Identification and Biological Activities of the Phenolic Compounds in Eisenia arborea

Four polyphenols were isolated and purified from a brown alga Eisenia arborea. These phlorotannin compounds showed strong radical scavenging and some enzyme inhibitory activities. All of the compounds showed strong antioxidative, acetylcholinesterase and butyrylcholinesterase inhibitory, and tyrosinase inhbibitory activities at 100 μg/mL. Dieckol and PFF inhibited butyrylcholinesterase, a new target for the treatment of Alzheimer’s disease, very strongly even at 10 μg/mL, more strongly than AChE. These two compounds also effectively inhibited tyrosinase. These results support the potential of developing natural antioxidants and antidementia agents from the brown alga.