Piperidine-4-methanthiol Ester Derivatives for a Selective Acetylcholinesterase Assay
作者:Tatsuya Kikuchi、Toshimitsu Okamura、Kiyoshi Fukushi、Toshiaki Irie
DOI:10.1248/bpb.33.702
日期:——
The activity of acetylcholinesterase (AChE) is measured to obtain pathological information about the cholinergic system in various disease states and to assess the effect of AChE inhibitors. Using Ellman's method that is commonly used in such examinations, butyrylcholinesterase inhibitors must be added to measure AChE-specific activity because of low selectivity of AChE toward traditional substrates; however, such inhibitors also inhibit AChE. Therefore, it is desirable to obtain an AChE selective substrate that can be used with the Ellman's method. Here, we synthesized novel AChE substrates, 1-methyl-4-acetylthiomethylpiperidine and 1,1-dimethyl-4-acetylthiomethylpiperidine, and evaluated the hydrolysis rate and AChE selectivity by comparison with the results obtained when traditional substrates were used. The hydrolysis rate of the novel compounds by human AChE was one order of magnitude lower than that of the traditional substrates, acetylthiocholine and acetyl-β-methylthiocholine, whereas the hydrolysis rate using human butyrylcholinesterase was two orders of magnitude lower than that of the traditional substrates. This indicated that AChE showed selectivity towards the novel substrates which was one order of magnitude higher than that of the traditional substrates. The hydrolysis of the novel compounds in a rat cerebral cortical homogenate and a monkey whole blood was completely inhibited by 1 μM of the specific AChE inhibitor, 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one, indicating the high specificity of AChE towards the novel substrates in a crude tissue sample. From these results, we conclude that the novel compounds developed would be suitable AChE-selective substrates for Ellman's method.
测量乙酰胆碱酯酶(AChE)的活性是为了获得各种疾病状态下胆碱能系统的病理信息,并评估 AChE 抑制剂的效果。由于乙酰胆碱酯酶对传统底物的选择性较低,因此使用此类检查中常用的埃尔曼方法,必须添加丁酰胆碱酯酶抑制剂才能测量乙酰胆碱酯酶特异性活性;但是,此类抑制剂也会抑制乙酰胆碱酯酶。因此,我们希望获得一种能与埃尔曼法一起使用的 AChE 选择性底物。在此,我们合成了新型 AChE 底物--1-甲基-4-乙酰基硫代甲基哌啶和 1,1-二甲基-4-乙酰基硫代甲基哌啶,并通过与使用传统底物时的结果进行比较,评估了其水解率和 AChE 选择性。人 AChE 对新型化合物的水解率比传统底物乙酰硫代胆碱和乙酰-β-甲基硫代胆碱低一个数量级,而使用人丁酰胆碱酯酶的水解率比传统底物低两个数量级。这表明 AChE 对新型底物的选择性比传统底物高一个数量级。1 μ<小>M小>的特异性 AChE 抑制剂--1,5-双(4-烯丙基二甲基铵苯基)戊-3-酮能完全抑制新型化合物在大鼠大脑皮层匀浆和猴子全血中的水解,这表明 AChE 在粗组织样本中对新型底物具有高度特异性。从这些结果中,我们得出结论:所开发的新型化合物将成为埃尔曼方法的 AChE 选择性底物。