. Moreover, fasting also dramatically decreased hepatic glutathione (GSH) content, which restricted the detoxification of GSH by neutralizing the reactive pyrrolic metabolite of RTS, further contributing to the enhanced hepatotoxicity. The present findings may have an impact on future PA toxicity tests with different dietary styles and/or risk assessment of metabolite-mediated toxins by considering the profound effects of fasting.
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Affiliation(s)
- Jiang Ma
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Chunyuan Zhang
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Yisheng He
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xinmeng Chen
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ge Lin
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China.
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Ma J, Li M, Li N, Chan WY, Lin G. Pyrrolizidine Alkaloid-Induced Hepatotoxicity Associated with the Formation of Reactive Metabolite-Derived Pyrrole-Protein Adducts. Toxins (Basel) 2021; 13:723. [PMID: 34679016 PMCID: PMC8540779 DOI: 10.3390/toxins13100723] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 12/19/2022] Open
Abstract
Pyrrolizidine alkaloids (PAs) with 1,2-unsaturated necine base are hepatotoxic phytotoxins. Acute PA intoxication is initiated by the formation of adducts between PA-derived reactive pyrrolic metabolites with cellular proteins. The present study aimed to investigate the correlation between the formation of hepatic pyrrole-protein adducts and occurrence of PA-induced liver injury (PA-ILI), and to further explore the use of such adducts for rapidly screening the hepatotoxic potency of natural products which contain PAs. Aqueous extracts of Crotalaria sessiliflora (containing one PA: monocrotaline) and Gynura japonica (containing two PAs: senecionine and seneciphylline) were orally administered to rats at different doses for 24 h to investigate PA-ILI. Serum alanine aminotransferase (ALT) activity, hepatic glutathione (GSH) level, and liver histological changes of the treated rats were evaluated to assess the severity of PA-ILI. The levels of pyrrole-protein adducts formed in the rats' livers were determined by a well-established spectrophotometric method. The biological and histological results showed a dose-dependent hepatotoxicity with significantly different toxic severity among groups of rats treated with herbal extracts containing different PAs. Both serum ALT activity and the amount of hepatic pyrrole-protein adducts increased in a dose-dependent manner. Moreover, the elevation of ALT activity correlated well with the formation of hepatic pyrrole-protein adducts, regardless of the structures of different PAs. The findings revealed that the formation of hepatic pyrrole-protein adducts-which directly correlated with the elevation of serum ALT activity-was a common insult leading to PA-ILI, suggesting a potential for using pyrrole-protein adducts to screen hepatotoxicity and rank PA-containing natural products, which generally contain multiple PAs with different structures.
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Affiliation(s)
- Jiang Ma
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong 4054577, China; (J.M.); (M.L.); (N.L.); (W.Y.C.)
- School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou 510000, China
| | - Mi Li
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong 4054577, China; (J.M.); (M.L.); (N.L.); (W.Y.C.)
| | - Na Li
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong 4054577, China; (J.M.); (M.L.); (N.L.); (W.Y.C.)
| | - Wood Yee Chan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong 4054577, China; (J.M.); (M.L.); (N.L.); (W.Y.C.)
| | - Ge Lin
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong 4054577, China; (J.M.); (M.L.); (N.L.); (W.Y.C.)
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Cheng T, Li W, Yang X, Wang H, Zhang F, Li N, Lin G, Zheng J. Antibody-based detection of lysine modification of hepatic protein in mice treated with retrorsine. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, TOXICOLOGY AND CARCINOGENESIS 2020; 38:315-328. [PMID: 33382013 DOI: 10.1080/26896583.2020.1832411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Many pyrrolizidine alkaloids (PAs), an important class of natural products, are hepatotoxic and carcinogenic. Increased attention has been paid to PA poisoning cases worldwide. Generally, most PAs themselves are not toxic. However, reactive intermediates formed from PAs by metabolic oxidation have been linked to toxicity and carcinogenesis. PAs themselves are generally not toxic, and their reactive metabolites resulting from metabolic oxidation are considered to be an essential responsible for PA toxicities. Protein modification by the electrophilic metabolites is proposed to play a key role in PA-induced cytotoxicity. The present study investigated the interaction of lysine residues of proteins with reactive metabolites of toxic PAs. Antibodies selectively recognizing lysine-based protein adduction were prepared and characterized. ELISA and immunoblot methods, in the presence and absence of synthetic model PA adducts, were used to test specific binding of the antibodies to modified lysine residues of BSA and to hepatic proteins extracted from mice treated with retrorsine. The lysine residue adduction was also detected in the tissues of retrorsine-treated mice by use of an immunohistochemical approach. In conclusion, the prepared antibodies selectively recognized the lysine adducts and may be used for the investigation of mechanisms of toxic action of PAs.
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Affiliation(s)
- Ting Cheng
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Provincial Key Laboratory of Pharmaceutics, Guizhou Medical University, Guiyang, Guizhou, P. R. China
- School of Pharmacy, Guizhou Medical University, Guiyang, Guizhou, P. R. China
| | - Weiwei Li
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Provincial Key Laboratory of Pharmaceutics, Guizhou Medical University, Guiyang, Guizhou, P. R. China
- School of Pharmacy, Guizhou Medical University, Guiyang, Guizhou, P. R. China
| | - Xiaojing Yang
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning, P. R. China
| | - Huali Wang
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Division of Gastroenterology, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Fan Zhang
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Division of Gastroenterology, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Na Li
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR
| | - Ge Lin
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR
| | - Jiang Zheng
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Provincial Key Laboratory of Pharmaceutics, Guizhou Medical University, Guiyang, Guizhou, P. R. China
- School of Pharmacy, Guizhou Medical University, Guiyang, Guizhou, P. R. China
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning, P. R. China
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Division of Gastroenterology, Department of Pediatrics, University of Washington, Seattle, WA, USA
- Key Laboratory of Environmental Pollution, Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, P. R. China
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Xu J, Wang W, Yang X, Xiong A, Yang L, Wang Z. Pyrrolizidine alkaloids: An update on their metabolism and hepatotoxicity mechanism. LIVER RESEARCH 2019. [DOI: 10.1016/j.livres.2019.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
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Ning J, Chen L, Rietjens IM. Role of toxicokinetics and alternative testing strategies in pyrrolizidine alkaloid toxicity and risk assessment; state-of-the-art and future perspectives. Food Chem Toxicol 2019; 131:110572. [DOI: 10.1016/j.fct.2019.110572] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 06/05/2019] [Accepted: 06/07/2019] [Indexed: 01/31/2023]
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Ma J, Ruan J, Chen X, Li D, Yao S, Fu PP, Ye Y, Gao H, Wang J, Lin G. Pyrrole-Hemoglobin Adducts, a More Feasible Potential Biomarker of Pyrrolizidine Alkaloid Exposure. Chem Res Toxicol 2019; 32:1027-1039. [PMID: 31012303 DOI: 10.1021/acs.chemrestox.8b00369] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Pyrrolizidine alkaloids (PAs) are naturally occurring phytotoxins widely distributed in about 3% of flowering plants. The formation of PA-derived pyrrole-protein adducts is considered as a primary trigger initiating PA-induced hepatotoxicity. The present study aims to (i) further validate our previous established derivatization method using acidified ethanolic AgNO3 for the analysis of pyrrole-protein adducts and (ii) apply this method to characterize the binding tendency, dose-response, and elimination kinetics of pyrrole-protein adducts in blood samples. Two pyrrole-amino acid conjugates, (±)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5 H-pyrrolizine (DHP)-cysteine (7-cysteine-DHP) and 9-histidine-DHP, were synthesized and used to demonstrate that acidified ethanolic AgNO3 derivatization can cleave both S-linkage and N-linkage of pyrrole-protein adducts. Subsequently, using precolumn AgNO3 derivatization followed by ultra-high-pressure liquid chromatography/mass spectrometry analysis, we quantified pyrrole-protein adducts in monocrotaline-treated rat blood protein fractions, including hemoglobin (Hb), plasma, albumin, and plasma residual protein fractions, and found that the amount of pyrrole-Hb adducts was significantly higher than that in all plasma fractions. Moreover, elimination half-life of pyrrole-Hb adducts was also significantly longer than pyrrole-protein adducts in plasma fractions (12.08 vs 2.54-2.93 days). In addition, we also tested blood samples obtained from five PA-induced liver injury patients and found that the amount of pyrrole-protein adducts in blood cells was also remarkably higher than that in plasma. In conclusion, our findings for the first time confirmed that the AgNO3 derivatization method could be used to measure both S- and N-linked pyrrole-protein adducts and also suggested that pyrrole-Hb adducts with remarkably higher level and longer life span could be a better biomarker of PA exposure.
