Suppressive effects of the diethyl ether fraction from a brown alga Sargassum fusiforme on allergic and inflammatory reactions

This study investigated the anti-allergic effect of a diethyl ether fraction from dried Sargassum fusiforme. In vivo experiments showed that percutaneous administration of this fraction suppressed mouse ear swelling induced by three types of sensitizers (arachidonic acid, 12-O-tetradecanoylphorbol-13-acetate and oxazolone). At a dose of 0.1 mg/mouse, the suppression ratios were from 47 to 61 %. Oral administration of the fraction also suppressed mouse ear swelling. At a dose of 1 mg/mouse, the suppression ratios were from 69 to 92 % which were comparable to those obtained by the typical natural inhibitor, epigallocatechin gallate (EGCG). In vitro experiments were performed to elucidate the inhibitory effects of the fraction on the enzymatic activities (phospholipase A2, cyclooxygenase-2, lipoxygenase and hyaluronidase) involved in inflammation and degranulation in rat basophilic leukemia (RBL)-2H3 cells to understand the mechanism that underlies the suppression of mouse ear swelling. Similar to EGCG, the fraction inhibited the enzymatic activities tested and suppressed degranulation in RBL cells in a dose-dependent manner. Therefore, the active components present in this S. fusiforme fraction achieve the anti-inflammatory effects by inhibiting the enzymatic activities and degranulation in the ear of mice. Thus, S. fusiforme and its diethyl ether fraction could be useful ingredients in functional foods.