- Di-aryl guanidinium derivatives: Towards improved α2-Adrenergic affinity and antagonist activity
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Compounds with excellent receptor engagement displaying α2-AR antagonist activity are useful not only for therapeutic purposes (e.g. antidepressants), but also to help in the crystallization of this particular GPCR. Therefore, based on our broad experience in the topic, we have prepared eighteen di-aryl (phenyl and/or pyridin-2-yl) mono- or di-substituted guanidines and 2-aminoimidazolines. The in vitro α2-AR binding affinity experiments in human brain tissue showed the advantage of a 2-aminoimidazolinium cation, a di-arylmethylene core, a conformationally locked pyridin-2-yl-guanidine and a di-substituted guanidinium to achieve good α2-AR engagement. After different in vitro [35S]GTPγS binding experiments in human prefrontal cortex tissue, it was possible to identify that compounds 7a, 7b and 7c were α2-AR partial agonist, whereas 8h was a potent α2-AR antagonist. Docking and MD studies with a model of α2A-AR and two crystal structures suggest that antagonism is achieved by compounds carrying a di-substituted guanidine which substituent occupy a pocket adjacent to TM5 without engaging S2005.42 or S2045.46, and a mono-substituted cationic group, which favorably interacts with E942.65.
- McMullan, Michela,Kelly, Brendan,Mihigo, Helene B.,Keogh, Aaron P.,Rodriguez, Fernando,Brocos-Mosquera, Iria,García-Bea, Aintzane,Miranda-Azpiazu, Patricia,Callado, Luis F.,Rozas, Isabel
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supporting information
(2020/11/05)
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- α2-adrenoceptor antagonists: Synthesis, pharmacological evaluation, and molecular modeling investigation of pyridinoguanidine, pyridino-2-aminoimidazoline and their derivatives
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We have previously identified phenylguanidine and phenyl-2-aminoimidazoline compounds as high affinity ligands with conflicting functional activity at the α2-adrenoceptor, a G-protein-coupled receptor with relevance in several neuropsychiatric conditions. In this paper we describe the design, synthesis, and pharmacological evaluation of a new series of pyridine derivatives [para substituted 2- and 3-guanidino and 2- and 3-(2-aminoimidazolino)pyridines, disubstituted 2-guanidinopyridines and N-substituted-2-amino-1,4-dihydroquinazolines] that were found to be antagonists/inverse agonists of the α2-adrenoceptor. Furthermore, the compounds exert their effects at the α2-adrenoceptor both in vitro in human prefrontal cortex tissue and in vivo in rat brain as shown by microdialysis experiments. We also provide a docking study at the α2A- and α2C-adrenoceptor subtypes demonstrating the structural features required for high affinity binding to the receptor.
- Kelly, Brendan,McMullan, Michela,Muguruza, Carolina,Ortega, Jorge E.,Meana, J. Javier,Callado, Luis F.,Rozas, Isabel
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p. 963 - 977
(2015/01/30)
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- Guanidine-based α2-adrenoceptor ligands: Towards selective antagonist activity
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Depression has been linked to a selective increase in the high affinity conformation of the α2-adrenergic autoreceptors (α2-ARs) in the human brain as well as to an overexpression of α2-ARs in the hippocampus and cerebral cortex. Thus, the development of novel α2-AR antagonists represents an attractive source of new antidepressants. This paper describes the design, synthesis and pharmacological evaluation of 30 new guanidinium and 2-iminoimidazolidinium as potential α2-AR antagonists. In order to design this new series of α2-AR antagonists, a pharmacophore model was developed using the GALAHAD software. This study suggested that increased substitution in the space surrounding the cationic guanidine moiety might lead selectively to antagonist activity. Following the preparation of compounds incorporating this feature and competitive radioligand binding, [ 35S]GTPγS functional assays revealed that this structural modification affords exclusively α2-AR antagonists, in contrast with the analogous unsubstituted compounds in which a mixture of antagonist/agonist activities was previously observed.
- O'Donovan, Daniel H.,Muguruza, Carolina,Callado, Luis F.,Rozas, Isabel
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supporting information
p. 242 - 254
(2014/06/24)
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- Pyridin-2-yl guanidine derivatives: Conformational control induced by intramolecular hydrogen-bonding interactions
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The synthesis and conformational analysis of a series of pyridin-2-yl guanidine derivatives using NMR, X-ray crystallography, and B3LYP/6-31+G* theoretical studies are reported. A remarkable difference was observed in the 1H NMR spectra of the guanidinium salts as compared with their N,N′-di-Boc protected and neutral analogues. This difference corresponds to a 180° change in the dihedral angle between the guanidine/ium moiety and the pyridine ring in the salts as compared to the Boc-protected derivatives, a conclusion that was supported by theoretical studies, X-ray data, and NMR analysis. Moreover, our data sustain the existence of two intramolecular hydrogen-bonding systems: (i) between the pyridine N1 atom and the guanidinium protons in the salts and (ii) within the tert-butyl carbamate groups of the Boc-protected derivatives. To verify that the observed conformational control arises from these intramolecular interactions, a new series of N-Boc-N′-propyl-substituted pyridin-2-yl guanidines were also prepared and studied.
- Kelly, Brendan,O'Donovan, Daniel H.,O'Brien, John,McCabe, Thomas,Blanco, Fernando,Rozas, Isabel
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p. 9216 - 9227
(2011/12/15)
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- A concise synthesis of asymmetrical N,N′-disubstituted guanidines
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We present a new and concise method for the preparation of asymmetrical N,N′-disubstituted guanidines starting from thiourea via the reaction of N-Boc-protected N′-alkyl/aryl substituted thioureas with an amine in the presence of mercury(II) chloride and
- O'Donovan, Daniel H.,Rozas, Isabel
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supporting information; experimental part
p. 4117 - 4119
(2011/09/19)
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- Acyl amidine and acyl, guanidine substituted biphenyl derivatives
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Novel compounds are disclosed having the formula STR1 and wherein R1, R2 and R3 are as defined herein. These compounds inhibit the action of angiotensin II and are useful, therefore, for example, as antihypertensive agents.
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- A Mild and Efficient Method for the Preparation of Guanidines
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A mild and efficient method for the preparation of guanidines by reaction of an acylated thiourea with an amine followed by removal of the acyl groups(s) from the intermediate acylguanidine is reported.Key Words: acylguanidine, acylthiourea, guanidine, water soluble carbodiimide
- Poss, Michael A.,Iwanowicz, Edwin,Reid, Joyce A.,Lin, James,Gu, Zhengxiang
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p. 5933 - 5936
(2007/10/02)
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