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Forsten E, Finger M, Scholand T, Deitert A, Kauffmann K, Büchs J. Inoculum cell count influences separation efficiency and variance in Ames plate incorporation and Ames RAMOS test. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167035. [PMID: 37709100 DOI: 10.1016/j.scitotenv.2023.167035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/29/2023] [Accepted: 09/11/2023] [Indexed: 09/16/2023]
Abstract
The Ames test is one of the most applied tools in mutagenicity testing of chemicals ever since its introduction by Ames et al. in the 1970s. Its principle is based on histidine auxotrophic bacteria that regain prototrophy through reverse mutations. In the presence of a mutagen, more reverse mutations occur that become visible as increased bacterial growth on medium without histidine. Many miniaturized formats of the Ames test have emerged to enable the testing of environmental water samples, increase experimental throughput, and lower the required amounts of test substances. However, most of these formats still rely on endpoint determinations. In contrast, the recently introduced Ames RAMOS test determines mutagenicity through online monitoring of the oxygen transfer rate. In this study, the oxygen transfer rate of Salmonella typhimurium TA100 during the Ames plate incorporation test was monitored and compared to the Ames RAMOS test to prove its validity further. Furthermore, the Ames RAMOS test in 96-well scale is newly introduced. For both the Ames plate incorporation and the Ames RAMOS test, the influence of the inoculum cell count on the negative control was highlighted: A lower inoculum cell count led to a higher coefficient of variation. However, a lower inoculum cell count also led to a higher separation efficiency in the Ames RAMOS test and, thus, to better detection of a mutagenic substance at lower concentrations.
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Affiliation(s)
- Eva Forsten
- AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany
| | - Maurice Finger
- AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany
| | - Theresa Scholand
- AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany
| | - Alexander Deitert
- AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany
| | - Kira Kauffmann
- AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany
| | - Jochen Büchs
- AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
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Tsuji K, Ishii T, Kobayakawa T, Higashi-Kuwata N, Shinohara K, Azuma C, Miura Y, Nakano H, Wada N, Hattori SI, Bulut H, Mitsuya H, Tamamura H. Structure-Activity Relationship Studies of SARS-CoV-2 Main Protease Inhibitors Containing 4-Fluorobenzothiazole-2-carbonyl Moieties. J Med Chem 2023; 66:13516-13529. [PMID: 37756225 DOI: 10.1021/acs.jmedchem.3c00777] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
The main protease (Mpro) of SARS-CoV-2 is an attractive target for the development of drugs to treat COVID-19. Here, we report the design, synthesis, and structure-activity relationship (SAR) studies of highly potent SARS-CoV-2 Mpro inhibitors including TKB245 (5)/TKB248 (6). Since we have previously developed Mpro inhibitors (3) and (4), several hybrid molecules of these previous compounds combined with nirmatrelvir (1) were designed and synthesized. Compounds such as TKB245 (5) and TKB248 (6), containing a 4-fluorobenzothiazole moiety at the P1' site, are highly effective in the blockade of SARS-CoV-2 replication in VeroE6 cells. Replacement of the P1-P2 amide with the thioamide surrogate in TKB248 (6) improved its PK profile in mice compared to that of TKB245 (5). A new diversity-oriented synthetic route to TKB245 (5) derivatives was also developed. The results of the SAR studies suggest that TKB245 (5) and TKB248 (6) are useful lead compounds for the further development of Mpro inhibitors.
