Effects of magnolialide isolated from the leaves of Laurus nobilis L. (Lauraceae) on immunoglobulin E-mediated type I hypersensitivity in vitro

Ethnopharmacological relevance: Laurus nobilis L (Lauraceae) has been used for folk medicines in the Mediterranean area and Europe to treat various disorders including skin inflammation (dermatitis) and asthma. Aim of the study: Our aim was to investigate the scientific evaluation of the compounds from Laurus nobilis L on immuniglobulin E (IgE)-mediated type I hypersensitivity responses in vitro such as atopic dermatitis and asthma. Methods and materials: Seven compounds were isolated and examined for the mast cell stabilizing effect on IgE-sensitized RBL-2H3 mast cells by measuring the beta-hexosaminidase activity. In addition, the effects on interleukin (IL)-4 production and IL-5-dependent Y16 early B cell proliferation were investigated as well as their cytotoxic effects on RBL-2H3 cells. Results: Among the seven isolated compounds, magnolialide attenuated the release of beta-hexosaminidase from RBL-2H3 cells with an IC50 value of 20.2 mu M, while the other compounds revealed no significant effects at concentrations tested. Furthermore, magnolialide significantly inhibited the IL-4 release with an IC50 value of 18.1 mu M and IL-4 mRNA expression with an IC50 value of 15.7 mu M in IgE-sensitized RBL-2H3 cells. In addition, the inhibition of IL-5-dependent proliferation of early B cells (Y16 cells) by magnolialide was demonstrated with an IC50 value of 18.4 mu M. Conclusion: These results suggest that the magnolialide might be a candidate for the treatment of IgE-mediated hypersensitivity responses such as atopic dermatitis and asthma by inhibiting mast cell degranulation, the IL-4 production, and IL-5-dependent early B cell proliferation, key factors in the development and amplification of type I hypersensitivity reactions. (C) 2013 Elsevier Ireland Ltd. All rights reserved.