Meyer Markus R, Schütz Aline, Maurer Hans H
Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, D-66421 Homburg (Saar), Germany.
Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, D-66421 Homburg (Saar), Germany.
Toxicol Lett. 2015 Jan 5;232(1):159-66. doi: 10.1016/j.toxlet.2014.10.026. Epub 2014 Oct 24.
Human esterases such as the human carboxylesterases (hCES) are important for the catalytic ester hydrolysis of xenobiotics and they play an important role in the detoxification of drugs (e.g., cocaine) but also in the activation of prodrugs (e.g., ramipril). Therefore, the aim of the presented study was to characterize the enzyme-catalyzed ester hydrolysis of ten drugs (cocaine, dimethocaine, ethylphenidate, 4-fluoro-3α-tropacocaine, 4-fluoro-3β-tropacocaine, heroin, methylphenidate, mitragynine, ramipril, and thebacon) by different esterase-containing systems (recombinant hCES1b, hCES1c, and hCES2, pooled human liver microsomes, pooled human liver S9 fraction, and pooled human plasma). Michaelis-Menten kinetic studies were done using in vitro incubations with the aforementioned enzyme-containing systems and LC coupled to ion trap MS for analysis. Ramipril and heroin were used as known model substrates to ensure reliable incubation conditions. The hydrolysis reactions followed classic Michaelis-Menten kinetics with exception of cocaine and 4-fluoro-3α-tropacocaine, for which hydrolysis rate was too low for reliable modeling. The substrates were mainly metabolized by the following enzymes systems: cocaine, hCES1c; dimethocaine, human plasma esterases; ethylphenidate, hCES1c; 4-fluoro-3β-tropacocaine, human plasma esterases; heroin, hCES2; methylphenidate, hCES1c; mitragynine, hCES1c; ramipril, hCES1b; thebacon, hCES2. Compounds bearing a small alcohol part and a larger acyl part showed higher affinity to hCES1 while those with a large alcohol part showed higher affinity to hCES2. The collected data are important for prediction of drug-drug or drug-food interactions as well as for individual variations in metabolism of drugs of abuse due to enzyme polymorphisms.
人类酯酶，如人类羧酸酯酶（hCES），对于催化外源性物质的酯水解很重要，它们在药物（如可卡因）的解毒过程中发挥重要作用，同时在前药（如雷米普利）的活化中也起重要作用。因此，本研究的目的是通过不同的含酯酶系统（重组hCES1b、hCES1c和hCES2、人肝微粒体池、人肝S9组分池和人血浆池）来表征十种药物（可卡因、地美卡因、哌醋甲酯、4-氟-3α-托派可卡因、4-氟-3β-托派可卡因、海洛因、哌甲酯、米托蒽醌、雷米普利和蒂巴因）的酶催化酯水解。使用上述含酶系统进行体外孵育，并结合液相色谱与离子阱质谱进行分析，开展米氏动力学研究。雷米普利和海洛因用作已知的模型底物以确保可靠的孵育条件。除可卡因和4-氟-3α-托派可卡因外，水解反应遵循经典的米氏动力学，这两种药物的水解速率过低，无法进行可靠的建模。这些底物主要由以下酶系统代谢：可卡因，hCES1c；地美卡因，人血浆酯酶；哌醋甲酯，hCES1c；4-氟-3β-托派可卡因，人血浆酯酶；海洛因，hCES2；哌甲酯，hCES1c；米托蒽醌，hCES1c；雷米普利，hCES1b；蒂巴因，hCES2。带有小醇部分和较大酰基部分的化合物对hCES1表现出更高的亲和力，而具有大醇部分的化合物对hCES2表现出更高的亲和力。收集到的数据对于预测药物-药物或药物-食物相互作用以及由于酶多态性导致的药物滥用代谢个体差异具有重要意义。
