Background
Activation of the κ opioid (KOP) receptor results in antinociceptive actions, while it is not involved in the unwanted effects including respiratory depression, dependence or abuse liability, as in the case of the µ opioid (MOP) receptor. Therefore, KOP agonists appear to possess some advantages over the most widely used MOR analgesics. Besides the analgesic activity, KOP agonists have also shown other beneficial effects such as anti-pruritic, anti-arthritic, anti-inflammatory, and neuroprotective effects. At present, the main classes of available chemically distinct KOP agonists include benzomorphans, morphinans, arylacetamides, diterpenes and peptides. Herein, we present a new molecular scaffold for KOP ligands of the class of diphenethylamines and biological investigations on in vitro and in vivo opioid activities.