Stereochemical studies on medicinal agents. 31. Only one pharmacophore is required for the .kappa. opioid antagonist selectivity of norbinaltorphimine
摘要:
We have investigated whether one or two pharmacophores are required for the kappa opioid receptor selectivity of the bivalent opioid antagonist norbinaltorphimine, (-)-1 (nor-BNI), by the synthesis and testing of its meso isomer 2. In smooth muscle preparations 2 was more potent than 1 and about half as selective as a kappa antagonist. Since 2 contains only one antagonist pharmacophore but yet retains substantial kappa selectivity, it is concluded that kappa selectivity is not dependent on the presence of two (-)-naltrexone-derived pharmacophores of 1. It is suggested that the kappa selectivity of (-)-1 and 2 is derived from the portions of the second halves of these molecules in that they mimic key "address" components of dynorphin at kappa opioid receptors.