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Brock WJ, Greene T, Van Landingham C, Gentry R. A weight of evidence evaluation of the mode of action of isoeugenol. Regul Toxicol Pharmacol 2024; 150:105642. [PMID: 38735521 DOI: 10.1016/j.yrtph.2024.105642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/21/2024] [Accepted: 05/06/2024] [Indexed: 05/14/2024]
Abstract
Isoeugenol is one of several phenylpropenoid compounds that is used as a fragrance, food flavoring agent and in aquaculture as a fish anesthetic. Carcinogenicity testing in rats and mice by NTP resulted in clear evidence of carcinogenicity (hepatic adenomas/carcinomas) in male mice only. A nongenotoxic threshold mode of action (MOA) is postulated for isoeugenol and is discussed considering the IPCS MOA and Human Relevance Framework. The weight of evidence indicates that isoeugenol is not genotoxic and that the carcinogenic outcome in male mice relates directly to the metabolism of individual compounds. Benchmark Dose (BMD) modeling was conducted to determine a Point of Departure (POD) and potential threshold of carcinogenicity. The results of the BMD evaluation for isoeugenol resulted in an estimated POD for carcinogenicity in the male mouse of 8 mg/kg with a lower limit of 4 mg/kg, representing a POD for the determination of an acceptable daily intake. With application of uncertainty factors, an ADI of 40 μg/kg is calculated. This daily dose in humans would be protective of human health, including carcinogenicity. A corresponding maximum residual level (MRL) of 3200 μg/kg fish is also estimated based on this POD that considers the threshold MOA.
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Affiliation(s)
- William J Brock
- Brock Scientific Consulting, LLC, Hilton Head Island, SC, USA.
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2
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Wu S, Daston G, Rose J, Blackburn K, Fisher J, Reis A, Selman B, Naciff J. Identifying chemicals based on receptor binding/bioactivation/mechanistic explanation associated with potential to elicit hepatotoxicity and to support structure activity relationship-based read-across. Curr Res Toxicol 2023; 5:100108. [PMID: 37363741 PMCID: PMC10285556 DOI: 10.1016/j.crtox.2023.100108] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 06/28/2023] Open
Abstract
The liver is the most common target organ in toxicology studies. The development of chemical structural alerts for identifying hepatotoxicity will play an important role in in silico model prediction and help strengthen the identification of analogs used in structure activity relationship (SAR)- based read-across. The aim of the current study is development of an SAR-based expert-system decision tree for screening of hepatotoxicants across a wide range of chemistry space and proposed modes of action for clustering of chemicals using defined core chemical categories based on receptor-binding or bioactivation. The decision tree is based on ∼ 1180 different chemicals that were reviewed for hepatotoxicity information. Knowledge of chemical receptor binding, metabolism and mechanistic information were used to group these chemicals into 16 different categories and 102 subcategories: four categories describe binders to 9 different receptors, 11 categories are associated with possible reactive metabolites (RMs) and there is one miscellaneous category. Each chemical subcategory has been associated with possible modes of action (MOAs) or similar key structural features. This decision tree can help to screen potential liver toxicants associated with core structural alerts of receptor binding and/or RMs and be used as a component of weight of evidence decisions based on SAR read-across, and to fill data gaps.
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Astrain-Redin N, Sanmartin C, Sharma AK, Plano D. From Natural Sources to Synthetic Derivatives: The Allyl Motif as a Powerful Tool for Fragment-Based Design in Cancer Treatment. J Med Chem 2023; 66:3703-3731. [PMID: 36858050 PMCID: PMC10041541 DOI: 10.1021/acs.jmedchem.2c01406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
Since the beginning of history, natural products have been an abundant source of bioactive molecules for the treatment of different diseases, including cancer. Many allyl derivatives, which have shown anticancer activity both in vitro and in vivo in a large number of cancers, are bioactive molecules found in garlic, cinnamon, nutmeg, or mustard. In addition, synthetic products containing allyl fragments have been developed showing potent anticancer properties. Of particular note is the allyl derivative 17-AAG, which has been evaluated in Phase I and Phase II/III clinical trials for the treatment of multiple myeloma, metastatic melanoma, renal cancer, and breast cancer. In this Perspective, we compile extensive literature evidence with descriptions and discussions of the most recent advances in different natural and synthetic allyl derivatives that could generate cancer drug candidates in the near future.
