Quercetin inhibits anaphylactic contraction of guinea pig ileum smooth muscle.

Certain flavonoids inhibit antigen-induced release of histamine from mast cells and basophils and also inhibit contraction of guinea pig ileum induced by histamine, acetylcholine, and PGE2. We examined the effect of one flavonoid, quercetin, on anaphylactic smooth muscle contraction of ileum from guinea pigs sensitized to egg albumin. Quercetin inhibited both the phasic and tonic components of anaphylactic contraction in a concentration-dependent fashion (IC50 approximately 10 microM). Whether this is primarily an effect on mast cell mediator release or inhibition of mediator effects on smooth muscle has not been established.