Anti-allergic and anti-inflammatory effects of bakkenolide B isolated from Petasites japonicas leaves

Aims of the study: To elucidate the anti-allergic and anti-inflammatory effects of Petasites genus, we studied the effects of several compounds isolated from Petasites japonicas leaves. Materials and methods: Bakkenolide B was isolated from Petasites japonicus leaves. Antigen-induced degranulation was measured in RBL-2H3 mast cells by measuring beta-hexosamidase activity. Induction of inducible nitric oxide synthase and cyclooxygenase 2 was measured by Western blotting in peritoneal macrophages. Ovalbumin-induced asthma model was used for in vivo efficacy test of bakkanolide B. Results: We found that bakkenolide B, a major component of the leaves, concentration-dependently inhibited RBL-2H3 mast cell degranulation. Bakkenolide B also inhibited the gene inductions of inducible nitric oxide synthase and cyclooxygenase 2 in mouse peritoneal macrophages. Furthermore, in an ovalbumin-induced asthma model, bakkenolide B strongly inhibited the accumulation of eosinophils, macrophages, and lymphocytes to bronchoalveolar lavage fluid. Conclusion: Bakkenolide B has suppressive properties for allergic and inflammatory responses and may be utilized as a potent agent for the treatment of asthma. (C) 2013 Published by Elsevier Ireland Ltd.