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Affiliation(s)
- Kohei Tsuji
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Takahiro Ishii
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Takuya Kobayakawa
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Nobuyo Higashi-Kuwata
- Department of Refractory Viral Infections, National Center for Global Health and Medicine Research Institute, Shinjuku-ku, Tokyo 162-8655, Japan
| | - Kouki Shinohara
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Chika Azuma
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Yutaro Miura
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Hiroki Nakano
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Naoya Wada
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Shin-Ichiro Hattori
- Department of Refractory Viral Infections, National Center for Global Health and Medicine Research Institute, Shinjuku-ku, Tokyo 162-8655, Japan
| | - Haydar Bulut
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Hiroaki Mitsuya
- Department of Refractory Viral Infections, National Center for Global Health and Medicine Research Institute, Shinjuku-ku, Tokyo 162-8655, Japan
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
- Department of Clinical Sciences, Kumamoto University Hospital, Chuo-ku, Kumamoto 860-8556, Japan
| | - Hirokazu Tamamura
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
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Coppi A, Davies R, Wegesser T, Ishida K, Karmel J, Han J, Aiello F, Xie Y, Corbett MT, Parsons AT, Monticello TM, Minocherhomji S. Characterization of false positive, contaminant-driven mutagenicity in impurities associated with the sotorasib drug substance. Regul Toxicol Pharmacol 2022; 131:105162. [DOI: 10.1016/j.yrtph.2022.105162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/14/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
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Novel, selective acrylamide linked quinazolines for the treatment of double mutant EGFR-L858R/T790M Non-Small-Cell lung cancer (NSCLC). Bioorg Chem 2021; 115:105234. [PMID: 34399322 DOI: 10.1016/j.bioorg.2021.105234] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/21/2021] [Accepted: 07/29/2021] [Indexed: 01/02/2023]
Abstract
T790M mutation is the most common mechanism of acquired resistance to first-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs). To overcome this resistance, 4-anilinoquinazoline-based irreversible inhibitors afatinib, dacomitinib has been developed. However, the clinical application of these irreversible inhibitors is limited due to its narrow selectivity against L858R/T790M mutant EGFR. In an attempt to develop potent and selective EGFR T790M inhibitors, we have designed and synthesized two series of novel acrylamide linked quinazolines. Among them, compounds 2i (IC50 0.171 µM) and 11h (IC50 0.159 µM) were identified as potent compounds, which displayed selective and potent anti-proliferative activity on gefitinib-resistant cell line NCI-H1975 as compared to the gefitinib and WZ4002 in cellular assay. Furthermore, a molecular dynamic simulation of 11h was carried out to assess the stability to form a complex with the L858R/T790M EGFR Kinase domain, which demonstrated that complex was stable for the 100 ns and form strong crucial covalent binding contacts with the thiol group of Cys797 residue. Finally, satisfactory in silico pharmacokinetics properties of 2i, 11h and 11i compounds were predicted. The synthesized compounds were also evaluated for in vitro cytotoxic activity/hepatotoxicity against HepG2 cell line through MTT assay. The results revealed that compounds exhibited lower cytotoxicity to HepG2 cells.
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Direct Comparison of the Lowest Effect Concentrations of Mutagenic Reference Substances in Two Ames Test Formats. TOXICS 2021; 9:toxics9070152. [PMID: 34209992 PMCID: PMC8309791 DOI: 10.3390/toxics9070152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/08/2021] [Accepted: 06/25/2021] [Indexed: 11/24/2022]
Abstract
The Ames assay is the standard assay for identifying DNA-reactive genotoxic substances. Multiple formats are available and the correct choice of an assay protocol is essential for achieving optimal performance, including fit for purpose detection limits and required screening capacity. In the present study, a comparison of those parameters between two commonly used formats, the standard pre-incubation Ames test and the liquid-based Ames MPF™, was performed. For that purpose, twenty-one substances with various modes of action were chosen and tested for their lowest effect concentrations (LEC) with both tests. In addition, two sources of rat liver homogenate S9 fraction, Aroclor 1254-induced and phenobarbital/β-naphthoflavone induced, were compared in the Ames MPF™. Overall, the standard pre-incubation Ames and the Ames MPF™ assay showed high concordance (>90%) for mutagenic vs. non-mutagenic compound classification. The LEC values of the Ames MPF™ format were lower for 17 of the 21 of the selected test substances. The S9 source had no impact on the test results. This leads to the conclusion that the liquid-based Ames MPF™ assay format provides screening advantages when low concentrations are relevant, such as in the testing of complex mixtures.
