In Vitro Antiallergic Activity of Flavonoids in Histamine Release Assay Using Rat Basophilic Leukemia (RBL-2H3) Cells

Abstract

We used an established cell line, rat basophilic leukemia cells (RBL-2H3) to screen 40 flavonoids for inhibitory activity on antigen-induced histamine release from immunogloblin E (IgE)-sensitized RBL-2H3 cells. To exclude non-specific inhibition, the cytotoxicity to RBL-2H3 cells was simultaneously determined. Flavonoid aglycones showed a stronger activity for histamine release-inhibition and cytotoxicity than glycosides, and both activities were almost in parallel. Baicalein showed histamine release-inhibitory activity with the IC₅₀ of 1.07×10^-5 M in this bioassay system. However, it showed a potent cytotoxicity (IC₅₀ 9.62×10^-6M). On the other hand, scutellarein (4′-hydroxybaicalein) showed a potent histamine release-inhibitory activity (IC₅₀ 3.15×10^-6M) and low cytotoxicity (IC₅₀ 6.11×10^-6M). We found that scutellarein has a potent histamine release-inhibitory y activity and low cytotoxicity.