Flavonoids and Asthma

Abstract

Asthma is a chronic disease, characterized by airway inflammation, airflow limitation, hyper-reactivity and airway remodeling. It is believed that asthma is caused by the interaction between genetic and environmental factors. The prevalence of allergic diseases, including asthma, has increased worldwide during the past two decades. Although the precise reasons that have caused this increase remain unknown, dietary change is thought to be one of the environmental factors. Flavonoids, which are polyphenolic plant secondary metabolites ubiquitously present in vegetables, fruits and beverages, possess antioxidant and anti-allergic traits, as well as immune-modulating activities. Flavonoids are powerful antioxidants and anti-allergic nutrients that inhibit the release of chemical mediators, synthesis of Th2 type cytokines, such as interleukin (IL)-4 and IL-13, and CD40 ligand expression by high-affinity immunoglobulin E (IgE) receptor-expressing cells, such as mast cells and basophils. They also inhibit IL-4-induced signal transduction and affect the differentiation of naïve CD4+ T cells into effector T-cells through their inhibitory effect on the activation of the aryl hydrocarbon receptor. Various studies of flavonoids in asthmatic animal models have demonstrated their beneficial effects. The results of several epidemiological studies suggest that an increase in flavonoid intake is beneficial for asthma. Moreover, clinical trials of flavonoids have shown their ameliorative effects on symptoms related to asthma. However, these human studies are currently limited; further validation is required to clarify whether an appropriate intake of flavonoids may constitute dietary treatment and for part of a preventive strategy for asthma.

Molecular Mechanisms of Quercitrin-induced Apoptosis in Non-small Cell Lung Cancer

“…These properties could explain the beneficial effects that flavonoid intake exerts in different human pathologies including hypertension, inflammatory conditions, and cancer (13). Quercitrin is the most abundant bioflavonoid compound, which is mainly present in the glycoside form (14).…”

Flavonoids as complementary medicine for allergic diseases: current evidence and future prospects

“…The findings of various epidemiologic studies indicate that a high intake of vegetables and fruit may provide protection against asthma and allergic rhinitis 8,16 . However, few such studies have dealt with direct associations between flavonoid intake and allergic diseases.…”

“…Subsequent investigations have demonstrated the benefits of various kinds of flavonoids, administered orally, or injected intraperitoneally or intravenously, in asthmatic, atopic dermatitis, food allergy and anaphylactic animal models. These flavonoids include fisetin, kaempferol, quercetin, isoquercitrin, rutin, 3-O-methylquercetin 5,7,3' ,4'-O-tetraacetate, nobiletin, narirutin, sulfuretin and hesperdin 8 .…”

“…The fact that both the interaction of CD40 ligand with CD40 and the action of IL-4 or IL-13 on B cells, which are required for the differentiation of . While exaggerated oxidative stress plays a significant role in the development of asthma and atopic dermatitis 22 , flavonoids are powerful antioxidants because they stabilise the reactive oxygen species, scavenge nitric oxide and inhibit xanthine oxidase activity 8 . Further, it has been shown that various flavonoids inhibit activation of nuclear factor-kappaB (NF-kB), which is one of the most important transcriptional factors to induce inflammatory responses and thus, to contribute to the development of asthma 23 .…”

“…However, because of limited evidence, no specific dietary management for allergic diseases has yet been established. Flavonoids are plant-derived nutrients, which possess antioxidant, anti-inflammatory, anti-allergic and immune-modulating properties 7,8 . This review presents current findings associated to the biological action and beneficial effects of flavonoids in allergic animal models, as well as the results of epidemiologic and intervention studies of allergic diseases.…”