HR-LCMS-Guided Metabolite Profiling and Multi-Target Molecular Docking of Ruellia tuberosa L. Reveals Potential Neuroprotective Leads Against Alzheimer’s Disease

Abstract

Ruellia tuberosa L. (Acanthaceae) is a traditionally used medicinal plant with documented antioxidant, anti-inflammatory, and neuroprotective folkloric applications. The present study aimed to comprehensively characterise the secondary metabolite profile of its hydroethanolic extract and to evaluate the neuroprotective potential of identified phytoconstituents through in silico molecular docking against key Alzheimer's disease (AD)-associated targets. Plant material was authenticated and sourced from the Siddha Medicinal Plants Garden, Mettur, Tamil Nadu, and extracted by maceration using a 70% hydroethanolic solvent system. High-resolution liquid chromatography–mass spectrometry (HR-LCMS) analysis was performed at the Sophisticated Analytical Instrument Facility (SAIF), IIT Bombay, using an Agilent Q-TOF instrument with dual AJS electrospray ionisation in both positive and negative ion modes, leading to the tentative identification of 64 phytoconstituents. Selected compounds were subsequently subjected to molecular docking using AutoDock Vina against three validated AD targets: acetylcholinesterase (AChE, PDB: 4EY7), glycogen synthase kinase-3β (GSK-3β, PDB: 1Q5K), and the N-methyl-D-aspartate receptor (NMDA, PDB: 1PBQ). Osmanthuside A demonstrated the highest binding affinity against AChE (−9.0 kcal/mol), comparable to the standard donepezil. Judeol exhibited strong inhibition of GSK-3β (−8.8 kcal/mol), and Cernuine showed the most potent interaction with the NMDA receptor (−9.1 kcal/mol), surpassing the reference compound memantine. These findings provide a multi-target computational framework supporting the neuroprotective ethnopharmacological claims of R. tuberosa and identify Osmanthuside A, Cernuine, Judeol, and Vernoflexuoside as promising lead molecules warranting further in vitro and in vivo investigation.