Citreorosein inhibits degranulation and leukotriene C4 generation through suppression of Syk pathway in mast cells

The aim of this study was to evaluate whether citreorosein (CIT), a naturally occurring anthraquinone isolated from Polygoni cuspidati (P. cuspidati) radix, modulates degranulation and 5-lipoxygenase (5-LO)-dependent leukotriene C(4) (LTC(4)) generation in mast cells. Cit suppresses both degranulation and the generation of LTC(4) in a dose-dependent manner in stem cell factor (SCF)-mediated mouse bone marrow-derived mast cells (BMMCs). With regard to its molecular mechanism of action, we investigated the effects of CIT on intracellular signaling and mast cell activation employing BMMCs. Binding of SCF to c-Kit on mast cell membranes induced increases in intrinsic tyrosine kinase Syk activity and activation of multiple downstream events including phosphorylation of phospholipase Cγ (PLCγ), mobilization of intracellular Ca(2+), phosphatidylinositol 3-kinase (PI3K), Akt, MAP kinases (MAPKs), translocation of phospho-phospholipase A(2) (PLA(2)) and 5-LO. The results from the biochemical analysis demonstrate that CIT attenuates degranulation and LTC(4) generation through the suppression of multiple step signaling and would be beneficial for the prevention of allergic inflammation.