Characterization of Hepatic and Intestinal Glucuronidation of Magnolol: Application of the Relative Activity Factor Approach to Decipher the Contributions of Multiple UDP-Glucuronosyltransferase Isoforms
Characterization of Hepatic and Intestinal Glucuronidation of Magnolol: Application of the Relative Activity Factor Approach to Decipher the Contributions of Multiple UDP-Glucuronosyltransferase Isoforms
复制标题
厚朴酚肝脏和肠道葡萄糖醛酸化的表征：应用相对活性因子方法破译多种 UDP-葡萄糖醛酸基转移酶亚型的贡献
DOI：
10.1124/dmd.111.042192
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发表时间：
2012-03-01
影响因子：
3.9
通讯作者：
Yang, Ling
中科院分区：
文献类型：
--
作者：
Zhu, Liangliang;Ge, Guangbo;Yang, Ling
厚朴酚是一种食品添加剂，常存在于薄荷糖和口香糖中。人类接触这种化合物可以达到很高的剂量；因此，表征厚朴酚在人体中的分布非常重要。先前的研究表明厚朴酚可以在人体体内进行广泛的葡萄糖醛酸化。在本研究中，使用体外测定来表征人类肝脏和肠道中的葡萄糖醛酸化途径。重组人 UDP-葡萄糖醛酸基转移酶 (UGT) 的测定表明，多种 UGT 亚型参与厚朴酚葡萄糖醛酸化，包括 UGT1A1、-1A3、-1A7、-1A8、-1A9、-1A10 和 -2B7。人肝微粒体 (HLM)、人肠微粒体 (HIM) 和大多数重组 UGT 的厚朴酚葡萄糖醛酸化表现出很强的底物抑制动力学。 UGT1A10 的底物抑制程度相对较低，而 UGT1A9 催化的反应遵循双相动力学。使用化学抑制研究和相对活性因子 (RAF) 方法来鉴定在 HLM 和 HIM 中的厚朴酚葡萄糖醛酸化中发挥重要作用的各个 UGT。结果表明UGT2B7主要负责HLM中的反应，而UGT2B7和UGT1A10是HIM中的重要贡献者。总之，当前的研究阐明了厚朴酚的葡萄糖醛酸化途径，并证明 RAF 方法可作为一种有效的方法来破译单个 UGT 在天然组织中给定葡萄糖醛酸化途径中的作用，该途径由具有可变和非典型动力学的多种亚型催化。
Magnolol is a food additive that is often found in mints and gums. Human exposure to this compound can reach a high dose; thus, characterization of magnolol disposition in humans is very important. Previous studies indicated that magnolol can undergo extensive glucuronidation in humans in vivo. In this study, in vitro assays were used to characterize the glucuronidation pathway in human liver and intestine. Assays with recombinant human UDP-glucuronosyltransferase enzymes (UGTs) revealed that multiple UGT isoforms were involved in magnolol glucuronidation, including UGT1A1, -1A3, -1A7, -1A8, -1A9, -1A10, and -2B7. Magnolol glucuronidation by human liver microsomes (HLM), human intestine microsomes (HIM), and most recombinant UGTs exhibited strong substrate inhibition kinetics. The degree of substrate inhibition was relatively low in the case of UGT1A10, whereas the reaction catalyzed by UGT1A9 followed biphasic kinetics. Chemical inhibition studies and the relative activity factor (RAF) approach were used to identify the individual UGTs that played important roles in magnolol glucuronidation in HLM and HIM. The results indicate that UGT2B7 is mainly responsible for the reaction in HLM, whereas UGT2B7 and UGT1A10 are significant contributors in HIM. In summary, the current study clarifies the glucuronidation pathway of magnolol and demonstrates that the RAF approach can be used as an efficient method for deciphering the roles of individual UGTs in a given glucuronidation pathway in the native tissue that is catalyzed by multiple isoforms with variable and atypical kinetics.