Ehlert F J, Oliff H S, Griffin M T
Department of Pharmacology, College of Medicine, University of California, Irvine, USA.
J Pharmacol Exp Ther. 1996 Feb;276(2):405-10.
A 3-chloropropylamine derivative (N-(3-chloropropyl)-4-piperidinyl diphenylactate) of the selective muscarinic antagonist N,N-dimethyl-4-piperidinyl diphenylacetate was synthesized and its conversion to a stable azetidinium ion and interaction with muscarinic receptors was investigated. When dissolved in aqueous solution at pH 7.4, N-(3-chloropropyl)-4-piperidinyl diphenylactate formed a stable azetidinium ion with a half-time of approximately 3.6 hr. The selectivity of the azetidinium ion for native M1, M2 and M3 subtypes of the muscarinic receptors was investigated in competitive binding experiments on the hippocampus, heart and submaxillary gland of rats, respectively, using N-[3H]methylscopolamine as the radioligand. The azetidinium ion exhibited equivalent high affinities for the M1 and M3 mucarinic receptor subtypes (KD = approximately 5 nM), but 10-fold lower affinity for the M2 muscarinic receptor subtype (KD = 44 nM). Similar competitive binding experiments were carried out on Chinese hamster ovary cells transfected with the M1 through M5 subtypes of the muscarinic receptor. In these experiments, the azetidinium ion exhibited similar high affinities for the M1, M3, M4 and M5 muscarinic receptor subtypes (KD = approximately 2.4 nM), but approximately 14-fold lower affinity for the M2 muscarinic receptor subtype (KD = 34 nM). In contrast to the azetidinium ion, the parent N-(3-chloropropyl)-4-piperidinyl diphenylactate compound was 130-fold less potent. An analogous series of experiments were carried out with the aziridinium ion derived from the muscarinic receptor alkylating agent, N-(2-chloroethyl)-4-piperidinyl diphenylactate. For these binding experiments, the incubations were carried out at 0 degrees C to prevent the aziridinium ion from alkylating muscarinic receptors. The aziridinium ion was found to have equivalent high affinities for the M1, M3, M4 and M5 subtypes of the muscarinic receptor (KD = approximately 6.6 nM), but about 11-fold lower affinity for the M2 muscarinic receptor subtype (KD = 72 nM). Our results suggest that 3-haloalkylamine derivatives of 4-piperidinyl diphenylactate may be candidate prodrugs that may penetrate into brain and form azetidinium ions that have a long-lasting central anticholinergic effect.
合成了选择性毒蕈碱拮抗剂N,N-二甲基-4-哌啶基二苯基乙酸酯的一种3-氯丙胺衍生物（N-(3-氯丙基)-4-哌啶基二苯基乙酸酯），并研究了其向稳定氮杂环丁烷离子的转化及其与毒蕈碱受体的相互作用。当N-(3-氯丙基)-4-哌啶基二苯基乙酸酯溶解于pH 7.4的水溶液中时，会形成一种半衰期约为3.6小时的稳定氮杂环丁烷离子。分别以N-[3H]甲基东莨菪碱作为放射性配体，在大鼠的海马体、心脏和下颌下腺进行竞争性结合实验，研究了该氮杂环丁烷离子对毒蕈碱受体天然M1、M2和M3亚型的选择性。该氮杂环丁烷离子对M1和M3毒蕈碱受体亚型表现出同等高亲和力（KD约为5 nM），但对M2毒蕈碱受体亚型的亲和力低10倍（KD = 44 nM）。对转染了毒蕈碱受体M1至M5亚型的中国仓鼠卵巢细胞进行了类似的竞争性结合实验。在这些实验中，该氮杂环丁烷离子对M1、M3、M4和M5毒蕈碱受体亚型表现出类似的高亲和力（KD约为2.4 nM），但对M2毒蕈碱受体亚型的亲和力低约14倍（KD = 34 nM）。与该氮杂环丁烷离子形成对比的是，母体N-(3-氯丙基)-4-哌啶基二苯基乙酸酯化合物的效力低130倍。用毒蕈碱受体烷基化剂N-(2-氯乙基)-4-哌啶基二苯基乙酸酯衍生的氮杂环丙烷离子进行了一系列类似实验。对于这些结合实验，在0℃下进行温育以防止氮杂环丙烷离子烷基化毒蕈碱受体。发现该氮杂环丙烷离子对毒蕈碱受体的M1、M3、M4和M5亚型具有同等高亲和力（KD约为6.6 nM），但对M2毒蕈碱受体亚型的亲和力低约11倍（KD = 72 nM）。我们的结果表明，4-哌啶基二苯基乙酸酯的3-卤代烷基胺衍生物可能是候选前药，它们可能渗透进入脑内并形成具有持久中枢抗胆碱能作用的氮杂环丁烷离子。
