Chemical finger-printing, antioxidant activity and in silico validation of phytometabolites of Octhochloa compressa

This study focused on evaluating the antioxidant properties of Octhochloa compressa, a Cholistani medicinal plant and to explore the interaction of its active phytochemical constituents with the biological macromolecule NADPH oxidase (PDB ID: 2CDU). Six different non-polar to polar solvent extracts were evaluated for their antioxidant activity using DPPH and FRAP assays. The key metabolites were then subjected to molecular docking against NADPH oxidase, density functional theory (DFT) and molecular dynamics (MD) simulations to validate the ligand-protein stability and conformational dynamics. The methanol extract revealed significantly highest scavenging potential (IC₅₀ = 110 ± 2.34 µg/mL) in DPPH assay and displayed the greatest amount of total phenolic (97.34 ± 3.34 mg GAE/g) and flavonoid (98.72 ± 2.46 µg CE/g) contents. Phytochemical profiling of the methanol extract identified 43 major bioactive compounds by using HPLC and GC-MS. Silico molecular docking of selected metabolites (lignan, oxindole, apigenin, anthocyanin, acridone) with NADPH oxidase revealed stable interactions, with binding energies ranging from - 6.060 to -6.654 kcal/mol. DFT analysis revealed dipole moments of 1.36-7.52 D and HOMO-LUMO gaps of 3.15-11.74 eV with anthocyanin and apigenin, predicted as the most reactive ligands. MD simulations further confirmed these findings, as the representative 2CDU-ligand complex rapidly equilibrated and maintained the stability across 1 ns and 10 ns trajectories (RMSD ~ 0.2 nm, Rg 2.38-2.46 nm), with persistent non-covalent interactions (- 300 to - 400 kJ/mol) and well-defined free energy minima, validating favorable and thermo-dynamically stable binding. Collectively, these results suggest that O. compressa is a rich source of anti-oxidants phyto-metabolites, capable of interacting with NADPH oxidase, emphasizing its role in the management of disorders related to oxidative stress.