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Affiliation(s)
- Jiang Ma
- School of Biomedical Sciences, Faculty of Medicine , The Chinese University of Hong Kong , Hong Kong.,Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines between The Chinese University of Hong Kong and Shanghai Institute of Materia Medica , Chinese Academy of Sciences , Shanghai 201203 , China
| | - Jianqing Ruan
- School of Biomedical Sciences, Faculty of Medicine , The Chinese University of Hong Kong , Hong Kong.,Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines between The Chinese University of Hong Kong and Shanghai Institute of Materia Medica , Chinese Academy of Sciences , Shanghai 201203 , China
| | - Xinmeng Chen
- School of Biomedical Sciences, Faculty of Medicine , The Chinese University of Hong Kong , Hong Kong.,Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines between The Chinese University of Hong Kong and Shanghai Institute of Materia Medica , Chinese Academy of Sciences , Shanghai 201203 , China
| | - Dongping Li
- Division of Gastroenterology, ZhongShan Hospital , Fudan University , Shanghai 200000 , China
| | - Sheng Yao
- Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines between The Chinese University of Hong Kong and Shanghai Institute of Materia Medica , Chinese Academy of Sciences , Shanghai 201203 , China.,State Key Laboratory of Drug Research , Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203 , China
| | - Peter P Fu
- National Center for Toxicological Research , U.S. Food and Drug Administration , Jefferson , Arkansas 72079-9502 , United States
| | - Yang Ye
- Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines between The Chinese University of Hong Kong and Shanghai Institute of Materia Medica , Chinese Academy of Sciences , Shanghai 201203 , China.,State Key Laboratory of Drug Research , Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203 , China
| | - Hong Gao
- Division of Gastroenterology, ZhongShan Hospital , Fudan University , Shanghai 200000 , China
| | - Jiyao Wang
- Division of Gastroenterology, ZhongShan Hospital , Fudan University , Shanghai 200000 , China
| | - Ge Lin
- School of Biomedical Sciences, Faculty of Medicine , The Chinese University of Hong Kong , Hong Kong.,Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines between The Chinese University of Hong Kong and Shanghai Institute of Materia Medica , Chinese Academy of Sciences , Shanghai 201203 , China
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Lu Y, Ma J, Lin G. Development of a two-layer transwell co-culture model for the in vitro investigation of pyrrolizidine alkaloid-induced hepatic sinusoidal damage. Food Chem Toxicol 2019; 129:391-398. [PMID: 31054999 DOI: 10.1016/j.fct.2019.04.057] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 12/01/2022]
Abstract
Pyrrolizidine alkaloids (PAs) are hepatotoxic and specifically damage hepatic sinusoidal endothelial cells (HSECs) via cytochrome P450 enzymes (CYPs)-mediated metabolic activation. Due to the lack of CYPs in HSECs, currently there is no suitable cell model for investigating PA-induced HSEC injury. This study aimed to establish a two-layer transwell co-culture model that mimics hepatic environment by including HepaRG hepatocytes and HSECs to evaluate cytotoxicity of PAs on their major target HSECs. In this model, PAs were metabolically activated by CYPs in HepaRG hepatocytes to generate reactive pyrrolic metabolites, which react with co-cultured HSECs leading to HSEC damage. Three representative PAs, namely retrorsine, monocrotaline, and clivorine, induced significant concentration-dependent cytotoxicity in HSECs in the co-culture model, but did no cause obvious cytotoxicity directly in HSECs. Using the developed co-cultured model, further mechanism studies of retrorsine-induced HSEC damage demonstrated that the reactive pyrrolic metabolite generated by CYP-mediated bioactivation in HepaRG hepatocytes caused formation of pyrrole-protein adducts, reduction of GSH content, and generation of reactive oxygen species in HSECs, leading to cell apoptosis. The established co-culture model is reliable and applicable for cytotoxic assessment of PA-induced HSEC damage and offers a novel platform for screening toxicity of different PAs on their target cells.
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Affiliation(s)
- Yao Lu
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Jiang Ma
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Ge Lin
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
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Khojasteh SC, Miller GP, Mitra K, Rietjens IMCM. Biotransformation and bioactivation reactions - 2017 literature highlights *. Drug Metab Rev 2018; 50:221-255. [PMID: 29954222 DOI: 10.1080/03602532.2018.1473875] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
This annual review is the third one to highlight recent advances in the study and assessment of biotransformations and bioactivations ( Table 1 ). We followed the same format as the previous years with selection and authoring each section (see Baillie et al. 2016 ; Khojasteh et al. 2017 ). We acknowledge that many universities no longer train students in mechanistic biotransformation studies reflecting a decline in the investment for those efforts by public funded granting institutions. We hope this work serves as a resource to appreciate the knowledge gained each year to understand and hopefully anticipate toxicological outcomes dependent on biotransformations and bioactivations. This effort itself also continues to evolve. I am pleased that Drs. Rietjens and Miller have again contributed to this annual review. We would like to welcome Kaushik Mitra as an author for this year's issue, and we thank Deepak Dalvie for his contributions to last year's edition. We have intentionally maintained a balance of authors such that two come from an academic setting and two come from industry. As always, please drop us a note if you find this review helpful. We would be pleased to hear your opinions of our commentary, and we extend an invitation to anyone who would like to contribute to a future edition of this review.
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Affiliation(s)
- S Cyrus Khojasteh
- a Department of Drug Metabolism and Pharmacokinetics , Genentech, Inc , South San Francisco , CA , USA
| | - Grover P Miller
- b Department of Biochemistry and Molecular Biology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Kaushik Mitra
- c Department of Safety Assessment and Laboratory Animal Resources , Merck Research Laboratories (MRL), Merck & Co., Inc , West Point , PA , USA
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Ma J, Xia Q, Fu PP, Lin G. Pyrrole-protein adducts - A biomarker of pyrrolizidine alkaloid-induced hepatotoxicity. J Food Drug Anal 2018; 26:965-972. [PMID: 29976414 PMCID: PMC9303027 DOI: 10.1016/j.jfda.2018.05.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 05/30/2018] [Indexed: 12/11/2022] Open
Abstract
Pyrrolizidine alkaloids (PAs) are phytotoxins identified in over 6000 plant species worldwide. Approximately 600 toxic PAs and PA N-oxides have been identified in about 3% flowering plants. PAs can cause toxicities in different organs particularly in the liver. The metabolic activation of PAs is catalyzed by hepatic cytochrome P450 and generates reactive pyrrolic metabolites that bind to cellular proteins to form pyrrole-protein adducts leading to PA-induced hepatotoxicity. The mechanisms that pyrrole-protein adducts induce toxicities have not been fully characterized. Methods for qualitative and quantitative detection of pyrrole-protein adducts have been developed and applied for the clinical diagnosis of PA exposure and PA-induced liver injury. This mini-review addresses the mechanisms of PA-induced hepatotoxicity mediated by pyrrole-protein adducts, the analytical methods for the detection of pyrrole-protein adducts, and the development of pyrrole-protein adducts as the mechanism-based biomarker of PA exposure and PA-induced hepatotoxicity.
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Affiliation(s)
- Jiang Ma
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines Between the Chinese University of Hong Kong and Shanghai Institute of Materia Medica, China Academy of Sciences, China
| | - Qingsu Xia
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA
| | - Peter P Fu
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 72079, USA.
| | - Ge Lin
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China; Joint Research Laboratory for Promoting Globalization of Traditional Chinese Medicines Between the Chinese University of Hong Kong and Shanghai Institute of Materia Medica, China Academy of Sciences, China.
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Chen L, Ning J, Louisse J, Wesseling S, Rietjens IMCM. Use of physiologically based kinetic modelling-facilitated reverse dosimetry to convert in vitro cytotoxicity data to predicted in vivo liver toxicity of lasiocarpine and riddelliine in rat. Food Chem Toxicol 2018; 116:216-226. [PMID: 29634986 DOI: 10.1016/j.fct.2018.04.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 03/15/2018] [Accepted: 04/05/2018] [Indexed: 01/10/2023]
Abstract
Lasiocarpine and riddelliine are pyrrolizidine alkaloids (PAs) present in food and able to cause liver toxicity. The aim of this study was to investigate whether physiologically based kinetic (PBK) modelling-facilitated reverse dosimetry can adequately translate in vitro concentration-response curves for toxicity of lasiocarpine and riddelliine to in vivo liver toxicity data for the rat. To this purpose, PBK models were developed for lasiocarpine and riddelliine, and predicted blood concentrations were compared to available literature data to evaluate the models. Concentration-response curves obtained from in vitro cytotoxicity assays in primary rat hepatocytes were converted to in vivo dose-response curves from which points of departure (PODs) were derived and that were compared to available literature data on in vivo liver toxicity. The results showed that the predicted PODs fall well within the range of PODs derived from available in vivo toxicity data. To conclude, this study shows the proof-of-principle for a method to predict in vivo liver toxicity for PAs by an alternative testing strategy integrating in vitro cytotoxicity assays with in silico PBK modelling-facilitated reverse dosimetry. The approach may facilitate prediction of acute liver toxicity for the large number of PAs for which in vivo toxicity data are lacking.
