Synthesis and Biological Evaluations of the 1,3,5-Triazine Derivatives as Cholinesterase Inhibitors, Antioxidant, and Biometal Chelators for Alzheimer's Disease.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder requiring treatments that address its complex pathology. Multi-target-directed ligands (MTDLs) offer a promising strategy by integrating multiple pharmacophores into single molecules. The aim of this study was the design, synthesis, and evaluation of the 12 novel 1,3,5-triazine-aniline-benzylidene derivatives (6a-l) as the MTDLs targeting cholinesterases (ChEs), oxidative stress, and biometal dyshomeostasis implicated in AD. In vitro assays showed several compounds exhibited moderate dual ChEs inhibition, with notable selectivity towards butyrylcholinesterase (BChE). Compounds bearing 3,4-dihydroxybenzylidene moieties (6i, 6j) displayed potent BChE inhibition, reaching sub-micromolar levels. Furthermore, many derivatives demonstrated strong antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, with several exhibiting low micromolar EC50 values (1.00-7.08 µM), superior to the standard antioxidants butylated hydroxytoluene (BHT) and quercetin, particularly those containing dihydroxy substitutions. The UV-Vis spectroscopy method confirmed the compound's ability to chelate to the relevant biometal ions (Cu2+, Zn2+, Fe2+, Fe3+, and Al3+), especially with Cu2+. Molecular docking studies for the representative dual ChEs inhibitor molecule (6j) supported the biological findings, revealing effective interactions with the amino acids within the active sites of both ChEs. These results underscore the potential of these novel hybrids as promising MTDL leads for further AD therapeutic development.