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In Vitro Antibacterial Activity and Synergistic Antibiotic Effects of Phlorotannins Isolated from Eisenia bicyclis Against Methicillin-Resistant Staphylococcus aureus


Correspondence to: Young-Mog Kim, Department of Food Science and Technology, Pukyong National University, Busan 608-737, Republic of Korea.



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. Copyright © 2012 John Wiley & Sons, Ltd.