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Deshmukh PU, Lad SB, Sudarsan A, Sudhakar S, Aggarwal T, Mandal S, Bagale SS, Kondabagil K, Pradeepkumar PI. Human Translesion Synthesis Polymerases polκ and polη Perform Error-Free Replication across N2-dG Methyleugenol and Estragole DNA Adducts. Biochemistry 2023; 62:2391-2406. [PMID: 37486230 DOI: 10.1021/acs.biochem.2c00663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
The secondary metabolites of polypropanoids, methyleugenol (MEG), and estragole (EG), found in many herbs and spices, are commonly used as food flavoring agents and as ingredients in cosmetics. MEG and EG have been reported to cause hepatocarcinogenicity in rodents, human livers, and lung cells. The formation of N2-dG and N6-dA DNA adducts is primarily attributed to the carcinogenicity of these compounds. Therefore, these compounds have been classified as "possible human carcinogens" by the International Agency for Research on Cancer and "reasonably anticipated to be a human carcinogen" by the National Toxicology Program. Herein, we report the synthesis of the N2-MEG-dG and N2-EG-dG modified oligonucleotides to study the mutagenicity of these DNA adducts. Our studies show that N2-MEG-dG and N2-EG-dG could be bypassed by human translesion synthesis (TLS) polymerases hpolκ and hpolη in an error-free manner. The steady-state kinetics of dCTP incorporation by hpolκ across N2-MEG-dG and N2-EG-dG adducts show that the catalytic efficiencies (kcat/Km) were ∼2.5- and ∼4.4-fold higher, respectively, compared to the unmodified dG template. A full-length primer extension assay demonstrates that hpolκ exhibits better catalytic efficiency than hpolη. Molecular modeling and dynamics studies capturing pre-insertion, insertion, and post-insertion steps reveal the structural features associated with the efficient bypass of the N2-MEG-dG adduct by hpolκ and indicate the reorientation of the adduct in the active site allowing the successful insertion of the incoming nucleotide. Together, these results suggest that though hpolκ and hpolη perform error-free TLS across MEG and EG during DNA replication, the observed carcinogenicity of these adducts could be attributed to the involvement of other low fidelity polymerases.
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Affiliation(s)
- Priyanka U Deshmukh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Shailesh B Lad
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Akhil Sudarsan
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sruthi Sudhakar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Tanvi Aggarwal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Soumyadeep Mandal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | | | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - P I Pradeepkumar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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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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Myristicin and Elemicin: Potentially Toxic Alkenylbenzenes in Food. Foods 2022; 11:foods11131988. [PMID: 35804802 PMCID: PMC9265716 DOI: 10.3390/foods11131988] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [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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