Identification of novel metabolites of prostaglandin E2 formed by isolated rat hepatocytes.
Identification of novel metabolites of prostaglandin E2 formed by isolated rat hepatocytes.
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DOI：
10.1006/abbi.1997.9921
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发表时间：
1997-04
影响因子：
3.9
通讯作者：
J. Hankin;P. Wheelan;R. Murphy
中科院分区：
文献类型：
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作者：
J. Hankin;P. Wheelan;R. Murphy
前列腺素E2（PGE 2）在离体大鼠肝细胞中的代谢导致形成四个主要以及几个次要的产品，其结构特征在于使用电喷雾串联质谱。鉴定的主要代谢物包括dinor-PGE 1、dinor-PGE 2和tetranor-PGE 1以及dinor-PGE 1和dinor-PGE 2的牛磺酸结合物。还鉴别了几种次要代谢产物，包括PGE 2的牛磺酸结合物和四氢萘PGE 1沿着以及PGE 2的葡糖苷酸结合物。这些牛磺酸共轭物以前没有被确定在前列腺素E2代谢的研究，但包括近50%的混合物的代谢产物孵育40分钟后。用氘标记的PGE 2（[3，3，4，4-D4] PGE 2）进行的实验导致在与肝细胞孵育期间，dinor-PGE 1、dinor-PGE 2和tetranor代谢物中的所有氘原子完全丢失。通过经典的β-氧化途径的代谢将预测一个氘原子由dinor-PGE 1保留，两个氘原子由dinor-PGE 2保留。当PGE 2与分离的大鼠肝细胞在含有30%D2O的缓冲液中孵育时，在二诺代谢物中可以观察到一个氘原子的大量掺入（30%），同时沿着10%的氘原子掺入四氢萘和残留的PGE 2中。氘标记的前列腺素E1（[3，3，4，4-D4] PGE 1）在离体大鼠肝细胞中被代谢为D2-dinor-PGE 1、tetranor-PGE 1和D2-dinor-PGE 1的牛磺酸结合物。在PGE 2的氘化底物而不是PGE 1的代谢过程中氘的损失，以及来自水性溶剂的氘原子掺入到PGE 2代谢物中表明δ 5双键和顺序异构化反应导致来自PGE 2的碳原子4的质子最终与水交换。
The metabolism of prostaglandin E2 (PGE2) in isolated rat hepatocytes led to the formation of four major as well as several minor products which were structurally characterized using electrospray tandem mass spectrometry. The major metabolites identified included dinor-PGE1, dinor-PGE2, and tetranor-PGE1 and the taurine conjugates of dinor-PGE1 and dinor-PGE2. Several minor metabolites including the taurine conjugates of PGE2 and tetranor PGE1 along with a glucuronide conjugate of PGE2 were also identified. These taurine conjugates had not been previously identified in studies of PGE2 metabolism, yet comprised nearly 50% of the mixture of metabolites after 40-min incubations. Experiments carried out with deuterium-labeled PGE2 ([3,3,4,4-D4]PGE2) resulted in the complete loss of all deuterium atoms in dinor-PGE1, dinor-PGE2, and tetranor metabolites during incubation with hepatocytes. Metabolism via classic beta-oxidation pathways would predict one deuterium atom retained by dinor-PGE1 and two deuterium atoms retained by dinor-PGE2. When PGE2 was incubated with isolated rat hepatocytes in buffer containing 30% D2O, substantial incorporation (30%) of one deuterium atom could be observed in the dinor metabolites along with 10% incorporation into the tetranor and residual PGE2. Deuterium-labeled PGE1 ([3,3,4,4-D4]PGE1) was metabolized to D2-dinor-PGE1, tetranor-PGE1, and the taurine conjugate of D2-dinor-PGE1 by isolated rat hepatocytes. The loss of deuterium during metabolism of the deuterated substrates of PGE2, but not PGE1, as well as the incorporation of deuterium atoms from the aqueous solvent into PGE2 metabolites suggested that the delta 5 double bond and sequential isomerization reactions lead to eventual exchange of the protons from carbon atom 4 of PGE2 with water.