Design, Synthesis, X-Ray Crystallographic Characterization, Anticholinesterase and Antioxidant Evaluation, and Molecular Modeling of Novel Dispiroindene-Pyrrolidine Derivatives as Multifunctional Anti-Alzheimer Agents.

A novel series of 5-chloro-N-alkyl-1',1″-dimethyl-4'-aryldispiro[indene-2,3'-pyrrolidine-2',3″-indoline]-1,2″(3H)-diones (4a-r) was rationally designed and synthesized via a one-pot multicomponent reaction of N-alkylated 5-chloroisatin derivatives, 2-(arylmethylidene)-2,3-dihydro-1H-inden-1-ones (2a-i), and sarcosine (3). To assess their potential therapeutic efficacy, the entire library of synthesized compounds was screened for its inhibitory profiles against both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), where most derivatives exhibited moderate to potent cholinesterase inhibitory activity. Notably, derivatives 4b, 4f, and 4o emerged as the most effective dual inhibitors, displaying strong potent activity against AChE (IC50 = 0.91 ± 0.02, 0.89 ± 0.01, and 0.74 ± 0.01 µM, respectively; donepezil IC50 = 0.68 ± 0.005 µM) alongside significant BChE inhibition (IC50 = 10.19 ± 0.16, 9.59 ± 0.08, and 9.11 ± 0.01 µM, respectively; donepezil IC50 = 2.97 ± 0.01 µM). The structure of the most active derivatives (4b, 4f, and 4o) was further confirmed by X-ray crystallographic analysis. In addition, antioxidant evaluation of compounds 4b, 4f, and 4o demonstrated that derivative 4f possessed the most superior radical scavenging profile (IC50 = 23.18 ± 0.33 µM), representing approximately a 5.5-fold enhancement in potency relative to ascorbic acid (IC50 = 128.20 ± 0.82 µM). Molecular docking studies revealed favorable binding interactions of the lead derivatives within the catalytic binding pockets of both AChE and BChE, with docking scores comparable to those of the standard inhibitor. Furthermore, in silico ADME profiling demonstrated promising pharmacokinetic behavior, characterized by robust gastrointestinal absorption and excellent predicted blood-brain barrier penetration, supporting the potential of these derivatives as promising multifunctional candidates for the development of anti-Alzheimer agents.