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Balaji R, Parani M. Development of an allele-specific PCR (AS-PCR) method for identifying high-methyl eugenol-containing purple Tulsi (Ocimum tenuiflorum L.) in market samples. Mol Biol Rep 2024; 51:439. [PMID: 38520476 DOI: 10.1007/s11033-024-09365-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 02/19/2024] [Indexed: 03/25/2024]
Abstract
BACKGROUND Ocimum tenuiflorum L. is a highly traded medicinal with several therapeutic values. Green Tulsi and purple Tulsi are two subtypes in O. tenuiflorum and both have the same medicinal properties. Recent reports have revealed that purple Tulsi contains higher quantities of methyl eugenol (ME), which is moderately toxic and potentially carcinogenic. Therefore, we developed an allele-specific PCR (AS-PCR) method to distinguish the green and purple Tulsi. METHODS AND RESULT Using the green Tulsi as a reference, 12 single nucleotide polymorphisms (SNPs) and 10 insertions/deletions (InDels) were identified in the chloroplast genome of the purple Tulsi. The C > T SNP at the 1,26,029 position in the ycf1 gene was selected for the development of the AS-PCR method. The primers were designed to amplify 521 bp and 291 bp fragments specific to green and purple Tulsi, respectively. This AS-PCR method was validated in 10 accessions from each subtype and subsequently verified using Sanger sequencing. Subsequently, 30 Tulsi powder samples collected from the market were subjected to molecular identification by AS-PCR. The results showed that 80% of the samples were purple Tulsi, and only 3.5% were green Tulsi. About 10% of the samples were a mixture of both green and purple Tulsi. Two samples (6.5%) did not contain O. tenuiflorum and were identified as O. gratissimum. CONCLUSION The market samples of Tulsi were predominantly derived from purple Tulsi. The AS-PCR method will be helpful for quality control and market surveillance of Tulsi herbal powders.
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Affiliation(s)
- Raju Balaji
- Department of Genetic Engineering, College of Engineering and Technology, Faculty of Engineering and Technology, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur, Kanchipuram, Chennai, TN, 603203, India
| | - Madasamy Parani
- Department of Genetic Engineering, College of Engineering and Technology, Faculty of Engineering and Technology, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur, Kanchipuram, Chennai, TN, 603203, India.
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2
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Nieschalke K, Bergau N, Jessel S, Seidel A, Baldermann S, Schreiner M, Abraham K, Lampen A, Monien BH, Kleuser B, Glatt H, Schumacher F. Urinary Excretion of Mercapturic Acids of the Rodent Carcinogen Methyleugenol after a Single Meal of Basil Pesto: A Controlled Exposure Study in Humans. Chem Res Toxicol 2023; 36:1753-1767. [PMID: 37875262 PMCID: PMC10664145 DOI: 10.1021/acs.chemrestox.3c00212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Indexed: 10/26/2023]
Abstract
Methyleugenol (ME), found in numerous plants and spices, is a rodent carcinogen and is classified as "possibly carcinogenic to humans". The hypothesis of a carcinogenic risk for humans is supported by the observation of ME-derived DNA adducts in almost all human liver and lung samples examined. Therefore, a risk assessment of ME is needed. Unfortunately, biomarkers of exposure for epidemiological studies are not yet available. We hereby present the first detection of N-acetyl-l-cysteine conjugates (mercapturic acids) of ME in human urine samples after consumption of a popular ME-containing meal, pasta with basil pesto. We synthesized mercapturic acid conjugates of ME, identified the major product as N-acetyl-S-[3'-(3,4-dimethoxyphenyl)allyl]-l-cysteine (E-3'-MEMA), and developed methods for its extraction and LC-MS/MS quantification in human urine. For conducting an exposure study in humans, a basil cultivar with a suitable ME content was grown for the preparation of basil pesto. A defined meal containing 100 g of basil pesto, corresponding to 1.7 mg ME, was served to 12 participants, who collected the complete urine at defined time intervals for 48 h. Using d6-E-3'-MEMA as an internal standard for LC-MS/MS quantification, we were able to detect E-3'-MEMA in urine samples of all participants collected after the ME-containing meal. Excretion was maximal between 2 and 6 h after the meal and was completed within about 12 h (concentrations below the limit of detection). Excreted amounts were only between 1 and 85 ppm of the ME intake, indicating that the ultimate genotoxicant, 1'-sulfooxy-ME, is formed to a subordinate extent or is not efficiently detoxified by glutathione conjugation and subsequent conversion to mercapturic acids. Both explanations may apply cumulatively, with the ubiquitous detection of ME DNA adducts in human lung and liver specimens arguing against an extremely low formation of 1'-sulfooxy-ME. Taken together, we hereby present the first noninvasive human biomarker reflecting an internal exposure toward reactive ME species.
