Effects of luteolin and other flavonoids on IgE-mediated allergic reactions.

The anti-allergic action of luteolin was investigated in the rodent experimental allergic models. In the present study, the effects of luteolin were compared to those of baicalein, quercetin, and prednisolone. Luteolin as well as baicalein, quercetin, and prednisolone inhibited the IgE antibody-mediated biphasic cutaneous reaction (immediate phase reaction and late phase reaction) in mice. However, these compounds did not affect the histamine-, serotonin-, and platelet activating factor-induced cutaneous reactions in rats. In an in vitro study, luteolin, baicalein, and quercetin inhibited IgE-mediated histamine release from bone marrow-derived cultured murine mast cells (BMMC) and rat peritoneal mast cells. These compounds also inhibited IgE-mediated TNF-alpha and IL-6 production from BMMC. From these results, luteolin inhibited the IgE-mediated biphasic cutaneous reaction mainly by the inhibition of histamine and cytokine release from mast cells, but not through mediator antagonistic effects.