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Affiliation(s)
- Lu Chen
- Division of Toxicology, Wageningen University, PO Box 8000, 6700 EA Wageningen, The Netherlands.
| | - Jia Ning
- Division of Toxicology, Wageningen University, PO Box 8000, 6700 EA Wageningen, The Netherlands
| | - Jochem Louisse
- Division of Toxicology, Wageningen University, PO Box 8000, 6700 EA Wageningen, The Netherlands
| | - Sebas Wesseling
- Division of Toxicology, Wageningen University, PO Box 8000, 6700 EA Wageningen, The Netherlands
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, PO Box 8000, 6700 EA Wageningen, The Netherlands
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Khojasteh SC, Rietjens IMCM, Dalvie D, Miller G. Biotransformation and bioactivation reactions - 2016 literature highlights. Drug Metab Rev 2017; 49:285-317. [PMID: 28468514 DOI: 10.1080/03602532.2017.1326498] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We are pleased to present a second annual issue highlighting a previous year's literature on biotransformation and bioactivation. Each contributor to this issue worked independently to review the articles published in 2016 and proposed three to four articles, which he or she believed would be of interest to the broader research community. In each synopsis, the contributing author summarized the procedures, analyses and conclusions as described in the original manuscripts. In the commentary sections, our authors offer feedback and highlight aspects of the work that may not be apparent from an initial reading of the article. To be fair, one should still read the original article to gain a more complete understanding of the work conducted. Most of the articles included in this review were published in Drug Metabolism and Disposition or Chemical Research in Toxicology, but attempts were made to seek articles in 25 other journals. Importantly, these articles are not intended to represent a consensus of the best papers of the year, as we did not want to make any arbitrary standards for this purpose, but rather they were chosen by each author for their notable findings and descriptions of novel metabolic pathways or biotransformations. I am pleased that Drs. Rietjens and Dalvie have again contributed to this annual review. We would like to welcome Grover P Miller as an author for this year's issue, and we thank Tom Baillie for his contributions to last year's edition. We have intentionally maintained a balance of authors such that two come from an academic setting and two come from industry. Finally, please drop us a note if you find this review helpful. We would be pleased to hear your opinions of our commentary, and we extend an invitation to anyone who would like to contribute to a future edition of this review. This article is dedicated to Professor Thomas Baillie for his exceptional contributions to the field of drug metabolism.
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Affiliation(s)
- S Cyrus Khojasteh
- a Department of Drug Metabolism and Pharmacokinetics , Genentech, Inc , South San Francisco , CA , USA
| | | | - Deepak Dalvie
- c Drug Metabolism and Pharmacokinetics, Celgene Corporation , San Diego , CA USA
| | - Grover Miller
- d Department of Biochemistry and Molecular Biology , University of Arkansas for Medical Sciences , Little Rock , AR , USA
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Wieland M, Mann S, Hafner-Marx A, Ignatius A, Metzner M. Hepatic Lipodystrophy in Galloway Calves. Vet Pathol 2017; 54:467-474. [PMID: 28055330 DOI: 10.1177/0300985816684928] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hepatic lipodystrophy in Galloway calves is a fatal liver disease affecting a small proportion of the Galloway breed described in different parts of Europe and North America during the past decades. The clinical findings include a diversity of neurological signs. Clinical pathology findings frequently indicate hepatobiliary disease. Postmortem examination reveals an enlarged, pale yellow, and firm liver. Histologic lesions include hepatic fibrosis, hepatic lipidosis, and bile duct hyperplasia. To date, the etiopathogenesis remains obscure. Infectious causes, intoxications, and a hereditary origin have been considered. We describe hepatic lipodystrophy in Galloway calves from an extensively farmed cow-calf operation in southern Germany. Main clinical findings in 6 calves were consistent with hepatic encephalopathy. Clinical pathology findings in 5 of 6 tested animals revealed increased concentration of total bilirubin (maximum value [MV], 54 μmol/l; reference range [RR], <8.5 μmol/l), direct bilirubin (MV, 20 μmol/l; RR, <3.4 μmol/l), increased activity of gamma glutamyl transferase (MV, 162 U/l; RR, <36 U/l) and glutamate dehydrogenase (MV, 420 U/l; RR, <16 U/l). In addition, activity of glutathione peroxidase was decreased in all tested ( n = 5) animals (MV, 61 U/g hemoglobin [Hb]; RR, >250 U/g Hb). Postmortem examination in 6 calves revealed a firm, diffusely enlarged yellow liver with a finely nodular surface. Histologic lesions included hepatic fibrosis, hepatic lipidosis, and bile duct hyperplasia. Our findings add to the existing data on hepatic lipodystrophy in the Galloway breed and outline a protocol to aid in the diagnosis of this disorder.
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Affiliation(s)
- M Wieland
- 1 Clinic for Ruminants with Ambulatory and Herd Health Services at the Centre for Clinical Veterinary Medicine, LMU Munich, Oberschleissheim, Germany.,2 Current address: Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, NY, USA
| | - S Mann
- 1 Clinic for Ruminants with Ambulatory and Herd Health Services at the Centre for Clinical Veterinary Medicine, LMU Munich, Oberschleissheim, Germany.,2 Current address: Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, NY, USA
| | - A Hafner-Marx
- 3 Bavarian Health and Food Safety Authority, Office Oberschleissheim, Oberschleissheim, Germany
| | - A Ignatius
- 4 Bavarian Animal Health Service, Günzburg, Germany
| | - M Metzner
- 1 Clinic for Ruminants with Ambulatory and Herd Health Services at the Centre for Clinical Veterinary Medicine, LMU Munich, Oberschleissheim, Germany
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Li W, Wang K, Lin G, Peng Y, Zheng J. Lysine Adduction by Reactive Metabolite(s) of Monocrotaline. Chem Res Toxicol 2016; 29:333-41. [DOI: 10.1021/acs.chemrestox.5b00488] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
| | | | - Ge Lin
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, Hong Kong
| | | | - Jiang Zheng
- Center for Developmental Therapeutics,
Seattle Children’s Research Institute, Division of Gastroenterology
and Hepatology, Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington 98102, United States
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14
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Ma L, Zhao H, Xia Q, Cai L, Fu PP. Synthesis and phototoxicity of isomeric 7,9-diglutathione pyrrole adducts: Formation of reactive oxygen species and induction of lipid peroxidation. J Food Drug Anal 2015; 23:577-586. [PMID: 28911718 PMCID: PMC9351797 DOI: 10.1016/j.jfda.2015.06.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Pyrrolizidine alkaloids (PAs) are hepatotoxic, genotoxic, and carcinogenic in experimental animals. Because of their widespread distribution in the world, PA-containing plants are probably the most common poisonous plants affecting livestock, wildlife, and humans. Upon metabolism, PAs generate reactive dehydro-PAs and other pyrrolic metabolites that lead to toxicity. Dehydro-PAs are known to react with glutathione (GSH) to form 7-GSH-(+/−)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (7-GS-DHP) in vivo and in vitro and 7,9-diGS-DHP in vitro. To date, the phototoxicity of GS-DHP adducts has not been well studied. In this study, we synthesized 7-GS-DHP, a tentatively assigned 9-GS-DHP, and two enantiomeric 7,9-diGS-DHP adducts by reaction of dehydromonocrotaline with GSH. The two 7,9-diGS-DHPs were separated by high performance liquid chromatography (HPLC) and their structures were characterized by 1H nuclear magnetic resonance (NMR) and 1H–1H correlation spectroscopy (COSY) NMR spectral analysis. Photoirradiation of 7-GS-DHP, 9-GS-DHP, and the two 7,9-diGS-DHPs as well as dehydromonocrotaline, dehydroheliotrine, and the 7-R enantiomer of DHP (DHR), by UVA light at 0 J/cm2, 14 J/cm2, and 35 J/cm2 in the presence of a lipid, methyl linoleate, all resulted in lipid peroxidation in a light dose-responsive manner. The levels of lipid peroxidation induced by the two isomeric 7,9-diGS-DHPs were significantly higher than that by 7-GS-DHP and 9-GS-DHP. When 7,9-diGS-DHP was irradiated in the presence of sodium azide (NaN3), the level of lipid peroxidation decreased; lipid peroxidation was enhanced when methanol was replaced by deuterated methanol. These results suggest that singlet oxygen is a product induced by the irradiation of 7,9-diGS-DHP. When irradiated in the presence of superoxide dismutase (SOD), the level of lipid peroxidation decreased, indicating that lipid peroxidation is also mediated by superoxide. These results indicate that lipid peroxidation is mediated by reactive oxygen species (ROS). These results suggest that 7,9-diGS-DHPs are phototoxic, generating lipid peroxidation mediated by ROS.
