A multireceptorial binding reinvestigation on an extended class of σ ligands:: N-[ω-(Indan-1-yl and tetralin-1-yl)alkyl] derivatives of 3,3-dimethylpiperidine reveal high affinities towards σ1 and EBP sites

New 1-[omega-(2,3-dihydro-1H-inden-1-yl)- and (2,3-dihydro-5-methoxy-1H-inden-1-yl)alkyl and 1-[omega-(1,2,3,4-tetrahydronaphthalen-1-yl)- and (6-methoxy- or 6-fluoro-1,2,3,4-tetrahydronaphthalen-1-yl)aIkyl] derivatives of 3,3-dimethylpiperidine were synthesized, as homologous compounds of an existing series of sigma ligands, in order to carry out sigma receptor subtypes structure-affinity relationships. The new compounds and some of their related analogues, already reported, were tested in new multi-receptorial radioligand binding assays. As reference compounds, the known sigma (1) ligands SA 4503, ED 1008 and NE 100 were also prepared and tested. All reported compounds showed high sigma (1) affinity assayed by (+)-[H-3]-pentazocine on guinea-pig brain (apparent K-i = 1.75-72.2 nM) and moderate or low sigma (2) affinity by [H-3]-DTG on rat liver, in contrast with previous results. One tertiary amine function spaced by a five-membered chain from a phenyl group is the structural feature shared by the most active compounds 26 and 43 and some reference al ligands. The reported ol ligands, including reference compounds, also demonstrated a high affinity towards EBP (Delta (8)-Delta (7) sterol isomerase) site (apparent K-i = 0.48-14.8 nM) and some of them (37 and 44) were good ligands at L-type Ca++ channel. 1-14-(2,3-Dihydro- 1H-inden-1-yl)butyl]-3,3-dimethylpiperidine (26) was the best mixed sigma (1) and EBP ligand (apparent K-i = 1.75 and 1.54 nM, respectively) with a good selectivity versus sigma (2) receptor (138- and 157-fold, respectively). (C) 2001 Elsevier Science Ltd. All rights reserved.