Anti-allergic phlorotannins from the edible brown alga, Eisenia arborea

Elsenia arborea, an edible brown alga, is occasionally used as a folk medicine due to its anti-allergic effect. In the present study to identify the anti-allergic constituents in the alga, the extract of the alga was purified by partition between solvents and by reversed phase chromatography. Separation of the extract was guided by the inhibitory activity upon beta-hexosaminidase release from the rat basophilic leukemia-2H3 cells. HPLC purification afforded six active compounds. Spectral analyses clarified their structures as eckol, 6,6'-bieckol, 6,8'-bieckol, 8,8'-bieckol, phlorofucofuroeckol-A, and phlorofucofuroeckol-B. Most of the phlorotannins exhibited activities similar to or greater than the typical inhibitor, epigallocatechin gallate. Phlorofucofuroeckol-B showed the greatest activity among the tested phlorotannins at 2.8 times greater than epigallocatechin gallate.