In this study, the inhibitory activities of fifty plant extracts on IgE-mediated degranulation in the rat basophilic leukemia cell line (RBL-2H3 cells) were measured; the release of interleukin (IL)-4 and β-hexosaminidase from IgE-sensitized cells treated with the plant extracts was measured; and the effects of the plant extracts on cell viability were tested. The results of the analysis of plant extracts at 20 ㎍/㎖, including the aerial part of Magnolia sieboldii K. Koch, exhibited suppressive activities upon the release of IL-4. Furthermore, several plant extracts including methanol extracted from Lindera erythrocarpa Makino (aerial part) at the same concentration significantly inhibited the release of β-hexosaminidase. Twenty-six of the plant extracts, including methanol extract of Weigela subsessilis (Nakai) L. H. Bailey (branch), showed a cell proliferation effect of over 80% at 100 ㎍/㎖. In conclusion, the results suggest that the leaf/stem of Geum japonicum Thunb. and the stamen/ovary of Nelumbo nucifera Gaertn., which exhibited effective inhibition on β-hexosaminidase release and IL-4 release from mast cells and showed high cell viability, could be useful candidates as anti-allergy materials.

Alpiniae officinarum Rhizoma (the rhizome of Alpinia officinarum Hance, known as lesser galangal), a family of Zingiberaceae, has been used to reduce pain of infection and inflammatory diseases in Asian countries. The present study was focused to evaluate the inhibitory degranulation effect of Alpiniae officinarum Rhizoma extract in RBL-2H3 rat basophilic leukemia cells. Cell viability was measured by MTT assay. RBL-2H3 cells were stimulated by phorbol 12-myristate 13-acetate and calcium ionophore A23187. Mast cell degranulation was analyzed by measuring release of β -hexosaminidase in RBL-2H3 cell. Gene expression was measured by qRT-PCR and signaling molecules were detected by immunoblotting. The Alpiniae officinarum Rhizoma extract suppressed β-hexosaminidase release in dose-dependent manner and inhibited cycloxygenase-2 and tumor necrosis factor-α gene expression. Furthermore, it was found that Alpiniae officinarum Rhizoma extract reduced mitogen-activated protein kinases, especially phosphorylated p38, at 0.75 ㎎/㎖ of Alpiniae officinarum Rhizoma extract concentrations. These data show that Alpiniae officinarum Rhizoma extract has immunosuppressive effect in mast cell induced allergic inflammation.

The marine carotenoid fucoxanthin can be found in marine brown seaweeds, macroalgae, diatoms, and microalgae, and has remarkable biological properties. Numerous studies have shown that fucoxanthin has considerable potential and promising applications in human health, but the underlying mechanisms involved in its anti-allergic activity are not fully understood. We here investigated the mechanisms by anti-allergic activity of fucoxanthin fraction from Eisenia bicyclis in immunoglobulin E-antigen complex (IgE/DNP-BSA)-stimulated RBL-2H3 mast cells. This study we found that the fucoxanthin inhibits the release of β-hexosaminidase and suppressed not only transcriptional activation of NF-kB, but also phosphorylation of ERK and JNK in IgE/DNP-BSA-treated RBL-2H3 cells. Fucoxanthin may be useful for preventing allergic diseases, including asthma and atopic dermatitis.