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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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Schrenk D, Allemang A, Fahrer J, Harms H, Li X, Lin G, Mahony C, Mulder P, Peijnenburg A, Pfuhler S, Punt A, Sievers H, Troutman J, Widjaja F. Toxins in Botanical Drugs and Plant-derived Food and Feed - from Science to Regulation: A Workshop Review. PLANTA MEDICA 2024; 90:219-242. [PMID: 38198805 DOI: 10.1055/a-2218-5667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
In September 2022, the 3rd International Workshop on pyrrolizidine alkaloids (PAs) and related phytotoxins was held on-line, entitled 'Toxins in botanical drugs and plant-derived food and feed - from science to regulation'. The workshop focused on new findings about the occurrence, exposure, toxicity, and risk assessment of PAs. In addition, new scientific results related to the risk assessment of alkenylbenzenes, a distinct class of herbal constituents, were presented. The presence of PAs and alkenylbenzenes in plant-derived food, feed, and herbal medicines has raised health concerns with respect to their acute and chronic toxicity but mainly related to the genotoxic and carcinogenic properties of several congeners. The compounds are natural constituents of a variety of plant families and species widely used in medicinal, food, and feed products. Their individual occurrence, levels, and toxic properties, together with the broad range of congeners present in nature, represent a striking challenge to modern toxicology. This review tries to provide an overview of the current knowledge on these compounds and indicates needs and perspectives for future research.
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Affiliation(s)
- Dieter Schrenk
- Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Ashley Allemang
- Central Product Safety, The Procter & Gamble Company, Mason, USA
| | - Jörg Fahrer
- Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Henrik Harms
- Federal Institute for Drugs and Medical Devices (BfArM), Bonn, Germany
| | - Xilin Li
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U. S. Food and Drug Administration, Jefferson, USA
| | - Ge Lin
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR
| | - Catherine Mahony
- Central Product Safety, Procter & Gamble Technical Centre, Reading, United Kingdom
| | - Patrick Mulder
- Wageningen Food Safety Research, Wageningen University & Research, Wageningen, the Netherlands
| | - Ad Peijnenburg
- Wageningen Food Safety Research, Wageningen University & Research, Wageningen, the Netherlands
| | - Stefan Pfuhler
- Central Product Safety, The Procter & Gamble Company, Mason, USA
| | - Ans Punt
- Wageningen Food Safety Research, Wageningen University & Research, Wageningen, the Netherlands
| | | | - John Troutman
- Central Product Safety, The Procter & Gamble Company, Mason, USA
| | - Frances Widjaja
- Division of Toxicology, Wageningen University & Research, Wageningen, the Netherlands
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3
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Wu KY, Wei YT, Luo YS, Shen LC, Chang BS, Chen YY, Huang YC, Huang HF, Chung WS, Chiang SY. Dose-response formation of N7-(3-benzo[1,3]dioxol-5-yl-2-hydroxypropyl)guanine in liver and urine correlates with micronucleated reticulocyte frequencies in mice administered safrole oxide. Food Chem Toxicol 2023; 181:114056. [PMID: 37739051 DOI: 10.1016/j.fct.2023.114056] [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: 04/23/2023] [Revised: 09/16/2023] [Accepted: 09/19/2023] [Indexed: 09/24/2023]
Abstract
Safrole oxide (SAFO), a metabolite of naturally occurring hepatocarcinogen safrole, is implicated in causing DNA adduct formation. Our previous study first detected the most abundant SAFO-induced DNA adduct, N7-(3-benzo[1,3] dioxol-5-yl-2-hydroxypropyl)guanine (N7γ-SAFO-G), in mouse urine using a well-developed isotope-dilution high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (ID-HPLC-ESI-MS/MS) method. This study further elucidated the genotoxic mode of action of SAFO in mice treated with SAFO 30, 60, 90, or 120 mg/kg for 28 days. The ID-HPLC-ESI-MS/MS method detected N7γ-SAFO-G with excellent sensitivity and specificity in mouse liver and urine of SAFO-treated mice. Our data provide the first direct evidence of SAFO-DNA adduct formation in rodent tissues. N7γ-SAFO-G levels in liver were significantly increased by SAFO 120 mg/kg compared with SAFO 30 mg/kg, suggesting rapid spontaneous or enzymatic depurination of N7γ-SAFO-G in tissue DNA. Urinary N7γ-SAFO-G exhibited a sublinear dose response. Moreover, the micronucleated peripheral reticulocyte frequencies increased dose-dependently and significantly correlated with N7γ-SAFO-G levels in liver (r = 0.8647; p < 0.0001) and urine (r = 0.846; p < 0.0001). Our study suggests that safrole-mediated genotoxicity may be caused partly by its metabolic activation to SAFO and that urinary N7γ-SAFO-G may serve as a chemically-specific cancer risk biomarker for safrole exposure.
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Affiliation(s)
- Kuen-Yuh Wu
- Institute of Food Safety and Health, College of Public Health, National Taiwan University, Taipei, Taiwan; Institute of Environmental and Occupational Health Science, College of Public Health, National Taiwan University, Taipei, Taiwan; Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Yu-Tzu Wei
- Institute of Environmental and Occupational Health Science, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Yu-Syuan Luo
- Institute of Food Safety and Health, College of Public Health, National Taiwan University, Taipei, Taiwan
| | - Li-Chin Shen
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
| | - Bao-Suei Chang
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Ya-Yin Chen
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Yan-Chi Huang
- Institute of Environmental and Occupational Health Science, College of Public Health, National Taiwan University, Taipei, Taiwan; School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Hui-Fen Huang
- School of Post-baccalaureate Chinese Medicine, Tzu Chi University, Hualien, Taiwan
| | - Wen-Sheng Chung
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
| | - Su-Yin Chiang
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan.
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4
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Götz ME, Sachse B, Schäfer B, Eisenreich A. Myristicin and Elemicin: Potentially Toxic Alkenylbenzenes in Food. Foods 2022; 11:1988. [PMID: 35804802 PMCID: PMC9265716 DOI: 10.3390/foods11131988] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/22/2022] [Accepted: 07/01/2022] [Indexed: 11/17/2022] Open
Abstract
Alkenylbenzenes represent a group of naturally occurring substances that are synthesized as secondary metabolites in various plants, including nutmeg and basil. Many of the alkenylbenzene-containing plants are common spice plants and preparations thereof are used for flavoring purposes. However, many alkenylbenzenes are known toxicants. For example, safrole and methyleugenol were classified as genotoxic carcinogens based on extensive toxicological evidence. In contrast, reliable toxicological data, in particular regarding genotoxicity, carcinogenicity, and reproductive toxicity is missing for several other structurally closely related alkenylbenzenes, such as myristicin and elemicin. Moreover, existing data on the occurrence of these substances in various foods suffer from several limitations. Together, the existing data gaps regarding exposure and toxicity cause difficulty in evaluating health risks for humans. This review gives an overview on available occurrence data of myristicin, elemicin, and other selected alkenylbenzenes in certain foods. Moreover, the current knowledge on the toxicity of myristicin and elemicin in comparison to their structurally related and well-characterized derivatives safrole and methyleugenol, especially with respect to their genotoxic and carcinogenic potential, is discussed. Finally, this article focuses on existing data gaps regarding exposure and toxicity currently impeding the evaluation of adverse health effects potentially caused by myristicin and elemicin.
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Affiliation(s)
| | | | | | - Andreas Eisenreich
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Str. 8-10, 10589 Berlin, Germany; (M.E.G.); (B.S.); (B.S.)
