Structure-Based Identification of Ponganone V from Pongamia pinnata as a Potential KPC-2 β-Lactamase Inhibitor: Insights from Docking, ADMET, and Molecular Dynamics

Carbapenem-resistant Enterobacterales (CREs) pose a critical threat to global public health, largely driven by the enzymatic activity of Klebsiella pneumoniae carbapenemase-2 (KPC-2), a class A serine β-lactamase that hydrolyzes most β-lactam antibiotics. While β-lactamase inhibitors like avibactam offer temporary relief, emerging KPC variants demand novel, sustainable inhibitory scaffolds. This study aimed to identify and characterize potential natural inhibitors of KPC-2 from Pongamia pinnata, leveraging a comprehensive in silico workflow. A curated library of 86 phytochemicals was docked against the active site of KPC-2 (PDB ID: 3DW0). The top-performing ligands were subjected to ADMET profiling (pkCSM), and 100 ns molecular dynamics simulations (GROMACS) to evaluate structural stability and interaction persistence, using avibactam as control. Ponganone V exhibited the most favorable binding energy (−9.0 kcal/mol), engaging Ser70 via a hydrogen bond and forming π–π interactions with Trp105. Glabrachromene II demonstrated a broader interaction network but reduced long-term stability. ADMET analysis confirmed high intestinal absorption, non-mutagenicity, and absence of hERG inhibition for both ligands. Molecular dynamics simulations revealed that Ponganone V maintained compact structure and stable hydrogen bonding throughout the 100 ns trajectory, closely mirroring the behavior of avibactam, whereas Glabrachromene II displayed increased fluctuation and loss of compactness beyond 80 ns. Principal Component Analysis (PCA) further supported these findings, with Ponganone V showing restricted conformational motion and a single deep free energy basin, while avibactam and Glabrachromene II exhibited broader conformational sampling and multiple energy minima. The integrated computational findings highlight Ponganone V as a potent and pharmacologically viable natural KPC-2 inhibitor, with strong binding affinity, sustained structural stability, and minimal toxicity. This study underscores the untapped potential of Pongamia pinnata phytochemicals as future anti-resistance therapeutics and provides a rational basis for their experimental validation.