{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,21]],"date-time":"2026-08-21T13:42:30Z","timestamp":1787319750707,"version":"build-2736575974"},"reference-count":56,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2022,8,8]],"date-time":"2022-08-08T00:00:00Z","timestamp":1659916800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"German Academic Exchange Service (DAAD)","award":["57381412"],"award-info":[{"award-number":["57381412"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The search for new antibiotics against multidrug-resistant (MDR), Gram-negative bacteria is crucial with respect to filling the antibiotics development pipeline, which is subject to a critical shortage of novel molecules. Screening of natural products is a promising approach for identifying antimicrobial compounds hosting a higher degree of novelty. Here, we report the isolation and characterization of four galloylglucoses active against different MDR strains of Escherichia coli and Klebsiella pneumoniae. A crude acetone extract was prepared from Paeonia officinalis Linnaeus leaves, and bioautography-guided isolation of active compounds from the extract was performed by liquid\u2013liquid extraction, as well as open column, flash, and preparative chromatographic methods. Isolated active compounds were characterized and elucidated by a combination of spectroscopic and spectrometric techniques. In vitro antimicrobial susceptibility testing was carried out on E. coli and K. pneumoniae using 2 reference strains and 13 strains hosting a wide range of MDR phenotypes. Furthermore, in vivo antibacterial activities were assessed using Galleria mellonella larvae, and compounds 1,2,3,4,6-penta-O-galloyl-\u03b2-d-glucose, 3-O-digalloyl-1,2,4,6-tetra-O-galloyl-\u03b2-d-glucose, 6-O-digalloyl-1,2,3,4-tetra-O-galloyl-\u03b2-d-glucose, and 3,6-bis-O-digalloyl-1,2,4-tri-O-galloyl-\u03b2-d-glucose were isolated and characterized. They showed minimum inhibitory concentration (MIC) values in the range of 2\u2013256 \u00b5g\/mL across tested bacterial strains. These findings have added to the number of known galloylglucoses from P. officinalis and highlight their potential against MDR Gram-negative bacteria.<\/jats:p>","DOI":"10.3390\/molecules27155045","type":"journal-article","created":{"date-parts":[[2022,8,8]],"date-time":"2022-08-08T22:33:11Z","timestamp":1659997991000},"page":"5045","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Isolation and Characterization of Galloylglucoses Effective against Multidrug-Resistant Strains of Escherichia coli and Klebsiella pneumoniae"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7375-7803","authenticated-orcid":false,"given":"Nelson E.","family":"Masota","sequence":"first","affiliation":[{"name":"Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Sandering 2, 97074 Wuerzburg, Germany"},{"name":"School of Pharmacy, Muhimbili University of Health and Allied Sciences, Upanga West, Dar es Salaam P.O. Box 65013, Tanzania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Knut","family":"Ohlsen","sequence":"additional","affiliation":[{"name":"Institute for Molecular Infection Biology, University of Wuerzburg, Josef-Schneider-Strasse 2, 97080 Wuerzburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Curd","family":"Schollmayer","sequence":"additional","affiliation":[{"name":"Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Sandering 2, 97074 Wuerzburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lorenz","family":"Meinel","sequence":"additional","affiliation":[{"name":"Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Sandering 2, 97074 Wuerzburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0364-7278","authenticated-orcid":false,"given":"Ulrike","family":"Holzgrabe","sequence":"additional","affiliation":[{"name":"Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Sandering 2, 97074 Wuerzburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,8,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Hoffman, P.S. 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