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Alkenylbenzenes in Foods: Aspects Impeding the Evaluation of Adverse Health Effects. Foods 2021; 10:foods10092139. [PMID: 34574258 PMCID: PMC8469824 DOI: 10.3390/foods10092139] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 12/15/2022] Open
Abstract
Alkenylbenzenes are naturally occurring secondary plant metabolites, primarily present in different herbs and spices, such as basil or fennel seeds. Thus, alkenylbenzenes, such as safrole, methyleugenol, and estragole, can be found in different foods, whenever these herbs and spices (or extracts thereof) are used for food production. In particular, essential oils or other food products derived from the aforementioned herbs and spices, such as basil-containing pesto or plant food supplements, are often characterized by a high content of alkenylbenzenes. While safrole or methyleugenol are known to be genotoxic and carcinogenic, the toxicological relevance of other alkenylbenzenes (e.g., apiol) regarding human health remains widely unclear. In this review, we will briefly summarize and discuss the current knowledge and the uncertainties impeding a conclusive evaluation of adverse effects to human health possibly resulting from consumption of foods containing alkenylbenzenes, especially focusing on the genotoxic compounds, safrole, methyleugenol, and estragole.
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Yang X, Feng Y, Zhang Z, Wang H, Li W, Wang DO, Peng Y, Zheng J. In Vitro and In Vivo Evidence for RNA Adduction Resulting from Metabolic Activation of Methyleugenol. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:15134-15141. [PMID: 33296206 DOI: 10.1021/acs.jafc.0c04880] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Methyleugenol (ME) is a ubiquitous component in spices and other culinary herbal products. A prevailing theory in ME toxicity is its ability to be metabolically activated by P450 enzymes and sulfotransferases, which initiates sequential reactions of the resulting metabolites with functional biomolecules. The present study aimed at a potential interaction between the reactive metabolites of ME and RNA. Cultured mouse primary hepatocytes were incubated with ME followed by RNA extraction and NaOH and alkaline phosphatase-based RNA hydrolysis. Three adenosine adducts were detected in the hydrolytic mixture by LC-MS/MS. The same adenosine adducts were also detected in hepatic tissues harvested from ME-treated mice. These three adducts were chemically synthesized and structurally characterized by 1H NMR. Additionally, two guanosine adducts and one cytidine adduct were detected in the in vivo samples. These results provided solid evidence that the reactive metabolites of ME attacked RNA, resulting in RNA adduction.
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Affiliation(s)
- Xiaojing Yang
- State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou 550004, P. R. China
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Yukun Feng
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
- Institute of Shandong Xinhua Pharmaceutical Co., Ltd., Zibo 255000, China
| | - Zhengyu Zhang
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Hui Wang
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Weiwei Li
- State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou 550004, P. R. China
| | - Dan Ohtan Wang
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Ying Peng
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Jiang Zheng
- State Key Laboratory of Functions and Applications of Medicinal Plants, Key Laboratory of Pharmaceutics of Guizhou Province, Guizhou Medical University, Guiyang, Guizhou 550004, P. R. China
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang 550025, P. R. China
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
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7
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Wen B, Gorycki P. Bioactivation of herbal constituents: mechanisms and toxicological relevance. Drug Metab Rev 2019; 51:453-497. [DOI: 10.1080/03602532.2019.1655570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Bo Wen
- Department of Drug Metabolism and Pharmacokinetics, GlaxoSmithKline, Collegeville, PA, USA
| | - Peter Gorycki
- Department of Drug Metabolism and Pharmacokinetics, GlaxoSmithKline, Collegeville, PA, USA
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8
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Bauer P, Buettner A. Characterization of Odorous and Potentially Harmful Substances in Artists' Acrylic Paint. Front Public Health 2018; 6:350. [PMID: 30555813 PMCID: PMC6281683 DOI: 10.3389/fpubh.2018.00350] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/12/2018] [Indexed: 01/18/2023] Open
Abstract
Acrylic paints are fast drying water based paints that are easy to handle and have a high covering capacity and therefore possess many characteristics that make them applicable in a wide range of applications, such as varnishes or artists paints. Due to their emitted volatile organic compounds, these paints are associated with different work-related diseases and are known to emit an unpleasant odor. In this study six acrylic paints for artists were analyzed regarding their odor-active constituents. Therefore, the samples were extracted with dichloromethane and purified via solvent assisted flavor evaporation prior to analysis of the distillates by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), and GC-GC-MS/O. Additionally all samples were sensorially characterized by a trained sensory panel. The identified odorous substances were primarily benzene derivatives (styrene, ethylbenzene, allylbenzene, propylbenzene) with a plastic-like, aromatic and solvent-like odor. Thereby, polycyclic aromatic hydrocarbons (naphthalene, indane, and tetralin derivatives) contributed to the plastic- and mothball-like odor whereas acrylic monomers (butyl acrylate) were found to be responsible for a mushroom-like and geranium leaf-like odor. As most of these substances are also known to be harmful, a reduction or replacement of these substances by less toxic and non-odor active ingredients is likely to turn out to be advisable in order to reduce the odor and potential negative physiological effects of paints.
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Affiliation(s)
- Patrick Bauer
- Chair of Aroma and Smell Research, Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Department Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany
| | - Andrea Buettner
- Chair of Aroma and Smell Research, Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Department Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging IVV, Freising, Germany
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9
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Martins C, Rueff J, Rodrigues AS. Genotoxic alkenylbenzene flavourings, a contribution to risk assessment. Food Chem Toxicol 2018; 118:861-879. [DOI: 10.1016/j.fct.2018.06.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/09/2018] [Accepted: 06/12/2018] [Indexed: 12/16/2022]
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10
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Methyl Chavicol and Its Synthetic Analogue as Possible Antioxidant and Antilipase Agents Based on the In Vitro and In Silico Assays. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:2189348. [PMID: 29849872 PMCID: PMC5925050 DOI: 10.1155/2018/2189348] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 01/07/2018] [Accepted: 01/31/2018] [Indexed: 12/20/2022]
Abstract
This study investigated the in vitro and in silico biological properties of the methyl chavicol (MC) and its analogue 2-[(4-methoxyphenyl)methyl]oxirane (MPMO), emphasizing the antioxidant and antilipase effects. MPMO was synthesized from MC that reacted with meta-chloroperbenzoic acid and, after separation and purification, was identified by 1H and 13C NMR and GC-MS. The antioxidant activity was investigated by DPPH, cooxidation β-carotene/linoleic acid, and thiobarbituric acid assays. With the use of colorimetric determination, the antilipase effect on the pancreatic lipase was tested, while the molecular interaction profiles were evaluated by docking molecular study. MC (IC50 = 312.50 ± 2.28 μg/mL) and MPMO (IC50 = 8.29 ± 0.80 μg/mL) inhibited the DPPH free radical. The inhibition of lipid peroxidation (%) was 73.08 ± 4.79 and 36.16 ± 4.11 to MC and MPMO, respectively. The malonaldehyde content was significantly reduced in the presence of MC and MPMO. MC and MPMO inhibited the pancreatic lipase in 58.12 and 26.93%, respectively. MC and MPMO (−6.1 kcal·mol−1) produced a binding affinity value lower than did diundecylphosphatidylcholine (−5.6 kcal·mol−1). These findings show that MC and MPMO present antioxidant and antilipase activities, which may be promising molecular targets for the treatment of diseases associated with oxidative damage and lipid metabolism.
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Groh IAM, Esselen M. Methyleugenol and selected oxidative metabolites affect DNA-Damage signalling pathways and induce apoptosis in human colon tumour HT29 cells. Food Chem Toxicol 2017; 108:267-275. [PMID: 28818686 DOI: 10.1016/j.fct.2017.08.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 08/01/2017] [Accepted: 08/11/2017] [Indexed: 12/13/2022]
Abstract
Previously the food carcinogen methyleugenol was found to be cytotoxic and genotoxic in multiple cell lines and in primary hepatocytes. In this study, the question addressed was whether methyleugenol and the selected oxidative metabolites, 1'-hydroxymethyleugenol, methyleugenol-2',3'-epoxide and 3'-oxomethylisoeugenol trigger a DNA damage response in the human colon carcinoma HT29 cell line. Most notably investigations by flow cytometry revealed that the metabolites induce an accumulation of HT29 cells in the G2 phase of the cell cycle. DNA damage response is characterised by a time-delayed phosphorylation of ATM (ataxia-telangiectasia, mutated)/ATR (ATM- and Rad3-related) kinases and checkpoint kinase 1 after 2 h of incubation, and the tumour suppressor protein p53 only after 24 h of incubation. The test compounds induced apoptotic cell death indicated by cleavage of caspase 3 and poly-(ADP-ribose)-polymerase after a prolonged incubation time up to 72 h. In addition, activation of ATM/ATR-signalling cascade might contribute to apoptosis induction to a certain extent. However, clarification of this relationship awaits experimental confirmation.
