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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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DiGeronimo PM, Balko JA. Sedation and Anesthesia of Amphibians. Vet Clin North Am Exot Anim Pract 2021; 25:31-47. [PMID: 34823696 DOI: 10.1016/j.cvex.2021.08.008] [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] [Indexed: 11/17/2022]
Abstract
Amphibians commonly are managed under human care for research, education, conservation, and companionship and frequently are in need of sedation, anesthesia, or end-of-life care involving euthanasia. Objective investigation of sedative and anesthetic protocols in these taxa still is in its infancy, but knowledge of current best practices is paramount to appropriate care. Tricaine methanesulfonate delivered via immersion (bath) is the most common anesthetic agent in amphibians, but several other effective techniques have been identified. This summary provides a comprehensive review of the current evidence-based literature regarding amphibian sedative, anesthetic, and euthanasia techniques.
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Affiliation(s)
- Peter M DiGeronimo
- Adventure Aquarium, 1 Riverside Drive, Camden, NJ 08103, USA; Animal & Bird Health Care Center, 1785 Springdale Road, Cherry Hill, NJ 08003, USA.
| | - Julie A Balko
- College of Veterinary Medicine, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607, USA
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Galex IA, Gallant CM, D'Avignon N, Kuchenbrod LM, Fletcher CA, Rogala AR. Evaluation of Effective and Practical Euthanasia Methods for Larval African Clawed Frogs ( Xenopus laevis). JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE 2020; 59:269-274. [PMID: 32164797 DOI: 10.30802/aalas-jaalas-19-000141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Larval, or tadpole-stage Xenopus laevis frogs are a popular research model for developmental biology and disease studies. Existing euthanasia guidance documents offer recommendations for both eggs and adult stages, yet do not specifically address the larval stage. Data evaluating effective euthanasia methods for groups of X. laevis tadpoles would therefore be useful. The goal of the current study was to evaluate the efficacy of various immersion euthanasia procedures on tadpoles: tricaine methanesulfonate (MS222) at 6 g/L, eugenol at 800 μL/L and rapid chilling (2 to 4 °C). We also evaluated tadpoles at various developmental stages (NF stages 46, 47 and 49). Tadpoles (n = 70) were exposed to euthanasia solution for 15 min, and controls (n = 40) were placed in housing tank water for 15 min. All animals were then placed in recovery tanks containing housing tank water for 4 h to confirm irreversibility of each agent. Cessation of the heartbeat was assessed at the end of euthanasia solution exposure and at each hour thereafter. We found that immersion in a 6 g/L solution of MS222 resulted in 100% euthanasia of all larval stages tested. Conversely, eugenol produced variable euthanasia rates that were affected by both age group and batches of stock solutions. Rapid chilling was completely ineffective as a euthanasia method in our study. Based on our findings, we recommend MS222 as an effective and practical means of euthanizing large numbers of X. laevis tadpoles.
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Affiliation(s)
- Ilana A Galex
- Division of Comparative Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Cameron M Gallant
- Division of Comparative Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Nicole D'Avignon
- Division of Comparative Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Lauren M Kuchenbrod
- Division of Comparative Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Craig A Fletcher
- Division of Comparative Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Allison R Rogala
- Division of Comparative Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolinal,
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Ke C, Liu Q, Li L, Chen J, Wang X, Huang K. Simultaneous determination of eugenol, isoeugenol and methyleugenol in fish fillet using gas chromatography coupled to tandem mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2016; 1031:189-194. [PMID: 27497157 DOI: 10.1016/j.jchromb.2016.07.048] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Revised: 07/26/2016] [Accepted: 07/28/2016] [Indexed: 11/17/2022]
Abstract
Gas chromatography (GC) coupled with triple quadrupole tandem mass spectrometry (MS/MS) operated in electron ionization mode (EI) has been shown to have advantages in the trace analysis of chemical compounds. Employing the instrument, a method has been built to simultaneously determine eugenol, isoeugenol' and methyleugenol, which have been widely used as fish anesthetic, in the fish fillet. Procedure for the sample preparation was achieved by using hexane extraction followed by phenyl solid phase extraction (SPE) cleanup, which was free of such steps as rotary evaporation and nitrogen blowing by taking the volatility of eugenol and its isomers into consideration. The method was validated by conducting recovery studies on fortified fish fillet samples at four concentrations. The linearity in the range of 5-500μg·L(-1) was forced through the origin giving a coefficient of determination (r(2)) greater than 0.9982. Limits of detection (LODs) for eugenol, isoeugenol' and methyleugenol were 0.4, 1.2' and 0.2μg·kg(-1), respectively. The limits of quantification (LOQs) were 1.2, 4' and 0.7μg·kg(-1) for eugenol, isoeugenol' and methyleugenol, respectively. The recoveries for eugenol and its isomers ranged from 76.4 to 99.9% with relative standard deviations (RSD) in a range from 2.18 to 15.5%. This method is quick, simple and suitable for determining the residues of eugenol, isoeugenol and methyleugenol simultaneously in batch samples of fish fillet.
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Affiliation(s)
- Changliang Ke
- South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 231, Xingang Road West, Guangzhou 510300, China; Key Laboratory of Aquatic Product Processing, Ministry of Agriculture, No. 213, Huadu Avenue East, Guangzhou 510800, China.
| | - Qi Liu
- South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 231, Xingang Road West, Guangzhou 510300, China; Key Laboratory of Aquatic Product Processing, Ministry of Agriculture, No. 213, Huadu Avenue East, Guangzhou 510800, China
| | - Liudong Li
- South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 231, Xingang Road West, Guangzhou 510300, China; Key Laboratory of Aquatic Product Processing, Ministry of Agriculture, No. 213, Huadu Avenue East, Guangzhou 510800, China
| | - Jiewen Chen
- South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 231, Xingang Road West, Guangzhou 510300, China; Key Laboratory of Aquatic Product Processing, Ministry of Agriculture, No. 213, Huadu Avenue East, Guangzhou 510800, China
| | - Xunuo Wang
- South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 231, Xingang Road West, Guangzhou 510300, China; Key Laboratory of Aquatic Product Processing, Ministry of Agriculture, No. 213, Huadu Avenue East, Guangzhou 510800, China
| | - Ke Huang
- South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 231, Xingang Road West, Guangzhou 510300, China; Key Laboratory of Aquatic Product Processing, Ministry of Agriculture, No. 213, Huadu Avenue East, Guangzhou 510800, China
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