Eckol from Ecklonia cava Suppresses Immunoglobulin E-mediated Mast Cell Activation and Passive Cutaneous Anaphylaxis in Mice (Running Title: Anti-Allergic Activity of Ecklonia cava).

Eckol, a precursor compound belonging to the dibenzo-1,4-dioxin class of phlorotannins, is a phloroglucinol derivative that exerts various activities. In the present study, we investigated the antiallergic effects of eckol isolated from the marine brown algae, Ecklonia cava using immunoglobulin E (IgE)/bovine serum albumin (BSA)-stimulated mouse bone marrow-derived cultured mast cells (BMCMC) and a mouse model of anaphylaxis. Eckol inhibited IgE/BSA-induced BMCMC degranulation by reducing β-hexosaminidase release. A flow cytometric analysis revealed that eckol decreases FceRI expression on cell surface and IgE binding to the FceRI in BMCMC. Moreover, eckol suppressed the production of the cytokines, interleukin (IL)-4, IL-5, IL-6, and IL-13 and the chemokine, thymus activation-regulated chemokine (TARC) by downregulating, IκB-α degradation and NF-κB nuclear translocation. Furthermore, it attenuated the passive cutaneous anaphylactic reaction induced by IgE/BSA-stimulation in the ear of BALB/c mice. These results suggest that eckol is a potential therapeutic candidate for the prevention and treatment of allergic disorders.