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15
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Luckert C, Hessel S, Lenze D, Lampen A. Disturbance of gene expression in primary human hepatocytes by hepatotoxic pyrrolizidine alkaloids: A whole genome transcriptome analysis. Toxicol In Vitro 2015; 29:1669-82. [PMID: 26100227 DOI: 10.1016/j.tiv.2015.06.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 05/29/2015] [Accepted: 06/19/2015] [Indexed: 11/30/2022]
Abstract
1,2-unsaturated pyrrolizidine alkaloids (PA) are plant metabolites predominantly occurring in the plant families Asteraceae and Boraginaceae. Acute and chronic PA poisoning causes severe hepatotoxicity. So far, the molecular mechanisms of PA toxicity are not well understood. To analyze its mode of action, primary human hepatocytes were exposed to a non-cytotoxic dose of 100 μM of four structurally different PA: echimidine, heliotrine, senecionine, senkirkine. Changes in mRNA expression were analyzed by a whole genome microarray. Employing cut-off values with a |fold change| of 2 and a q-value of 0.01, data analysis revealed numerous changes in gene expression. In total, 4556, 1806, 3406 and 8623 genes were regulated by echimidine, heliotrine, senecione and senkirkine, respectively. 1304 genes were identified as commonly regulated. PA affected pathways related to cell cycle regulation, cell death and cancer development. The transcription factors TP53, MYC, NFκB and NUPR1 were predicted to be activated upon PA treatment. Furthermore, gene expression data showed a considerable interference with lipid metabolism and bile acid flow. The associated transcription factors FXR, LXR, SREBF1/2, and PPARα/γ/δ were predicted to be inhibited. In conclusion, though structurally different, all four PA significantly regulated a great number of genes in common. This proposes similar molecular mechanisms, although the extent seems to differ between the analyzed PA as reflected by the potential hepatotoxicity and individual PA structure.
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Affiliation(s)
- Claudia Luckert
- Department of Food Safety, Federal Institute for Risk Assessment, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany; Department of Nutritional Toxicology, Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Stefanie Hessel
- Department of Food Safety, Federal Institute for Risk Assessment, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany.
| | - Dido Lenze
- Institute of Pathology, Charité-Universitätsmedizin Berlin, Hindenburgdamm 30, 12200 Berlin, Germany
| | - Alfonso Lampen
- Department of Food Safety, Federal Institute for Risk Assessment, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
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16
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Xia Q, Ma L, He X, Cai L, Fu PP. 7-glutathione pyrrole adduct: a potential DNA reactive metabolite of pyrrolizidine alkaloids. Chem Res Toxicol 2015; 28:615-20. [PMID: 25768656 DOI: 10.1021/tx500417q] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pyrrolizidine alkaloid (PA)-containing plants are the most common poisonous plants affecting livestock, wildlife, and humans. PAs require metabolic activation to form pyrrolic metabolites to exert cytotoxicity and tumorigenicity. We previously determined that metabolism of tumorigenic PAs produced four DNA adducts, designated as DHP-dG-3, DHP-dG-4, DHP-dA-3, and DHP-dA-4, that are responsible for liver tumor initiation. 7-Glutathione-(±)-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (7-GS-DHP), formed in vivo and in vitro, and 7,9-di-GS-DHP, formed in vitro, are both considered detoxified metabolites. However, in this study we determined that incubation of 7-GS-DHP with 2'-deoxyguanosine (dG) and 2'-deoxyadenosine (dA) yields DHP-dG-3, DHP-dG-4, DHP-dA-3, and DHP-dA-4 adducts as well as the reactive metabolite DHP. Furthermore, reaction of 7-GS-DHP with calf thymus DNA in aqueous solution at 37 °C for 4, 8, 16, 24, 48, or 72 h, followed by enzymatic hydrolysis yielded DHP-dG-3, DHP-dG-4, DHP-dA-3, and DHP-dA-4 adducts. Under our current experimental conditions, DHP-dA-3 and DHP-dA-4 adducts were formed in a trace amount from the reaction of 7,9-di-GS-DHP with dA. No DHP-dG-3 or DHP-dG-4 adducts were detected from the reaction of 7,9-di-GS-DHP with dG. This study represents the first report that the 7-GS-DHP adduct can be a potential reactive metabolite of PAs leading to DNA adduct formation.
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Affiliation(s)
- Qingsu Xia
- †National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas 72079, United States
| | - Liang Ma
- †National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas 72079, United States
| | - Xiaobo He
- †National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas 72079, United States
| | - Lining Cai
- ‡Biotranex LLC, Monmouth Junction, New Jersey 08852, United States
| | - Peter P Fu
- †National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas 72079, United States
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17
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An application of target profiling analyses in the hepatotoxicity assessment of herbal medicines: comparative characteristic fingerprint and bile acid profiling of Senecio vulgaris L. and Senecio scandens Buch.-Ham. Anal Bioanal Chem 2014; 406:7715-27. [DOI: 10.1007/s00216-014-8175-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 09/05/2014] [Accepted: 09/09/2014] [Indexed: 01/15/2023]
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18
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Xiong A, Yang F, Fang L, Yang L, He Y, Wan YJY, Wan YYJ, Xu Y, Qi M, Wang X, Yu K, Tsim KWK, Wang Z. Metabolomic and genomic evidence for compromised bile acid homeostasis by senecionine, a hepatotoxic pyrrolizidine alkaloid. Chem Res Toxicol 2014; 27:775-86. [PMID: 24641316 DOI: 10.1021/tx400451q] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pyrrolizidine alkaloids (PAs) are among the most hepatotoxic natural products that produce irreversible injury to humans via the consumption of herbal medicine and honey, and through tea preparation. Toxicity and death caused by PA exposure have been reported worldwide. Metabolomics and genomics provide scientific and systematic views of a living organism and have become powerful techniques for toxicology research. In this study, senecionine hepatotoxicity on rats was determined via a combination of metabolomic and genomic analyses. From the global analysis generated from two omics data, the compromised bile acid homeostasis in vivo was innovatively demonstrated and confirmed. Serum profiling of bile acids was altered with significantly elevated conjugated bile acids after senecionine exposure, which was in accordance with toxicity. Similarly, the hepatic mRNA levels of several key genes associated with bile acid metabolism were significantly changed. This process included cholesterol 7-α hydroxylase, bile acid CoA-amino acid N-acetyltransferase, sodium taurocholate cotransporting polypeptide, organic anion-transporting polypeptides, and multidrug-resistance-associated protein 3. In conclusion, a cross-omics study provides a comprehensive analysis method for studying the toxicity caused by senecionine, which is a hepatotoxic PA. Moreover, the change in bile acid metabolism and the respective transporters may provide a new PA toxicity mechanism.
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Affiliation(s)
- Aizhen Xiong
- The MOE Key Laboratory for Standardization of Chinese Medicines and The SATCM Key Laboratory for New Resources and Quality Evaluation of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine , 1200 Cailun Road, Shanghai 201203, China
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19
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Lin G, Wang JY, Li N, Li M, Gao H, Ji Y, Zhang F, Wang H, Zhou Y, Ye Y, Xu HX, Zheng J. Hepatic sinusoidal obstruction syndrome associated with consumption of Gynura segetum. J Hepatol 2011; 54:666-73. [PMID: 21146894 DOI: 10.1016/j.jhep.2010.07.031] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 06/29/2010] [Accepted: 07/28/2010] [Indexed: 12/18/2022]
Abstract
BACKGROUND & AIMS One major cause of hepatic sinusoidal obstruction syndrome (HSOS) is the intake of pyrrolizidine alkaloid (PA)-containing products. Over 8000 PA-induced HSOS cases have been reported worldwide and at least 51 among them were suspected to be attributed to exposure to the Chinese medicine 'Tusanqi'. PA-induced hepatotoxicity involves cytochrome P450-mediated metabolic activation of PAs to electrophilic pyrrolic metabolites which react with macromolecules, such as proteins. However, no studies have found such protein adduction in HSOS patients. We report one HSOS case confirmed by liver biopsy, where the patient claimed taking 'Tusanqi' as self-medication. METHODS The herb was analyzed by HPLC-MS, and its induced hepatotoxicity in rats was assessed by monitoring the alteration of serum ALT level and liver morphology. Blood pyrrole-protein adducts were determined by UPLC-MS. RESULTS The herb the patient consumed was identified as Gynura segetum, an erroneous substitute of non-PA-containing Sedum aizoon, called 'Tusanqi'. Hepatotoxic PAs senecionine and seneciphylline were detected in G. segetum. In the PA-exposed patient, serum pyrrole-protein adducts were detected by a newly developed analytical approach. The animal study showed a good correlation of liver injury with the ingestion of G. segetum. CONCLUSIONS For the first time, serum pyrrole-protein adducts were unequivocally detected in a PA-induced HSOS patient, and such adducts show a potential to be developed as a biomarker for the assessment of PA-induced HSOS. Similar to the well-known case of aristolochic acid-poisoning, the observed HSOS was confirmed to arise from the consumption of PA-containing G. segetum, an erroneous substitute of non-PA-containing S. aizoon.
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Affiliation(s)
- Ge Lin
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, Hong Kong.
