Enantioselective Biotransformation of Hexabromocyclododecane by in Vitro Rat and Trout Hepatic Sub-Cellular Fractions

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• 作者：Mohamed Abou-Elwafa Abdallah ; Chibuzor Uchea ; J. Kevin Chipman ; Stuart Harrad
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：March 4, 2014
• 年：2014
• 卷：48
• 期：5
• 页码：2732-2740
• 全文大小：447K
• 年卷期：v.48,no.5(March 4, 2014)
• ISSN：1520-5851

文摘

伪-, 尾-, and 纬-Hexabromocyclododecanes (HBCDs) were subjected to in vitro biotransformation experiments with rat and trout liver S9 fractions for different incubation times (10, 30, and 60 min) at 2 concentration levels (1 and 10 渭M). The metabolic degradation of target HBCDs followed first order kinetics. Whereas 尾-HBCD undergoes rapid biotransformation (t_0.5 = 6.4 and 38.1 min in rat and trout, respectively), 伪-HBCD appears the most resistant to metabolic degradation (t_0.5 = 17.1 and 134.9 min). The biotransformation rate in trout was slower than in rat. Investigation of HBCD degradation profiles revealed the presence of at least 3 pentabromocyclododecene (PBCD) and 2 tetrabromocyclododecadiene (TBCD) isomers indicating reductive debromination as a metabolic pathway for HBCDs. Both mono- and di- hydroxyl metabolites were identified for parent HBCDs, while only mono hydroxyl metabolites were detected for PBCDs and TBCDs. Interestingly, 未-HBCD was detected only in trout S9 fraction assays indicating metabolic interconversion of test HBCD diastereomers during biotransformation in trout. Finally, enantioselective analysis showed significant enrichment of the (鈭?-伪-HBCD enantiomer (EF = 0.321 and 0.419 after 60 min incubation in rat and trout, respectively). The greater enrichment of (鈭?-伪-HBCD in rat than in trout underlines the species-specific differences in HBCD metabolism and the need for caution when extending similar results from animal studies to humans.