Discovery of Environment-Sensitive Fluorescent Agonists for α₁-Adrenergic Receptors

A series of novel fluorescent agonists were well developed herein with turn-on switch for α₁-adrenergic receptors (α₁-ARs) by conjugating the environment-sensitive fluorophore 4-chloro-7-nitrobenzoxadiazole with phenylephrine. Overall, these probes exhibited efficient binding and apparent fluorescence intensity changes (up to 10-fold) upon binding with α₁-ARs. Moreover, these probes have been successfully applied for selectively imaging α₁-ARs in the living cells. The dynamic process of α₁-ARs internalization was traced successfully with these newly designed fluorescent agonists. Fluorescence polarization assay demonstrated specific interactions between these probes and α₁-ARs. With these new probes, a bioluminescence resonance energy transfer binding assay has been well established and applied to the high-throughput screening of unlabeled α₁-ARs agonist and antagonist. It is expected that these environment-sensitive fluorescent turn-on agonists may provide useful new tools in studying pharmacology and physiology of α₁-ARs during drug discovery.