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Affiliation(s)
- Isabel Anna Maria Groh
- Institute of Food Chemistry and Toxicology, Technical University of Kaiserslautern, Kaiserslautern, Germany
| | - Melanie Esselen
- Institute of Food Chemistry, Westfälische Wilhelms University of Münster, Münster, Germany.
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12
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Ning J, Louisse J, Spenkelink B, Wesseling S, Rietjens IMCM. Study on inter-ethnic human differences in bioactivation and detoxification of estragole using physiologically based kinetic modeling. Arch Toxicol 2017; 91:3093-3108. [PMID: 28357488 PMCID: PMC5562778 DOI: 10.1007/s00204-017-1941-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 02/21/2017] [Indexed: 12/21/2022]
Abstract
Considering the rapid developments in food safety in the past decade in China, it is of importance to obtain insight into what extent safety and risk assessments of chemicals performed for the Caucasian population apply to the Chinese population. The aim of the present study was to determine physiologically based kinetic (PBK) modeling-based predictions for differences between Chinese and Caucasians in terms of metabolic bioactivation and detoxification of the food-borne genotoxic carcinogen estragole. The PBK models were defined based on kinetic constants for hepatic metabolism derived from in vitro incubations using liver fractions of the two ethnic groups, and used to evaluate the inter-ethnic differences in metabolic activation and detoxification of estragole. The models predicted that at realistic dietary intake levels, only 0.02% of the dose was converted to the ultimate carcinogenic metabolite 1′-sulfooxyestragole in Chinese subjects, whereas this amounted to 0.09% of the dose in Caucasian subjects. Detoxification of 1′-hydroxyestragole, mainly via conversion to 1′-oxoestragole, was similar within the two ethnic groups. The 4.5-fold variation in formation of the ultimate carcinogenic metabolite of estragole accompanied by similar rates of detoxification may indicate a lower risk of estragole for the Chinese population at similar levels of exposure. The study provides a proof of principle for how PBK modeling can identify differences in ethnic sensitivity and provide a more refined risk assessment for a specific ethnic group for a compound of concern.
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Affiliation(s)
- Jia Ning
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands.
| | - Jochem Louisse
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Bert Spenkelink
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Sebastiaan Wesseling
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
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13
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Feng Y, Wang H, Wang Q, Huang W, Peng Y, Zheng J. Chemical Interaction of Protein Cysteine Residues with Reactive Metabolites of Methyleugenol. Chem Res Toxicol 2017; 30:564-573. [DOI: 10.1021/acs.chemrestox.6b00290] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yukun Feng
- Wuya
College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Hui Wang
- Wuya
College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Qian Wang
- Wuya
College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, P. R. China
| | - Wenlin Huang
- Department
of Biochemistry, University of Washington, Seattle, Washington 98195, United States
| | - 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
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14
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Physiologically based kinetic modeling of the bioactivation of myristicin. Arch Toxicol 2016; 91:713-734. [PMID: 27334372 PMCID: PMC5306082 DOI: 10.1007/s00204-016-1752-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 06/08/2016] [Indexed: 11/08/2022]
Abstract
The present study describes physiologically based kinetic (PBK) models for the alkenylbenzene myristicin that were developed by extension of the PBK models for the structurally related alkenylbenzene safrole in rat and human. The newly developed myristicin models revealed that the formation of the proximate carcinogenic metabolite 1′-hydroxymyristicin in liver is at most 1.8 fold higher in rat than in human and limited for the ultimate carcinogenic metabolite 1′-sulfoxymyristicin to (2.8–4.0)-fold higher in human. In addition, a comparison was made between the relative importance of bioactivation for myristicin and safrole. Model predictions indicate that for these related compounds, the formation of the 1′-sulfoxy metabolites in rat and human liver is comparable with a difference of <2.2-fold over a wide dose range. The results from this PBK analysis support that risk assessment of myristicin may be based on the BMDL10 derived for safrole of 1.9–5.1 mg/kg bw per day. Using an estimated daily intake of myristicin of 0.0019 mg/kg bw per day resulting from the use of herbs and spices, this results in MOE values for myristicin that amount to 1000–2700, indicating a priority for risk management. The results obtained illustrate that PBK modeling provides insight into possible species differences in the metabolic activation of myristicin. Moreover, they provide an example of how PBK modeling can facilitate a read-across in risk assessment from a compound for which in vivo toxicity studies are available to a related compound for which tumor data are not reported, thus contributing to alternatives in animal testing.
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15
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Kristanc L, Kreft S. European medicinal and edible plants associated with subacute and chronic toxicity part I: Plants with carcinogenic, teratogenic and endocrine-disrupting effects. Food Chem Toxicol 2016; 92:150-64. [PMID: 27090581 DOI: 10.1016/j.fct.2016.04.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 04/08/2016] [Accepted: 04/10/2016] [Indexed: 12/14/2022]
Abstract
In recent decades, the use of herbal medicines and food products has been widely embraced in many developed countries. These products are generally highly accepted by consumers who often believe that "natural" equals "safe". This is, however, an oversimplification because several botanicals have been found to contain toxic compounds in concentrations harmful to human health. Acutely toxic plants are in most cases already recognised as dangerous as a result of their traditional use, but plants with subacute and chronic toxicity are difficult or even impossible to detect by traditional use or by clinical research studies. In this review, we systematically address major issues including the carcinogenicity, teratogenicity and endocrine-disrupting effects associated with the use of herbal preparations with a strong focus on plant species that either grow natively or are cultivated in Europe. The basic information regarding the molecular mechanisms of the individual subtypes of plant-induced non-acute toxicity is given, which is followed by a discussion of the pathophysiological and clinical characteristics. We describe the genotoxic and carcinogenic effects of alkenylbenzenes, pyrrolizidine alkaloids and bracken fern ptaquiloside, the teratogenicity issues regarding anthraquinone glycosides and specific alkaloids, and discuss the human health concerns regarding the phytoestrogens and licorice consumption in detail.
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Affiliation(s)
- Luka Kristanc
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Vrazov Trg 2, 1000 Ljubljana, Slovenia; Primary Healthcare of Gorenjska, ZD Kranj, Gosposvetska Ulica 10, 4000 Kranj, Slovenia.
| | - Samo Kreft
- Faculty of Pharmacy, University of Ljubljana, Tržaška Cesta 32, 1000 Ljubljana, Slovenia
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Punt A, Paini A, Spenkelink A, Scholz G, Schilter B, van Bladeren PJ, Rietjens IMCM. Evaluation of Interindividual Human Variation in Bioactivation and DNA Adduct Formation of Estragole in Liver Predicted by Physiologically Based Kinetic/Dynamic and Monte Carlo Modeling. Chem Res Toxicol 2016; 29:659-68. [PMID: 26952143 DOI: 10.1021/acs.chemrestox.5b00493] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Estragole is a known hepatocarcinogen in rodents at high doses following metabolic conversion to the DNA-reactive metabolite 1'-sulfooxyestragole. The aim of the present study was to model possible levels of DNA adduct formation in (individual) humans upon exposure to estragole. This was done by extending a previously defined PBK model for estragole in humans to include (i) new data on interindividual variation in the kinetics for the major PBK model parameters influencing the formation of 1'-sulfooxyestragole, (ii) an equation describing the relationship between 1'-sulfooxyestragole and DNA adduct formation, (iii) Monte Carlo modeling to simulate interindividual human variation in DNA adduct formation in the population, and (iv) a comparison of the predictions made to human data on DNA adduct formation for the related alkenylbenzene methyleugenol. Adequate model predictions could be made, with the predicted DNA adduct levels at the estimated daily intake of estragole of 0.01 mg/kg bw ranging between 1.6 and 8.8 adducts in 10(8) nucleotides (nts) (50th and 99th percentiles, respectively). This is somewhat lower than values reported in the literature for the related alkenylbenzene methyleugenol in surgical human liver samples. The predicted levels seem to be below DNA adduct levels that are linked with tumor formation by alkenylbenzenes in rodents, which were estimated to amount to 188-500 adducts per 10(8) nts at the BMD10 values of estragole and methyleugenol. Although this does not seem to point to a significant health concern for human dietary exposure, drawing firm conclusions may have to await further validation of the model's predictions.
