Benzylimidazolines as h5-HT<sub>1B/1D</sub> Serotonin Receptor Ligands: A Structure−Affinity Investigation
作者:Ho Law、Malgorzata Dukat、Milt Teitler、David K. H. Lee、Lucia Mazzocco、Raj Kamboj、Vik Rampersad、Thomas Prisinzano、Richard A. Glennon
DOI:10.1021/jm970513p
日期:1998.6.1
Benzylimidazolines may represent a class of 5-HT1D ligands that has yet to be exploited. On the basis of a previous report that the 2-(substituted-benzyl)imidazoline alpha-adrenergic agonist oxymetazoline (8) binds with high affinity at calf brain 5-HT1D receptors, we explored the structure-affinity relationships of a series of related derivatives. Each of the aromatic substituents was removed and then reinstated in a systematic manner to determine the influence of the individual substituents on binding. It was found that all of the aromatic substituents of 8 act in concert to impart high affinity. However, although the 3-hydroxy group could be removed without significantly reducing affinity for h5-HT1D (i.e., human 5-HT1D alpha) receptors, this modification reduced h5-HT1B (i.e., human 5-HT1D beta) receptor affinity by nearly 50-fold. The 2,6-dimethyl groups also contribute to binding but seem to play a greater role for h5-HT1B binding than h5-HT1D binding.With the appropriate structural modifications, several compounds were identified that display 20- to >100-fold selectivity for h5-HT1D versus h5-HT1B receptors. Preliminary functional data suggest that these compounds behave as agonists. Given that 5-HT1D agonists are currently being explored for their antimigraine action and that activation of h5-HT1B receptors might be associated with cardiovascular side effects, h5-HT1D-selective agents may offer a new lead for the development of therapeutically efficacious agents.