Eupatilin Blocks Mediator Release Via Tyrosine Kinase Inhibition in Activated Guinea Pig Lung Mast Cells

Eupatilin, an extract from Artemisia asiatica Nakai, is known to exert anti-gastric ulcer, anticancer, and anti-inflammatory effects. The aim of this study was to elucidate whether eupatilin has antiallergic reactions in activated guinea pig lung mast cells compared to apigenin and genistein. Mast cells were purified from guinea pig lung tissues by using enzyme digestion and rough and discontinuous density Percoll gradient. The purified mast cells were sensitized with immunoglobulin (Ig) G 1 (anti-OVA antibody) and challenged with ovalbumin (OVA). Histamine was assayed using an automated fluorometric analyzer, leukotrienes by radioimmunoassay, and tyrosine phosphorylation by immunoblotting. Intracellular Ca 2+ was analyzed by confocal laser scanning microscopy, protein kinase C (PKC) activity using protein phosphorylated with [γ- 32 P]ATP, and phopholipase D activity (PLD) and phosphatidic acid by using labeled phosphatidyl alcohol. Eupatilin, apigenin, or genistein reduced histamine release and leukotriene synthesis in a does-dependent manner. Eupatilin inhibited mediators to a greater extent than apigenin or genistein. Eupatilin, apigenin, and genistein initially blocked phosphorylation of Syk tyrosine and Ca 2+ influx, PLD activity, phosphatidic acid, and Ca 2+ -dependent PKC α/βII activities during mast cell activation in a dose-dependent manner. Our data suggest that eupatilin initially inhibits Syk kinase, and then blocks downstream multisignal pathways and Ca 2+ influx during mast cell activation triggered by a specific antigen–antibody reaction. Thus, eupatilin may have use clinically as a treatment for inflammatory disorders associated with allergic diseases including asthma.