Enzyme-treated date plum leave extract ameliorates atopic dermatitis-like skin lesion in hairless mice

Objective: To evaluate the effect of different extracts of Diospyros lotus leaves in atopic dermatitis Methods: Diospyros lotus leaves were extracted in ethanol and treated with or without hydrochloric acid or α-rhamnosidase to obtain three different extracts-ethanol, acid-hydrolyzed, and enzyme-hydrolyzed leaf extracts of date plum. The myricitrin content in all samples was measured using HPLC analysis. In vitro antioxidant and anti-inflammatory activities of the extracts were determined by measuring DPPH radical scavenging activities and nitric oxide production in RAW264.7 cells, respectively. Sevenweek-old male hairless mice were used to evaluate the anti-atopic dermatitis effects of three extracts in vivo. Splenocytes and mast cells were used to further determine the anti-atopic dermatitis effects of the major compound in the ethanol leaf extract.Results: Enzyme-hydrolyzed leaf extract showed significant in vitro antioxidant and anti-inflammatory activities, and attenuated atopic dermatitis-like skin symptoms and clinical signs more significantly than ethanol and acid-hydrolyzed leaf extracts in 1-fluoro-2,4-dinitrobenzene and house dust mite antigen-treated hairless mice. Enzyme-hydrolyzed leaf extract also suppressed the serum level of immunoglobulin E, interleukin(IL)-4, tumor necrosis factor(TNF)-α, interferon(IFN)-γ, thymic stromal lymphopoietin, and thymus and activation-regulated chemokine in mice with atopic dermatitis. Furthermore, histological analysis revealed that enzymehydrolyzed leaf extract suppressed the increased epidermal thickness, dermal infiltration of inflammatory cells, and infiltration and degranulation of mast cells more markedly than the other two extracts in atopic dermatitis-like skin lesions. In addition, this extract effectively inhibited the production of IFN-γ, IL-4, and thymus and activation-regulated chemokine compared with the other two extracts in concanavalin A-stimulated splenocytes. Myricitrin, a major compound of enzyme-hydrolyzed leaf extract, suppressed atopic dermatitis biomarkers in stimulated mouse splenocytes andHMC-1 human mast cells. Conclusions: These results suggest that enzyme-hydrolyzed leaf extract might be a potential candidate to treat atopic dermatitis.