Design, Synthesis, and Biological Evaluation of Pyridazinones Containing the (2-Fluorophenyl) Piperazine Moiety as Selective MAO-B Inhibitors.

Twelve pyridazinones (-) containing the (2-fluorophenyl) piperazine moiety were designed, synthesized, and evaluated for monoamine oxidase (MAO) -A and -B inhibitory activities. was found to be the most potent MAO-B inhibitor with an IC value of 0.013 µM, followed by (IC = 0.039 µM). Inhibitory potency for MAO-B was more enhanced by bromo substitution () than by bromo substitution (). For substitution, inhibitory potencies for MAO-B were as follows: -Cl () > -N(CH) () > -OCH () > Br () > F () > -CH () > -H (). and efficiently inhibited MAO-A with IC values of 1.57 and 4.19 µM and had the highest selectivity indices (SIs) for MAO-B (120.8 and 107.4, respectively). and were found to be reversible and competitive inhibitors of MAO-B with K values of 0.014 and 0.0071, respectively. Moreover, was less toxic to healthy fibroblast cells (L929) than . Molecular docking simulations with MAO binding sites returned higher docking scores for and with MAO-B than with MAO-A. These results suggest that and are selective, reversible, and competitive inhibitors of MAO-B and should be considered lead candidates for the treatment of neurodegenerative disorders like Alzheimer's disease.