Suppressive effect of tamarixetin, isolated from Inula japonica, on degranulation and eicosanoid production in bone marrow-derived mast cells.

Abstract

The aim of this study was to evaluate the inhibitory effect of tamarixetin on the production of inflammatory mediators in IgE/antigen-induced mouse bone marrow-derived mast cells (BMMCs). The effects of tamarixetin on mast cell activation were investigated with regard to degranulation, eicosanoid generation, Ca2+ influx, and immunoblotting of various signaling molecules. Tamarixetin effectively decreased degranulation and the eicosanoid generation such as leukotriene C4 and prostaglandin D2 in BMMCs. To elucidate the mechanism involved, we investigated the effect of tamarixetin on the phosphorylation of signal molecules. Tamarixetin inhibited the phosphorylation of Akt and its downstream signal molecules including IKK and nuclear factor κB. In addition, tamarixetin downregulated the phosphorylation of cytosolic phospholipase A2 (cPLA2) and p38 mitogen-activated protein kinase. Taken together, this study suggests that tamarixetin inhibits degranulation and eicosanoid generation through the PLCγ1 as well as Akt pathways in BMMCs, which would be potential for the prevention of allergic inflammatory diseases.