Development of Fluorescent Ligands for the Human 5-HT_1A Receptor

Abstract

In this work, we report the design and synthesis of a set of fluorescent probes targeting the human 5-HT 1A receptor (h5-HT 1A R). Among the synthesized compounds, derivative 4 deserves special attention as being a high-affinity ligand (K i = 2 nM) with good fluorescent properties (I em > 1000 au and a fluorescence quantum yield, Φ f , of 0.26), which enables direct observation of the h5-HT 1A R in cells. Thus, it represents the first efficacious fluorescent probe for the specific labeling of h5-HT 1A R in cells. Our results provide the basis for the introduction of a variety of tags in scaffolds of G protein-coupled receptor (GPCR) ligands that enable visualization, covalent binding, or affinity pull-down of receptors. These strategies should contribute to the optimization of the therapeutic exploitation of known or new members of the GPCR superfamily by providing valuable information about their location or level of expression.

Synthesis and biological evaluation of 2-fluoro and 3-trifluoromethyl-phenyl-piperazinylalkyl derivatives of 1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione as potential antidepressant agents

“…The study allowed us to identify some potent 5-HT 1A (5, 14, 17-21), 5-HT 7 (17,18,20) and mixed 5-HT 1A /5-HT 7 (12,15,21) receptor ligands with weak inhibitory potencies for PDE4B and PDE10A. The study reveals that 5-HT 1A and 5-HT 7 receptor affinity benefits from the introduction of a fluorine moiety while introduction of imidazole ring into 7, 8 position of theophylline had no significant effect on inhibitory potencies for selected PDE.…”

“…On the basis of the binding affinity results, a series of compounds possessing affinity below 3 nM for 5-HT 1A R (5,8,9,(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) and below 50 nM for 5-HT 7 receptors (9,12,15,17,18,20,21) was selected for functional profile characterization. Intrinsic activity studies were performed using in vitro measures of receptor activation.…”

“…Intrinsic activity studies were performed using in vitro measures of receptor activation. No activation of any of the receptors was observed, and the compounds showed antagonist properties, especially the 5-HT 1A (5,9,12,14,15,(17)(18)(19)(20)(21) (Figures 4 and 5). In case of 5-HT 7 R, there are significant differences between the binding and functional tests results for selected compounds.…”

“…A very important class of 5-HT receptors ligands are derivatives of 1,4-disubstituted arylpiperazine ( Figure 1). Such arylpiperazine derivative with longchain substituents incorporated on the basic nitrogen of the phenylpiperazine ring -long-chain arylpiperazines (LCAPs) -are commonly studied classes of bioactive compounds [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] . Despite the enormous progress in central nervous system (CNS) drug discovery, particularly in the areas of mood disorders and schizophrenia, new drugs are still being sought.…”

Characterization of 5-HT1A receptors and their complexes with G-proteins in budded baculovirus particles using fluorescence anisotropy of Bodipy-FL-NAN-190

“…Numerous ligands (both full and partial agonists and antagonists) are available that bind to this receptor with high specificity and they have been used to study the location and function of 5-HT 1A receptors. While radiolabeled 5-HT 1A ligands have been available for decades they have several limitations (requiring separation of bound and free ligand before measurement, for example) and recent developments in the design of fluorescently labeled ligands that specifically bind to 5-HT 1A receptors have enabled, for example, the visualization and real time measurement of ligand binding to intact cells (Alonso et al, 2010). In addition to being applicable in microscopy-based measurements that offer high temporal and spatial resolution, assays based on fluorescent ligands or labels offer additional possibilities such as measurement of interactions between multiple fluorescent (or quenching) moieties using resonance energy transfer based methods such as FRET and fluorescence correlation spectroscopy, or enhancement of specific signals using fluorescence lifetime based approaches etc.…”