Hop Extract Acts as an Antioxidant with Antimicrobial Effects against Propionibacterium Acnes and Staphylococcus Aureus

Molecules. 2019 Jan 9;24(2):223. doi: 10.3390/molecules24020223.


Acne is associated with hyperkeratosis, elevated levels of skin sebum and growth of Propionibacterium acnes (P. acnes) and Staphylococcus aureus (S. aureus). Furthermore, P. acnes promotes inflammation by inducing IL-6 production and oxidative stress. The aim of this study was to assess the antioxidant, anti-inflammatory and antibacterial potential of a hop-CO₂-extract with 50% humulone and lupulone. The susceptibility of P. acnes and S. aureus to the hop extract was tested by using the broth microdilution technique. The minimal inhibitory concentrations (MIC) for P. acnes and S. aureus were 3.1 and 9.4 µg/mL, respectively. In addition, the hop extract showed an antioxidative effect with a half maximal inhibitory concentration (IC50) of 29.43 µg/mL as well as additional anti-inflammatory effects by reducing the IL-6 expression (IC50: 0.8 µg/mL). In addition, a gel formulation with 0.3% hop extract (w/w) had antibacterial activity against P. acnes and S. aureus (inhibition zone value: 5.5 mm and 3 mm, respectively) which was significantly superior to the placebo gel. The positive control (a gel with the antibiotic clindamycin) showed an inhibition zone of 9 mm. Due to its antioxidant, anti-inflammatory and antibacterial effects hop extract might be a treatment option for acne-prone skin.

Keywords: P. acnes; S. aureus; acne; antimicrobial activity; antioxidant activity; hop extract.

MeSH terms

  • Acne Vulgaris / drug therapy
  • Acne Vulgaris / metabolism
  • Acne Vulgaris / microbiology
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology*
  • Antioxidants / chemistry
  • Antioxidants / pharmacology*
  • Cells, Cultured
  • Humans
  • Humulus / chemistry*
  • Interleukin-6 / metabolism
  • Keratinocytes / cytology
  • Keratinocytes / drug effects
  • Keratinocytes / microbiology
  • Microbial Sensitivity Tests
  • Plant Extracts / chemistry
  • Plant Extracts / pharmacology*
  • Propionibacterium acnes / drug effects*
  • Reactive Oxygen Species / metabolism
  • Staphylococcus aureus / drug effects*
  • Staphylococcus aureus / metabolism


  • Anti-Bacterial Agents
  • Antioxidants
  • IL6 protein, human
  • Interleukin-6
  • Plant Extracts
  • Reactive Oxygen Species