Development of Novel Inhibitors for Alzheimer's Disease from Erythrina variegata L. Extract-Derived Clusters Using Molecular Docking, QSAR Modeling, Quantum Chemical Calculations, and Molecular Dynamics Simulations

High Resolution Image Download MS PowerPoint Slide The objective of this investigation is to identify and enhance compounds from the medicinal plant Erythrina variegata L. that possess potential inhibitory activity against acetylcholinesterase (AChE). Consequently, this investigation will contribute to the pursuit of supportive therapeutic agents for Alzheimer’s disease. The initial research matrix was composed of nanocluster materials that were derived from the crude extract. The identification of 13 compounds was achieved by utilizing an ultraperformance liquid chromatography system in conjunction with quadrupole time-of-flight mass spectrometry for structural elucidation. Compound VN62 was chosen due to its favorable binding energy (E S = −8.038 kcal/mol) and RMSD = 1.388 Å, as evidenced by molecular docking simulations and analytical results with the AChE protein (PDB ID: 1EVE ). The pIC 50 values were predicted using reliable QSAR models, such as QSAR GA-MLR, QSAR GA-ANN, and QSAR KPLS-LF, which were constructed on this basis. Five novel derivatives (VN62N1–VN62N5) were designed from VN62, subsequently semisynthesized, and structurally confirmed using spectroscopic methods, guided by QSAR and docking results. The AChE inhibitory activity was assessed in vitro, and VN62 demonstrated an IC 50 of 1.34 μg/mL (pIC 50 = 5.498). Conversely, the newly designed derivatives demonstrated a trend toward enhanced activity. Furthermore, a multicriteria evaluation model integrating QSAR, docking, ADMET, and quantum descriptors identified VN62N4 as the top-ranked candidate overall. Molecular dynamics simulations over 400 ns confirmed the structural stability of the VN62N4–AChE complex, as evidenced by stable RMSD, low RMSF in active-site residues, and persistent hydrogen bonding and hydrophobic interactions. The findings verify the efficacy of a comprehensive, multimethod in silico screening strategy in directing the development of AChE inhibitors.