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Shao Y, Schiwy A, Glauch L, Henneberger L, König M, Mühlenbrink M, Xiao H, Thalmann B, Schlichting R, Hollert H, Escher BI. Optimization of a pre-metabolization procedure using rat liver S9 and cell-extracted S9 in the Ames fluctuation test. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 749:141468. [PMID: 32827816 DOI: 10.1016/j.scitotenv.2020.141468] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 08/01/2020] [Accepted: 08/02/2020] [Indexed: 06/11/2023]
Abstract
Many environmental pollutants pose a toxicological hazard only after metabolic activation. In vitro bioassays using cell lines or bacteria have often no or reduced metabolic activity, which impedes their use in the risk assessment. To improve the predictive capability of in vitro assays, external metabolization systems like the liver S9 fraction are frequently combined with in vitro toxicity assays. While it is typical for S9 fractions that samples and testing systems are combined in the same exposure system, we propose to separate the metabolism step and toxicity measurement. This allows for a modular combination of metabolic activation by enzymes isolated from rat liver (S9) or a biotechnological alternative (ewoS9R) with in vitro bioassays that lack metabolic capacity. Benzo(a)pyrene and 2-aminoanthracene were used as model compounds to optimize the conditions for the S9 metabolic degradation/activation step. The Ames assay with Salmonella typhimurium strains TA98 and TA100 was applied to validate the set-up of decoupling the S9 activation/metabolism from the bioassay system. S9 protein concentration of 0.25 mgprotein/mL, a supplement of 0.13 mM NADPH and a pre-incubation time of 100 min are recommended for activation of samples prior to dosing them to in vitro bioassays using the regular dosing protocols of the respective bioassay. EwoS9R performed equally well as Moltox S9, which is a step forward in developing true animal-free in vitro bioassays. After pre-incubation with S9 fraction, chemicals induced bacteria revertants in both the TA98 and the TA100 assay as efficiently as the standard Ames assay. The pre-incubation of chemicals with S9 fraction could serve for a wide range of cellular in vitro assays to efficiently combine activation and toxicity measurement, which may greatly facilitate the application of these assays for chemical hazard assessment and monitoring of environmental samples.
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Affiliation(s)
- Ying Shao
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany; Key Laboratory of the Three Gorges Reservoir Eco-environment, Ministry of Education, Chongqing University, Shazheng street 174, Shapingba, 400044 Chongqing, China.
| | - Andreas Schiwy
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Department of Evolutionary Ecology and Ecotoxicology, Goethe University, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany
| | - Lisa Glauch
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Luise Henneberger
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Maria König
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Marie Mühlenbrink
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Hongxia Xiao
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany
| | - Beat Thalmann
- EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany
| | - Rita Schlichting
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany
| | - Henner Hollert
- Department of Ecosystem Analysis, Institute for Environmental Research, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Department of Evolutionary Ecology and Ecotoxicology, Goethe University, Max-von-Laue-Str. 13, 60438 Frankfurt/Main, Germany
| | - Beate I Escher
- UFZ - Helmholtz Centre for Environmental Research, Department of Cell Toxicology, Permoser Str. 15, 04318 Leipzig, Germany; EWOMIS GmbH, Schießstraße 26c, 63486 Bruchköbel, Germany; Eberhard Karls University of Tübingen, Environmental Toxicology, Centre for Applied Geosciences, 72074 Tubingen, Germany
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Mutagenicity evaluation of pesticide analogs using standard and 6-well miniaturized bacterial reverse mutation tests. Toxicol In Vitro 2020; 69:105006. [PMID: 32976929 DOI: 10.1016/j.tiv.2020.105006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/11/2020] [Accepted: 09/21/2020] [Indexed: 11/21/2022]
Abstract
The Ames test is widely used in the mutagenicity evaluation of new and existing chemicals as a part of a compound selection strategy, regulatory control, the equivalence assessment, carcinogenic potential measurement etc. Intensification of the chemical industry and synthesis of plenty of new molecules has led to the necessity of tests with a higher throughput capacity. The 6-well miniaturized bacterial reverse mutation test and the standard Ames test were compared using 14 technical grade active ingredients (TGAIs) of pesticides. With some exceptions, the responses obtained in the miniscreen Ames are similar to those seen in the standard method: 4 overall test outcomes were negative and 9 were positive in both test versions, but 1 discordant result between the miniscreen and standard version. Comparison of the standard and the miniscreen Ames test resulted in 98% of concordance across five strains and conditions (±S9). The overall judgment is that the miniscreen Ames test can be used to assess the mutagenicity of pesticide analogs. It has the advantage of decreasing the number of materials and animals (for S9) and keeping a high-test performance.
