Synthesis, cholinesterase/MAO-A inhibition, antioxidant potential and detailed computational analysis of 3,5-difluorobenzenesulfonate-tagged ethoxyvanillin hydrazones

Abstract

A new series of hydrazones were prepared and assessed for their inhibitory activity against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and monoamine oxidase-A (MAO-A) along with their antioxidant activity. Among the tested compounds, 5i displayed the maximum inhibitory activity with IC₅₀ = 11.29 ± 0.98 nM for AChE, IC₅₀ = 1.12 ± 0.41 nM for BChE, and IC₅₀ = 102.70 ± 5.26 nM for MAO-A. Notably, compound 5i was found to be more potent than the standard. Additionally, the IC₅₀ values obtained from antioxidant assays ranged from 9.22 ± 0.91 nM to 19.48 ± 0.05 nM, indicating the strong free-radical scavenging property. Structure–activity relationship (SAR) studies proved that electron-withdrawing substituents play a pivotal role in increasing the inhibitory efficiency and antioxidant capacity. To validate these results, molecular docking and dynamics studies were conducted to investigate the binding contacts and possible inhibition mechanisms in the active sites of the enzyme. DFT, GCR descriptors, and ESP analyses elucidated the electronic features governing the activity. The compounds exhibited moderate cytotoxicity in HUVEC cells, with IC₅₀ values ranging from 35.94 to 64.27 µM, indicating a favorable safety profile within the tested concentration range. The outcomes highlighted the substantial multifunctional potential of the evaluated hydrazones as AChE, BChE, and MAO-A inhibitors with complementary antioxidant activity, and cytotoxicity results indicated their potential for further advancement in the management of neurodegenerative conditions.