Discovery of pyrazoline analogs as multi-targeting cholinesterase, β-secretase and Aβ aggregation inhibitors through lead optimization strategy.

The multi-target directed ligands (MTDLs) strategy has been evolved as the propitious approach for the development of therapeutics for Alzheimer's disease (AD). In an earlier report, we described the novel series of chalcone derivatives bearing N-aryl piperazine scaffold as MTDLs for the treatment of AD. Herein, we report the lead optimization of the series culminating in potent, multi-targeting compounds (32-57), evaluated through in-vitro and in-vivo biological studies. The optimal compound 48 exhibited potent inhibitory activities against AChE (IC = 2.89 ± 0.706 μM), BuChE (IC = 0.151 ± 0.089 μM), along with BACE-1 (% inhibition = 36.64 ± 1.343 %) and amyloid-β aggregation inhibition. Compound 48 showed excellent blood-brain barrier permeability (Pe = 7.28 ± 0.474 × 10 cm s) in PAMPA assay and was found safe in the in vivo acute oral toxicity study. The molecular binding interaction pattern and protein-ligand stability was displayed by lead compound 48 with selected targets. Furthermore, in-vivo behavioural studies demonstrated the amelioration of cognitive dysfunctions and significant memory improvement in Y-maze test (scopolamine-induced amnesia model) in mice on the administration of compound 48 at a dose of 20 mg/kg. The reduction in the level of AChE and increased in ACh activity was observed in ex vivo biochemical analysis. Moreover, compound 48 displayed antioxidant potential on measurement of catalase (CAT) and malondialdehyde (MDA) activity in ex vivo analysis. We anticipate that compound 48, from the pyrazoline series, may be a lead molecule for the discovery of safe and effective therapeutic agents for AD.