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Kauffmann K, Gremm L, Brendt J, Schiwy A, Bluhm K, Hollert H, Büchs J. Alternative type of Ames test allows for dynamic mutagenicity detection by online monitoring of respiration activity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 726:137862. [PMID: 32481210 DOI: 10.1016/j.scitotenv.2020.137862] [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] [Received: 12/20/2019] [Revised: 03/05/2020] [Accepted: 03/10/2020] [Indexed: 06/11/2023]
Abstract
The Ames test is the most commonly used mutagenicity test worldwide. It is based on a microbial system that uses histidine auxotrophic Salmonella typhimurium strains. Due to either spontaneous mutations or mutations induced by a mutagenic compound, the cells can regain their ability to grow without histidine supplementation. The degree of mutagenicity of a sample correlates with the number of cells that are able to grow in media that lack histidine. All test variants published up to now are endpoint determinations providing no information about cell growth and respiration activity during the cultivation time. This study aimed to develop an alternative type of Ames test by characterizing the respiration activity of Salmonella typhimurium over time for dynamic mutagenicity detection. It focuses on elucidating the mechanisms underlying this novel test system, and serves as a general proof of principle. Respiration activity (oxygen transfer and uptake rate) and biomass growth of Salmonella typhimurium TA 100 and TA 98 were mechanistically modeled to understand and predict the behavior of the bacteria during the Ames test. The results simulated by the model were experimentally validated by the online monitoring of respiration activity over cultivation time using a Respiration Activity MOnitoring System (RAMOS). The simulated prediction was observed to fit well to the experimental data. When a mutagenic compound was added, its mutagenicity could be detected online due to the elevated cell number and respiration of histidine prototrophic cells. Laborious manual evaluation of mutagenicity after cultivation is not necessary. Mutagenicity evaluation with the presented alternative Ames RAMOS test fitted well to results from an Ames fluctuation test. In the future, a miniaturized RAMOS device for microtiter plates should allow for a high-throughput Ames RAMOS test.
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Affiliation(s)
- Kira Kauffmann
- AVT-Chair for Biochemical Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074 Aachen, Germany.
| | - Lisa Gremm
- AVT-Chair for Biochemical Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074 Aachen, Germany.
| | - Julia Brendt
- Institute for Environmental Research, Department of Ecosystem Analysis, Worringerweg 1, 52074 Aachen, Germany.
| | - Andreas Schiwy
- Institute for Environmental Research, Department of Ecosystem Analysis, Worringerweg 1, 52074 Aachen, Germany; Department of Evolutionary Ecology and Environmental Toxicology, Goethe University Frankfurt, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany.
| | - Kerstin Bluhm
- Institute for Environmental Research, Department of Ecosystem Analysis, Worringerweg 1, 52074 Aachen, Germany.
| | - Henner Hollert
- Institute for Environmental Research, Department of Ecosystem Analysis, Worringerweg 1, 52074 Aachen, Germany; Department of Evolutionary Ecology and Environmental Toxicology, Goethe University Frankfurt, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany.
| | - Jochen Büchs
- AVT-Chair for Biochemical Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074 Aachen, Germany.
