ABSTRACT
Lobelia chinensis Lour. has commonly been used in traditional Chinese medicine for the treatment of antidote, diuretic, diarrhea, and inflammation. This study aimed to identify the active compounds in an aqueous extract of L. chinensis responsible for its anti-atopic effect in vitro using RBL-2H3 cells. A chemical investigation of secondary metabolites in an aqueous extract of L. chinensis led to the isolation of nine chemical constituents, which included the four marker compounds, and these were evaluated for their inhibitory effects on IL-4 mRNA expression and the release of β-hexosaminidase in propidium iodide-induced RBL-2H3 cells. We found diosmetin and fraxidin inhibited cellular IL-4 mRNA expression, and that diosmetin and 6,8-dimethoxycoumarin inhibited DNP-specific IgE-induced degranulation in these cells. Our study suggests that diosmetin, fraxidin, and 6,8-dimethoxycoumarin are potential candidates for the treatment of atopic diseases.
ABSTRACT
The rhizomes of Dioscorea japonica Thunb. are widely consumed as food and also used to treat diabetes and polyuria in Korea. This study was undertaken to study the anti-atopic dermatitis effects of a 95% ethanolic extract (DJE) of D. japonica in an oxazolone-stimulated murine model of atopic dermatitis (AD). The therapeutic effects of DJE on AD-like skin lesions were assessed on both ears. DJE (1%) or dexamethasone (0.5%; the positive control) were applied to skin lesions for three weeks. Serum levels of IgE and IL-4 were assessed by ELISA (enzyme-linked immunosorbent assay). Histopathological examinations were performed by hematoxylin and eosin (H&E) and toluidine blue staining and revealed DJE significantly reduced dermal thickness and inflammatory cell infiltration when applied to oxazolone-treated ear skin. DJE-treated AD mice also showed lower serum levels of IgE and IL-4 than oxazolone-stimulated controls. Our findings demonstrate DJE might be a useful safe, topical agent for the treatment of atopic diseases.