{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T14:58:23Z","timestamp":1790866703250,"version":"4.1.0"},"reference-count":39,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,19]],"date-time":"2026-09-19T00:00:00Z","timestamp":1789776000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100016247","name":"Wroc\u0142aw University of Environmental and Life Sciences","doi-asserted-by":"publisher","award":["N060\/0009\/24\/FWBN"],"award-info":[{"award-number":["N060\/0009\/24\/FWBN"]}],"id":[{"id":"10.13039\/100016247","id-type":"DOI","asserted-by":"publisher"}]},{"award":["N060\/0009\/24\/FWBN"],"award-info":[{"award-number":["N060\/0009\/24\/FWBN"]}],"id":[{"id":"https:\/\/ror.org\/05cs8k179","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100009687","name":"Polish Ministry of Health subvention","doi-asserted-by":"publisher","award":["SUBZ.A060.26.072"],"award-info":[{"award-number":["SUBZ.A060.26.072"]}],"id":[{"id":"10.13039\/501100009687","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Int. J. Mol. Sci.","IJMS"],"abstract":"<jats:p>Optimizing hop (Humulus lupulus L.) extraction protocols for maximum antibacterial efficacy remains an open methodological challenge in developing plant-based natural antimicrobials. We compared five extraction protocols\u2014hot ethanol, cold ethanol, espresso\/steam, hot water, and cold water\u2014applied to four hop varieties (Citra, Lubelski, Magnat and Marynka), with a commercial supercritical CO2 extract as a reference preparation. We characterized extracts by HPLC (\u03b1-acids, \u03b2-acids, iso-\u03b1-acids) and GC-MS (volatile profile of cold ethanol extracts) and determined antibacterial activity as minimum inhibitory concentration (MIC) against reference and clinically relevant multidrug-resistant (MDR) strains of Escherichia coli and Staphylococcus aureus. Friedman tests confirmed a statistically significant effect of extraction method on MIC values (p \u2264 0.004 for E. coli ATCC 25922, S. aureus ATCC 29213, and clinical MRSA). Ethanol-based protocols consistently produced the highest hop acid concentrations and the lowest MICs against S. aureus ATCC 29213 (0.125\u20130.250 mg\/mL) and against clinical MRSA (as low as 0.016 mg\/mL), compared with 1.0\u201315.0 mg\/mL for aqueous and steam-based extracts. Clinical MRSA demonstrated increased susceptibility to selected ethanol extracts and to the CO2 reference. MDR uropathogenic E. coli (UPEC) maintained high-level resistance (MIC 15 mg\/mL) to all preparations except the CO2 reference (MIC 6 mg\/mL). Spearman correlation identified \u03b1-acid content as the dominant predictor of antibacterial activity (\u03c1 = \u22120.927, p &lt; 0.001 for S. aureus ATCC 29213). These results suggest ethanol-based and supercritical CO2 extraction as optimal protocols for producing hop extracts with antibacterial properties targeting Gram-positive pathogens, including MRSA, and provide a rationale for their use as natural antimicrobials.<\/jats:p>","DOI":"10.3390\/ijms27188364","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T14:23:56Z","timestamp":1790864636000},"page":"8364","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Determinants of Antibacterial Activity in Humulus lupulus Hop Extracts: Phytochemical Profiling of Prenylated Acylphloroglucinols and Efficacy Against Methicillin-Resistant Staphylococcus aureus and Multidrug-Resistant Uropathogenic Escherichia coli"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4181-4997","authenticated-orcid":false,"given":"Przemys\u0142aw","family":"Leszczy\u0144ski","sequence":"first","affiliation":[{"name":"Department of Fermentation and Cereals Technology, Faculty of Biotechnology and Food Science, Wroclaw University of Environmental and Life Sciences, Che\u0142mo\u0144skiego 37 Street, 51-630 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1972-1548","authenticated-orcid":false,"given":"Dorota","family":"Wojnicz","sequence":"additional","affiliation":[{"name":"Department of Biology and Medical Parasitology, Faculty of Medicine, Wroclaw Medical University, Mikulicza-Radeckiego 9, 50-345 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8540-0876","authenticated-orcid":false,"given":"Dorota","family":"Tichaczek-Goska","sequence":"additional","affiliation":[{"name":"Department of Biology and Medical Parasitology, Faculty of Medicine, Wroclaw Medical University, Mikulicza-Radeckiego 9, 50-345 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3731-4631","authenticated-orcid":false,"given":"Micha\u0142","family":"Gle\u0144sk","sequence":"additional","affiliation":[{"name":"Department of Pharmacognosy and Herbal Medicines, Wroclaw Medical University, Borowska 211a, 50-556 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"resources","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4614-7177","authenticated-orcid":false,"given":"Alan","family":"Gasi\u0144ski","sequence":"additional","affiliation":[{"name":"Department of Fermentation and Cereals Technology, Faculty of Biotechnology and Food Science, Wroclaw University of Environmental and Life Sciences, Che\u0142mo\u0144skiego 37 Street, 51-630 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"}]},{"given":"Joanna","family":"Kawa-Rygielska","sequence":"additional","affiliation":[{"name":"Department of Fermentation and Cereals Technology, Faculty of Biotechnology and Food Science, Wroclaw University of Environmental and Life Sciences, Che\u0142mo\u0144skiego 37 Street, 51-630 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"629","DOI":"10.1016\/S0140-6736(21)02724-0","article-title":"Global Burden of Bacterial Antimicrobial Resistance in 2019: A Systematic Analysis","volume":"399","author":"Murray","year":"2022","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1038\/s41573-020-00114-z","article-title":"Natural Products in Drug Discovery: Advances and Opportunities","volume":"20","author":"Atanasov","year":"2021","journal-title":"Nat. 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