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20
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Amin KA, Hassan MS, Awad EST, Hashem KS. The protective effects of cerium oxide nanoparticles against hepatic oxidative damage induced by monocrotaline. Int J Nanomedicine 2011; 6:143-9. [PMID: 21289991 PMCID: PMC3026579 DOI: 10.2147/ijn.s15308] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Objective The objective of the present study was to determine the ability of cerium oxide (CeO2) nanoparticles to protect against monocrotaline (MCT)-induced hepatotoxicity in a rat model. Method Twenty male Sprague Dawley rats were arbitrarily assigned to four groups: control (received saline), CeO2 (given 0.0001 nmol/kg intraperitoneally [IP]), MCT (given 10 mg/kg body weight IP as a single dose), and MCT + CeO2 (received CeO2 both before and after MCT). Electron microscopic imaging of the rat livers was carried out, and hepatic total glutathione (GSH), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) enzymatic activities were quantified. Results Results showed a significant MCT-induced decrease in total hepatic GSH, GPX, GR, and GST normalized to control values with concurrent CeO2 administration. In addition, MCT produced significant increases in hepatic CAT and SOD activities, which also ameliorated with CeO2. Conclusions These results indicate that CeO2 acts as a putative novel and effective hepatoprotective agent against MCT-induced hepatotoxicity.
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Affiliation(s)
- Kamal A Amin
- Department of Biochemistry, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, Egypt.
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21
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He YQ, Yang L, Liu HX, Zhang JW, Liu Y, Fong A, Xiong AZ, Lu YL, Yang L, Wang CH, Wang ZT. Glucuronidation, a new metabolic pathway for pyrrolizidine alkaloids. Chem Res Toxicol 2010; 23:591-9. [PMID: 20092275 DOI: 10.1021/tx900328f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pyrrolizidine alkaloids (PAs) possess significant hepatotoxicity to humans and animals after metabolic activation by liver P450 enzymes. Metabolism pathways of PAs have been studied for several decades, including metabolic activation, hydroxylation, N-oxidation, and hydrolysis. However, the glucuronidation of intact PAs has not been investigated, although glucuronidation plays an important role in the elimination and detoxication of xenobiotics. In this study, PAs glucuronidation was investigated, and three important points were found. First, we demonstrated that senecionine (SEN)-a representative hepatotoxic PA-could be conjugated by glucuronic acid via an N-glucuronidation reaction catalyzed by uridine diphosphate glucuronosyl transferase in human liver microsomes. Second, glucuronidation of SEN was catalyzed not only by human but also other animal species and showed significant species differences. Rabbits, cattle, sheep, pigs, and humans showed the significantly higher glucuronidation activity than mice, rats, dogs, and guinea pigs on SEN. Kinetics of SEN glucuronidation in humans, pigs, and rabbits followed the one-site binding model of the Michaelis-Menten equation, while cattle and sheep followed the two-sites binding model of the Michaelis-Menten equation. Third, besides SEN, other hepatotoxic PAs including monocrotaline, adonifoline, and isoline also underwent N-glucuronidation in humans and several animal species such as rabbits, cattle, sheep, and pigs.
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Affiliation(s)
- Yu-Qi He
- The MOE Key Laboratory for Standardization of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, 1200 Cai Lun Road, Shanghai 201210, China
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22
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Chen YT, Liao JW, Hung DZ. Protective effects of fomepizole on 2-chloroethanol toxicity. Hum Exp Toxicol 2010; 29:507-12. [DOI: 10.1177/0960327109358612] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
2-Chloroethanol (2-CE) is a widely used industrial solvent. In Taiwan, Taiwanese farmers apply 2-CE on grape-vines to accelerate grape growth, a practice that in some cases have caused poisoning in humans. Thus, there is strong interest in identifying antidotes to 2-CE. This study examines the protective role in 2-CE intoxicated rats. Alcohol dehydrogenase and glutathione were hypothesized to be important in the metabolism of 2-CE. This study used fomepizole, an alcohol dehydrogenase inhibitor, and chemicals that affected glutathione metabolism to study 2-CE toxicity. Notably, fomepizole 5 mg/kg significantly increased median lethal dose (LD50) of 2-CE from 65.1 to 180 mg/kg and reduced the production of a potential toxic metabolite chloroacetaldehyde (CAA) in animal plasma. In contrast, disulfiram (DSF), an aldehyde dehydrogenase inhibitor, increased the toxicity of 2-CE on the lethality in rats. Additional or pretreatment with N-acetylcysteine (NAC) and fomepizole significantly reduced plasma CAA concentrations. Fomepizole also significantly reduced 2-CEinhibited glutathione activity. Otherwise, pretreatment with NAC for 4 days followed by co-treatment with fomepizole significantly decreased formation of the metabolic CAA. These results indicated that its catalytic enzyme might play a vital role during 2-CE intoxication, and the combination of fomepizole and NAC could be a protective role in cases of acute 2-CE intoxication.
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Affiliation(s)
- Yng-Tay Chen
- Department of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Jiunn-Wang Liao
- Graduate Institute of Veterinary Pathobiology, National Chung-Hsing University, Taichung, Taiwan, Republic of China
| | - Dong-Zong Hung
- Toxicology Center, China Medical University Hospital and Graduate Institute of Drug Safety, China Medical University, Taichung, Taiwan, Republic of China,
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Xiong A, Yang L, He Y, Zhang F, Wang J, Han H, Wang C, Bligh SWA, Wang Z. Identification of metabolites of adonifoline, a hepatotoxic pyrrolizidine alkaloid, by liquid chromatography/tandem and high-resolution mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:3907-3916. [PMID: 19918941 DOI: 10.1002/rcm.4329] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Hepatotoxic pyrrolizidine alkaloid (HPA)-containing plants have always been a threat to human and livestock health worldwide. Adonifoline, a main HPA in Senecio scandens Buch.-Ham. ex D. Don (Qianli guang), was used officially as an infusion in cases of oral and pharyngeal infections in China. In this study in vivo metabolism of adonifoline was studied for the first time by identifying the metabolites of adonifoline present in bile, urine and feces of rats using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS(n)) (ion trap) as well as liquid chromatography/electrospray ionization high-resolution mass spectrometry (LC/ESI-HRMS) (quadrupole-time of flight). In total 19 metabolites were identified and, among them, retronecine-N-oxides were confirmed by matching their fragmentation patterns with their fully characterized synthetic compounds. These metabolites are all involved in both phase I and phase II metabolic processes and the principal in vivo metabolism pathways of adonifoline were proposed.
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Affiliation(s)
- Aizhen Xiong
- The MOE Key Laboratory for Standardization of Chinese Medicines and The SATCM Key Laboratory for New Resources and Quality Evaluation of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201210, China
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24
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Lin G, Tang J, Liu XQ, Jiang Y, Zheng J. Deacetylclivorine: A Gender-Selective Metabolite of Clivorine Formed in Female Sprague-Dawley Rat Liver Microsomes. Drug Metab Dispos 2007; 35:607-13. [PMID: 17237157 DOI: 10.1124/dmd.106.014100] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Clivorine, a naturally occurring pyrrolizidine alkaloid, causes liver toxicity via its metabolic activation to generate toxic metabolite (pyrrolic ester). Female Sprague-Dawley (SD) rats are reported to be less susceptible to clivorine intoxication than male SD rats. However, the biochemical mechanism causing such gender difference is largely unknown. The present study investigated hepatic microsomal metabolism of clivorine in female rats to delineate the mechanism of the gender difference. Two pathways, which directly metabolize clivorine, were observed. First, the metabolic activation to produce the toxic pyrrolic ester followed by formations of bound pyrroles, dehydroretronecine, 7-glutathionyldehydroretronecine, and clivoric acid were found in female rats, and CYP3A1/2 isozymes were identified to catalyze the metabolic activation. Compared with male rats ( approximately 21%), the metabolic activation in female rats was significantly lower ( approximately 4%) possibly because of significantly lower CYP3A1/2 levels expressed in female rats. Second, a direct hydrolysis to generate the novel female rat-specific metabolite deacetylclivorine was shown as the predominant pathway ( approximately 16% clivorine metabolism) in female rat liver microsomes and was determined to be mediated by microsomal hydrolase A. Furthermore, when the metabolic activation was completely inhibited by ketoconazole, the amount of deacetylclivorine formed in a 1-h incubation significantly increased from 19.44 +/- 3.00 to 54.87 +/- 9.30 nmol/mg protein, suggesting that the two pathways compete with each other. Therefore, the lower susceptibility of female SD rats to clivorine intoxication is suggested to be caused by the significantly higher extent of the direct hydrolysis and a lower degree of the metabolic activation.
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Affiliation(s)
- Ge Lin
- Department of Pharmacology, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR.
