Inhibitory Effects of Costunolide Isolated from Laurus nobilis on IgE-induced Degranulation of Mast Cell-like RBL-2H3 Cells and the Growth of Y16 pro-B Cells

This study investigated the inhibitory effects of costunolide isolated from the leaves of Laurus nobilis L. (Lauraceae) on basophil-mediated allergic reactions and interleukin (IL)-5-mediated B cell growth. The effects of costunolide on beta-hexosaminidase (a key parameter of degranulation) release and IL-4 expression in rat basophilic leukemia (RBL-2H3) cells were determined by measuring beta-hexosaminidase activity and by semi-quantitative RT-PCR, respectively. The effects of costunolide on Y16 pro-B cell viability and growth were determined by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay. Costunolide was found significantly to inhibit beta-hexosaminidase activity (p<0.01) and IL-4 transcription in RBL-2H3 cells in a dose-dependent manner. Its 50% inhibitory concentration (IC50) was 34 mu m, while that of the positive control, ketotifen, was 24 mu m (IL-4 mRNA transcription). Moreover, costunolide dose-dependently suppressed pro-B cell growth in IL-5-stimulated Y16 cells. These results provide evidence that costunolide stabilizes mast cells by inhibiting IgE-mediated degranulation and inhibits IL-5-stimulated B cell growth. Copyright (C) 2011 John Wiley & Sons, Ltd.