Quercetin showed in vitro promise as a carbapenem adjuvant against a carbapenem-resistant Klebsiella pneumoniae isolate

Quercetin enhanced the antibacterial activity of carbapenems against a single carbapenem-resistant Klebsiella pneumoniae (CRKP) isolate in laboratory assays, according to the abstract of a study published in Scientific Reports. The isolate carried both the bla_NDM-1 and bla_KPC-2 genes, and the enhancement was observed when quercetin was tested at 2 µg/µL.

The study screened a library of phytochemicals selected for their reported potential to inhibit resistance enzymes rather than for direct antimicrobial activity. The researchers used ADMET profiling, or assessment of absorption, distribution, metabolism, excretion and toxicity, followed by molecular docking against the NDM-1 and KPC-2 β-lactamase enzymes. Quercetin, eriodictyol and luteolin produced favorable predicted docking scores: −9.1, −8.32 and −8.66 kcal/mol against KPC-2, and −8.74, −8.72 and −8.73 kcal/mol against NDM-1, respectively.

Molecular dynamics simulations were then performed for quercetin complexes with NDM-1 and KPC-2 to examine the predicted conformational behavior of those complexes. These computational findings supported further investigation of quercetin, but the docking and simulation results were predictions rather than direct measurements of enzyme inhibition. The reported in vitro assay showed potentiation of carbapenem activity against the CRKP isolate, while the abstract states that the assays did not directly assess β-lactamase inhibition.

The findings therefore identify quercetin as a preliminary carbapenem-adjuvant candidate under laboratory conditions, with supporting computational analyses and an observed improvement in antibacterial activity. The mechanism responsible for that potentiation remains unconfirmed, and the supplied evidence does not establish whether quercetin directly inhibits NDM-1, KPC-2 or another target. The results are also limited in scope because the reported laboratory testing involved one CRKP isolate; the abstract does not provide evidence about activity against a broader isolate collection or clinical effectiveness in people. The article was published on 12 October 2026 as an open-access, early version of peer-reviewed research and was described as subject to further edits before replacement by the final version of record.

Subject of Research: In vitro and computational evaluation of quercetin as a potential carbapenem adjuvant against a carbapenem-resistant Klebsiella pneumoniae isolate

Article Title: Phytochemical screening as an inhibitor of β-lactamases to overcome the carbapenem-resistant of Klebsiella pneumoniae

Article References: Azmal, M., Paul, J. K., Shohan, M. N. H., Haque, A. N. M. S. N. B., Mrinmoy, M., Talukder, O. F., Mishu, M. A., Mia, M. W., & Ghosh, A. (2026). Phytochemical screening as an inhibitor of β-lactamases to overcome the carbapenem-resistant of Klebsiella pneumoniae. Scientific Reports. https://doi.org/10.1038/s41598-026-68970-0

Image Credits: AI Generated

DOI: 10.1038/s41598-026-68970-0

Keywords: quercetin, Klebsiella pneumoniae, carbapenem resistance, β-lactamases, NDM-1, KPC-2, molecular docking, ADMET profiling, in vitro assay, Scientific Reports, Phytochemical, screening