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25
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Wang YP, Yan J, Beger RD, Fu PP, Chou MW. Metabolic activation of the tumorigenic pyrrolizidine alkaloid, monocrotaline, leading to DNA adduct formation in vivo. Cancer Lett 2005; 226:27-35. [PMID: 16004930 DOI: 10.1016/j.canlet.2004.11.039] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 11/25/2004] [Accepted: 11/28/2004] [Indexed: 10/26/2022]
Abstract
Monocrotaline is a representative naturally occurring genotoxic pyrrolizidine alkaloid. Metabolism of monocrotaline by liver microsomes of F344 female rats generated (+/-)6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) and monocrotaline-N-oxide as major metabolites. Metabolism in the presence of triacetyleandomycin, a P450 3A enzyme inhibitor, reduced the formation of DHP by 52% and monocrotaline N-oxide formation by 59%. Dexamethasone significantly induced microsomal monocrotaline metabolizing enzyme activities in rat liver and lung. Previously, we have identified a set of DHP-derived DNA adducts from DHP-modified calf thymus DNA by (32)P-post labeling/HPLC analysis. Metabolism of monocrotaline in the presence of calf thymus DNA resulted in a similar set of DHP-DNA adducts. These DHP-DNA adducts were also found in the liver DNA of rats treated with monocrotaline. The time course of the DHP-derived DNA adduct formation and removal in the liver of rats gavaged with a single dose (10mg/kg) of monocrotaline was similar to that of rats treated with riddelliine. The levels of DHP-DNA adducts in liver DNA of rats treated with monocrotaline were much lower than that of riddelliine-treated rats. Results from this study indicate that (i) DHP is a common reactive metabolite for retronecine-type of pyrrolizidine alkaloids, (ii) the formation of DHP-derived DNA adducts in the liver DNA of rats treated with monocrotaline suggests that monocrotaline-induced tumorigenicity is through a genotoxic mechanism.
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Affiliation(s)
- Yu-Ping Wang
- Division of Biochemical Toxicology, National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA
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26
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Duringer JM, Buhler DR, Craig AM. Comparison of hepatic in vitro metabolism of the pyrrolizidine alkaloid senecionine in sheep and cattle. Am J Vet Res 2004; 65:1563-72. [PMID: 15566096 DOI: 10.2460/ajvr.2004.65.1563] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To compare hepatic metabolism of pyrrolizidine alkaloids (PAs) between sheep and cattle and elucidate the protective mechanism of sheep. SAMPLE POPULATION Liver microsomes and cytosol from 8 sheep and 8 cattle. PROCEDURE The PA senecionine, senecionine N-oxide (nontoxic metabolite) and 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP; toxic metabolite) were measured in microsomal incubations. The kcat (turnover number) was determined for DHP and N-oxide formation. Chemical and immunochemical inhibitors were used to assess the role of cytochrome P450s, flavin-containing monooxygenases (FMOs), and carboxylesterases in senecionine metabolism. The CYP3A, CYP2B, and FMO concentrations and activities were determined, in addition to the role of glutathione (GSH) in senecionine metabolism. RESULTS DHP concentration did not differ between species. Sheep formed more N-oxide, had higher N-oxide kcat, and metabolized senecionine faster than cattle. The P450 concentrations and isoforms had a large influence on DHP formation, whereas FMOs had a large influence on N-oxide formation. In cattle, CYP3A played a larger role in DHP formation than in sheep. FMO activity was greater in sheep than in cattle. Addition of GSH to in vitro microsomal incubations decreased DHP formation; addition of cytosol decreased N-oxide formation. CONCLUSIONS AND CLINICAL RELEVANCE Hepatic metabolism differences alone do not account for the variation in susceptibility seen between these species. Rather, increased ruminal metabolism in sheep appears to be an important protective mechanism, with hepatic enzymes providing a secondary means to degrade any PAs that are absorbed from the rumen.
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Affiliation(s)
- Jennifer M Duringer
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
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Fu PP, Xia Q, Lin G, Chou MW. Pyrrolizidine Alkaloids—Genotoxicity, Metabolism Enzymes, Metabolic Activation, and Mechanisms. Drug Metab Rev 2004; 36:1-55. [PMID: 15072438 DOI: 10.1081/dmr-120028426] [Citation(s) in RCA: 368] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Pyrrolizidine alkaloid-containing plants are widely distributed in the world and are probably the most common poisonous plants affecting livestock, wildlife, and humans. Because of their abundance and potent toxicities, the mechanisms by which pyrrolizidine alkaloids induce genotoxicities, particularly carcinogenicity, were extensively studied for several decades but not exclusively elucidated until recently. To date, the pyrrolizidine alkaloid-induced genotoxicities were revealed to be elicited by the hepatic metabolism of these naturally occurring toxins. In this review, we present updated information on the metabolism, metabolizing enzymes, and the mechanisms by which pyrrolizidine alkaloids exert genotoxicity and tumorigenicity.
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Affiliation(s)
- Peter P Fu
- National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
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28
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Affiliation(s)
- Roger A Coulombe
- Department of Veterinary Sciences, Utah State University, Logan, UT 84322-4620, USA
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Genotoxic Pyrrolizidine Alkaloids — Mechanisms Leading to DNA Adduct Formation and Tumorigenicity. Int J Mol Sci 2002. [DOI: 10.3390/i3090948] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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30
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Abstract
Pyrrolizidine poisoning in humans is regarded by most clinical toxicologists as of little relevance. However, a number of individual case studies in the West and some severe cases of mass poisoning by contaminated grains have led to increased interest in these alkaloids. The increasing use of herbal remedies, some of which contain toxic pyrrolizidines, suggests that the incidence of pyrrolizidine poisoning is likely to increase. In this review the authors describe the chemistry and metabolism of pyrrolizidine alkaloids, the salient features of pyrrolizidine poisoning, and the methods available for detection of these compounds in human fluids.
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Affiliation(s)
- M J Stewart
- Indigenous Toxicology Unit, Department of Chemical Pathology, South African Institute for Medical Research, University of the Witwatersrand Medical School, Johannesburg, South Africa.
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31
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Gordon LI. Gemtuzumab Ozogamicin (Mylotarg) and hepatic veno-occlusive disease: take two acetaminophen, and... Bone Marrow Transplant 2001; 28:811-2. [PMID: 11781639 DOI: 10.1038/sj.bmt.1703241] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2001] [Accepted: 07/31/2001] [Indexed: 01/04/2023]
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32
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Steenkamp V, Stewart MJ, van der Merwe S, Zuckerman M, Crowther NJ. The effect of Senecio latifolius a plant used as a South African traditional medicine, on a human hepatoma cell line. JOURNAL OF ETHNOPHARMACOLOGY 2001; 78:51-58. [PMID: 11585688 DOI: 10.1016/s0378-8741(01)00321-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A number of traditional remedies used in South Africa contain pyrrolizidine alkaloids, some of which are hepatotoxic. We investigated the effect on human HuH-7 cells of Senecio latifolius DC., a plant that is a component of some traditional remedies and which is known to contain toxic pyrrolizidine alkaloids. Cells were also treated with extracts of a standard pyrrolizidine, retrorsine. The changes in the gross morphology of the cells were studied using light microscopy after haematoxylin and eosin staining. The cytoskeleton was investigated using fluorescence-labelled anti-beta-tubulin antibody and the nuclear organisation was studied using fluorescence-labelled antinuclear antibodies. The plant extracts gave rise to dose-dependent gross morphological changes. At high doses, we observed necrosis and at lower doses, destruction of the cytoskeleton, nuclear fragmentation and apoptosis. Doses of less than the equivalent of 330 ng/ml retrorsine led to multinucleated cells with failure in spindle formation and clumping of nuclear chromatin. This latter finding suggests that chronic low-dose treatment with such traditional remedies could give rise to teratogenic and/or carcinogenic effects.
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MESH Headings
- Antineoplastic Agents, Phytogenic/isolation & purification
- Antineoplastic Agents, Phytogenic/pharmacology
- Apoptosis/drug effects
- Carcinoma, Hepatocellular/drug therapy
- Carcinoma, Hepatocellular/pathology
- Cell Survival/drug effects
- DNA, Neoplasm/drug effects
- DNA, Neoplasm/metabolism
- Flow Cytometry
- Fluorescent Antibody Technique, Indirect
- Humans
- Liver Neoplasms/drug therapy
- Liver Neoplasms/pathology
- Medicine, Traditional
- Plants, Medicinal/chemistry
- Pyrrolizidine Alkaloids/pharmacology
- Senecio/chemistry
- South Africa
- Tumor Cells, Cultured
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Affiliation(s)
- V Steenkamp
- Department of Chemical Pathology, South African Institute for Medical Research, University of the Witwatersrand Medical School, 7 York Road, Parktown 2193, Gauteng, South Africa
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Wang X, Kanel GC, DeLeve LD. Support of sinusoidal endothelial cell glutathione prevents hepatic veno-occlusive disease in the rat. Hepatology 2000; 31:428-34. [PMID: 10655267 DOI: 10.1002/hep.510310224] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Depletion of sinusoidal endothelial cell glutathione (GSH) has been proposed as a common mechanism leading to hepatic veno-occlusive disease (HVOD). This study examines whether intraportal infusion of GSH can prevent HVOD in the monocrotaline rat model. HVOD was induced in rats with monocrotaline 160 mg/kg i.g. on day 0. GSH was infused intraportally by mini-osmotic pump. Monocrotaline decreased GSH in sinusoidal endothelial cells, but not in liver homogenate. Infusion of GSH, 2 micromol/hr starting day - 1, prevented the decrease in sinusoidal endothelial cell GSH and protected against histological and clinical evidence of HVOD. Protection by GSH was dose-dependent (0.5-2 micromol/hr). In rats receiving continuous GSH infusion, treatment with buthionine sulfoximine starting day - 2 decreased sinusoidal endothelial cell GSH and attenuated the protective effect of GSH against monocrotaline. GSH infusion starting 24 hours after monocrotaline ("glutathione rescue") offered substantial protection to most rats. N-acetyl-L-cysteine conferred protection, but N-acetyl-D-cysteine (an antioxidant that is not a precursor for GSH) had little or no protective effect, and 4-hydroxy TEMPO, a free radical scavenger, was not protective. Discontinuation of the GSH infusion 5 days after monocrotaline administration led to severe hepatic veno-occlusive disease on day 6. In conclusion, monocrotaline selectively depletes sinusoidal endothelial cell GSH. Intraportal infusion of GSH protects against monocrotaline toxicity, at least partially by maintaining sinusoidal endothelial cell GSH levels. Glutathione infusion started after monocrotaline is partially protective. Monocrotaline induces prolonged changes in the liver that remain suppressed as long as GSH is infused.