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Affiliation(s)
- Kai Nieschalke
- Department
of Nutritional Toxicology, Institute of Nutritional Science, University of Potsdam, 14558 Nuthetal, Germany
- Department
of Food Safety, German Federal Institute
for Risk Assessment (BfR), 10589 Berlin, Germany
| | - Nick Bergau
- Department
of Food Safety, German Federal Institute
for Risk Assessment (BfR), 10589 Berlin, Germany
| | - Sönke Jessel
- Biochemical
Institute for Environmental Carcinogens, Prof. Dr. Gernot Grimmer-Foundation, 22927 Grosshansdorf, Germany
| | - Albrecht Seidel
- Biochemical
Institute for Environmental Carcinogens, Prof. Dr. Gernot Grimmer-Foundation, 22927 Grosshansdorf, Germany
| | - Susanne Baldermann
- Department
Plant Quality and Food Security, Leibniz
Institute of Vegetable and Ornamental Crops (IGZ), 14979 Grossbeeren, Germany
- Faculty of
Life Sciences: Food, Nutrition & Health, University of Bayreuth, 95326 Kulmbach, Germany
| | - Monika Schreiner
- Department
Plant Quality and Food Security, Leibniz
Institute of Vegetable and Ornamental Crops (IGZ), 14979 Grossbeeren, Germany
| | - Klaus Abraham
- Department
of Food Safety, German Federal Institute
for Risk Assessment (BfR), 10589 Berlin, Germany
| | - Alfonso Lampen
- Department
of Food Safety, German Federal Institute
for Risk Assessment (BfR), 10589 Berlin, Germany
| | - Bernhard H. Monien
- Department
of Food Safety, German Federal Institute
for Risk Assessment (BfR), 10589 Berlin, Germany
| | - Burkhard Kleuser
- Department
of Nutritional Toxicology, Institute of Nutritional Science, University of Potsdam, 14558 Nuthetal, Germany
- Department
of Pharmacology and Toxicology, Institute of Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
| | - Hansruedi Glatt
- Department
of Food Safety, German Federal Institute
for Risk Assessment (BfR), 10589 Berlin, Germany
| | - Fabian Schumacher
- Department
of Nutritional Toxicology, Institute of Nutritional Science, University of Potsdam, 14558 Nuthetal, Germany
- Department
of Pharmacology and Toxicology, Institute of Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
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3
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Davidsen JM, Cohen SM, Eisenbrand G, Fukushima S, Gooderham NJ, Guengerich FP, Hecht SS, Rietjens IMCM, Rosol TJ, Harman CL, Taylor SV. FEMA GRAS assessment of derivatives of basil, nutmeg, parsley, tarragon and related allylalkoxybenzene-containing natural flavor complexes. Food Chem Toxicol 2023; 175:113646. [PMID: 36804339 DOI: 10.1016/j.fct.2023.113646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/26/2023] [Accepted: 01/30/2023] [Indexed: 02/18/2023]
Abstract
In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a program for the re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavoring ingredients in food. In this publication, tenth in the series, NFCs containing a high percentage of at least one naturally occurring allylalkoxybenzene constituent with a suspected concern for genotoxicity and/or carcinogenicity are evaluated. In a related paper, ninth in the series, NFCs containing anethole and/or eugenol and relatively low percentages of these allylalkoxybenzenes are evaluated. The Panel applies the threshold of toxicological concern (TTC) concept and evaluates relevant toxicology data on the NFCs and their respective constituent congeneric groups. For NFCs containing allylalkoxybenzene constituent(s), the estimated intake of the constituent is compared to the TTC for compounds with structural alerts for genotoxicity and when exceeded, a margin of exposure (MOE) is calculated. BMDL10 values are derived from benchmark dose analyses using Bayesian model averaging for safrole, estragole and methyl eugenol using EPA's BMDS software version 3.2. BMDL10 values for myristicin, elemicin and parsley apiole were estimated by read-across using relative potency factors. Margins of safety for each constituent congeneric group and MOEs for each allylalkoxybenzene constituent for each NFC were determined that indicate no safety concern. The scope of the safety evaluation contained herein does not include added use in dietary supplements or any products other than food. Ten NFCs, derived from basil, estragon (tarragon), mace, nutmeg, parsley and Canadian snakeroot were determined or affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavor ingredients based on an evaluation of each NFC and the constituents and congeneric groups therein.
