Anti-inflammatory effect of quercetin and galangin in LPS-stimulated RAW264.7 macrophages and DNCB-induced atopic dermatitis animal models

Flavonols are compounds that have been shown to possess potent anti‑inflammatory effects in cellular and animal models of inflammation. In the present study, the anti‑inflammatory effects and mechanisms of two natural flavonols, quercetin and galangin, in lipopolysaccharide (LPS)‑stimulated RAW264.7 macrophages were investigated. It was identified that quercetin and galangin markedly reduced the production of nitric oxide (NO), inducible NO synthase and interleukin‑6, and the nuclear translocation of nuclear factor‑κB (NF‑κB). In addition, LPS‑induced activation of extracellular signal‑regulated kinase 1/2 (Erk1/2) and c‑Jun N‑terminal kinase (JNK) was suppressed by quercetin and galangin. Taken together, these data implied that NF‑κB, Erk1/2 and JNK may be potential molecular targets of quercetin and galangin in an LPS‑induced inflammatory response. Subsequently, the effects of oral administration of quercetin or galangin, either alone or in combination, in a 2,4‑dinitrochlorobenzene‑induced atopic dermatitis (AD) mouse model were investigated. As a result, measurements of ear thickness and the levels of serum immunoglobulin E, and histological analysis revealed that the two flavonols led to a decrease in inflammation, whereas, in combination, they were even more effective. These results suggested that quercetin and galangin may be promising therapeutic agents for AD. Additionally, their combination may be a novel therapeutic strategy for the prevention of AD.