Saikosaponin-d inhibits β-conglycinin induced activation of rat basophilic leukemia-2H3 cells.

β-Conglycinin is one of the major storage proteins in soybean and has been identified as a potential diagnostic marker for severe allergic reactions to soybean. Unfortunately, there is a lack of information on the signal transduction pathways of β-conglycinin induced mast cell activation and how to alleviate these allergic reactions. Bupleurum falcatum, a traditional oriental medicine, has been widely utilized in the treatment of influenza, fever, malaria and menstrual disorders. Furthermore, it has been reported that saikosaponins, the important principle of B. falcatum, possesses anti-allergic activities. Therefore, the present study investigated whether or not saikosaponin-d, an extract of B. falcatum, was effective in the treatment of allergic reactions cased by β-conglycinin, using a rat basophilic leukemia-2H3 cell line. There were multiple signaling pathways contributing to the development of β-conglycinin-mediated rat basophilic leukemia-2H3 cell activation. The intracellular calcium mobilization and tyrosine phosphorylation were early events, which in turn elicited reactive oxygen species production, gene activation of Cdc42 and c-Fos, and ultimately led to β-hexosaminidase release. Saikosaponin-d inhibited rat basophilic leukemia-2H3 cell degranulation by suppressing these critical incidents in the signal transduction pathway. These results suggest that saikosaponin-d exhibited anti-allergic activity and could become an effective herbal therapy for alleviating soybean allergy.