Design and development of 1,5-diarylpyrazole-based multitarget-directed ligands as dual COX-2/HDAC6 inhibitors for...

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder, requiring multitarget-directed ligands capable of modulating interconnected pathological pathways. Here, a pharmacophore-hybridization strategy combining COX-2-selective 1,5-diarylpyrazole scaffolds with a zinc-binding group was used to design dual COX-2/HDAC6 inhibitors. Twenty hybrids were synthesized and evaluated, identifying 10a and 11e as the most potent compounds, with IC₅₀ values of 0.18 and 0.66 μM for COX-2, and 0.15, 0.12 μM for HDAC6, respectively. Molecular dynamics simulations confirmed stable binding of 11e to both enzymes, with persistent hydrogen bonding, minimal RMSD fluctuations, and favorable binding free energies (ΔG_bind = -29.3 and -51.5 kcal/mol for HDAC6 and COX-2, respectively). Compound 11e exhibited potent neuroprotective activity by markedly enhancing α-tubulin acetylation, suppressing the expression of pro-inflammatory mediators (COX-2, IL-1β, IL-6, and TNF-α), promoting amyloid-β clearance, restoring memory-related gene expression, and significantly reducing Tau hyperphosphorylation. Histopathological analyses confirmed decreased phosphorylated STAT3 and Tau levels, preserved neuronal morphology via MAP2 stabilization, and protection of synaptic integrity through synaptophysin regulation. Behavioral studies in a scopolamine-induced AD mouse model demonstrated substantial improvements in learning and memory. These findings establish 11e as a potent dual COX-2/HDAC6 inhibitor and a promising multitarget scaffold for developing disease-modifying therapies for AD and related neurodegenerative disorders.