Phlomis umbrosa root inhibits mast cell‐dependent allergic reactions and inflammatory cytokine secretion

The effect of an aqueous extract of Phlomis umbrosa Turcz. (Labiatae) root (PUAE) on mast cell‐dependent allergic reactions and inflammatory cytokine secretion were investigated. PUAE (0.01–1 g/kg) inhibited compound 48/80‐induced systemic allergic reaction. When PUAE was employed in a systemic allergic reaction test, the plasma histamine levels were reduced in a dose‐dependent manner. PUAE (0.1 and 1 g/kg) also significantly inhibited the local allergic reaction activated by anti‐dinitrophenyl (DNP) IgE. PUAE (0.001–1 mg/mL) dose‐dependently inhibited the histamine release from rat peritoneal mast cells activated by compound 48/80 or anti‐DNP IgE. PUAE (0.01–1 mg/mL) inhibited the secretion of interleukin (IL)‐1 β in phorbol 12‐myristate 13‐acetate plus calcium ionophore A23187‐stimulated human mast cell line (HMC‐1) cells. PUAE (1 mg/mL) inhibited the gene expression and production of the main inflammatory cytokine, TNF‐ α , in HMC‐1 cells. These results provide evidence that PUAE may be beneficial in the treatment of allergic diseases. Copyright © 2007 John Wiley & Sons, Ltd.