Anti type I allergic property of Japanese butterbur extract and its mast cell degranulation inhibitory ingredients

Pollenosis is a disease that affects 1 in 10 of the Japanese population. During the season of cedar pollen dispersal, many patients suffer from symptoms such as sniffling, sternutation, and itching of the eyes. Japanese butterbur is a popular vegetable and is one of the few domestic vegetables in Japan. The anti type I allergic effects of an aqueous ethanol extract from aerial parts of Japanese butterbur (JBE) were evaluated in rats and RBL-2H3 mast cells. In the passive cutaneous anaphylaxis reaction in rats, a single oral treatment of JIBE (1000 mg/kg) was found to suppress the reaction. In IgE-sensitized RIBL-2H3 cells, JIBE (10-100 mu g/mL inhibited P-hexosaminidase release, leukotriene C-4/D-4/E-4 synthesis, and TNF-alpha production. Moreover, a high concentration of JBE (1000 mu g/mL) suppressed smooth muscle constriction induced by histamine (10 mu M) and leukotriene D-4 (10 nM) in a guinea pig trachea strip. The search for components in JBE with an inhibitory activity on mast cell degranulation was guided by inhibition of fl-hexsosaminidase release. Two eremophilane-type sesquiterpenes, six polyphenolic compounds, and two triterpene glycosides were isolated. Of these compounds, fukinolic acid, a principal polyphenol constituent, showed potent inhibitory activity (IC50 value = 2.1 mu g/mL). Consequently, On the basis of its inhibition of mast cell activation and direct smooth muscle reaction induced by released mediators, JBE was found to suppress the type I allergic reaction.