Structure-activity relationship studies of CNS agents. Part 10(1): 1-Aryl-2-[3-(4-aryl-1-piperazinyl)propyl]-1,4-dihydro-3(2H)-isoquino linones: two modes of the interaction with the 5-HT1A receptor site.

The synthesis and 5-HT1A and 5-HT2 receptor affinities of 1-aryl-2-[3-(4-aryl-1-piperazinyl)propyl]-1,4-dihydro-3(2H)- isoquinolinones 7-28 are reported. The two derivatives 7 and 13 were the most potent 5-HT1A ligands (Ki 1.72 +/- 0.07 and 2.75 +/- 0.59 nM, respectively) of all the investigated compounds. It has been found that the effect of the substituent in the 1-arylpiperazine portion is opposite to the observed in simple 1-arylpiperazine. The molecular modelling results indicate that the investigated derivatives may interact with 5-HT1A sites in two different ways: as ordinary 4-substituted 1-arylpiperazines, or in such a manner that the aryl substituent at position 1 of the 3(2H)-isoquinolinone moiety and N-4 piperazine atom mimics remarkably well the bioactive conformation of simple 1-arylpiperazines.