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Affiliation(s)
- Ans Punt
- Division of Toxicology, Wageningen University , Tuinlaan 5, 6703 HE Wageningen, The Netherlands
| | - Alicia Paini
- Division of Toxicology, Wageningen University , Tuinlaan 5, 6703 HE Wageningen, The Netherlands.,Nestlé Research Center , P.O. Box 44, 1000 Lausanne 26, Switzerland
| | - Albertus Spenkelink
- Division of Toxicology, Wageningen University , Tuinlaan 5, 6703 HE Wageningen, The Netherlands
| | - Gabriele Scholz
- Nestlé Research Center , P.O. Box 44, 1000 Lausanne 26, Switzerland
| | - Benoit Schilter
- Nestlé Research Center , P.O. Box 44, 1000 Lausanne 26, Switzerland
| | - Peter J van Bladeren
- Division of Toxicology, Wageningen University , Tuinlaan 5, 6703 HE Wageningen, The Netherlands.,Nestec S.A , Avenue Nestlé 55, 1800 Vevey, Switzerland
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University , Tuinlaan 5, 6703 HE Wageningen, The Netherlands
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Alajlouni AM, Al_Malahmeh AJ, Kiwamoto R, Wesseling S, Soffers AE, Al-Subeihi AA, Vervoort J, Rietjens IM. Mode of action based risk assessment of the botanical food-borne alkenylbenzene apiol from parsley using physiologically based kinetic (PBK) modelling and read-across from safrole. Food Chem Toxicol 2016; 89:138-50. [DOI: 10.1016/j.fct.2016.01.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 12/01/2022]
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Kobets T, Duan JD, Brunnemann KD, Etter S, Smith B, Williams GM. Structure-Activity Relationships for DNA Damage by Alkenylbenzenes in Turkey Egg Fetal Liver. Toxicol Sci 2015; 150:301-11. [DOI: 10.1093/toxsci/kfv322] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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Groh IAM, Rudakovski O, Gründken M, Schroeter A, Marko D, Esselen M. Methyleugenol and oxidative metabolites induce DNA damage and interact with human topoisomerases. Arch Toxicol 2015; 90:2809-2823. [DOI: 10.1007/s00204-015-1625-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 10/22/2015] [Indexed: 11/25/2022]
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20
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Tsai CJ, Li JH, Feng CH. Dual dispersive liquid–liquid microextraction for determination of phenylpropenes in oils by gas chromatography–mass spectrometry. J Chromatogr A 2015; 1410:60-7. [DOI: 10.1016/j.chroma.2015.07.095] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 01/01/2023]
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Rietjens IMCM, Cohen SM, Fukushima S, Gooderham NJ, Hecht S, Marnett LJ, Smith RL, Adams TB, Bastaki M, Harman CG, Taylor SV. Impact of Structural and Metabolic Variations on the Toxicity and Carcinogenicity of Hydroxy- and Alkoxy-Substituted Allyl- and Propenylbenzenes. Chem Res Toxicol 2014; 27:1092-103. [DOI: 10.1021/tx500109s] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I. M. C. M. Rietjens
- Division
of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands
| | - S. M. Cohen
- Department
of Pathology and Microbiology, University of Nebraska Medical Center, 4400 Emile Street, Omaha, Nebraska 68198, United States
| | - S. Fukushima
- Japan Bioassay Research
Center, 2445, Hirasawa, Hadano-shi, Kanagawa 257-0015, Japan
| | - N. J. Gooderham
- Department
of Surgery and Cancer, Imperial College, London SW7 2AZ, United Kingdom
| | - S. Hecht
- Masonic
Cancer Center and Department of Laboratory Medicine and Pathology, University of Minnesota, MMC 806, 420 Delaware St. SE, Minneapolis, Minnesota 55455, United States
| | - L. J. Marnett
- Department
of Biochemistry, Center in Molecular Toxicology, Vanderbilt University School of Medicine, 1161 21st Avenue S # T1217, Nashville, Tennessee 37232-0146, United States
| | - R. L. Smith
- Molecular
Toxicology, Imperial College, London SW7 2AZ, United Kingdom
| | - T. B. Adams
- Verto Solutions, 1101,
17th Street NW Suite 700, Washington,
D.C. 20036, United States
| | - M. Bastaki
- Verto Solutions, 1101,
17th Street NW Suite 700, Washington,
D.C. 20036, United States
| | - C. G. Harman
- Verto Solutions, 1101,
17th Street NW Suite 700, Washington,
D.C. 20036, United States
| | - S. V. Taylor
- Verto Solutions, 1101,
17th Street NW Suite 700, Washington,
D.C. 20036, United States
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Basaglia G, Fiori J, Leoni A, Gotti R. Determination of Estragole in Fennel Herbal Teas by HS-SPME and GC–MS. ANAL LETT 2013. [DOI: 10.1080/00032719.2013.834444] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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23
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van den Berg SJPL, Punt A, Soffers AEMF, Vervoort J, Ngeleja S, Spenkelink B, Rietjens IMCM. Physiologically based kinetic models for the alkenylbenzene elemicin in rat and human and possible implications for risk assessment. Chem Res Toxicol 2012; 25:2352-67. [PMID: 22992039 DOI: 10.1021/tx300239z] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present study describes physiologically based kinetic (PBK) models for the alkenylbenzene elemicin (3,4,5-trimethoxyallylbenzene) in rat and human, based on the PBK models previously developed for the structurally related alkenylbenzenes estragole, methyleugenol, and safrole. Using the newly developed models, the level of metabolic activation of elemicin in rat and human was predicted to obtain insight in species differences in the bioactivation of elemicin and read across to the other methoxy allylbenzenes, estragole and methyleugenol. Results reveal that the differences between rat and human in the formation of the proximate carcinogenic metabolite 1'-hydroxyelemicin and the ultimate carcinogenic metabolite 1'-sulfoxyelemicin are limited (<3.8-fold). In addition, a comparison was made between the relative importance of bioactivation for elemicin and that of estragole and methyleugenol. Model predictions indicate that compound differences in the formation of the 1'-sulfoxymetabolites are limited (<11-fold) in rat and human liver. The insights thus obtained were used to perform a risk assessment for elemicin using the margin of exposure (MOE) approach and read across to the other methoxy allylbenzene derivatives for which in vivo animal tumor data are available. This reveals that elemicin poses a lower priority for risk management as compared to its structurally related analogues estragole and methyleugenol. Altogether, the results obtained indicate that PBK modeling provides an important insight in the occurrence of species differences in the metabolic activation of elemicin. Moreover, they provide an example of how PBK modeling can facilitate a read across in risk assessment from compounds for which in vivo toxicity studies are available to a compound for which only limited toxicity data have been described, thus contributing to the development of alternatives for animal testing.
