High-throughput screening of novel antagonists on melanin-concentrating hormone receptor-1

Aim： To find new antagonists on human melanin-concentrating hormone receptor-1 （MCHR-1） through high-throughput screening （HTS） of a diverse compound library. Methods： MCHR-1, [^3H]SNAP7941, and FlashBlue G-proteincoupled receptor beads were used to measure the receptor-binding activities of various compounds based on scintillation proximity assay （SPA） technology. The guanosine 5＇ （γ-[^35S]thio） triphosphate （[^35S]GTPγS） binding assay was subsequently applied to functionally characterize the ＂hits＂ identified by the HTS campaign. Results： Of the 48 240 compounds screened with the SPA method, 12 hits were confirmed to possess MCHR-1 binding activities, 8 were functionally studied subsequently with the [^35S]GTPγS binding assay, and only 1 compound （NC 127816） displayed moderate human MCHR- 1 binding affinity （Ki=115.7 nmol/L） and relatively potent antagonism （KB=23.8 nmol/L）. This compound shares a novel scaffold （1-ethoxy-2H-2-aza-1-phospha-naphthalene 1-oxide） with 3 other analogs in the group. Conclusion： Considering the marked difference in molecular shape and electrostatic status between NC 127816 and the structures reported elsewhere, we anticipate that its derivatives may represent a new class of potent MCHR-1 modulators.