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Affiliation(s)
- Jeanne M Davidsen
- Flavor and Extract Manufacturers Association, 1101 17th Street, N.W., Suite 700, Washington, D.C, 20036, USA
| | - Samuel M Cohen
- Havlik-Wall Professor of Oncology, Dept. of Pathology and Microbiology, University of Nebraska Medical Center, 983135 Nebraska Medical Center, Omaha, NE, 68198-3135, USA
| | - Gerhard Eisenbrand
- University of Kaiserslautern, Germany (Retired), Kühler Grund 48/1, 69126, Heidelberg, Germany
| | - Shoji Fukushima
- Japan Bioassay Research Center, 2445 Hirasawa, Hadano, Kanagawa, 257-0015, Japan
| | - Nigel J Gooderham
- Dept. of Metabolism, Digestion, Reproduction, Imperial College London, Sir Alexander Fleming Building, London, SW7 2AZ, United Kingdom
| | - F Peter Guengerich
- Dept. of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37232-0146, USA
| | - Stephen S Hecht
- Masonic Cancer Center and Dept. of Laboratory Medicine and Pathology, Cancer and Cardiovascular Research Building, 2231 6th St, S.E, Minneapolis, MN, 55455, USA
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Stippeneng 6708 WE, Wageningen, the Netherlands
| | - Thomas J Rosol
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, 1 Ohio University, Athens, OH, 45701, USA
| | - Christie L Harman
- Flavor and Extract Manufacturers Association, 1101 17th Street, N.W., Suite 700, Washington, D.C, 20036, USA
| | - Sean V Taylor
- Scientific Secretary to the FEMA Expert Panel, 1101 17th Street, N.W., Suite 700, Washington, D.C, 20036, USA.
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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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5
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Human Family 1-4 cytochrome P450 enzymes involved in the metabolic activation of xenobiotic and physiological chemicals: an update. Arch Toxicol 2021; 95:395-472. [PMID: 33459808 DOI: 10.1007/s00204-020-02971-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 12/29/2020] [Indexed: 12/17/2022]
Abstract
This is an overview of the metabolic activation of drugs, natural products, physiological compounds, and general chemicals by the catalytic activity of cytochrome P450 enzymes belonging to Families 1-4. The data were collected from > 5152 references. The total number of data entries of reactions catalyzed by P450s Families 1-4 was 7696 of which 1121 (~ 15%) were defined as bioactivation reactions of different degrees. The data were divided into groups of General Chemicals, Drugs, Natural Products, and Physiological Compounds, presented in tabular form. The metabolism and bioactivation of selected examples of each group are discussed. In most of the cases, the metabolites are directly toxic chemicals reacting with cell macromolecules, but in some cases the metabolites formed are not direct toxicants but participate as substrates in succeeding metabolic reactions (e.g., conjugation reactions), the products of which are final toxicants. We identified a high level of activation for three groups of compounds (General Chemicals, Drugs, and Natural Products) yielding activated metabolites and the generally low participation of Physiological Compounds in bioactivation reactions. In the group of General Chemicals, P450 enzymes 1A1, 1A2, and 1B1 dominate in the formation of activated metabolites. Drugs are mostly activated by the enzyme P450 3A4, and Natural Products by P450s 1A2, 2E1, and 3A4. Physiological Compounds showed no clearly dominant enzyme, but the highest numbers of activations are attributed to P450 1A, 1B1, and 3A enzymes. The results thus show, perhaps not surprisingly, that Physiological Compounds are infrequent substrates in bioactivation reactions catalyzed by P450 enzyme Families 1-4, with the exception of estrogens and arachidonic acid. The results thus provide information on the enzymes that activate specific groups of chemicals to toxic metabolites.