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Schilter B, Burnett K, Eskes C, Geurts L, Jacquet M, Kirchnawy C, Oldring P, Pieper G, Pinter E, Tacker M, Traussnig H, Van Herwijnen P, Boobis A. Value and limitation of in vitro bioassays to support the application of the threshold of toxicological concern to prioritise unidentified chemicals in food contact materials. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2019; 36:1903-1936. [PMID: 31550212 DOI: 10.1080/19440049.2019.1664772] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Some of the chemicals in materials used for packaging food may leak into the food, resulting in human exposure. These include so-called Non-intentionally Added Substances (NIAS), many of them being unidentified and toxicologically uncharacterized. This raises the question of how to address their safety. An approach consisting of identification and toxicologically testing all of them appears neither feasible nor necessary. Instead, it has been proposed to use the threshold of toxicological concern (TTC) Cramer class III to prioritise unknown NIAS on which further safety investigations should focus. Use of the Cramer class III TTC for this purpose would be appropriate if amongst others sufficient evidence were available that the unknown chemicals were not acetylcholinesterase inhibitors or direct DNA-reactive mutagens. While knowledge of the material and analytical chemistry may efficiently address the first concern, the second could not be addressed in this way. An alternative would be use of a bioassay capable of detecting DNA-reactive mutagens at very low levels. No fully satisfactory bioassay was identified. The Ames test appeared the most suitable since it specifically detects DNA-reactive mutagens and the limit of biological detection of highly potent genotoxic carcinogens is low. It is proposed that for a specific migrate, the evidence for absence of mutagenicity based on the Ames test, together with analytical chemistry and information on packaging manufacture could allow application of the Cramer class III TTC to prioritise unknown NIAS. Recommendations, as well as research proposals, have been developed on sample preparation and bioassay improvement with the ultimate aim of improving limits of biological detection of mutagens. Although research is still necessary, the proposed approach should bring significant benefits over the current practices used for safety evaluation of food contact materials.
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Affiliation(s)
- Benoit Schilter
- Food Safety Research Department, Nestlé Research, Vers-chez-les-Blanc, Switzerland
| | | | - Chantra Eskes
- Services & Consultations on Alternative Methods (SeCAM), Magliaso, Switzerland and Swiss 3R Competence Centre (3RCC), Bern, Switzerland
| | - Lucie Geurts
- International Life Sciences Institute Europe, Brussels, Belgium
| | - Mélanie Jacquet
- Danone Food Safety Center, Danone S.A., Danone Food Safety Center, Palaiseau, France
| | - Christian Kirchnawy
- Technical Competence Center, OFI - Austrian Research Institute for Chemistry and Technology, Vienna, Austria
| | | | | | - Elisabeth Pinter
- Department of Applied Life Sciences, University of Applied Sciences, Vienna, Austria
| | - Manfred Tacker
- Department of Applied Life Sciences, University of Applied Sciences, Vienna, Austria
| | | | | | - Alan Boobis
- Department of Medicine, Imperial College London, London, UK
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Rainer B, Pinter E, Czerny T, Riegel E, Kirchnawy C, Marin-Kuan M, Schilter B, Tacker M. Suitability of the Ames test to characterise genotoxicity of food contact material migrates. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2018; 35:2230-2243. [PMID: 30257137 DOI: 10.1080/19440049.2018.1519259] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Non-intentionally added substances (NIAS) are chemical impurities which can migrate from packaging materials (FCM) into food. Safety assessment of NIAS is required by European law, but currently there is no comprehensive testing strategy available. In this context, one key element is to get insight on the potential presence of genotoxic NIAS in FCM migrates. This raises questions about the limit at which genotoxins can be detected in complex mixtures such as FCM migrates, and if such limits of detection (LOD) would be compatible with safety. In this context, the present review assesses the suitability of the Ames assay to address genotoxicity of FCM migrates. Lowest effective concentrations of packaging-related and other chemicals in test media were retrieved from scientific literature and used as surrogates of LODs to be benchmarked against a value of 0.01 mg kg-1 (10 ppb) in migrates. This is a pragmatic threshold used in FCM safety evaluation to prioritise substances requiring proper identification and risk assessment. The analysis of the data shows that only potent genotoxins can theoretically be detectable at a level of 0.01 mg kg-1 in migrates or food. Only a minority (10%) of genotoxic chemicals reported to be associated with FCMs could be picked up at a level of 0.01 mg kg-1 or lower. Overall, this review shows that the Ames test in its present form cannot be used as standalone method for evaluating the genotoxic potential of FCM migrates, but must be used together with other information from analytical chemistry and FCM manufacturing.
