Biotechnology Institute, School of Environment and Chemical Engineering, Dalian Jiaotong University, Dalian 116028, China; Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
School of Environment and Life Science, Kaili University, Kaili 556011, China.
Toxicol In Vitro. 2017 Oct;44:280-286. doi: 10.1016/j.tiv.2017.06.020. Epub 2017 Jun 21.
DDAB (6,8-dichloro-9,9-dimethyl-7-oxo-7,9-dihydroacridin-2-yl benzoate) is a newly developed near-infrared fluorescent probe for human carboxylesterase 2 (hCE2), exhibiting high specificity and good reactivity for real-time monitoring the enzymatic activities of hCE2 in complex biological systems. In order to explore the applicability of DDAB in commonly used animal species, the interspecies difference in DDAB hydrolysis was carefully investigated by using liver microsomes from human and five experimental animals including mouse, rat, dog, minipig and monkey. Metabolite profiling demonstrated that DDAB hydrolysis could be catalyzed by all tested liver microsomes from different animals but displayed significant difference in the reaction rate. Chemical inhibition assays demonstrated that carboxylesterases (CEs) were the major enzymes involved in DDAB hydrolysis in all tested liver microsomes, indicating that DDAB was a selective substrate of CEs in a variety of mammals. However, the differential effects of loperamide (LPA, a specific inhibitor against hCE2) on DDAB hydrolysis among various species were observed. The apparent kinetic parameters and the maximum intrinsic clearances (CL) for DDAB hydrolysis in liver microsomes from different animals were determined, and the order of CL values for the formation of DDAO was CyLM>MLM≈PLM>RLM>HLM≈DLM. These findings were helpful for the rational use of DDAB as an imaging tool for CE2 in different mammals, as well as for translational researches on the function of mammalian CEs and CE2-associated drug-drug interactions.
DDAB（6,8-二氯-9,9-二甲基-7-氧代-7,9-二氢吖啶-2-基苯甲酸酯）是一种新开发的近红外荧光探针，用于人羧酸酯酶 2（hCE2），对实时监测复杂生物体系中 hCE2 的酶活性具有高特异性和良好的反应性。为了探索 DDAB 在常用动物物种中的适用性，本研究通过使用来自人类和五种实验动物（小鼠、大鼠、狗、小型猪和猴子）的肝微粒体，仔细研究了 DDAB 水解的种间差异。代谢物分析表明，DDAB 水解可被来自不同动物的所有测试肝微粒体催化，但反应速率存在显著差异。化学抑制试验表明，羧酸酯酶（CEs）是参与所有测试肝微粒体中 DDAB 水解的主要酶，表明 DDAB 是多种哺乳动物中 CE 的选择性底物。然而，在各种物种中观察到洛哌丁胺（LPA，一种针对 hCE2 的特异性抑制剂）对 DDAB 水解的差异影响。确定了来自不同动物的肝微粒体中 DDAB 水解的表观动力学参数和最大内在清除率（CL），并确定了 DDAO 形成的 CL 值的顺序为 CyLM>MLM≈PLM>RLM>HLM≈DLM。这些发现有助于合理使用 DDAB 作为不同哺乳动物中 CE2 的成像工具，以及用于哺乳动物 CEs 和与 CE2 相关的药物相互作用的功能的转化研究。
