Microwave-Assisted Synthesis and In Vitro Anti-Alzheimer Evaluation of Novel 1,3,5-Triazine-Nicotinic Hydrazide Derivatives as Acetylcholinesterase and Butyrylcholinesterase Inhibitors

Alzheimer's disease (AD) is a progressive neurodegenerative disorder posing major global health challenges due to its complex pathophysiology and increasing prevalence among the elderly. In the present work, the molecular hybridization technique was utilized to design and synthesize nicotinic hydrazide-1,3,5-triazine hybrids. Accordingly, this study aimed to design, perform in silico screening, synthesize, and evaluate the in vitro and in vivo anti-AD potential of the proposed compounds. Docking studies revealed that the compounds displayed key interactions with catalytic site and peripheral anionic site residues. Based on binding affinity, ten compounds were synthesized and characterized using different spectroscopic techniques. In vitro AChE and BChE inhibitory assays revealed that the compound 4A36 showed the highest inhibitory ability with log IC₅₀ values of 5.97 μM against AChE and 4.57 μM against BChE. In addition, cytotoxicity screening revealed that 4A36 was non-toxic in SH-SY5Y neuroblastoma cells in the concentration range of 15.625-250 µg/mL. Acute oral toxicity evaluation of the compound revealed no adverse effects up to 175 mg/kg b.w. Further, in vivo studies using the scopolamine-induced model further validated the therapeutic promise of the compound. At a dose of 30 mg/kg b.w., the compound demonstrated significant improvements in learning and memory, reduced MDA levels with concurrent elevation of antioxidant Enzymes SOD and Catalase, and reduced AChE activity in hippocampal tissue. Histopathological observations revealed that treatment groups, especially at higher dose (30 mg/kg b.w.), preserved the granular layer of the dentate gyrus and improved neuronal integrity compared to the disease control. These findings indicate that 4A36 at a dose of 30 mg/kg b.w. may be considered as a promising lead compound in AD.

1,3,5‐triazine; AChE; Alzheimer's disease; BChE; neuroprotection; nicotinic hydrazide.