Testing of NTRC-824 (Compound 5) at the NTS1 receptor shows no binding activity in the NTS1 assay up to 30 μM, making NTRC-824 (Compound 5) selective for NTS2 in both the binding and functional assays. NTRC-824 (Compound 5) is the first nonpeptide compound that behaves like, and is more active than, the endogenous ligand.