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Biselli S, Bresinsky M, Tropmann K, Forster L, Honisch C, Buschauer A, Bernhardt G, Pockes S. Pharmacological characterization of a new series of carbamoylguanidines reveals potent agonism at the H 2R and D 3R. Eur J Med Chem 2021; 214:113190. [PMID: 33548637 DOI: 10.1016/j.ejmech.2021.113190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/31/2020] [Accepted: 01/08/2021] [Indexed: 12/12/2022]
Abstract
Even today, the role of the histamine H2 receptor (H2R) in the central nervous system (CNS) is widely unknown. In previous research, many dimeric, high-affinity and subtype-selective carbamoylguanidine-type ligands such as UR-NK22 (5, pKi = 8.07) were reported as H2R agonists. However, their applicability to the study of the H2R in the CNS is compromised by their molecular and pharmacokinetic properties, such as high molecular weight and, consequently, a limited bioavailability. To address the need for more drug-like H2R agonists with high affinity, we synthesized a series of monomeric (thio)carbamoylguanidine-type ligands containing various spacers and side-chain moieties. This structural simplification resulted in potent (partial) agonists (guinea pig right atrium, [35S]GTPγS and β-arrestin2 recruitment assays) with human (h) H2R affinities in the one-digit nanomolar range (pKi (139, UR-KAT523): 8.35; pKi (157, UR-MB-69): 8.69). Most of the compounds presented here exhibited an excellent selectivity profile towards the hH2R, e.g. 157 being at least 3800-fold selective within the histamine receptor family. The structural similarities of our monomeric ligands to pramipexole (6), a dopamine receptor agonist, suggested an investigation of the binding behavior at those receptors. The target compounds were (partial) agonists with moderate affinity at the hD2longR and agonists with high affinity at the hD3R (e.g. pKi (139, UR-KAT523): 7.80; pKi (157, UR-MB-69): 8.06). In summary, we developed a series of novel, more drug-like H2R and D3R agonists for the application in recombinant systems in which either the H2R or the D3R is solely expressed. Furthermore, our ligands are promising lead compounds in the development of selective H2R agonists for future in vivo studies or experiments utilizing primary tissue to unravel the role and function of the H2R in the CNS.
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Affiliation(s)
- Sabrina Biselli
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany; Agrolab Labor GmbH, 84079, Bruckberg, Germany
| | - Merlin Bresinsky
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Katharina Tropmann
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Lisa Forster
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Claudia Honisch
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany; Institute of Biomolecular Chemistry - National Research Council (ICB-CNR), Padua Unit Via F. Marzolo, 1, 35131, Padova, Italy
| | - Armin Buschauer
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Günther Bernhardt
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Steffen Pockes
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany; Department of Neurology, University of Minnesota, Minneapolis, MN, 55455, USA; Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, MN, 55414, USA.
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Kagermeier N, Werner K, Keller M, Baumeister P, Bernhardt G, Seifert R, Buschauer A. Dimeric carbamoylguanidine-type histamine H2 receptor ligands: A new class of potent and selective agonists. Bioorg Med Chem 2015; 23:3957-69. [PMID: 25639885 DOI: 10.1016/j.bmc.2015.01.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 12/21/2014] [Accepted: 01/07/2015] [Indexed: 11/23/2022]
Abstract
The bioisosteric replacement of the acylguanidine moieties in dimeric histamine H2 receptor (H2R) agonists by carbamoylguanidine groups resulted in compounds with retained potencies and intrinsic activities, but considerably improved stability against hydrolytic cleavage. These compounds achieved up to 2500 times the potency of histamine when studied in [(35)S]GTPγS assays on recombinant human and guinea pig H2R. Unlike 3-(imidazol-4-yl)propyl substituted carbamoylguanidines, the corresponding 2-amino-4-methylthiazoles revealed selectivity over histamine receptor subtypes H1R, H3R and H4R in radioligand competition binding studies. H2R binding studies with three fluorescent compounds and one tritium-labeled ligand, synthesized from a chain-branched precursor, failed due to pronounced cellular accumulation and high non-specific binding. However, the dimeric H2R agonists proved to be useful pharmacological tools for functional studies on native cells, as demonstrated for selected compounds by cAMP accumulation and inhibition of fMLP-stimulated generation of reactive oxygen species in human monocytes.
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