Keller Max, Tränkle Christian, She Xueke, Pegoli Andrea, Bernhardt Günther, Buschauer Armin, Read Roger W
Department of Pharmaceutical/Medicinal Chemistry II, Institute of Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany; School of Chemistry, University of New South Wales, UNSW Sydney NSW 2052, Australia.
Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Straße 3, D-53121 Bonn, Germany.
Bioorg Med Chem. 2015 Jul 15;23(14):3970-90. doi: 10.1016/j.bmc.2015.01.015. Epub 2015 Jan 14.
A series of new dibenzodiazepinone-type muscarinic receptor ligands, including two homo-dimeric compounds, was prepared. Sixteen representative compounds were characterized in equilibrium binding studies with [(3)H]N-methylscopolamine ([(3)H]NMS) at the muscarinic receptor subtype M2, and seven selected compounds were additionally investigated at M1, M3, M4 and M5 with respect to receptor subtype selectivity. The side chain of the known M2 preferring muscarinic receptor antagonist DIBA was widely varied with respect to chain length and type of the basic group (amine, imidazole, guanidine and piperazine). Most of the structural changes were well tolerated with respect to muscarinic receptor binding, determined by displacement of [(3)H]NMS. Compounds investigated at all subtypes shared a similar selectivity profile, which can be summarized as M2>M1≈M4>M3≈M5 (46, 50, 57, 62-64) and M2>M1≈M4>M3>M5 (1, 58). The homo-dimeric dibenzodiazepinone derivatives UNSW-MK250 (63) and UNSW-MK262 (64) exhibited the highest M2 receptor affinities (pIC50=9.0 and 9.2, respectively). At the M2 receptor a steep curve slope of -2 was found for the dimeric ligand 63, which cannot be described according to the law of mass action, suggesting a more complex mechanism of binding. In addition to equilibrium binding studies, for selected ligands, we determined pEC50,diss, an estimate of affinity to the allosteric site of M2 receptors occupied with [(3)H]NMS. Compounds 58 and 62-64 were capable of retarding [(3)H]NMS dissociation by a factor >10 (Emax,diss >92%), with highest potency (pEC50,diss=5.56) residing in the dimeric compound 64. As the monomeric counterpart of 64 was 100 times less potent (62: pEC50,diss=3.59), these data suggest that chemical dimerization of dibenzodiazepinone-type M receptor ligands can enhance allosteric binding.
制备了一系列新的二苯并二氮杂䓬酮型毒蕈碱受体配体，包括两种同二聚体化合物。在毒蕈碱受体亚型M2上，用[³H]N-甲基东莨菪碱（[³H]NMS）进行平衡结合研究，对16种代表性化合物进行了表征；另外，针对受体亚型选择性，在M1、M3、M4和M5上对7种选定的化合物进行了研究。已知的对M2有偏好的毒蕈碱受体拮抗剂DIBA的侧链在链长和碱性基团类型（胺、咪唑、胍和哌嗪）方面有很大变化。通过[³H]NMS的置换来确定，大多数结构变化在毒蕈碱受体结合方面耐受性良好。在所有亚型上研究的化合物具有相似的选择性特征，可总结为M2>M1≈M4>M3≈M5（46、50、57、62 - 64）和M2>M1≈M4>M3>M5（1、58）。同二聚体二苯并二氮杂䓬酮衍生物UNSW - MK250（63）和UNSW - MK262（6）表现出最高的M2受体亲和力（pIC50分别为9.0和9.2）。在M2受体上，发现二聚体配体63的曲线斜率为 - 2，这无法根据质量作用定律来描述，表明其结合机制更为复杂。除了平衡结合研究外，对于选定的配体，我们还测定了pEC50,diss，这是对与被[³H]NMS占据的M2受体变构位点亲和力的一种估计。化合物58和62 - 64能够使[³H]NMS的解离延迟>10倍（Emax,diss>92%），其中二聚体化合物64的效力最高（pEC50,diss = 5.56）。由于64的单体对应物效力低100倍（62：pEC50,diss = 3.59），这些数据表明二苯并二氮杂䓬酮型M受体配体的化学二聚化可以增强变构结合。
