CHEMBL5738803

Opioid Receptor Binding Assay: The Ki (binding affinity) for μ opioid receptors was determined using a competitive displacement assay as previously described in Neumeyer (Journal of Med. Chem. 2012, p3878), which is incorporated herein in its entirety. Briefly, membrane protein from CHO (Chinese Hamster Ovarian) cells that stably expressed the cloned human μ opioid receptor were incubated with 12 different concentrations of the compound set forth herein in the presence of 0.25 nM [3H]DAMGO (see Tiberi et al., Can. J. Physiol. Pharmacol. 1988, Vol. 66, p1368, which is incorporated by reference herein in its entirety) in a final volume of 1 mL of 50 mM Tris-HCl, pH 7.5 at 25° C. Incubation times of 60 min were used for [3H]DAMGO (see Gulati et al., Life Sci. 1990, Vol. 47, p 159, which is incorporated by reference herein in its entirety). Nonspecific binding was measured by inclusion of 10 μM naloxone. The binding was terminated by filtering the samples through Schleicher & Schuell No. 32 glass fiber filters using a Brandel 48-well cell harvester. The filters were subsequently washed three times with 3 mL of cold 50 mM Tris-HCl, pH 7.5, and were counted in 2 mL Ecoscint A scintillation fluid. IC50 values were calculated by least squares fit to a logarithm-probit analysis. Ki values of unlabelled compounds were calculated from the equation Ki=(IC50)/1+S where S=(concentration of radioligand)/(Kd of radioligand) (Cheng and Prusoff, 1973).