Synthesis and pharmacological evaluation of several N-(2-nitrophenyl)piperazine derivatives

Six newly synthesized heterocyclic (2-nitroplienyl)piperazines. with a specific structure of the heteroaryl group, which mimics the catechol moiety of dopamine (benzimidazoles and substituted benzimidazoles), were evaluated for their binding affinity to rat dopamine (DA), serotonin (5-HT) and alpha I receptors. All compounds with a benzimidazole group had a 5-HT2A/D-2 receptors binding ratio characteristic for atypical neuroleptics (> 1, pK(i) values). Compound 7e, 4-bromo-6-{2-[4-(2-nitrophenyl)piperazin-1-yl]etliyl}-1H-benziniidazole, expressed higher affinities for all receptor classes than clozapine. Also, it exhibited the best characteristic for atypical neuroleptics and presents a compound with the best profile for further in vivo investigations.