{
  "abstract": "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—hot ethanol, cold ethanol, espresso/steam, hot water, and cold water—applied to four hop varieties (Citra, Lubelski, Magnat and Marynka), with a commercial supercritical CO2 extract as a reference preparation. We characterized extracts by HPLC (α-acids, β-acids, iso-α-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 ≤ 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 (0.125–0.250 mg/mL) and against clinical MRSA (as low as 0.016 mg/mL), compared with 1.0–15.0 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 α-acid content as the dominant predictor of antibacterial activity (ρ = −0.927, p < 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.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Fermentation and Cereals Technology, Faculty of Biotechnology and Food Science, Wroclaw University of Environmental and Life Sciences, Chełmońskiego 37 Street, 51-630 Wroclaw, Poland",
    "Department of Biology and Medical Parasitology, Faculty of Medicine, Wroclaw Medical University, Mikulicza-Radeckiego 9, 50-345 Wroclaw, Poland",
    "Department of Pharmacognosy and Herbal Medicines, Wroclaw Medical University, Borowska 211a, 50-556 Wroclaw, Poland"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Przemysław Leszczyński",
      "orcid": "0000-0002-4181-4997"
    },
    {
      "affs": [
        1
      ],
      "name": "Dorota Wojnicz",
      "orcid": "0000-0003-1972-1548"
    },
    {
      "affs": [
        1
      ],
      "name": "Dorota Tichaczek-Goska",
      "orcid": "0000-0002-8540-0876"
    },
    {
      "affs": [
        2
      ],
      "name": "Michał Gleńsk",
      "orcid": "0000-0002-3731-4631"
    },
    {
      "affs": [
        0
      ],
      "name": "Alan Gasiński",
      "orcid": "0000-0002-4614-7177"
    },
    {
      "affs": [
        0
      ],
      "name": "Joanna Kawa-Rygielska"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fwt3djtj2bywp.bib",
  "cited_by": 0,
  "doi": "10.3390/ijms27188364",
  "fulltext_url": null,
  "id": "fwt3djtj2bywp",
  "issns": [
    "1422-0067"
  ],
  "landing_url": "https://www.mdpi.com/1422-0067/27/18/8364",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3004|Hops Chemistry and Applications"
    ]
  ],
  "openalex": "W7214508123",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-19",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/fwt3djtj2bywp.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:55Z",
      "native_id": "10.3390/ijms27188364",
      "source": "crossref",
      "url": "https://www.mdpi.com/1422-0067/27/18/8364"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:3004|Hops Chemistry and Applications",
      "subfield": "pharmacology-toxicology"
    }
  ],
  "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",
  "title_text": "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",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:55Z",
  "url": "https://research.draconitic.com/paper/fwt3djtj2bywp",
  "venue": "International Journal of Molecular Sciences",
  "versions": []
}