Discovery of Novel Biased Opioid Receptor Ligands through Structure-Based Pharmacophore Virtual Screening and Experiment

Abstract

G_i‐protein biased agonists with minimal β‐arrestin recruitment have shown opportunities for alternative safe pain treatment to overcome the serious adverse effects of human mu opioid receptor (μ‐OR) agonists. In order to discover novel non‐morphine OR agonists, we applied hierarchical virtual screening of our in‐house database against a pharmacophore based on modeling the active conformation of ORs.We discovered Initial hit compound (4), a novel μ‐OR agonist with pyrazoloisoquinoline scaffold. We applied computational R‐group screening to compound 4 and synthesized 14 derivatives predicted to be best. Of these, the new Gi‐protein biased compound (19) shows EC50 = 179 nM at μ‐OR. This resulting in significant pain‐relief effects for mice at the phase II period in formalin tests. This study provides a new strategy to identify diverse sets of promising compounds that might prove useful for drug developments targeting other G protein‐coupled receptors (GPCRs).