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Affiliation(s)
- Nora Astrain-Redin
- Department of Pharmaceutical Technology and Chemistry, University of Navarra, E-31008 Pamplona, Spain
| | - Carmen Sanmartin
- Department of Pharmaceutical Technology and Chemistry, University of Navarra, E-31008 Pamplona, Spain
| | - Arun K Sharma
- Department of Pharmacology, Penn State Cancer Institute, CH72, Penn State College of Medicine, 500 University Drive, Hershey, Pennsylvania 17033, United States
| | - Daniel Plano
- Department of Pharmaceutical Technology and Chemistry, University of Navarra, E-31008 Pamplona, Spain
- Department of Pharmacology, Penn State Cancer Institute, CH72, Penn State College of Medicine, 500 University Drive, Hershey, Pennsylvania 17033, United States
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Wang M, Zhang J, Zhang J, Sun K, Li Q, Kuang B, Wang MMZ, Hou S, Gong N. Methyl eugenol attenuates liver ischemia reperfusion injury via activating PI3K/Akt signaling. Int Immunopharmacol 2021; 99:108023. [PMID: 34358859 DOI: 10.1016/j.intimp.2021.108023] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 12/11/2022]
Abstract
BACKGROUND Liver ischemia reperfusion injury (LIRI) often occurs during liver transplantation, resection, and various circulatory shock procedures, leading to severe metabolic disorders, inflammatory immune responses, oxidative stress injury, and cell apoptosis. Methyl eugenol (ME) is structurally similar to eugenol and has anti-inflammatory and apoptotic pharmacological effects. However, whether ME protects the liver from LIRI damage requires further investigation. METHODS We established a partially warm LIRI model by subjecting C57BL/6J mice to 60 min of ischemia, followed by reperfusion for 6 h. We also established a hypoxia-reoxygenation injury (H/R) cell model by subjecting AML12 (a mouse liver cell line) cells to 24 h hypoxia, followed by 18 h normoxia. The extent of liver injury was assessed by serum transaminase concentrations, hematoxylin and eosin staining, quantitative real-time PCR, myeloperoxidase activity, and TUNEL analysis. Apoptosis was detected using flow cytometry. The protein levels of p-PI3K, PI3K, p-Akt, Akt, p-Bad, Bad, Bcl-2, Bax, and cleaved caspase-3 were detected by western blotting. LY294002, an inhibitor of PI3K/Akt signaling, was used to elucidate the relationship between ME and PI3K/Akt signaling. RESULTS ME successfully alleviated LIRI-induced liver injury, inflammatory response, and apoptosis induced, as well as liver cell injury induced by hypoxia reoxygenation. ME is known to activate the PI3K/Akt signaling pathway in hepatocyte injury in vivo and in vitro, and when this signaling pathway is inhibited, the protective effect of ME is abrogated. CONCLUSIONS The use of ME is a potential therapeutic approach for regulating LIRI by activating PI3K/Akt signaling.
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Affiliation(s)
- Mengqin Wang
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China
| | - Ji Zhang
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China
| | - Jiasi Zhang
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China
| | - Kailun Sun
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China
| | - Qingwen Li
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China
| | - Baicheng Kuang
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China
| | - M M Zhiheng Wang
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China
| | - Shuaiheng Hou
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China
| | - Nianqiao Gong
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Organ Transplantation of Ministry of Education, National Health Commission and Chinese Academy of Medical Sciences, Wuhan, Hubei 430030, China.
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Tian M, Zhou S, Li W, Li J, Yang L, Peng Y, Zheng J. Metabolic Activation of Aegeline Mediated by CYP2C19. Xenobiotica 2021; 51:1217-1228. [PMID: 33892609 DOI: 10.1080/00498254.2021.1913666] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
1. Aegeline (AGL) is a natural alkaloidal amide mainly isolated from the leaves and fruits of tropical plant Aegle marmelos, with multiple pharmacological activities.2. As one component of several dietary supplements, AGL caused a series of acute and chronic liver injuries. Nevertheless, the mechanisms of AGL-induced hepatotoxicity remain unclear. This study was conducted to identify reactive metabolite(s), to determine related metabolic pathways, and define the possible association of the bioactivation with AGL cytotoxicity.3. A demethylation metabolite (M1) and a GSH conjugate (M2) were detected in rat liver microsomal incubations containing AGL and GSH. The two metabolites were both found in bile of rats and rat primary hepatocytes after AGL administration.4. Recombinant P450 enzyme incubations showed that CYP2C19 was the principal enzyme catalyzing this metabolic activation.5. Ticlopidine, a selective inhibitor of CYP2C19, decreased the formation of M1 and M2 in hepatocytes and attenuated the susceptibility of hepatocytes to the cytotoxicity of AGL. The results suggest that AGL was metabolized to a p-quinone methide intermediate which could in part participate in AGL-induced cytotoxicity.