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Affiliation(s)
- X Wang
- Division of Gastrointestinal Diseases, Research Center for Liver Diseases, USC Keck School of Medicine, Los Angeles, CA, USA
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34
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Huan JY, Miranda CL, Buhler DR, Cheeke PR. Species differences in the hepatic microsomal enzyme metabolism of the pyrrolizidine alkaloids. Toxicol Lett 1998; 99:127-37. [PMID: 9817084 DOI: 10.1016/s0378-4274(98)00152-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Species differences in pyrrolic metabolites and senecionine (SN) N-oxide formation among eight animal species (sheep, cattle, gerbils, rabbits, hamsters, Japanese quail, chickens, rats) varying in susceptibility to pyrrolizidine alkaloid (PA) intoxication were measured in vitro by hepatic microsomal incubations. The results suggested that there is not a strong correlation between the production of pyrrolic metabolites and susceptibility of animals to PA toxicity. The rate of PA activation in hamsters, a resistant species, measured by formation of (+/-)6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) far exceeded the rate of SN N-oxide formation (detoxification) (DHP/N-oxide = 2.29). In contrast, SN N-oxide was the major metabolite in sheep, another resistant species, with much lower production of DHP (DHP/N-oxide = 0.26). The roles of cytochrome P450s and flavin-containing monooxygenases (FMO) in bioactivation and detoxification of pyrrolizidine alkaloids (PA) were studied in vitro using sheep and hamster hepatic microsomes. Chemical and immunochemical inhibition data suggested that the conversion of SN to DHP is catalyzed mainly by cytochrome P450s (68-82%), whereas the formation of SN N-oxide is carried out largely by FMO (55-71%). There also appeared to be a high rate of glutathione-DHP conjugation in hamster (63%) and sheep (79%) liver microsomal incubation mixtures. Therefore, low rates of pyrrole metabolite production coupled with glutathione conjugation in sheep may explain the resistance of sheep to SN, whereas the high rate of GSH-DHP conjugation may be one of the factors contributing to the resistance of hamsters to intoxication by this PA.
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Affiliation(s)
- J Y Huan
- Toxicology Program, Oregon State University, Corvallis 97311, USA
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35
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Schultze AE, Roth RA. Chronic pulmonary hypertension--the monocrotaline model and involvement of the hemostatic system. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 1998; 1:271-346. [PMID: 9776954 DOI: 10.1080/10937409809524557] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Monocrotaline (MCT) is a toxic pyrrolizidine alkaloid of plant origin. Administration of small doses of MCT or its active metabolite, monocrotaline pyrrole (MCTP), to rats causes delayed and progressive lung injury characterized by pulmonary vascular remodeling, pulmonary hypertension, and compensatory right heart hypertrophy. The lesions induced by MCT(P) administration in rats are similar to those observed in certain chronic pulmonary vascular diseases of people. This review begins with a synopsis of the hemostatic system, emphasizing the role of endothelium since endothelial cell dysfunction likely underlies the pathogenesis of MCT(P)-induced pneumotoxicity. MCT toxicology is discussed, focusing on morphologic, pulmonary mechanical, hemodynamic, and biochemical and molecular alterations that occur after toxicant exposure. Fibrin and platelet thrombosis of the pulmonary microvasculature occurs after administration of MCT(P) to rats, and several investigators have hypothesized that thrombi contribute to the lung injury and pulmonary hypertension. The evidence for involvement of the various components of the hemostatic system in MCT(P)-induced vascular injury and remodeling is reviewed. Current evidence is consistent with involvement of platelets and an altered fibrinolytic system, yet much remains to be learned about specific events and signals in the vascular pathogenesis.
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MESH Headings
- Animals
- Disease Models, Animal
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/pathology
- Hemostasis/drug effects
- Humans
- Hypertension, Pulmonary/blood
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/etiology
- Hypertrophy, Right Ventricular/blood
- Hypertrophy, Right Ventricular/chemically induced
- Hypertrophy, Right Ventricular/etiology
- Monocrotaline/adverse effects
- Monocrotaline/analogs & derivatives
- Monocrotaline/toxicity
- Plants, Medicinal/adverse effects
- Plants, Toxic/adverse effects
- Rats
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Affiliation(s)
- A E Schultze
- Department of Pathology, College of Veterinary Medicine, University of Tennessee, Knoxville, USA
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36
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Yan CC, Huxtable RJ. Effect of taurine and guanidinoethane sulfonate on glutathione metabolism in the rat. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 442:33-9. [PMID: 9635012 DOI: 10.1007/978-1-4899-0117-0_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- C C Yan
- Department of Pharmacology, University of Arizona, College of Medicine, Tucson 85724, USA
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37
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Yan CC, Huxtable RJ. Effect of taurine on biliary metabolites of glutathione in liver perfused with the pyrrolizidine alkaloid, monocrotaline. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 442:85-9. [PMID: 9635018 DOI: 10.1007/978-1-4899-0117-0_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- C C Yan
- Department of Pharmacology, University of Arizona, College of Medicine, Tucson 85724, USA
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38
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Yan CC, Huxtable RJ. Effects of monocrotaline, a pyrrolizidine alkaloid, on glutathione metabolism in the rat. Biochem Pharmacol 1996; 51:375-9. [PMID: 8573205 DOI: 10.1016/0006-2952(95)02189-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Monocrotaline (MONO), a pyrrolizidine alkaloid, causes veno-occlusive disease of the liver, pulmonary arterial hypertension, and right ventricular hypertrophy. Toxicity is due to the hepatic formation of a pyrolic metabolite that can be detoxified by conjugation with glutathione (GSH). We have shown that the GSH content of the liver affects the quantity of the pyrrolic metabolite that is released from the liver. We have now examined whether MONO, in turn, affects GSH metabolism. Twenty-four hours after administration of MONO to rats (65 mg/kg, i.p.), the highest concentration of bound pyrrolic metabolites was found in the liver, followed by the lung and kidney. Heart and brain contained lower concentrations of these metabolites. Significantly higher levels of GSH were found in liver and lungs of MONO-treated rats than in saline-injected control animals. In the liver, activities of the following enzymes were elevated: gamma-glutamylcysteine synthetase, GSH synthetase, gamma-glutamyl transpeptidase, dipeptidase, and microsomal GSH transferase. The same changes were seen in the lung. In the heart, gamma-glutamyl transpeptidase activity was decreased markedly, and cytosolic GSH transferase activity was elevated. In the kidney, the activities of GSH synthetase, gamma-glutamyl transpeptidase, and cytosolic GSH transferase were increased. Our results establish a mutual interaction of MONO and sulfur metabolism. It appears that an early metabolic action of MONO is to modify sulfur amino acid metabolism, diverting cysteine metabolism from oxidation to taurine towards synthesis of GSH.
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Affiliation(s)
- C C Yan
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson 85724, USA
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39
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Yan CC, Huxtable RJ. Effects of taurine and guanidinoethane sulfonate on toxicity of the pyrrolizidine alkaloid monocrotaline. Biochem Pharmacol 1996; 51:321-9. [PMID: 8573199 DOI: 10.1016/0006-2952(95)02185-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Monocrotaline (MONO), a pyrrolizidine alkaloid, causes pulmonary arterial hypertension and right ventricular hypertrophy due to hepatic metabolism to the alkylating pyrrole dehydromonocrotaline. Taurine a sulfonic amino acid, is hepato- and cardioprotective in a variety of conditions. We have examined the effects of taurine and its amidino analog, guanidinoethane sulfonate (GES), in rats injected i.p. with MONO (65 mg/kg). Taurine and GES were given as 1% solutions in drinking water beginning 14 days before administration of MONO and continuing for 14 days therafter, when the rats were killed. The MONO group had right ventricular hypertrophy and pulmonary hyperplasia. Compared with control, no significant changes in the right ventricle/left ventricle weight ratio, or the right ventricle/body weight ratio occurred in rats also given taurine of GES. Lung weights in these two groups were higher than in the control group, but below that of the MONO-alone group. The lethality of MONO over 14 days was decreased by taurine (LD50 for MONO alone 80 mg/kg; for MONO + taurine 121 mg/kg). Rats given only MONO had lower hepatic concentrations of GSH and cysteine (Cys), and higher activities of microsomal GSH transferase activity were no different from control. Gamma-Glutamylcysteine (Glu-Cys) synthetase and gamma-glutamyl transpeptidase activities were elevated. In MONO-injected rats given GES, hepatic GSH levels were higher and Cys levels were lower than in either the MONO alone or MONO + taurine groups. Gamma-Glu-Cys synthetase activity was depressed. Microsomal GSH transferase, GSH peroxidase and gamma-glutamyl transpeptidase activities were elevated. Livers of MONO-injected animals showed higher levels of serine (reversed by both taurine and GES) and glycine (Gly; reversed by GES) and lower levels of glutamine. Compared with control rats, the following changes occurred in serum amino acids: MONO alone: increased aspartate, taurine and lysine; taurine-supplemented: increased taurine, methionine (Met) and lysine, and decreased Gly; GES-supplemented: decreased asparagine, serine, Gly, arginine, taurine, and valine. Compared with the MONO-alone group, the taurine-supplemented group had higher glutamate (Glu), Met and alanine, and the GES-supplemented group higher alanine and lower serine, Gly, arginine and valine. We conclude that taurine protects against MONO-induced lethality and right ventricular hypertrophy. GES also protects against right ventricular hypertrophy. However, these agents act by different mechanisms, taurine preventing many of the biochemical changes induced by MONO, with GES inducing additional changes.
