6-[2-(4-Arylpiperazin-1-yl)ethyl]-4-halo-1,3-dihydro-2H-benzimidazole-2-thiones: synthesis and pharmacological evaluation

Abstract

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-benzi -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) D-1 and D-2 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 D-2 and 5-HT1A receptors, with the most active of them having 34 and 170 time higher affinity than non-halogenated congeners in the D-2 DA receptor radioassays (compounds 9.1b and 9.2b, respectively). Divergently, these compounds were without significant affinities for the D-1 DA receptors.

Sintetisano je osam novih jedinjenja kod kojih je atom halogena uveden u benzimidazol-2-tionsku dopaminergičku farmakoforu 5-[2-(4-arilpiperazin-1-il)etil]-1,3-dihidro-2N-benzimidazol-2-tiona sa arilpiperazinskim delom molekula izabranim shodno pozna- tim zahtevima o odnosu strukture i reaktivnosti. Za sva novosintetisana jedinjenja je određen afinitet vezivanja za dopaminske (D1 i D2) i 5-NT1A receptore u in vitro eksperimentima kompeticije sa radioligandima. Kao izvor dopaminskih i 5-NT1A receptora su korištene sinaptozomalne membrane izolovane iz goveđeg nukleusa kaudatusa i hipokampusa. Sva novosintetisana jedinjenja pokazala su se kao jaki kompetitori [3H]spiperona i [3H]8-OH-DPAT, od kojih najaktivnija (9.1b i 9.2b) poseduju 34 i 170 puta veći afinitet ka D2 DA receptorima od polaznih, nehalogenovanih jedinjenja. Sa druge strane, ova jedinjenja ne poseduju značajan afinitet ka D1 dopaminskim receptorima. .