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Affiliation(s)
- Min Tian
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Shenzhi Zhou
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Wei Li
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Jiaru Li
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Lan Yang
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Ying Peng
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Jiang Zheng
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China.,State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou 550025, P. R. China.,Key Laboratory of Environmental Pollution, Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, Guizhou 550025, P. R. China
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Metabolism of carcinogenic alpha-asarone by human cytochrome P450 enzymes. Naunyn Schmiedebergs Arch Pharmacol 2019; 393:213-223. [DOI: 10.1007/s00210-019-01724-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/28/2019] [Indexed: 01/23/2023]
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7
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Marabini L, Galli CL, La Fauci P, Marinovich M. Effect of plant extracts on the genotoxicity of 1′-hydroxy alkenylbenzenes. Regul Toxicol Pharmacol 2019; 105:36-41. [DOI: 10.1016/j.yrtph.2019.03.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 10/27/2022]
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Smith RL, Cohen SM, Fukushima S, Gooderham NJ, Hecht SS, Guengerich FP, Rietjens IMCM, Bastaki M, Harman CL, McGowen MM, Taylor SV. The safety evaluation of food flavouring substances: the role of metabolic studies. Toxicol Res (Camb) 2018; 7:618-646. [PMID: 30090611 PMCID: PMC6062396 DOI: 10.1039/c7tx00254h] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 03/21/2018] [Indexed: 12/13/2022] Open
Abstract
The safety assessment of a flavour substance examines several factors, including metabolic and physiological disposition data. The present article provides an overview of the metabolism and disposition of flavour substances by identifying general applicable principles of metabolism to illustrate how information on metabolic fate is taken into account in their safety evaluation. The metabolism of the majority of flavour substances involves a series both of enzymatic and non-enzymatic biotransformation that often results in products that are more hydrophilic and more readily excretable than their precursors. Flavours can undergo metabolic reactions, such as oxidation, reduction, or hydrolysis that alter a functional group relative to the parent compound. The altered functional group may serve as a reaction site for a subsequent metabolic transformation. Metabolic intermediates undergo conjugation with an endogenous agent such as glucuronic acid, sulphate, glutathione, amino acids, or acetate. Such conjugates are typically readily excreted through the kidneys and liver. This paper summarizes the types of metabolic reactions that have been documented for flavour substances that are added to the human food chain, the methodologies available for metabolic studies, and the factors that affect the metabolic fate of a flavour substance.
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Affiliation(s)
- Robert L Smith
- Molecular Toxicology , Imperial College School of Medicine , London SW7 2AZ , UK
| | - Samuel M Cohen
- Dept. of Pathology and Microbiology , University of Nebraska Medical Centre , 983135 Nebraska Medical Centre , Omaha , NE 68198-3135 , USA
| | - Shoji Fukushima
- Japan Bioassay Research Centre , 2445 Hirasawa , Hadano , Kanagawa 257-0015 , Japan
| | - Nigel J Gooderham
- Dept. of Surgery and Cancer , Imperial College of Science , Sir Alexander Fleming Building , London SW7 2AZ , UK
| | - Stephen S Hecht
- Masonic Cancer Centre and Dept. of Laboratory Medicine and Pathology , University of Minnesota , Cancer and Cardiovascular Research Building , 2231 6th St , SE , Minneapolis , MN 55455 , USA
| | - F Peter Guengerich
- Department of Biochemistry , Vanderbilt University School of Medicine , 638B Robinson Research Building , 2200 Pierce Avenue , Nashville , Tennessee 37232-0146 , USA
| | - Ivonne M C M Rietjens
- Division of Toxicology , Wageningen University , Tuinlaan 5 , 6703 HE Wageningen , The Netherlands
| | - Maria Bastaki
- Flavor and Extract Manufacturers Association , 1101 17th Street , NW Suite 700 , Washington , DC 20036 , USA . ; ; Tel: +1 (202)293-5800
| | - Christie L Harman
- Flavor and Extract Manufacturers Association , 1101 17th Street , NW Suite 700 , Washington , DC 20036 , USA . ; ; Tel: +1 (202)293-5800
| | - Margaret M McGowen
- Flavor and Extract Manufacturers Association , 1101 17th Street , NW Suite 700 , Washington , DC 20036 , USA . ; ; Tel: +1 (202)293-5800
| | - Sean V Taylor
- Flavor and Extract Manufacturers Association , 1101 17th Street , NW Suite 700 , Washington , DC 20036 , USA . ; ; Tel: +1 (202)293-5800
