Primary role of cytochrome P450 2B6 in the oxidative metabolism of 2,2',4,4',6-pentabromodiphenyl ether (BDE-100) to hydroxylated BDEs.
Primary role of cytochrome P450 2B6 in the oxidative metabolism of 2,2',4,4',6-pentabromodiphenyl ether (BDE-100) to hydroxylated BDEs.
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DOI：
10.1021/tx500446c
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发表时间：
2015-02
影响因子：
4.1
通讯作者：
Michael S. Gross;Deena M. Butryn;B. McGarrigle;D. Aga;J. Olson
中科院分区：
文献类型：
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作者：
Michael S. Gross;Deena M. Butryn;B. McGarrigle;D. Aga;J. Olson
人类通过各种途径接触多溴联苯醚（PBDEs）对健康造成有害影响。多溴二苯醚通过细胞色素p450 （p450）生物转化为羟基化代谢物（OH-BDEs），这可能增加了它们的神经毒性作用。本研究利用重组人p450和合集人肝微粒体（HLMs）研究了2,2',4,4'，6-五溴联苯醚（BDE-100）的体外代谢。BDE-100是人体内最丰富的PBDE同系物之一。10个重组p450分别与BDE-100孵育，监测p450特异性代谢。P450 2B6被发现是主要的酶，负责几乎所有的六种单oh -五溴二苯醚和两种二oh -五溴二苯醚代谢物的形成。4种代谢物分别为3-羟基-2,2',4,4‘，6-五溴二苯醚（3-OH-BDE-100）， 5’-羟基-2,2',4,4‘，6-五溴二苯醚（5’-OH-BDE-100）， 6'-羟基-2,2',4,4‘，6-五溴二苯醚（6’-OH-BDE-100）和4'-羟基-2,2',4,5‘，6-五溴二苯醚（4’-OH-BDE-103）。利用衍生化oh - bde的质谱碎片特征对剩下的两个单oh -五溴二苯醚代谢物进行了假设，从而可以预测邻oh -五溴二苯醚和对oh -五溴二苯醚的位置异构体。基于实际溶剂类导体筛选模型（cosmos - rs）的理论沸点计算和实验色谱保留时间的附加信息，分别确定了假设的代谢物为2'-羟基-2,3',4,4‘，6-五溴二苯醚（2’-OH-BDE-119）和4-羟基-2,2',4',5,6-五溴二苯醚（4- oh - bde -91）。P450 - 2B6和HLMs对BDE-100代谢的动力学研究显示，Km值分别在4.9 ~ 7.0 μM和6 ~ 10 μM之间，表明其对OH-BDEs的形成具有高亲和力。与先前研究报道的2,2',4,4'-四溴联苯醚（BDE-47）和2,2',4,4'，5-五溴联苯醚（BDE-99）的代谢相比，BDE-100由于存在第三个邻位取代的溴原子而被p450代谢得更慢。
Human exposure to polybrominated diphenyl ethers (PBDEs) through various routes poses deleterious health effects. PBDEs are biotransformed into hydroxylated metabolites (OH-BDEs) via cytochrome P450s (P450s), which may add to their neurotoxic effects. This study characterizes the in vitro metabolism of 2,2',4,4',6-pentabromodiphenyl ether (BDE-100), one of the most abundant PBDE congeners found in humans, by recombinant human P450s and pooled human liver microsomes (HLMs). Ten recombinant P450s were individually incubated with BDE-100 to monitor P450-specific metabolism. P450 2B6 was found to be the predominant enzyme responsible for nearly all formation of six mono-OH-pentaBDE and two di-OH-pentaBDE metabolites. Four metabolites were identified as 3-hydroxy-2,2',4,4',6-pentabromodiphenyl ether (3-OH-BDE-100), 5'-hydroxy-2,2',4,4',6-pentabromodiphenyl ether (5'-OH-BDE-100), 6'-hydroxy-2,2',4,4',6-pentabromodiphenyl ether (6'-OH-BDE-100), and 4'-hydroxy-2,2',4,5',6-pentabromodiphenyl ether (4'-OH-BDE-103) through use of reference standards. The two remaining mono-OH-pentaBDE metabolites were hypothesized using mass spectral fragmentation characteristics of derivatized OH-BDEs, which allowed prediction of an ortho-OH-pentaBDE and a para-OH-pentaBDE positional isomer. Additional information based on theoretical boiling point calculations using COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) and experimental chromatographic retention times were used to identify the hypothesized metabolites as 2'-hydroxy-2,3',4,4',6-pentabromodiphenyl ether (2'-OH-BDE-119) and 4-hydroxy-2,2',4',5,6-pentabromodiphenyl ether (4-OH-BDE-91), respectively. Kinetic studies of BDE-100 metabolism using P450 2B6 and HLMs revealed Km values ranging from 4.9 to 7.0 μM and 6-10 μM, respectively, suggesting a high affinity toward the formation of OH-BDEs. Compared to the metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) reported in previous studies, BDE-100 appears to be more slowly metabolized by P450s due to the presence of a third ortho-substituted bromine atom.