Development of Fluorescent Estrogen Receptor Ligands with pH Sensor Functionality

Estrogen receptors (ERs) and their ligands regulate a variety of physiological processes in humans, and altered ER signaling is associated with serious disorders, including breast cancer. Estrogens also bind to other receptors such as G-protein-coupled receptor 30 (GPER), and so fluorescent estrogen ligands would be useful for various functional studies and for development of drug candidates. Here we describe fluorescent estrogen receptor ligands based on 3-aryl-7-hydroxycoumarin. Notably, these ligands also function as pH-dependent OFF-ON-OFF type fluorescent sensors, enabling the detection of specific ranges of pH.