Highly Selective Drug-Derived Fluorescent Probes for the Cannabinoid Receptor Type 1 (CB₁R)

Abstract

The cannabinoid receptor type 1 (CB 1 R) is pivotal within the endocannabinoid system regulating various signaling cascades with effects in appetite regulation, pain perception, memory formation, and thermoregulation. Still, understanding of CB 1 R's cellular signaling, distribution, and expression dynamics is very fragmentary. Real-time visualization of CB 1 R is crucial for addressing these questions. Selective drug-like CB 1 R ligands with a defined pharmacological profile were investigated for the construction of CB 1 R fluorescent probes using a reverse designapproach. A modular design concept with a diethyl glycine-based building block as the centerpiece allowed for the straightforward synthesis of novel probe candidates. Validated by computational docking studies, radioligand binding, and cAMP assay, this systematic approach allowed for the identification of novel pyrrole-based CB 1 R fluorescent probes. Application in fluorescencebased target-engagement studies and live cell imaging exemplify the great versatility of the tailored CB 1 R probes for investigating CB 1 R localization, trafficking, pharmacology, and its pathological implications.