Synthesis and receptor binding of 5-amino[3H]2methyl-3-isothiazolol ([3H]thiomuscimol), a specific GABAa agonist photoaffinity label
作者:B. Frølund、B. Ebert、L. W. Lawrence、S. D. Hurt、P. Krogsgaard-Larsen
DOI:10.1002/jlcr.2580360909
日期:1995.9
The synthesis of tritium labelled thiomuscimol(5-amino[3H]2methyl-3-isothiazolol) (7c), a specific and high-affinity agonist photoaffinity label for GABAA receptors, is described. The synthesis of 7c is based on a procedure for the preparation of 5-amino[2H]2methyl-3-isothiazolol (7b). Methyl 3-ethoxyisothiazole-5-carboxylate (3), synthesized from 3-hydroxyisothiazole-5-carboxamide (1) via the corresponding methyl ester (2), was reduced with sodium borotritide to give 3-ethoxy-5-hydroxy[3H]2methyl-3-isothiazole (4c). 3-Ethoxy-5-phthalimido[3H]2-methylisothiazole (6c), synthesized from the 5-chloro[3H]2methyl analogue (5c) of (4c), was deprotected by treatment with concentrated hydrochloric acid to give 7c with a specific radioactivity of 29 Ci/mmol. In pilot binding assays, 7c was shown to bind to membranes from rat forebrain in a saturable manner and with KD and Bmax values of 28 ± 6 nM and 50 ± 4 fmol/mg original tissue, respectively.
本文描述了氚标记的硫代麝香草酚(5-氨基[3H]2甲基-3-异噻唑啉)(7c)的合成过程,这是一种特异性和高亲和力的 GABAA 受体激动剂光亲和标记。7c 的合成基于 5-氨基[2H]2-甲基-3-异噻唑啉酮(7b)的制备过程。3-ethoxyisothiazole-5-carboxylate (3) 由 3-hydroxyisothiazole-5-carboxamide (1) 通过相应的甲基酯 (2) 合成,用三硼化钠还原得到 3-乙氧基-5-羟基[3H]2-甲基-3-异噻唑 (4c)。3- 乙氧基-5-邻苯二甲酰亚胺基[3H]2-甲基异噻唑(6c)由(4c)的 5-氯[3H]2-甲基类似物(5c)合成,经浓盐酸处理脱保护后得到 7c,比放射性为 29 Ci/mmol。在先导结合试验中,7c 与大鼠前脑膜的结合达到饱和,KD 和 Bmax 值分别为 28 ± 6 nM 和 50 ± 4 fmol/mg。