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Can estragole in fennel seed decoctions really be considered a danger for human health? A fennel safety update. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 2012:860542. [PMID: 22899959 PMCID: PMC3414240 DOI: 10.1155/2012/860542] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 06/20/2012] [Indexed: 01/11/2023]
Abstract
Fennel (Foeniculum vulgare Mill.) mature fruit (commonly known as seeds) and essential oil of fennel are widely used as flavoring agents in food products such as liqueurs, bread, cheese, and an ingredient of cosmetics and pharmaceutical products. Moreover fennel infusions are the classical decoction for nursing babies to prevent flatulence and colic spasm. Traditionally in Europe and Mediterranean areas fennel is used as antispasmodic, diuretic, anti-inflammatory, analgesic, secretomotor, secretolytic, galactagogue, eye lotion, and antioxidant remedy and integrator. Topically, fennel powder is used as a poultice for snake bites. In Asian cultures fennel was ingested to speed the elimination of poisons. As one of the ancient Saxon people's nine sacred herbs, fennel was credited with the power to cure. Fennel was also valued as a magic herb: in the Middle Ages it was draped over doorways on Midsummer's Eve to protect the household from evil spirits. Recently because of estragole carcinogenicity, fennel has been charged to be dangerous for humans especially if used as decoction for babies. But this allegation do not consider the remedy is prepared as a matrix of substances, and recent researches confirm that pure estragole is inactivated by many substance contained in the decoction.
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Martati E, Boersma MG, Spenkelink A, Khadka DB, van Bladeren PJ, Rietjens IMCM, Punt A. Physiologically Based Biokinetic (PBBK) Modeling of Safrole Bioactivation and Detoxification in Humans as Compared With Rats. Toxicol Sci 2012; 128:301-16. [DOI: 10.1093/toxsci/kfs174] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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26
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Al-Subeihi AA, Spenkelink B, Punt A, Boersma MG, van Bladeren PJ, Rietjens IM. Physiologically based kinetic modeling of bioactivation and detoxification of the alkenylbenzene methyleugenol in human as compared with rat. Toxicol Appl Pharmacol 2012; 260:271-84. [DOI: 10.1016/j.taap.2012.03.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 02/15/2012] [Accepted: 03/07/2012] [Indexed: 11/25/2022]
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27
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Maria Groh IA, Cartus AT, Vallicotti S, Kajzar J, Merz KH, Schrenk D, Esselen M. Genotoxic potential of methyleugenol and selected methyleugenol metabolites in cultured Chinese hamster V79 cells. Food Funct 2012; 3:428-36. [DOI: 10.1039/c2fo10221h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chiang SY, Lee PY, Lai MT, Shen LC, Chung WS, Huang HF, Wu KY, Wu HC. Safrole-2′,3′-oxide induces cytotoxic and genotoxic effects in HepG2 cells and in mice. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2011; 726:234-41. [DOI: 10.1016/j.mrgentox.2011.09.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2011] [Revised: 08/09/2011] [Accepted: 09/25/2011] [Indexed: 12/16/2022]
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29
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Martati E, Boersma MG, Spenkelink A, Khadka DB, Punt A, Vervoort J, van Bladeren PJ, Rietjens IMCM. Physiologically Based Biokinetic (PBBK) Model for Safrole Bioactivation and Detoxification in Rats. Chem Res Toxicol 2011; 24:818-34. [DOI: 10.1021/tx200032m] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Fang ZZ, Zhang YY, Wang XL, Cao YF, Huo H, Yang L. Bioactivation of herbal constituents: simple alerts in the complex system. Expert Opin Drug Metab Toxicol 2011; 7:989-1007. [DOI: 10.1517/17425255.2011.586335] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Chen XW, Serag ES, Sneed KB, Zhou SF. Herbal bioactivation, molecular targets and the toxicity relevance. Chem Biol Interact 2011; 192:161-76. [PMID: 21459083 DOI: 10.1016/j.cbi.2011.03.016] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 03/25/2011] [Accepted: 03/29/2011] [Indexed: 12/26/2022]
Abstract
There have been increasing reports on the adverse reactions associated with herbal consumption. For many of these adverse reactions, the underlying biochemical mechanisms are unknown, but bioactivation of herbal compounds to generate reactive intermediates have been implicated. This minireview updates our knowledge on metabolic activation of herbal compounds, molecular targets and the toxicity relevance. A number of studies have documented that some herbal compounds can be converted to toxic or even carcinogenic metabolites by Phase I [e.g. cytochrome P450s (CYPs)] and less frequently by Phase II enzymes. For example, aristolochic acids (AAs) in Aristolochia spp, which undergo reduction of the nitro group by hepatic CYP1A1/2 or peroxidases in extrahepatic tissues to generate highly reactive cyclic nitrenium ions. The latter can react with macromolecules (DNA and protein), resulting in activation of H-ras and myc oncogenes and gene mutation in renal cells and finally carcinogenesis of the kidneys. Teucrin A and teuchamaedryn A, two diterpenoids found in germander (Teuchrium chamaedrys) used as an adjuvant to slimming herbal supplements that caused severe hepatotoxicity, are converted by CYP3A4 to reactive epoxide which reacts with proteins such as CYP3A and epoxide hydrolase and inactivate them. Some naturally occurring alkenylbenzenes (e.g. safrole, methyleugenol and estragole) and flavonoids (e.g. quercetin) can undergo bioactivation by sequential 1-hydroxylation and sulfation, resulting in reactive intermediates capable of forming DNA adducts. Extensive pulegone metabolism generated p-cresol that is a glutathione depletory. The hepatotoxicity of kava is possibly due to intracellular glutathione depletion and/or quinone formation. Moreover, several herbal compounds including capsaicin from chili peppers, dially sulfone in garlic, methysticin and dihydromethysticin in kava, oleuropein in olive oil, and resveratrol found in grape seeds are mechanism-based (suicide) inhibitors of various CYPs. Together with advances of proteomics, metabolomics and toxicogenomics, an integrated systems toxicological approach may provide deep insights into mechanistic aspects of herb-induced toxicities, and contribute to bridging the relationships between herbal bioactivation, protein/DNA adduct formation and the toxicological consequences.
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Affiliation(s)
- Xiao-Wu Chen
- Department of General Surgery, The First People's Hospital of Shunde affiliated to Southern Medical University, Shunde, Foshan, Guangdong, China
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Al-Subeihi AA, Spenkelink B, Rachmawati N, Boersma MG, Punt A, Vervoort J, van Bladeren PJ, Rietjens IM. Physiologically based biokinetic model of bioactivation and detoxification of the alkenylbenzene methyleugenol in rat. Toxicol In Vitro 2011; 25:267-85. [DOI: 10.1016/j.tiv.2010.08.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 08/11/2010] [Accepted: 08/30/2010] [Indexed: 10/19/2022]
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Punt A, Jeurissen SM, Boersma MG, Delatour T, Scholz G, Schilter B, van Bladeren PJ, Rietjens IMCM. Evaluation of Human Interindividual Variation in Bioactivation of Estragole Using Physiologically Based Biokinetic Modeling. Toxicol Sci 2009; 113:337-48. [DOI: 10.1093/toxsci/kfp272] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Nesslany F, Parent-Massin D, Marzin D. Risk assessment of consumption of methylchavicol and tarragon: the genotoxic potential in vivo and in vitro. Mutat Res 2009; 696:1-9. [PMID: 19913108 DOI: 10.1016/j.mrgentox.2009.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 10/19/2009] [Accepted: 10/30/2009] [Indexed: 10/20/2022]
Abstract
Methylchavicol (or estragole), a natural flavouring substance present in tarragon, was confirmed as a genotoxic chemical in the in vitro UDS test in cultured rat hepatocytes and in the in vivo UDS test in hepatocytes of exposed rats. Deep-frozen tarragon was clearly less genotoxic than methylchavicol at equivalent dose levels, and desiccated tarragon was negative. Both forms of tarragon tested in vitro have the ability to decrease significantly the genotoxicity of methylchavicol added to the culture medium at concentrations </=10 muM for deep-frozen and </=55 muM for desiccated tarragon. The decrease may be attributed to antimutagenic properties of tarragon leaves and/or to adsorption of methylchavicol, which would decrease its bioavailability. Desiccated tarragon powder was not genotoxic in the in vivo UDS test when administered up to the maximum dose of 6.25 g/kg bw (18.75 mg/kg bw of methylchavicol). In vivo, desiccated tarragon did not show antimutagenic properties, because it did not decrease the genotoxicity of methylchavicol added at high concentrations. Considering the low exposure level at the maximum daily tarragon consumption, the rapid detoxification and excretion in humans and the no-genotoxic-effect-level of methylchavicol by the oral route when given to rats as tarragon leaves, a high margin of exposure exists. We can conclude that tarragon consumption presents no genotoxic risk to humans.
