The effect of 17-N substituents on the activity of the opioid κ receptor in nalfurafine derivatives
摘要:
We have previously reported the essential structure of the opioid kappa receptor agonist nalfurafine hydrochloride (TRK-820) for binding to the kappa receptor. In the course of this study, we focused on the effect of the substituent at 17-N in nalfurafine on the binding affinity for the j receptor. The exchange of the 17-N substituent in nalfurafine from cyclopropylmethyl to fluoro-substituted alkyl groups, which are strong electron withdrawing substituents, almost completely diminished the binding affinities for the mu and delta opioid receptors, but the binding affinity for the j receptor was still maintained. As a result, nalfurafine derivatives with 17-fluoro-substituted alkyl groups showed higher selectivities for the j receptor than did nalfurafine itself. With regard to the j agonistic activities, the conversion of the 17-N substituent in nalfurafine from cyclopropylmethyl to fluoro-substituted alkyl groups led to the gradual decrease of the agonistic activities in the order corresponding to their binding affinities for the j receptor. In contrast, the derivative with the bulky 17-isobutyl group showed lower affinity and agonistic activity for the j receptor than the derivatives with the smaller functional groups. This research suggested that both the electronic property and the steric characteristics of the 17-N substituent would have a great influence on the binding property for the j receptor. (c) 2012 Elsevier Ltd. All rights reserved.
The effect of 17-N substituents on the activity of the opioid κ receptor in nalfurafine derivatives
摘要:
We have previously reported the essential structure of the opioid kappa receptor agonist nalfurafine hydrochloride (TRK-820) for binding to the kappa receptor. In the course of this study, we focused on the effect of the substituent at 17-N in nalfurafine on the binding affinity for the j receptor. The exchange of the 17-N substituent in nalfurafine from cyclopropylmethyl to fluoro-substituted alkyl groups, which are strong electron withdrawing substituents, almost completely diminished the binding affinities for the mu and delta opioid receptors, but the binding affinity for the j receptor was still maintained. As a result, nalfurafine derivatives with 17-fluoro-substituted alkyl groups showed higher selectivities for the j receptor than did nalfurafine itself. With regard to the j agonistic activities, the conversion of the 17-N substituent in nalfurafine from cyclopropylmethyl to fluoro-substituted alkyl groups led to the gradual decrease of the agonistic activities in the order corresponding to their binding affinities for the j receptor. In contrast, the derivative with the bulky 17-isobutyl group showed lower affinity and agonistic activity for the j receptor than the derivatives with the smaller functional groups. This research suggested that both the electronic property and the steric characteristics of the 17-N substituent would have a great influence on the binding property for the j receptor. (c) 2012 Elsevier Ltd. All rights reserved.
A morphinan derivative represented by formula (1) or a pharmacologically acceptable acid-addition salt thereof, and analgesic, diuretic, antitussive and brain cell protective agents each containing the derivative or the salt as the active ingredient. These compounds have potent analgesic, diuretic and antitussive effects as a highly selective κ-opioid agonist, and are useful as analgesic, diuretic and antitussive agents. In addition, they have a significant brain cell protective effect and are useful as a brain cell protective agent.