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Affiliation(s)
- Bernhard Rainer
- a Department of Applied Life Sciences , University of Applied Sciences, FH Campus Wien , Vienna , Austria
| | - Elisabeth Pinter
- a Department of Applied Life Sciences , University of Applied Sciences, FH Campus Wien , Vienna , Austria
| | - Thomas Czerny
- a Department of Applied Life Sciences , University of Applied Sciences, FH Campus Wien , Vienna , Austria
| | - Elisabeth Riegel
- a Department of Applied Life Sciences , University of Applied Sciences, FH Campus Wien , Vienna , Austria
| | - Christian Kirchnawy
- b Department for Microbiology and Cell Culture , OFI - Austrian Research Institute for Chemistry and Technology , Vienna , Austria
| | - Maricel Marin-Kuan
- c Chemical Food Safety , Nestlé Research Center , Lausanne , Switzerland
| | - Benoît Schilter
- c Chemical Food Safety , Nestlé Research Center , Lausanne , Switzerland
| | - Manfred Tacker
- a Department of Applied Life Sciences , University of Applied Sciences, FH Campus Wien , Vienna , Austria
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Zwarg JRRM, Morales DA, Maselli BS, Brack W, Umbuzeiro GA. Miniaturization of the microsuspension Salmonella/microsome assay in agar microplates. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2018; 59:488-501. [PMID: 29668047 DOI: 10.1002/em.22195] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 03/06/2018] [Accepted: 03/16/2018] [Indexed: 06/08/2023]
Abstract
The Salmonella/microsome assay (Ames test) is the most widely used mutagenicity test for the evaluation of pure chemicals and environmental samples. There are several versions of protocols available in the literature, including those that reduce the amount of sample needed for testing with liquid and agar media. The microsuspension version of the Salmonella/microsome assay is more sensitive than the standard protocol. It is performed using 5-times concentrated bacteria and less sample and S9 mixture, but still uses conventional Petri dishes (90 × 15 mm). It has been extensively used for environmental sample testing, including in effect-directed analysis (EDA). The objective of this study was to miniaturize the microsuspension assay using 12-well microplates instead of the conventional plates. For validation of this miniaturization, thirteen mutagenic compounds were tested using three Salmonella strains that were selected based on their different spontaneous reversion frequencies (low, medium, and high). The conditions of the miniaturized procedure were made as similar as possible to the microsuspension protocol, using the same testing design, metabolic activation, and data interpretation, and the tests were conducted in parallel. The miniaturized plate assay (MPA) and microsuspension procedures provided similar sensitivities although MPA is less laborious and require less sample and reagents, thereby reducing overall costs. We conclude that the MPA is a promising tool and can be particularly suitable for environmental studies such as EDA or monitoring programs. Environ. Mol. Mutagen. 59:488-501, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Daniel A Morales
- School of Technology, State University of Campinas (UNICAMP), Limeira, SP, Brazil
| | - Bianca S Maselli
- Pharmaceutical Sciences Faculty, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Werner Brack
- Department Effect-Directed Analysis, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
- RWTH University of Aachen, Aachen, Germany
| | - Gisela A Umbuzeiro
- School of Technology, State University of Campinas (UNICAMP), Limeira, SP, Brazil
- Pharmaceutical Sciences Faculty, University of São Paulo (USP), São Paulo, SP, Brazil
