👤 Enas A Abd El-Haleim

Contemporary evidence indicates that Alzheimer's disease (AD) is characterized by two convergent levels of pathological alteration. The first involves neurochemical downregulation, whereas the second encompasses broader neuropathological changes. Together, these findings underscore the need for multifaceted therapeutic strategies, such as multi-target-directed ligands (MTDLs). In this study, hydrazide-hydrazone based derivatives 3a-l and 5a-c were rationally optimized from previously synthesized compounds Ia-o to address multiple AD-related targets. Structural elongation was approached by introducing a glycyl fragment into the hydrazinylidene side chain of the indole scaffold. The new derivatives were subjected to a sequential biological evaluation pipeline to identify the most promising candidates. Preliminary in vitro screening against AChE and BChE highlighted compounds 3c, 3f, and 3 k, each exhibiting >80% inhibition of AChE. Further in vitro profiling demonstrated their inhibitory potencies across additional AD-relevant enzymes, including AChE, BChE, BACE-1, MAO-A, MAO-B, and COX-2. In in vivo assessment, all synthesized derivatives showed notable anti-inflammatory activity in the carrageenan-induced rat paw edema model. Moreover, compounds 3c, 3f, and 3k produced significant spatial memory improvement in the diseased mice, along with marked enhancement of AD hallmarks and associated histopathological alterations. To gain mechanistic insights, the derivatives were investigated in silico, where molecular docking elucidated favorable binding modes within AChE, BACE-1, and MAO-B active sites. Among them, compound 3f displayed the most consistent performance across biological assays and computational studies and was further subjected to molecular dynamics simulation, which confirmed its stable accommodation within all three enzyme binding pockets. In conclusion, the molecular elongation strategy successfully generated a new series of MTDL candidates with multi-enzyme inhibitory activity against AChE, BChE, BACE-1, and MAO-B, highlighting their potential as promising anti-AD therapeutics. Show less

The development of multi-target directed ligands (MTDLs) amassed great attention to combat the multifactorial nature of Alzheimer's disease (AD). The present study showcases the synthesis of a novel series of 3-hydrazinyl indole phenacetamide derivatives aimed at addressing AD and neuroinflammation by targeting acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and β-secretase (BACE1) enzymes. The primarily in vivo anti-inflammatory screening nominated derivatives 5a-f, 5h, 5j and 5o for the initial in vitro screening against AChE. Compounds 5a-c, 5j, and 5o, exhibited the most potent inhibitory activity against AChE and BChE, were subsequently subjected to further in vivo biological evaluations. Also, 5a-c were inspected for their impact on hallmarks of AD and histopathological changes. N-phenylacetamide indole derivative bearing unsubstituted phenylhydrazinyl side chain 5a depicted the most cognitive enhancement compared to the reference standard donepezil and significantly improved spatial memory capabilities, mitigated histopathological alterations, reduced AD hallmarks, AChE, BACE1, amyloid beta (Aβ), and p-tubulin associated unit (p-Tau), and modulated oxidative and inflammatory markers, GSH and IL-1β. Moreover, in vitro BACE1 enzyme inhibition assay revealed moderate BACE1 inhibitory activity for derivatives 5a-c. Further, in silico docking studies for the most active derivatives 5a-c in AChE and BACE1 binding pockets evidenced interacting with key amino acid residues supporting their remarkable biological activity. Furthermore, molecular dynamics simulations confirmed the stability of derivative 5a within the AChE and BACE1 binding sites throughout the simulation period. Collectively, N-phenylacetamide indole derivative bearing unsubstituted phenylhydrazinyl side chain 5a represents a promising multi-target candidate, combining AChE, BChE and BACE1 inhibition and can be considered as a lead compound for further development in AD therapy. Show less