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Punt A, Paini A, Boersma MG, Freidig AP, Delatour T, Scholz G, Schilter B, van Bladeren PJ, Rietjens IMCM. Use of physiologically based biokinetic (PBBK) modeling to study estragole bioactivation and detoxification in humans as compared with male rats. Toxicol Sci 2009; 110:255-69. [PMID: 19447879 PMCID: PMC2708596 DOI: 10.1093/toxsci/kfp102] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The extent of bioactivation of the herbal constituent estragole to its ultimate carcinogenic metabolite 1′-sulfooxyestragole depends on the relative levels of bioactivation and detoxification pathways. The present study investigated the kinetics of the metabolic reactions of both estragole and its proximate carcinogenic metabolite 1′-hydroxyestragole in humans in incubations with relevant tissue fractions. Based on the kinetic data obtained a physiologically based biokinetic (PBBK) model for estragole in human was defined to predict the relative extent of bioactivation and detoxification at different dose levels of estragole. The outcomes of the model were subsequently compared with those previously predicted by a PBBK model for estragole in male rat to evaluate the occurrence of species differences in metabolic activation. The results obtained reveal that formation of 1′-oxoestragole, which represents a minor metabolic route for 1′-hydroxyestragole in rat, is the main detoxification pathway of 1′-hydroxyestragole in humans. Due to a high level of this 1′-hydroxyestragole oxidation pathway in human liver, the predicted species differences in formation of 1′-sulfooxyestragole remain relatively low, with the predicted formation of 1′-sulfooxyestragole being twofold higher in human compared with male rat, even though the formation of its precursor 1′-hydroxyestragole was predicted to be fourfold higher in human. Overall, it is concluded that in spite of significant differences in the relative extent of different metabolic pathways between human and male rat there is a minor influence of species differences on the ultimate overall bioactivation of estragole to 1′-sulfooxyestragole.
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Affiliation(s)
- Ans Punt
- Division of Toxicology, Wageningen University, 6703 HE Wageningen, The Netherlands
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Mitchell MD, Elrick MM, Walgren JL, Mueller RA, Morris DL, Thompson DC. Peptide-Based In Vitro Assay for the Detection of Reactive Metabolites. Chem Res Toxicol 2008; 21:859-68. [PMID: 18370411 DOI: 10.1021/tx700344m] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael D. Mitchell
- Drug Safety Research and Development, Pfizer Global Research and Development, 700 Chesterfield Parkway West T1A, Chesterfield, Missouri 63017, and ChemGate, Inc., 562 Stonegate Terrace, Glencoe, Illinois 60022
| | - Mollisa M. Elrick
- Drug Safety Research and Development, Pfizer Global Research and Development, 700 Chesterfield Parkway West T1A, Chesterfield, Missouri 63017, and ChemGate, Inc., 562 Stonegate Terrace, Glencoe, Illinois 60022
| | - Jennie L. Walgren
- Drug Safety Research and Development, Pfizer Global Research and Development, 700 Chesterfield Parkway West T1A, Chesterfield, Missouri 63017, and ChemGate, Inc., 562 Stonegate Terrace, Glencoe, Illinois 60022
| | - Richard A. Mueller
- Drug Safety Research and Development, Pfizer Global Research and Development, 700 Chesterfield Parkway West T1A, Chesterfield, Missouri 63017, and ChemGate, Inc., 562 Stonegate Terrace, Glencoe, Illinois 60022
| | - Dale L. Morris
- Drug Safety Research and Development, Pfizer Global Research and Development, 700 Chesterfield Parkway West T1A, Chesterfield, Missouri 63017, and ChemGate, Inc., 562 Stonegate Terrace, Glencoe, Illinois 60022
| | - David C. Thompson
- Drug Safety Research and Development, Pfizer Global Research and Development, 700 Chesterfield Parkway West T1A, Chesterfield, Missouri 63017, and ChemGate, Inc., 562 Stonegate Terrace, Glencoe, Illinois 60022
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Jeurissen SMF, Punt A, Delatour T, Rietjens IMCM. Basil extract inhibits the sulfotransferase mediated formation of DNA adducts of the procarcinogen 1'-hydroxyestragole by rat and human liver S9 homogenates and in HepG2 human hepatoma cells. Food Chem Toxicol 2008; 46:2296-302. [PMID: 18433972 DOI: 10.1016/j.fct.2008.03.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2007] [Revised: 12/23/2007] [Accepted: 03/10/2008] [Indexed: 11/28/2022]
Abstract
The effects of a basil extract on the sulfation and concomitant DNA adduct formation of the proximate carcinogen 1'-hydroxyestragole were studied using rat and human liver S9 homogenates and the human hepatoma cell line HepG2. Basil was chosen since it contains the procarcinogen estragole that can be metabolized to 1'-hydroxyestragole by cytochrome P450 enzymes. Basil extract addition to incubations of rat and human liver S9 homogenates with 1'-hydroxyestragole, the sulfotransferase cofactor PAPS, and 2'-deoxyguanosine resulted in a dose-dependent inhibition of N2-(trans-isoestragol-3'-yl)-2'-deoxyguanosine formation. Because the inhibition resembled the inhibition by the sulfotransferase inhibitor pentachlorophenol and since the inhibition was not observed in incubations with the direct electrophile 1'-acetoxyestragole it is concluded that the inhibition occurs at the level of the sulfotransferase mediated bioactivation step. Additional experiments in HepG2 cells revealed the same protective effect of basil extract in intact cells, demonstrating that the inhibitors are able to enter the cells. The results of this study suggest that bioactivation and subsequent adverse effects of 1'-hydroxyestragole might be lower in a matrix of other basil ingredients than what would be expected on the basis of experiments using 1'-hydroxyestragole as a single compound.
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Affiliation(s)
- Suzanne M F Jeurissen
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands
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Jeurissen SMF, Punt A, Boersma MG, Bogaards JJP, Fiamegos YC, Schilter B, van Bladeren PJ, Cnubben NHP, Rietjens IMCM. Human Cytochrome P450 Enzyme Specificity for the Bioactivation of Estragole and Related Alkenylbenzenes. Chem Res Toxicol 2007; 20:798-806. [PMID: 17407329 DOI: 10.1021/tx700012d] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human cytochrome P450 enzymes involved in the bioactivation of estragole to its proximate carcinogen 1'-hydroxyestragole were identified and compared to the enzymes of importance for 1'-hydroxylation of the related alkenylbenzenes methyleugenol and safrole. Incubations with Supersomes revealed that all enzymes tested, except P450 2C8, are intrinsically able to 1'-hydroxylate estragole. Experiments with Gentest microsomes, expressing P450 enzymes to roughly average liver levels, indicated that P450 1A2, 2A6, 2C19, 2D6, and 2E1 might contribute to estragole 1'-hydroxylation in the human liver. Especially P450 1A2 is an important enzyme based on the correlation between P450 1A2 activity and estragole 1'-hydroxylation in human liver microsomal samples and inhibition of estragole 1'-hydroxylation by the P450 1A2 inhibitor alpha-naphthoflavone. Kinetic studies revealed that, at physiologically relevant concentrations of estragole, P450 1A2 and 2A6 are the most important enzymes for bioactivation in the human liver showing enzyme efficiencies (kcat/Km) of, respectively, 59 and 341 min-1 mM-1. Only at relatively high estragole concentrations, P450 2C19, 2D6, and 2E1 might contribute to some extent. Comparison to results from similar studies for safrole and methyleugenol revealed that competitive interactions between estragole and methyleugenol 1'-hydroxylation and between estragole and safrole 1'-hydroxylation are to be expected because of the involvement of, respectively, P450 1A2 and P450 2A6 in the bioactivation of these compounds. Furthermore, poor metabolizer phenotypes in P450 2A6 might diminish the chances on bioactivation of estragole and safrole, whereas lifestyle factors increasing P450 1A2 activities such as cigarette smoking and consumption of charbroiled food might increase those chances for estragole and methyleugenol.
