New coumarin-based fluorescent melatonin ligands. Design, synthesis and pharmacological characterization

The design and synthesis of a series of new fluorescent coumarin-containing melatonin analogues is presented. The combination of high-binding affinities for human melatonergic receptors (h-MT1R and h-MT2R) and fluorescent properties, derived from the inclusion of melatonin pharmacophoric elements in the coumarin scaffold, yielded suitable candidates for the development of MT1R and MT2R fluorescent probes for imaging in biological media. [Display omitted] •New coumarin-based fluorescent ligands at human melatonergic receptors (h-MTRs).•N-(2-(6-Methoxy-2-oxo-2H-chromen-4-yl)ethyl)acetamide: nanomolar affinity at h-MTRs.•Coumarin – melatonin superposition studies: a rationale for h-MTRs affinities.