Gudasheva Tatiana A, Deeva Olga A, Mokrov Grigory V, Dyabina Alina S, Yarkova Milada A, Seredenin Sergey B
Federal State Budgetary Institution "Research Zakusov Institute of Pharmacology" (FSBI "Zakusov Institute of Pharmacology"), Moscow, Russian Federation.
Med Chem. 2019;15(4):383-399. doi: 10.2174/1573406415666181119164846.
The 18 kDa translocator protein (TSPO), previously known as the peripheral- type benzodiazepine receptor, plays a key role for the synthesis of neurosteroids by promoting transport of cholesterol from the outer to the inner mitochondrial membrane, which is the ratelimiting step in neurosteroid biosynthesis. Neurosteroids interact with nonbenzodiazepine site of GABAa receptor causing an anxiolytic effect without the side effects.
Using the original peptide drug-based design strategy, the first putative dipeptide ligand of the TSPO N-carbobenzoxy-L-tryptophanyl-L-isoleucine amide (GD-23) was obtained. Molecular docking of GD-23 in the active pocket of the TSPO receptor using Glide software was carried out. The lead compounds GD-23 and its analogues were synthesized using activated succinimide esters coupling method. The anxiolytic activity of GD-23 and its analogues was investigated in vivo, using two validated behavioral tests, illuminated open field and elevated plus-maze.
The in vivo studies revealed that the following parameters are necessary for the manifestation of anxiolytic activity of new compounds: the L-configuration of tryptophan, the presence of an amide group at the C-terminus, the specific size of the N-acyl substituent at the Nterminus. Compound GD-23 (N-carbobenzoxy-L-tryptophanyl-L-isoleucine amide) demonstrated a high anxiolytic-like effect in the doses of 0.05-1.0 mg/kg i.p. comparable with that of diazepam. Compound GD-23 was also active in the open field test when was administered orally in the doses of 0.1-5.0 mg/kg. The involvement of TSPO receptor in the mechanism of anxiolytic-like activity of new compounds was proved by the antagonism of compound GD-23 with TSPO selective inhibitor PK11195 as well as with inhibitors of enzymes which are involved in the biosynthesis of neurosteroids, trilostane and finasteride.
A series of N-acyl-tryptophanyl-containing dipeptides were designed and synthesized as 18 kDa translocator protein (TSPO) ligands. Using a drug-based peptide design method a series of the first dipeptide TSPO ligands have been designed and synthesized and their anxiolytic activity has been evaluated. In general, some of the compounds displayed a high level of anxiolytic efficacy comparable with that of diazepam. The involvement of TSPO receptor in the mechanism of anxiolytic activity of new compounds was proved using two methods. On this basis, the N-acyl-Ltryptophanyl- isoleucine amides could potentially be a novel class of TSPO ligands with anxiolytic activity.
18 kDa转位蛋白（TSPO），以前称为外周型苯二氮䓬受体，通过促进胆固醇从线粒体外膜向内膜的转运，在神经甾体合成中起关键作用，而这是神经甾体生物合成中的限速步骤。神经甾体与GABAa受体的非苯二氮䓬位点相互作用，产生抗焦虑作用且无副作用。
采用基于原始肽药物的设计策略，获得了TSPO的首个推定二肽配体N-苄氧羰基-L-色氨酰-L-异亮氨酸酰胺（GD-23）。使用Glide软件对GD-23在TSPO受体的活性口袋中进行分子对接。采用活性琥珀酰亚胺酯偶联法合成先导化合物GD-23及其类似物。使用两种经过验证的行为测试，即光照旷场试验和高架十字迷宫试验，在体内研究GD-23及其类似物的抗焦虑活性。
体内研究表明，新化合物抗焦虑活性的表现需要以下参数：色氨酸的L-构型、C末端存在酰胺基团、N末端N-酰基取代基的特定大小。化合物GD-23（N-苄氧羰基-L-色氨酰-L-异亮氨酸酰胺）在腹腔注射剂量为0.05 - 1.0 mg/kg时表现出高抗焦虑样效应，与地西泮相当。当口服给药剂量为0.1 - 5.0 mg/kg时，化合物GD-23在旷场试验中也具有活性。通过化合物GD-23与TSPO选择性抑制剂PK11195以及参与神经甾体生物合成的酶抑制剂曲洛司坦和非那雄胺的拮抗作用，证明了TSPO受体参与新化合物抗焦虑样活性的机制。
设计并合成了一系列含N-酰基-色氨酰基的二肽作为18 kDa转位蛋白（TSPO）配体。采用基于药物的肽设计方法，设计并合成了一系列首个二肽TSPO配体，并评估了它们的抗焦虑活性。总体而言，一些化合物表现出与地西泮相当的高抗焦虑疗效。使用两种方法证明了TSPO受体参与新化合物抗焦虑活性的机制。在此基础上，N-酰基-L-色氨酰基-异亮氨酸酰胺可能是一类具有抗焦虑活性的新型TSPO配体。