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Affiliation(s)
- Suzanne M F Jeurissen
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands
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Maralhas A, Monteiro A, Martins C, Kranendonk M, Laires A, Rueff J, Rodrigues AS. Genotoxicity and endoreduplication inducing activity of the food flavouring eugenol. Mutagenesis 2006; 21:199-204. [PMID: 16595588 DOI: 10.1093/mutage/gel017] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Eugenol (1-allyl-3-methoxy-4-hydroxybenzene; CAS No. 97-53-0), a compound extracted from clove oil and marjoram, is widely used as a food flavouring substance and is present in spices such as basil, cinnamon and nutmeg. It is also used in dentistry as an antiseptic and analgesic. Structural similarities with the class IIB IARC carcinogen safrole raises questions on its putative carcinogenicity. We evaluated the genotoxicity of eugenol in V79 cells using chromosomal aberrations (CAs), with and without rat liver biotransformation (S9). Eugenol induced CAs, with significant increases (3.5% aberrant cells) at 2500 microM, demonstrating cytotoxicity at higher doses. S9 increased the induction of CAs in a dose-dependent manner to 15% at 2500 microM, with a high frequency of chromatid exchanges. In particular, an increase of endoreduplicated cells was observed, from 0% at control levels to 2.3 and 5% at 2000 microM, without and with S9, respectively. Since endoreduplication has been linked to inhibition of topoisomerase II, the topoisomerase II inhibitor ICRF-193 was used as a control inducer of endoreduplication (0.1-0.5 microM), increasing the number of endoreduplicated cells from 0% (control) to 3.5% (0.5 microM). S9 did not influence endoreduplication by ICRF-193. Both eugenol and ICRF-193 were also assayed for inhibition of topoisomerase II, and both showed a dose-dependent inhibitory effect, with ICRF-193 being a more potent inhibitor. Our results confirm that eugenol is genotoxic and raises the possibility of it having topoisomerase II inhibiting activity.
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Affiliation(s)
- Alexandra Maralhas
- Department of Genetics, Faculty of Medical Sciences, Universidade Nova de Lisboa R. da Junqueira 96, Portugal
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Fabian EJ, Metzler M. Selective metabolism of E-3,4-bis(4-ethylphenyl)hex-3-ene in rat liver microsomes. Arch Toxicol 2005; 80:17-26. [PMID: 16187102 DOI: 10.1007/s00204-005-0007-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Accepted: 05/23/2005] [Indexed: 10/25/2022]
Abstract
The synthetic stilbene derivative E-3,4-bis(4-ethylphenyl)hex-3-ene (E-DE-BPH) has been proposed as a potential anticancer drug with a new mode of action. We report here on the in vitro metabolism of E-DE-BPH in liver microsomes of rats and pigs. The formation of five metabolites, which could be separated on a reverse-phase HPLC column with UV detection, was observed in microsomal incubations. To facilitate the structural identification of these metabolites, two different deuterium-labeled forms of E-DE-BPH were synthesized. By comparing the mass spectra obtained for the metabolites of unlabeled E-DE-BPH and of the two deuterated forms, it could be demonstrated that E-DE-BPH was oxidized by liver microsomes exclusively at the benzylic positions of the molecule. The major metabolite was identified as E-3-(4-(1-hydroxyethyl)phenyl)-4-(4-ethylphenyl)hex-3-ene. Four minor metabolites were formed from the major metabolite, either by hydroxylation at the other benzylic position to yield a bishydroxylated metabolite, or by oxidation of the hydroxyl group to form E-3-(4-acetylphenyl)-4-(4-ethylphenyl)hex-3-ene. The latter compound was also obtained by chemical oxidation of the monohydroxylated metabolite of E-DE-BPH. Since no products containing hydroxyl groups at the aromatic rings or at other aliphatic sites of the molecule were detected, a surprisingly selective oxidative metabolism of E-DE-BPH appears to occur with rat and pig liver microsomes.
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Affiliation(s)
- Eric J Fabian
- Institute of Applied Biosciences, Section of Food Chemistry and Toxicology, University of Karlsruhe, P.O. Box 6980, 76128 Karlsruhe, Germany.
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Zhao J, Miao J, Zhao B, Zhang S, Yin D. Safrole oxide inhibits angiogenesis by inducing apoptosis. Vascul Pharmacol 2005; 43:69-74. [PMID: 15936989 DOI: 10.1016/j.vph.2005.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Accepted: 04/26/2005] [Indexed: 01/24/2023]
Abstract
Our previous studies indicate that 3, 4-(methylenedioxy)-1-(2', 3'-epoxypropyl)-benzene (safrole oxide), a newly synthesized compound, induces apoptosis in vascular endothelial cells (VECs) and A549 lung cancer cells. To our knowledge, the inhibition of angiogenesis by safrole oxide has not been reported yet. We report here that cultured rat aorta treated with safrole oxide exhibited a significant microvessel reduction as determined by counting the number of microvessels in a phase contrast microscope. There were more microvessels formed in the presence of A549 lung cancer cells in rat aorta model, while a dramatic inhibition of angiogenesis was obtained by adding 220-450 micromol l(-1) of safrole oxide to the growth medium (P<.01). The culture of rat aorta treated with safrole oxide produced only some abortive endothelial cells but not microvessels. Furthermore, safrole oxide induced antiangiogenic effect in the chorioallantoic membranes (CAM) as a dose dependent manner. Eggs treated with 2-11 micromol 100 microl(-1) per egg of the safrole oxide for 48 h exhibited a significant reduction in blood vessel area of the CAM, a process likely mediated by apoptosis as demonstrated by DNA fragmentation. Our results suggest that safrole oxide has antiangiogenic activity and this effect might occur by induction of cellular apoptosis.
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Affiliation(s)
- Jing Zhao
- Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China
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Rietjens IMCM, Martena MJ, Boersma MG, Spiegelenberg W, Alink GM. Molecular mechanisms of toxicity of important food-borne phytotoxins. Mol Nutr Food Res 2005; 49:131-58. [PMID: 15635687 DOI: 10.1002/mnfr.200400078] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
At present, there is an increasing interest for plant ingredients and their use in drugs, for teas, or in food supplements. The present review describes the nature and mechanism of action of the phytochemicals presently receiving increased attention in the field of food toxicology. This relates to compounds including aristolochic acids, pyrrolizidine alkaloids, beta-carotene, coumarin, the alkenylbenzenes safrole, methyleugenol and estragole, ephedrine alkaloids and synephrine, kavalactones, anisatin, St. John's wort ingredients, cyanogenic glycosides, solanine and chaconine, thujone, and glycyrrhizinic acid. It can be concluded that several of these phytotoxins cause concern, because of their bioactivation to reactive alkylating intermediates that are able to react with cellular macromolecules causing cellular toxicity, and, upon their reaction with DNA, genotoxicity resulting in tumors. Another group of the phytotoxins presented is active without the requirement for bioactivation and, in most cases, these compounds appear to act as neurotoxins interacting with one of the neurotransmitter systems. Altogether, the examples presented illustrate that natural does not equal safe and that in modern society adverse health effects, upon either acute or chronic exposure to phytochemicals, can occur as a result of use of plant- or herb-based foods, teas, or other extracts.
