Synthesis, characterization and molecular docking study of pyrazolines synthesized from chalcones: Antioxidant and acetylcholinesterase activities

Pyrazolines are heterocyclic compounds with nitrogen-containing rings, known mainly for their pharmacological potential. In recent times, much attention has been paid to the synthesis of these compounds to discover a wide spectrum of biological activities. Therefore, thirteen pyrazoline derivatives were synthesized from a cyclization reaction between chalcones and phenylhydrazines and showed total yields of 56 - 90%. All compounds were fully characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (1H and 13C NMR), and gas chromatography/mass spectrometry (GC/MS). Compounds were submitted to antioxidant activity using DPPH assay and acetylcholinesterase tests. It was observed that different substituents on the A and B rings of the pyrazolines have an influence on the antioxidant activity. Compounds 3, 7, 11 and 13 showed good activity with IC50 0.4017, 0.2892, 0.1100 and 0.0578, respectively. In the acetylcholinesterase enzyme inhibition assay, compounds 8 and 9 showed very good inhibition, similar to the used standards. The synthesized compounds that were shown to be active in the in vitro assay of acetylcholinesterase inhibition were investigated and subjected to molecular docking studies, and the results obtained showed great binding affinity and the best pose for compounds 3-(4-bromophenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole (6) and 3-(4-chlorophenyl)-5-(4methoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (8), according to the results experimental.