An integrated in silico approach to identify pyridine-based AChE and BChE inhibitors for Alzheimer's disease

Among all the neural diseases Alzheimer's disease (AD) represents a major and critical global health challenge, along with limited diseases-altering therapeutic interventions efficacy. This study deploys collective approaches of in silico study which includes molecular docking, ADMET profiling, density functional theory (DFT), and MD simulations simulation to evaluate pyridine-based dual inhibitors which can target acetylcholinesterase (AChE PBD ID: 4EY7) and butyrylcholinesterase (BChE PDB ID: 6I0B). From a curated library of 55 ZINC-derived compounds, virtual screening using AutoDock Vina identified lead candidates exhibiting superior binding affinities (-11.5 to - 8.0 kcal/mol for AChE; - 10.9 to - 7.4 kcal/mol for BChE) compared to marketed drugs donepezil and tacrine. Compound 46 emerged as the top AChE inhibitor, while compound 49 demonstrated optimal BChE inhibition. DFT analysis at the B3LYP/6-31G(d) level revealed distinct electronic properties: compound 46 exhibited a wider HOMO-LUMO gap (5.32 eV) correlating with enhanced kinetic stability, whereas compound 49 displayed a narrower gap (5.10 eV) and elevated dipole moment, supporting target-selective binding. Extended MD simulations with 200 ns of total duration confirmed that compounds 46 and 49 (two complexes) have structurally stable conformations compared with each other; however, compound 49 was found to be thermodynamically more stable according to MM-PBSA predicted binding free energy (-54.96 ± 4.36 kcal/mol) than compound 46 (-44.73 + 4.85 kcal/mol). ADMET predictions showed good intestinal absorption and CNS permeability; however, it will be necessary to improve both the solubility of these compounds as well as their CYP3A4-related liability. This multi-tiered computational strategy was able to identify both compounds 46 and 49 as highly promising candidates for further experimental validation as dual cholinesterase inhibitors that will be incorporated into efforts to develop new AD treatment approaches.