The inhibitory effects of components from a brown alga, Eisenia arborea, on degranulation of mast cells and eicosanoid synthesis

The anti-allergic effect of an edible brown alga, Eisenia arborea, was investigated by determining the anti-degranulation activity on RBL cells or KU812 cells and the inhibitory effects on enzymatic activities involved in eicosanoid (leukotoriene and prostaglandin) synthesis. When the stimulated cells were treated with a M/C (methanol:chloroform = 1:2, v/v) extract of the alga, the histamine release of the cells was suppressed in a dose-dependent manner, and eicosanoid release from the cells was also strongly inhibited. Furthermore, the M/C extract and six phlorotannins (eckol, 6,6′-bieckol, 6,8′-bieckol, 8,8′-bieckol, phlorofucofuroeckol-A, phlorofucofuroeckol-B) derived from the extract inhibited enzymatic activities responsible for eicosanoid synthesis. This is the first report of the enzymatic activity inhibition by the phlorotannins 6,6′-bieckol, 6,8′-bieckol and PFF-B. Since histamine and eicosanoids are known to mediate the allergic reaction, inhibition of these mediators and enzymatic activities could be responsible for the anti-allergic effect of the alga.