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Wang Q, Spenkelink B, Boonpawa R, Rietjens IMCM, Beekmann K. Use of Physiologically Based Kinetic Modeling to Predict Rat Gut Microbial Metabolism of the Isoflavone Daidzein to S-Equol and Its Consequences for ERα Activation. Mol Nutr Food Res 2020; 64:e1900912. [PMID: 32027771 PMCID: PMC7154660 DOI: 10.1002/mnfr.201900912] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 11/06/2019] [Indexed: 12/13/2022]
Abstract
SCOPE To predict gut microbial metabolism of xenobiotics and the resulting plasma concentrations of metabolites formed, an in vitro-in silico-based testing strategy is developed using the isoflavone daidzein and its gut microbial metabolite S-equol as model compounds. METHODS AND RESULTS Anaerobic rat fecal incubations are optimized and performed to derive the apparent maximum velocities (Vmax ) and Michaelis-Menten constants (Km ) for gut microbial conversion of daidzein to dihydrodaidzein, S-equol, and O-desmethylangolensin, which are input as parameters for a physiologically based kinetic (PBK) model. The inclusion of gut microbiota in the PBK model allows prediction of S-equol concentrations and slightly reduced predicted maximal daidzein concentrations from 2.19 to 2.16 µm. The resulting predicted concentrations of daidzein and S-equol are comparable to in vivo concentrations reported. CONCLUSION The optimized in vitro approach to quantify kinetics for gut microbial conversions, and the newly developed PBK model for rats that includes gut microbial metabolism, provide a unique tool to predict the in vivo consequences of daidzein microbial metabolism for systemic exposure of the host to daidzein and its metabolite S-equol. The predictions reveal a dominant role for daidzein in ERα-mediated estrogenicity despite the higher estrogenic potency of its microbial metabolite S-equol.
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Affiliation(s)
- Qianrui Wang
- Division of ToxicologyWageningen University and ResearchWageningen6708 WEThe Netherlands
| | - Bert Spenkelink
- Division of ToxicologyWageningen University and ResearchWageningen6708 WEThe Netherlands
| | - Rungnapa Boonpawa
- Faculty of Natural Resources and Agro‐IndustryKasetsart University Chalermphrakiat Sakon Nakhon Province CampusSakon Nakhon47000Thailand
| | | | - Karsten Beekmann
- Division of ToxicologyWageningen University and ResearchWageningen6708 WEThe Netherlands
- Present address:
Wageningen Food Safety ResearchP. O. Box 2306700 AEWageningenThe Netherlands
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7
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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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8
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Strikwold M, Spenkelink B, Woutersen RA, Rietjens IMCM, Punt A. Development of a Combined In Vitro Physiologically Based Kinetic (PBK) and Monte Carlo Modelling Approach to Predict Interindividual Human Variation in Phenol-Induced Developmental Toxicity. Toxicol Sci 2018; 157:365-376. [PMID: 28498972 DOI: 10.1093/toxsci/kfx054] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
With our recently developed in vitro physiologically based kinetic (PBK) modelling approach, we could extrapolate in vitro toxicity data to human toxicity values applying PBK-based reverse dosimetry. Ideally information on kinetic differences among human individuals within a population should be considered. In the present study, we demonstrated a modelling approach that integrated in vitro toxicity data, PBK modelling and Monte Carlo simulations to obtain insight in interindividual human kinetic variation and derive chemical specific adjustment factors (CSAFs) for phenol-induced developmental toxicity. The present study revealed that UGT1A6 is the primary enzyme responsible for the glucuronidation of phenol in humans followed by UGT1A9. Monte Carlo simulations were performed taking into account interindividual variation in glucuronidation by these specific UGTs and in the oral absorption coefficient. Linking Monte Carlo simulations with PBK modelling, population variability in the maximum plasma concentration of phenol for the human population could be predicted. This approach provided a CSAF for interindividual variation of 2.0 which covers the 99th percentile of the population, which is lower than the default safety factor of 3.16 for interindividual human kinetic differences. Dividing the dose-response curve data obtained with in vitro PBK-based reverse dosimetry, with the CSAF provided a dose-response curve that reflects the consequences of the interindividual variability in phenol kinetics for the developmental toxicity of phenol. The strength of the presented approach is that it provides insight in the effect of interindividual variation in kinetics for phenol-induced developmental toxicity, based on only in vitro and in silico testing.