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Affiliation(s)
- C C Yan
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson 85724, USA
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40
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Huxtable RJ, Yan CC, Wild S, Maxwell S, Cooper R. Physicochemical and metabolic basis for the differing neurotoxicity of the pyrrolizidine alkaloids, trichodesmine and monocrotaline. Neurochem Res 1996; 21:141-6. [PMID: 9182239 DOI: 10.1007/bf02529131] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Monocrotaline and trichodesmine are structurally closely related pyrrolizidine alkaloids (PAs) exhibiting different extrahepatic toxicities, trichodesmine being neurotoxic (LD(50) 57 mu mol/kg) and monocrotaline pneumotoxic (LD(50) 335 mu mol/kg). We have compared certain physicochemical properties and metabolic activities of these two PAs in order to understand the quantitative and qualitative differences in toxicity. Both PAs were metabolized in the isolated, perfused rat liver to highly reactive pyrrolic dehydroalkaloids that appear to be responsible for the toxicity of PAs. More dehydrotrichodesmine (468 nmol/g liver) than dehydromonocrotaline (116 nmol/g liver) was released from liver into perfusate on perfusion for 1 hr with 0.5 mM of the parent PA. Dehydrotrichodesmine had a significantly longer aqueous half-life (5.4 sec) than that of dehydromonocrotaline (3.4 sec). In vivo, significantly higher levels of bound pyrroles were found in the brain 18 hr after injection of trichodesmine (25 mg/kg; i.p.) than were seen following either an equal dose (25 mg/kg; i.p.) or an equitoxic dose (90 mg/kg; i.p.) of monocrotaline. Trichodesmine had a higher partition coefficient than monocrotaline for both chloroform and heptane, indicating its greater lipophilicity. The pK(a) of trichodesmine (7.07) was only slightly higher than that of monocrotaline (pK(a¿ 6.83), suggesting that a difference in degree of ionization was not a major factor affecting the relative ability of the dehydroalkaloids to cross the blood-brain barrier. We conclude that the greater lethality and neurotoxicity of trichodesmine compared to monocrotaline is due to two structural characteristics: (i) steric hindrance at position 14 of dehydrotrichodesmine results in greater resistance to hydrolysis, allowing more to be released from the liver and to be delivered to the brain; (ii) the larger isopropyl substituent at position 14 of dehydrotrichodesmine renders the molecule more lipophilic, leading to greater penetration of the brain.
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Affiliation(s)
- R J Huxtable
- Department of Pharmacology, University of Arizona College of Medicine, Tucson 85724, USA
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41
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Yan CC, Huxtable RJ. Effect of the pyrrolizidine alkaloid monocrotaline on taurine and sulfur amino acid metabolism in the rat liver. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 403:135-45. [PMID: 8915351 DOI: 10.1007/978-1-4899-0182-8_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- C C Yan
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson 85724, USA
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42
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Yan CC, Huxtable RJ. Effect of taurine on toxicity of the pyrrolizidine alkaloid monocrotaline in rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 403:315-25. [PMID: 8915367 DOI: 10.1007/978-1-4899-0182-8_33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- C C Yan
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson 85724, USA
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Yan CC, Huxtable RJ. Effect of the pyrrolizidine alkaloid, monocrotaline, on bile composition of the isolated, perfused rat liver. Life Sci 1995; 57:617-26. [PMID: 7623629 DOI: 10.1016/0024-3205(95)00312-t] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Monocrotaline is a hepatotoxic pyrrolizidine alkaloid, releasing high levels of metabolites into bile of isolated, perfused liver. Although perfusion of rat liver with 0.5 mM monocrotaline does not affect bile flow over a 1 hr study period, it markedly affects bile composition. Biliary release of conjugated and free GSH increases 30-fold. Marked increases are also observed in the biliary concentration of the related sulfur-containing substances, cysteine and cysteinylglycine. However, biliary release of the sulfur amino acids, taurine and methionine, is unaffected. Only two amino acids show mildly increased releases, 23% for glycine and 46% for aspartate. Release of bile acids, cholesterol and phospholipids also decrease, both in terms of mM concentration in bile and in terms of nmol secreted per g liver. Thus, exposure to monocrotaline causes disturbances in sulfur metabolism in the liver and in the composition of bile. The consequences of the digestive properties of bile and gastrointestinal toxicity remain to be established. As sulfhydryl compounds are involved in detoxification of monocrotaline metabolites, these findings indicate a mutual interaction of pyrrolizidine toxicity and sulfur metabolism. This suggests that dietary sulfur amino acid intake may influence susceptibility to pyrrolizidine poisoning.
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Affiliation(s)
- C C Yan
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson 85724, USA
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Yan CC, Huxtable RJ. The effect of the pyrrolizidine alkaloids, monocrotaline and trichodesmine, on tissue pyrrole binding and glutathione metabolism in the rat. Toxicon 1995; 33:627-34. [PMID: 7660367 DOI: 10.1016/0041-0101(95)00004-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
One day after in vivo administration of equitoxic doses of the hepatotoxic and pneumotoxic pyrrolizidine alkaloid, monocrotaline (65 mg/kg, i. p.) or the related hepatotoxic and neurotoxic alkaloid trichodesmine (15 mg/kg, i. p.) hepatic GSH levels are increased by more than 50%. These doses of alkaloids represent 60% of the LD50 values. Accompanying these changes in GSH levels is an increase in the overall rate of GSH synthesis in supernatants of alkaloid-exposed livers. The ability of the rat to metabolize the two alkaloids was shown by the appearance of tissuebound pyrrolic metabolites of pyrrolizidines in various organs. The levels of these metabolites appear to correlate with organ toxicity. For the hepatic and pneumotoxic alkaloid, monocrotaline, higher levels are found in liver (17 nmoles/g tissue) and lung (10 nmoles/g) than for trichodesmine (7 nmoles/g and 8 nmoles/g, respectively). For the neurotoxic alkaloid, trichodesmine, higher levels are found in brain (3.8 nmoles/g tissue) than for monocrotaline (1.7 nmoles/g tissue).
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Affiliation(s)
- C C Yan
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson 85724, USA
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45
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Higgins MJ, Ficsor G, Aaron CS, Petry TW, Yu RL, Friedman SB. Micronuclei in mice treated with monocrotaline with and without phenobarbital pretreatment. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 1995; 26:37-43. [PMID: 7641706 DOI: 10.1002/em.2850260106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Monocrotaline is a very potent toxin, producing significant effects of pneumotoxicity, hepatotoxicity, and teratogenicity, as well as carcinogenicity. In addition, the compound has been clearly shown to be mutagenic after metabolic activation. The goal of the experiments reported here was to confirm the reported clastogenesis induced by this agent in vivo and to evaluate the impact of modulation of metabolic activity by phenobarbital, a potent P-450 inducer (both Phase I and Phase II enzymes). The method used in addressing this problem relied on a new technique for monitoring clastogenesis in vivo, i.e., the acridine orange micronucleus assay method originally exploited by Hayashi et al. [1990]. The result of our experiments confirmed monocrotaline to be an effective clastogen in vivo, using the acridine orange method of assessment. The peak in induction of micronuclei occurred on the second day following intraperitoneal administration of the drug. Administration of phenobarbital prior to monocrotaline did appear to modulate the micronucleus induction. At 30 mg/kg bw monocrotaline, the pretreatment with phenobarbital appears to increase the intensity of monocrotaline clastogenesis, while the effect at higher doses (60 and 125 mg/kg bw) is a reduction in potency, presumably reflecting increased importance of Phase II metabolism for monocrotaline at these doses. Thus the study reported here confirms the potent in vivo clastogenesis of monocrotaline, and provides evidence for a dose-related shift in mechanism for the phenomenon.
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