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)-1β 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.