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Affiliation(s)
- Marije Strikwold
- Division of Toxicology, Wageningen University, 6708 WE Wageningen, The Netherlands.,Van Hall Larenstein University of Applied Sciences, 8901 BV Leeuwarden, The Netherlands
| | - Bert Spenkelink
- Division of Toxicology, Wageningen University, 6708 WE Wageningen, The Netherlands
| | - Ruud A Woutersen
- Division of Toxicology, Wageningen University, 6708 WE Wageningen, The Netherlands.,TNO Innovation for Life, 3700 AJ Zeist, The Netherlands.,WUR/TNO Centre for Innovative Toxicology, 6700 EA Wageningen, The Netherlands
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, 6708 WE Wageningen, The Netherlands.,WUR/TNO Centre for Innovative Toxicology, 6700 EA Wageningen, The Netherlands
| | - Ans Punt
- Division of Toxicology, Wageningen University, 6708 WE Wageningen, The Netherlands
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9
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Methyleugenol DNA adducts in human liver are associated with SULT1A1 copy number variations and expression levels. Arch Toxicol 2017; 91:3329-3339. [PMID: 28326452 DOI: 10.1007/s00204-017-1955-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/09/2017] [Indexed: 10/19/2022]
Abstract
Methyleugenol is a rodent hepatocarcinogen occurring in many herbs and spices as well as essential oils used for flavoring. Following metabolic activation by cytochromes P450 (CYPs) and sulfotransferases (SULTs), methyleugenol can form DNA adducts. Previously, we showed that DNA adduct formation by methyleugenol in mouse liver is dependent on SULT1A1 expression and that methyleugenol DNA adducts are abundant in human liver specimens. In humans, SULT1A1 activity is affected by genetic polymorphisms, including single-nucleotide polymorphisms (SNPs) and copy number variations (CNVs). Here we investigated the relationship between individual methyleugenol DNA adduct levels and SULT1A1 in human liver samples. Using isotope-dilution ultraperformance liquid chromatography coupled with tandem mass spectrometry, we quantified methyleugenol DNA adducts in 121 human surgical liver samples. Frequent CNVs, including deletions (f = 3.3%) and duplications (f = 36.4%) of SULT1A1, were identified using qPCR and TaqMan assays in the donors' genomic DNA. SULT1A1 mRNA and protein levels were quantified using microarray data and Western blot analysis, respectively. Methyleugenol DNA adducts were detected in all 121 liver samples studied. Their levels varied 122-fold between individuals and were significantly correlated to both mRNA and protein levels of SULT1A1 (r s = 0.43, and r s = 0.44, respectively). Univariate and multivariate statistical analysis identified significant associations of SULT1A1 CNVs with mRNA (p = 1.7 × 10-06) and protein (p = 4.4 × 10- 10) levels as well as methyleugenol DNA adduct levels (p = 0.003). These data establish the importance of SULT1A1 genotype for hepatic methyleugenol DNA adducts in humans, and they confirm a strong impact of SULT1A1 CNVs on SULT1A1 hepatic phenotype.
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10
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Louisse J, Beekmann K, Rietjens IMCM. Use of Physiologically Based Kinetic Modeling-Based Reverse Dosimetry to Predict in Vivo Toxicity from in Vitro Data. Chem Res Toxicol 2016; 30:114-125. [PMID: 27768849 DOI: 10.1021/acs.chemrestox.6b00302] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The development of reliable nonanimal based testing strategies, such as in vitro bioassays, is the holy grail in current human safety testing of chemicals. However, the use of in vitro toxicity data in risk assessment is not straightforward. One of the main issues is that concentration-response curves from in vitro models need to be converted to in vivo dose-response curves. These dose-response curves are needed in toxicological risk assessment to obtain a point of departure to determine safe exposure levels for humans. Recent scientific developments enable this translation of in vitro concentration-response curves to in vivo dose-response curves using physiologically based kinetic (PBK) modeling-based reverse dosimetry. The present review provides an overview of the examples available in the literature on the prediction of in vivo toxicity using PBK modeling-based reverse dosimetry of in vitro toxicity data, showing that proofs-of-principle are available for toxicity end points ranging from developmental toxicity, nephrotoxicity, hepatotoxicity, and neurotoxicity to DNA adduct formation. This review also discusses the promises and pitfalls, and the future perspectives of the approach. Since proofs-of-principle available so far have been provided for the prediction of toxicity in experimental animals, future research should focus on the use of in vitro toxicity data obtained in human models to predict the human situation using human PBK models. This would facilitate human- instead of experimental animal-based approaches in risk assessment.
