Exploring pyrazolidinone and pyrazolidinedione scaffolds for Alzheimer's therapy: multitarget COX-2 inhibitors with anti-amyloid β, anti-tau, antioxidant, and neuroprotective activities.

COX-2 enzyme is implicated in Alzheimer's disease (AD) through amyloid beta (Aβ) accumulation, tau aggregation, and neuroinflammation. However, clinical outcomes of COX-2 inhibitors in AD have been inconsistent. This study explores a novel series of pyrazolidinones and pyrazolidinediones as selective COX-2 inhibitors. Among these, 4-hydrazonopyrazolidinediones exhibited potent COX-2 inhibition, reducing PGE2 release in a THP-1 cell model. Compounds 15 and 16 demonstrated multitargeting potential by inhibiting Aβ and tau aggregation (PHF6 and R3) and showed significant neuroprotective effects against Aβ and HO-induced toxicity in SH-SY5Y cells without cytotoxicity. Additionally, both compounds displayed high permeability in PAMPA and MDCK-MDR1 assays, indicating their potential to cross the blood-brain barrier and reach therapeutic targets. These findings highlight the potential of reviving COX-2 inhibitors as multitargeted therapeutic agents for AD, offering a promising strategy to address multiple pathological aspects of the disease, including neuroinflammation, amyloid aggregation, and tau pathology.