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Serotonin, or 5-hydroxytryptamine (5-HT), is a biogenic amine most noted as a neurotransmitter, an activator of the utmost subtype family of G-protein- coupled receptors (GPCR). Drugs targeting 5-HT1A and other 5-HT receptors treat central nervous system diseases such as schizophrenia and depression. Recent advances in serotonin receptor structure research gave us several crystal 5-HT1A receptor structures, most notably 5-HT1A bound to the antipsychotic drug aripiprazole (Abilify®). This discovery prompted us to evaluate a series of newly synthesized ligands for serotonergic activity since those arylpiperazine derivatives share minimal general structure with aripiprazole. The results of molecular docking analysis of unsubstituted starting substances encouraged us to propound further modifications of the tail and head parts of the parent molecules to maximize receptor binding affinity. Intrigued by the results of molecular analysis, all foreseen derivatives were synthesized. The pharmacological activity of all nine (5a and 6a are synthesized previously) compounds was assessed by the in vitro tests and in silico pharmacokinetics predictions for the most promising candidates. All tested ligands have improved affinity compering to parent compounds (10a and 11a), 8b and 9b expressed the best pharmacological profile with an improved binding affinity toward serotonin 5-HT1A receptors (Ki 12.1 and 4.8 nM, respectively).

A total of 14 novel arylpiperazines were synthesized, and pharmacologically evaluated by measuring their affinities towards the D2 dopamine receptor (DRD2) in a [3H]spiperone competition assay. All the herein described compounds consist of a benzimidazole moiety connected to N-(2-methoxyphenyl)piperazine via linkers of various lengths. Molecular docking analysis and molecular dynamics simulations were performed on the DRD2–arylpiperazine complexes with the objective of exploring the receptor–ligand interactions and properties of the receptor binding site. The recently published crystal structure of DRD2 was used throughout this study. The major finding is that high affinity arylpiperazines must interact with both the orthosteric binding site and the extended binding pocket of DRD2 and therefore should contain a linker of 5 or 6 methylene groups long. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172032]

Series of eight novel 5-substituted derivatives of benzimidazole were synthesized by condensation of corresponding diamine with ethyl-4-[4-(2-chlorophenyl)piperazin-1-yl] butanoate in refluxing 4N hydrochloric acid. In vitro antibacterial activity against ten strains namely, Bacillus subtilis, Clostridium sporogenes, Streptosporangium longisporum, Micrococcus flavus, Sarcina lutea, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Proteus vulgaris and antifungal activity against two fungal strains namely, Candida albicans and Saccharomyces cerevisiae, were evaluated. Of all the compounds screened for activity 2-{3-[4-(2-chlorophenyl)piperazin-1-yl]propyl}-5-iodo-1H-benzimidazole and 2-{3-[4-(2-chlorophenyl)piperazin-1-yl]propyl}-5-methyl-1H-benzimidazole were associated with higher antifungal activity than commercial drugs. [Projekat Ministarstva nauke Republike Srbije, br. 172032]