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Affiliation(s)
- Jochem Louisse
- Division of Toxicology, Wageningen University , Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Karsten Beekmann
- 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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11
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Herrmann K, Engst W, Florian S, Lampen A, Meinl W, Glatt HR. The influence of the SULT1A status - wild-type, knockout or humanized - on the DNA adduct formation by methyleugenol in extrahepatic tissues of mice. Toxicol Res (Camb) 2016; 5:808-815. [PMID: 30090391 PMCID: PMC6060700 DOI: 10.1039/c5tx00358j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Accepted: 02/10/2016] [Indexed: 11/21/2022] Open
Abstract
Methyleugenol, present in herbs and spices, has demonstrated carcinogenic activity in the liver and, to a lesser extent, in extrahepatic tissues of rats and mice. It forms DNA adducts after hydroxylation and sulphation. As previously reported, hepatic DNA adduct formation by methyleugenol in mice is strongly affected by their sulphotransferase (SULT) 1A status. Now, we analysed the adduct formation in extrahepatic tissues. The time course of the adduct levels was determined in transgenic (tg) mice, expressing human SULT1A1/2, after oral administration of methyleugenol (50 mg per kg body mass). Nearly maximal adduct levels were observed 6 h after treatment. They followed the order: liver > caecum > kidney > colon > stomach > small intestine > lung > spleen. We then selected liver, caecum, kidney and stomach for the main study, in which four mouse lines [wild-type (wt), Sult1a1-knockout (ko), tg, and humanized (ko-tg)] were treated with methyleugenol at varying dose levels. In the liver, caecum and kidney, adduct formation was nearly completely dependent on the expression of SULT1A enzymes. In the liver, human SULT1A1/2 led to higher adduct levels than mouse Sult1a1, and the effects of both enzymes were approximately additive. In the caecum, human SULT1A1/2 and mouse Sult1a1 were nearly equally effective, again with additive effects in tg mice. In the kidney, only human SULT1A1/2 played a role: no adducts were detected in wt and ko mice even at the highest dose tested and the adduct levels were similar in tg and ko-tg mice. In the stomach, adduct formation was unaffected by the SULT1A status. IN CONCLUSION (i) the SULT1A enzymes only affected adduct formation in those tissues in which they are highly expressed (mouse Sult1a1 in the liver and caecum, but not in the kidney and stomach; human SULT1A1/2 in the liver, caecum and kidney, not in the stomach of tg mice and humans), indicating a dominating role of local bioactivation; (ii) the additivity of the effects of both enzymes in the liver and caecum implies that the enzyme level was limiting in the adduct formation; (iii) SULT1A forms dominated the activation of methyleugenol in several tissues, but non-Sult1a1 forms or SULT-independent mechanisms were involved in its adduct formation in the stomach.
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Affiliation(s)
- K Herrmann
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbrücke , Department of Nutritional Toxicology , Nuthetal , Germany
| | - W Engst
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbrücke , Department of Nutritional Toxicology , Nuthetal , Germany
| | - S Florian
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbrücke , Department of Nutritional Toxicology , Nuthetal , Germany
| | - A Lampen
- Federal Institute for Risk Assessment (BfR) , Department of Food Safety , Berlin , Germany . ; Tel: +49 (0)30-691-6846
| | - W Meinl
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbrücke , Department of Nutritional Toxicology , Nuthetal , Germany
| | - H R Glatt
- German Institute of Human Nutrition (DIfE) Potsdam-Rehbrücke , Department of Nutritional Toxicology , Nuthetal , Germany
- Federal Institute for Risk Assessment (BfR) , Department of Food Safety , Berlin , Germany . ; Tel: +49 (0)30-691-6846
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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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