Forsythia fructus inhibits the mast-cell-mediated allergic inflammatory reactions

Mast cells are key as effector cells in the early phase allergic inflammation and in diverse immunological and pathological processes. Forsythia fructus (F. fructus) has used as a traditional medicine for inflammatory diseases. In the present study, we determined the effect of F. fructus extracts on compound 48/80-induced paw oedema and vascular permeability in vivo. In addition, we investigated in vitro whether F. fructus has inhibitory effects on compound 48/80-induced histamine releases from rat peritoneal mast cells (RPMC), and on phorbol 12-myristate 13-acetate (PMA) plus A23187-induced tumor necrosis factor-alpha (TNF-alpha) releases from human mast cells (HMC-1). In mice orally administrered F. fructus (100 microg/g) for 1 h, compound-48/80-induced oedema and vascular permeability were significantly reduced rather than those receiving intravenous injection of ketotifen, mast cell stabilizer. F. fructus dose-dependently inhibited the histamine release induced by compound 48/80 from RPMCs. Moreover, F. fructus had no cytotoxic effects on cell viability and had inhibitory effects on TNF-alpha secretion from HMC-1. These results suggest that F. fructus is a potential herb medicine for treatment of inflammatory diseases through downmodulating mast cell activation.