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β-Arrestins are a small family of proteins important for signal transduction at G protein-coupled receptors (GPCRs). β-Arrestins are involved in the desensitization of GPCRs. Recently, biased ligands possessing different efficacies in activating the G protein-versus the β-arrestin-dependent signals downstream of a single GPCR have emerged, which can be used to selectively modulate GPCR signal transduction in such a way that desirable signals are enhanced to produce therapeutic effects while undesirable signals of the same GPCR are suppressed to avoid side effects. In the present study, we evaluated agonist bias for compounds developed along a drug discovery project of β 2-adrenoceptor agonists. About 150 compounds, including derivatives of fenoterol, 2-amino-1phenylethanol and 2-amino-2-phenylethanol, were obtained or synthesized, and initially screened for their β-adrenoceptormediated activities in the guinea pig tracheal smooth muscle relaxation assay or the cardiomyocyte contractility assay. Nineteen bioactive compounds were further assessed using both the HTRF cAMP assay and the PathHunter β-arrestin assay. Their concentration-response data in stimulating cAMP synthesis and β-arrestin recruitment were applied to the Black-Leff operational model for ligand bias quantitation. As a result, three compounds (L-2, L-4, and L-12) with the core structure of 5-(1-amino-2hydroxyethyl)-8-hydroxyquinolin-2(1H)-one were identified as a new series of β-arrestin-biased β 2-adrenoceptor agonists, whereas salmeterol was found to be G s-biased. These findings would facilitate the development of novel drugs for the treatment of both heart failure and asthma.

β‐Arrestins are implicated in desensitization of activated G protein‐coupled receptors (GPCRs) and transduction of signals in their own right. Biased ligands possessing different efficacies in activating different G protein‐dependent and β‐arrestin‐dependent signals downstream of a single GPCR have been described. Here, we report the characterization of agonist bias for compounds developed along a drug discovery project of β2‐adrenoceptor agonists. Compounds, including derivatives of fenoterol, 2‐amino‐1‐phenylethanol and 2‐amino‐2‐phenylethanol, were obtained or synthesized and their effects on cardiomyocyte contractility, cAMP synthesis and β‐arrestin recruitment were determined in β2‐adrenoceptor‐expressing cells. Gs versus β‐arrestin bias were analyzed by the operational model. Gs versus Gs/Gi bias were studied by means of sensitivity towards pertussis toxin, a Gi disruptor. Three compounds with a core structure of 5‐(1‐amino‐2‐hydroxyethyl)‐8‐hydroxyquinolin‐2(1H)‐one were identified as β‐arrestin‐biased β2‐adrenoceptor agonists. These findings would facilitate the development of novel drugs for the treatment of heart failure and asthma.Support or Funding InformationThis work was supported by the Ministry of Science and Technology of the People's Republic of China under the National Key Research and Development Program of China [2018YFA0507603], the National Science and Technology Major Project [2013ZX09507001‐001002, 2013ZX09301305‐001, 2013ZX09508104, 2018ZX09739009], the National Basic Research Program [2012CB518000], the National Natural Science Foundation of China [81673355, 81872752, 31521062, 81630008, 81790621], Beijing Municipal Science & Technology Commission [Z171100000417006], and the intramural research program of the NIH, USA.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.