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Munerato MC, Sinigaglia M, Reguly ML, de Andrade HHR. Genotoxic effects of eugenol, isoeugenol and safrole in the wing spot test of Drosophila melanogaster. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2005; 582:87-94. [PMID: 15781214 DOI: 10.1016/j.mrgentox.2005.01.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 12/24/2004] [Accepted: 01/07/2005] [Indexed: 11/26/2022]
Abstract
In the present study, the phenolic compounds eugenol, isoeugenol and safrole were investigated for genotoxicity in the wing spot test of Drosophila melanogaster. The Drosophila wing somatic mutation and recombination test (SMART) provides a rapid means to evaluate agents able to induce gene mutations and chromosome aberrations, as well as rearrangements related to mitotic recombination. We applied the SMART in its standard version with normal bioactivation and in its variant with increased cytochrome P450-dependent biotransformation capacity. Eugenol and safrole produced a positive recombinagenic response only in the improved assay, which was related to a high CYP450-dependent activation capacity. This suggests, as previously reported, the involvement of this family of enzymes in the activation of eugenol and safrole rather than in its detoxification. On the contrary, isoeugenol was clearly non-genotoxic at the same millimolar concentrations as used for eugenol in both the crosses. The responsiveness of SMART assays to recombinagenic compounds, as well as the reactive metabolites from eugenol and safrole were considered responsible for the genotoxicity observed.
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Affiliation(s)
- Maria Cristina Munerato
- Departamento de Odontologia Conservadora, Faculdade de Odontologia, Universidade Federal do Rio Grande do Sul, Brazil
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Rietjens IMCM, Boersma MG, van der Woude H, Jeurissen SMF, Schutte ME, Alink GM. Flavonoids and alkenylbenzenes: mechanisms of mutagenic action and carcinogenic risk. Mutat Res 2005; 574:124-38. [PMID: 15914212 DOI: 10.1016/j.mrfmmm.2005.01.028] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 12/13/2004] [Accepted: 01/10/2005] [Indexed: 11/17/2022]
Abstract
The present review focuses on the mechanisms of mutagenic action and the carcinogenic risk of two categories of botanical ingredients, namely the flavonoids with quercetin as an important bioactive representative, and the alkenylbenzenes, namely safrole, methyleugenol and estragole. For quercetin a metabolic pathway for activation to DNA-reactive species may include enzymatic and/or chemical oxidation of quercetin to quercetin ortho-quinone, followed by isomerisation of the ortho-quinone to quinone methides. These quinone methides are suggested to be the active alkylating DNA-reactive intermediates. Recent results have demonstrated the formation of quercetin DNA adducts in exposed cells in vitro. The question that remains to be answered is why these genotoxic characteristics of quercetin are not reflected by carcinogenicity. This might in part be related to the transient nature of quercetin quinone methide adducts, and suggests that stability and/or repair of DNA adducts may need increased attention in in vitro genotoxicity studies. Thus, in vitro mutagenicity studies should put more emphasis on the transient nature of the DNA adducts responsible for the mutagenicity in vitro, since this transient nature of the formed DNA adducts may play an essential role in whether the genotoxicity observed in vitro will have any impact in vivo. For alkenylbenzenes the ultimate electrophilic and carcinogenic metabolites are the carbocations formed upon degradation of their 1'-sulfooxy derivatives, so bioactivation of the alkenylbenzenes to their ultimate carcinogens requires the involvement of cytochromes P450 and sulfotransferases. Identification of the cytochrome P450 isoenzymes involved in bioactivation of the alkenylbenzenes identifies the groups within the population possibly at increased risk, due to life style factors or genetic polymorphisms leading to rapid metaboliser phenotypes. Furthermore, toxicokinetics for conversion of the alkenylbenzenes to their carcinogenic metabolites and kinetics for repair of the DNA adducts formed provide other important aspects that have to be taken into account in the high to low dose risk extrapolation in the risk assessment on alkenylbenzenes. Altogether the present review stresses that species differences and mechanistic data have to be taken into account and that new mechanism- and toxicokinetic-based methods and models are required for cancer risk extrapolation from high dose experimental animal data to low dose carcinogenic risks for man.
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Affiliation(s)
- Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Tuinlaan 5, 6703 HE, Wageningen, The Netherlands.
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Sakano K, Inagaki Y, Oikawa S, Hiraku Y, Kawanishi S. Copper-mediated oxidative DNA damage induced by eugenol: possible involvement of O-demethylation. Mutat Res 2005; 565:35-44. [PMID: 15576237 DOI: 10.1016/j.mrgentox.2004.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2004] [Revised: 08/25/2004] [Accepted: 08/25/2004] [Indexed: 10/26/2022]
Abstract
Eugenol used as a flavor has potential carcinogenicity. DNA adduct formation via 2,3-epoxidation pathway has been thought to be a major mechanism of DNA damage by carcinogenic allylbenzene analogs including eugenol. We examined whether eugenol can induce oxidative DNA damage in the presence of cytochrome P450 using [32P]-5'-end-labeled DNA fragments obtained from human genes relevant to cancer. Eugenol induced Cu(II)-mediated DNA damage in the presence of cytochrome P450 (CYP)1A1, 1A2, 2C9, 2D6, or 2E1. CYP2D6 mediated eugenol-dependent DNA damage most efficiently. Piperidine and formamidopyrimidine-DNA glycosylase treatment induced cleavage sites mainly at T and G residues of the 5'-TG-3' sequence, respectively. Interestingly, CYP2D6-treated eugenol strongly damaged C and G of the 5'-ACG-3' sequence complementary to codon 273 of the p53 gene. These results suggest that CYP2D6-treated eugenol can cause double base lesions. DNA damage was inhibited by both catalase and bathocuproine, suggesting that H2O2 and Cu(I) are involved. These results suggest that Cu(I)-hydroperoxo complex is primary reactive species causing DNA damage. Formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine was significantly increased by CYP2D6-treated eugenol in the presence of Cu(II). Time-of-flight-mass spectrometry demonstrated that CYP2D6 catalyzed O-demethylation of eugenol to produce hydroxychavicol, capable of causing DNA damage. Therefore, it is concluded that eugenol may express carcinogenicity through oxidative DNA damage by its metabolite.
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Affiliation(s)
- Katsuhisa Sakano
- Department of Environmental and Molecular Medicine, Mie University School of Medicine, Mie 514-8507, Japan
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Abstract
Risk characterization comprises hazard identification describing the intrinsic toxic potential of a chemical, knowledge of dose-response-relationships, as well as of toxicokinetics describing quantitatively the relation between external and internal dose and exposure assessment. Compounds that induce reversible effects, which are repaired during and after exposure, are considered thresholded and allow definition of a NOEL. Biological reactive intermediates of chemicals have the potential to bind covalently to cellular macromolecules like proteins and DNA. Such interaction may not be repaired completely. If damage is not repaired, the effect persists and accumulates upon repeated exposure. In such cases a NOEL cannot be determined. Thus, in the risk assessment process, data on covalent binding (CB) are of qualitative and together with toxicokinetics of quantitative significance. Qualitatively, CB, especially with DNA and in correlation with this to proteins, is indicative for an irreversible and non-thresholded mutagenic and carcinogenic effect. Absence or presence of CB assists to differentiate between primarily genotoxic and thresholded non-genotoxic carcinogens. Quantitatively, toxicokinetics together with CB are used to quantify internal exposure and target dose, which is a prerequisite for species-species extrapolation, and for extrapolation from high dose to low dose. For example, the toxicokinetics of the reactive intermediates of styrene and ethylene have been determined in rodents and humans and modeled to predict dose-responses of internal exposure. It is described in this communication that such information, together with other parameters like cell proliferation as a result of cytotoxicity, is the basis for quantitative risk assessment of human exposure to these compounds. Also for chlorobenzene, the relevance of toxicokinetics for estimating the human health risk is demonstrated.
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Affiliation(s)
- H Greim
- Institute of Toxicology and Environmental Hygiene, Technical University München, Hohenbachernstrasse 15-17, D-85350 Weihenstephan, Freising, Germany.
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