6-[2-(4-arylpiperazin-1-yl)ethyl]-4-halo-1,3-dihydro-2h-benzimidazole-2-thiones: Synthesis and pharmacological evaluation

Eight new compounds with halogen atom introduced into the benzimidazole- 2-thione dopaminergic pharmacophore of 5-[2-(4-arylpiperazin-1-yl)ethyl]-1,3-dihydro- 2H-benzimidazole-2-thiones with the arylpiperazine part of the molecule being selected according to known structure-affinity requirements, have been synthesized. All the new compounds were evaluated for the in vitro binding affinity at the dopamine (DA) D1 and D2 and serotonin 5-HT1A receptors by the competitive radioassays, performed on synaptosomal membranes prepared from fresh bovine caudate nuclei and hippocampi. All the new compounds were strong competitors for the binding of the radioligands to the D2 and 5-HT1A receptors, with the most active of them having 34 and 170 time higher affinity than non-halogenated congeners in the D2 DA receptor radioassays (compounds 9.1b and 9.2b, respectively). Divergently, these compounds were without significant affinities for the D1 DA receptors. .