Polyphenols as Potential β-Lactamase Inhibitors: An Integrated Computational and Experimental Study

The production of β-lactamases is the main mechanism underlying carbapenem resistance. This study combined in silico and in vitro approaches to identify potential polyphenols as carbapenemase inhibitors. Molecular docking, molecular dynamics, and ADMET prediction were performed to assess the binding affinity, stability, and safety of quercetin, kaempferol, caffeic acid, and 3,4-dihydroxybenzoic acid against KPC-2, NDM-1, and OXA-48 carbapenemases. In vitro antibacterial assays and checkerboard analyses were conducted against <i>Klebsiella pneumoniae</i>, <i>Escherichia coli</i>, and <i>Pseudomonas aeruginosa</i> to assess antibacterial and synergistic effects. Then, the inhibition of the β-lactam hydrolytic activity was confirmed. In silico results showed that quercetin, kaempferol, and caffeic acid exhibited strong binding affinity and consistent stability towards the targets. Therefore, quercetin and kaempferol showed the strongest affinities (-8.0 kcal/mol) and stable interactions with key catalytic residues. ADMET profiles indicated good pharmacokinetic behavior and low acute toxicity. In vitro assays revealed that the polyphenols exhibited MIC values ranging from 12.5 to 25 mg/L and MBC values of 25-50 mg/L. Combined with cefotaxime, they enhanced bacterial susceptibility and inhibited β-lactam hydrolysis, with quercetin achieving complete inhibition at 200 mg/L. These findings highlight the potential of the four polyphenols as natural β-lactamase inhibitors. Further enzyme kinetics and in vivo studies are needed to confirm their therapeutic relevance.