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Chen Y, Chen Y, Jastrzebska B, Golczak M, Gulati S, Tang H, Seibel W, Li X, Jin H, Han Y, Gao S, Zhang J, Liu X, Heidari-Torkabadi H, Stewart PL, Harte WE, Tochtrop GP, Palczewski K. A novel small molecule chaperone of rod opsin and its potential therapy for retinal degeneration. Nat Commun 2018; 9:1976. [PMID: 29773803 PMCID: PMC5958115 DOI: 10.1038/s41467-018-04261-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 04/13/2018] [Indexed: 12/21/2022] Open
Abstract
Rhodopsin homeostasis is tightly coupled to rod photoreceptor cell survival and vision. Mutations resulting in the misfolding of rhodopsin can lead to autosomal dominant retinitis pigmentosa (adRP), a progressive retinal degeneration that currently is untreatable. Using a cell-based high-throughput screen (HTS) to identify small molecules that can stabilize the P23H-opsin mutant, which causes most cases of adRP, we identified a novel pharmacological chaperone of rod photoreceptor opsin, YC-001. As a non-retinoid molecule, YC-001 demonstrates micromolar potency and efficacy greater than 9-cis-retinal with lower cytotoxicity. YC-001 binds to bovine rod opsin with an EC50 similar to 9-cis-retinal. The chaperone activity of YC-001 is evidenced by its ability to rescue the transport of multiple rod opsin mutants in mammalian cells. YC-001 is also an inverse agonist that non-competitively antagonizes rod opsin signaling. Significantly, a single dose of YC-001 protects Abca4 -/- Rdh8 -/- mice from bright light-induced retinal degeneration, suggesting its broad therapeutic potential.
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Affiliation(s)
- Yuanyuan Chen
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- The McGowan Institute for Regenerative Medicine, University of Pittsburgh, 450 Technology Drive Suite 300, Pittsburgh, PA, 15219, USA.
- Department of Ophthalmology, University of Pittsburgh, 3501 Fifth Avenue, Pittsburgh, PA, 15260, USA.
| | - Yu Chen
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
- Yueyang Hospital and Clinical Research Institute of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, 200437, Shanghai, China
| | - Beata Jastrzebska
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, 1819 E. 101st Street, Cleveland, OH, 44106, USA
| | - Marcin Golczak
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, 1819 E. 101st Street, Cleveland, OH, 44106, USA
| | - Sahil Gulati
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, 1819 E. 101st Street, Cleveland, OH, 44106, USA
| | - Hong Tang
- Drug Discovery Center, University of Cincinnati, 2180 E. Galbraith Road, Cincinnati, OH, 45237, USA
| | - William Seibel
- Drug Discovery Center, University of Cincinnati, 2180 E. Galbraith Road, Cincinnati, OH, 45237, USA
| | - Xiaoyu Li
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Hui Jin
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Yong Han
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Songqi Gao
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Jianye Zhang
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Xujie Liu
- Department of Ophthalmology, University of Pittsburgh, 3501 Fifth Avenue, Pittsburgh, PA, 15260, USA
| | - Hossein Heidari-Torkabadi
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Phoebe L Stewart
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, 1819 E. 101st Street, Cleveland, OH, 44106, USA
| | - William E Harte
- Office of Translation and Innovation, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Gregory P Tochtrop
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, 1819 E. 101st Street, Cleveland, OH, 44106, USA.
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