Forsythia suspensa fruit extracts and the constituent matairesinol confer anti-allergic effects in an allergic dermatitis mouse model

Forsythia suspensa is used in traditional medicine to treat inflammation. To clarify the anti-inflammatory and anti-allergic effects of F. suspensa fruits, we determined the therapeutic effects of crude extract, fractions, and a constituent from F. suspensa fruits on a murine atopic dermatitis (AD) model. We investigated the inhibitory effects of F. suspensa extract (FSE), extract fractions, and the constituent matairesinol on histamine release from MC/9 mast cells activated by compound 48/80 and the development of AD-like skin lesions and symptoms in NC/Nga mice exposed to Dermatophagoides farinae (mite) extract. High performance liquid chromatography (HPLC) analysis of FSE and its fractions were evaluated using matairesinol standard. FSE, FSE methylene chloride fraction (FSE-MC), and FSE water fraction (FSE-water) inhibited compound 48/80-induced histamine release from MC/9 mast cells. Topical application of FSE or FSE-MC to NC/Nga mice exposed to Dermatophagoides farinae suppressed the development of AD-like skin lesions. Quantitative HPLC analysis of FSE and FSE-MC identified the presence of matairesinol. Topical application of matairesinol to NC/Nga mice effectively reduced AD symptoms, inhibited inflammatory cell infiltration, and lowered immunoglobulin E levels in serum. Further study demonstrated that DfE-induced changes in IL-4 and IFN-γ mRNA expression in the ears of NC/Nga mice were reversed by matairesinol application. These results indicate that the F. suspensa and its constituent matairesinol might be a therapeutic candidate for treating allergic inflammatory disorders such as AD.