N-Homolupinanoyl and N-(ω-lupinylthio)alkanoyl derivatives of some tricyclic systems as ligands for muscarinic M1 and M2 receptor subtypes

A set of N-homolupinanoyl- and N-(v-lupinylthio)alkanoyl derivatives of tricyclic systems (as phenothiazine, iminodibenzyl and dihydropyridobenzodiazepinone) has been prepared and tested for affinity for rat muscarinic M1 and M2 receptor subtypes labeled with [3H]pirenzepine and [3H]AF-DX 384. Good affinity for both M1 and M2 subtypes was displayed by most compounds, often with nanomolar Ki values, which for lupinylthiopropionyl- and lupinylthiobutyryl-phenothiazines (13/16) were comparable to those of pirenzepine and methoctramine, respectively. However, only moderate selectivity for one or the other subtype was seen.