Inhibitory effect of phloretin and biochanin A on IgE-mediated allergic responses in rat basophilic leukemia RBL-2H3 cells

Aims: Anti-allergic effects and action mechanism of phloretin (Phi) and biochanin A (BioA) on the IgE-antigen complex-mediated allergic responses in rat basophilic leukemia RBL-2H3 cells were investigated. Main methods: Cell viability, formation of reactive oxygen species (ROS), DPPH radical-scavenging activity, beta-hexosaminidase release, production of interleukin (IL)-4, IL-13, and tumor necrosis factor-alpha (TNE-alpha) and phosphorylation of Akt and mitogen-activated protein kinase (MAPK) were determined by MTT assay, 2,7-dichlorofluorescein diacetate (DCF-DA) assay, DPPH radical-scavenging assay, reverse transcriptase polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA) and western blot analysis, respectively. Key findings: Phi and BioA dose-dependently inhibited the formation of ROS and the release of beta-hexosaminidase from the RBL-2H3 cells and also showed DPPH radical-scavenging activity. Phi and BioA suppressed the antigen-induced phosphorylation of the downstream signaling intermediates, including MAPK and Akt, which are critical for the production of pro-inflammatory cytokines, and also significantly attenuated the production of IgE-mediated pro-inflammatory cytokines, such as IL-4, IL-13, and TNF-alpha. Significance: Phloretin and biochanin A attenuate the degranulation and allergic cytokine production through inhibition of intracellular ROS production and the phosphorylation of Akt and the MAPKs, such as ERK1/2, p38, and JNK. The results of this study suggested that these two plant flavonoids may have potent anti-allergic activity in vitro. (C) 2013 Elsevier Inc. All rights reserved.