Flavonoids are secondary products of plants that include thousands of compounds classified in several classes. Preclinical
studies mainly carried out in rodents suggest that they may have a role in the prevention of immunoglobulin E (IgE) synthesis and mast
cell degranulation. Interestingly, using animal models with allergic asthma, it can be concluded that preventive treatment with particular
flavonoid classes can reduce airway hyperresponsiveness, which is accompanied by lowered inflammatory mediators such as histamine
and cytokines, and cell infiltration. In addition, there are some clinical trials in patients with allergic asthma or rhinitis that offer promising
results with regard to these natural compounds. On the other hand, the dissection of cellular mechanisms that have interacted with
flavonoids allow their effectiveness to be understood. Among these mechanisms there is a lower expression of IgE receptor or other
membrane receptors, the modulation of calcium influx, and the downregulation of particular signaling pathways that eventually produces
lower primary and secondary mediator release. In conclusion, some particular flavonoids could be an alternative or complementary therapy
in the prevention and treatment of some allergies. Nevertheless, an increased number of clinical trials is required in order to confirm
the therapeutic role of flavonoids.
Keywords: Flavonol, flavone, flavanone, flavanol, IgE, asthma, rhinitis, mast cell.
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