Palladium (II)-Quinoxaline Complex as A Potent Antioxidant, Antimicrobial, and Antidiabetic Agent: Design, Synthesis, in Vitro and in Silico Evaluation

A Schiff base ligand (E)-11-(2-phenylhydrazono)-11H-indeno[1,2-b] quinoxaline was synthesized by the condensation of o-phenylenediamine with ninhydrin followed by its Pd (II) complex under refluxing condition. The newly formed compounds have been systematically characterized by various spectroscopic and analytical techniques which include UV–Vis, FT-IR, ¹H-NMR, Mass spectroscopy; additionally supported by elemental analysis for their chemical composition. A square-planar geometry has been proposed for the Pd(II) complex. The Pd (II) complex demonstrated notable antioxidant potential in ABTS and FRAP assays. Pd(II) complex demonstrated antimicrobial activity against Staphylococcus aureus and Candida albicans. Dose-dependent α-amylase inhibition (IC₅₀ = 326.47 µg/mL) exhibiting a mixed mode was observed. In silico studies using molecular docking indicate a binding energy of -7.65 kcal/mol and stable interactions at the α-amylase active site. Molecular dynamics simulations (100 ns) revealed structural stability of the ligand–enzyme complex. MM/GBSA free energy calculations estimated a binding free energy of −61.4 kcal/mol, dominated by van der Waals and lipophilic interactions. These findings underscore the potential of the Pd(II) complex as a promising antidiabetic and antimicrobial agent and warrant further investigation into its mechanism of action and in vivo efficacy.