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Dang NL, Hughes TB, Miller GP, Swamidass SJ. Computational Approach to Structural Alerts: Furans, Phenols, Nitroaromatics, and Thiophenes. Chem Res Toxicol 2017; 30:1046-1059. [PMID: 28256829 DOI: 10.1021/acs.chemrestox.6b00336] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Structural alerts are commonly used in drug discovery to identify molecules likely to form reactive metabolites and thereby become toxic. Unfortunately, as useful as structural alerts are, they do not effectively model if, when, and why metabolism renders safe molecules toxic. Toxicity due to a specific structural alert is highly conditional, depending on the metabolism of the alert, the reactivity of its metabolites, dosage, and competing detoxification pathways. A systems approach, which explicitly models these pathways, could more effectively assess the toxicity risk of drug candidates. In this study, we demonstrated that mathematical models of P450 metabolism can predict the context-specific probability that a structural alert will be bioactivated in a given molecule. This study focuses on the furan, phenol, nitroaromatic, and thiophene alerts. Each of these structural alerts can produce reactive metabolites through certain metabolic pathways but not always. We tested whether our metabolism modeling approach, XenoSite, can predict when a given molecule's alerts will be bioactivated. Specifically, we used models of epoxidation, quinone formation, reduction, and sulfur-oxidation to predict the bioactivation of furan-, phenol-, nitroaromatic-, and thiophene-containing drugs. Our models separated bioactivated and not-bioactivated furan-, phenol-, nitroaromatic-, and thiophene-containing drugs with AUC performances of 100%, 73%, 93%, and 88%, respectively. Metabolism models accurately predict whether alerts are bioactivated and thus serve as a practical approach to improve the interpretability and usefulness of structural alerts. We expect that this same computational approach can be extended to most other structural alerts and later integrated into toxicity risk models. This advance is one necessary step toward our long-term goal of building comprehensive metabolic models of bioactivation and detoxification to guide assessment and design of new therapeutic molecules.
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Affiliation(s)
- Na Le Dang
- Department of Pathology and Immunology, Washington University School of Medicine , Campus Box 8118, 660 S. Euclid Avenue, St. Louis, Missouri 63110, United States
| | - Tyler B Hughes
- Department of Pathology and Immunology, Washington University School of Medicine , Campus Box 8118, 660 S. Euclid Avenue, St. Louis, Missouri 63110, United States
| | - Grover P Miller
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205, United States
| | - S Joshua Swamidass
- Department of Pathology and Immunology, Washington University School of Medicine , Campus Box 8118, 660 S. Euclid Avenue, St. Louis, Missouri 63110, United States
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Roemer E, Dempsey R, Lawless-Pyne J, Lukman S, Evans AD, Trelles-Sticken E, Wittke S, Schorp M. Toxicological assessment of kretek cigarettes part 4: Mechanistic investigations, smoke chemistry and in vitro toxicity. Regul Toxicol Pharmacol 2014; 70 Suppl 1:S41-53. [DOI: 10.1016/j.yrtph.2014.09.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 09/29/2014] [Indexed: 10/24/2022]
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12
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Lesgards JF, Baldovini N, Vidal N, Pietri S. Anticancer Activities of Essential Oils Constituents and Synergy with Conventional Therapies: A Review. Phytother Res 2014; 28:1423-46. [DOI: 10.1002/ptr.5165] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 03/09/2014] [Accepted: 04/11/2014] [Indexed: 01/19/2023]
Affiliation(s)
| | - Nicolas Baldovini
- Faculté des Sciences; University of Nice-Sophia Antipolis, CNRS UMR 7272, Institut de Chimie de Nice; Avenue Valrose 06108 Nice Cedex 2 France
| | - Nicolas Vidal
- Aix Marseille Université, CNRS, ICR UMR 7273; 13397 Marseille France
| | - Sylvia Pietri
- Aix Marseille Université, CNRS, ICR UMR 7273; 13397 Marseille France
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Sipe HJ, Lardinois OM, Mason RP. Free radical metabolism of methyleugenol and related compounds. Chem Res Toxicol 2014; 27:483-9. [PMID: 24564854 PMCID: PMC4002132 DOI: 10.1021/tx400256b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methyleugenol, the methyl ether of eugenol, both of which are flavorant constituents of spices, has been listed by the National Toxicology Program's Report on Carcinogens as reasonably anticipated to be a human carcinogen. This finding is based on the observation of increased incidence of malignant tumors at multiple tissue sites in experimental animals of different species. By contrast, eugenol is not listed. In this study, we show that both methyleugenol and eugenol readily undergo peroxidative metabolism in vitro to form free radicals with large hyperfine interactions of the methylene allylic hydrogen atoms. These large hyperfine splittings indicate large electron densities adjacent to those hydrogen atoms. Methyleugenol undergoes autoxidation such that the commercial product contains 10-30 mg/L hydroperoxide and is capable of activating peroxidases without the presence of added hydrogen peroxide. Additionally, the hydroperoxide is not a good substrate for catalase, which demonstrates that these antioxidant defenses will not be effective in protecting against methyleugenol exposure.
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Affiliation(s)
- Herbert J Sipe
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health , P.O. Box 12233, Research Triangle Park, North Carolina 27709, United States
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