In vitro antibacterial activity and synergistic antibiotic effects of phlorotannins isolated from Eisenia bicyclis against methicillin-resistant Staphylococcus aureus

Phytother Res. 2013 Aug;27(8):1260-4. doi: 10.1002/ptr.4851. Epub 2012 Oct 8.


Six phlorotannins, isolated from Eisenia bicyclis, were evaluated for antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentrations (MIC) of the compounds were in the range 32 to 64 µg/mL. Phlorofucofuroeckol-A (PFF) exhibited the highest anti-MRSA activity, with an MIC of 32 µg/mL. An investigation of the interaction between these compounds and the β-lactam antibiotics ampicillin, penicillin, and oxacillin revealed synergistic action against MRSA in combination with compound PFF. To our knowledge, this is the first report on the anti-MRSA activity of phlorotannins from E. bicyclis. The results obtained in this study suggest that the compounds derived from E. bicyclis can be a good source of natural antibacterial agents against MRSA.

Keywords: Eisenia bicyclis; antibacterial activity; methicillin-resistant Staphylococcus aureus; phlorotannins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ampicillin / pharmacology
  • Animals
  • Anti-Bacterial Agents / isolation & purification
  • Anti-Bacterial Agents / pharmacology*
  • Benzofurans / isolation & purification
  • Benzofurans / pharmacology*
  • Dioxins / isolation & purification
  • Dioxins / pharmacology*
  • Drug Synergism
  • Methicillin-Resistant Staphylococcus aureus / drug effects*
  • Microbial Sensitivity Tests
  • Oxacillin / pharmacology
  • Penicillins / pharmacology
  • Phaeophyceae / chemistry*
  • Tannins / isolation & purification
  • Tannins / pharmacology*


  • Anti-Bacterial Agents
  • Benzofurans
  • Dioxins
  • Penicillins
  • Tannins
  • phlorofucofuroeckol A
  • Ampicillin
  • Oxacillin