Protective effect of Rhododendron weyrichii flower extract against UVB-induced proinflammatory cytokine production in human keratinocytes

ABSTRACT

Ultraviolet B (UVB) radiation is harmful to the skin and induces cytokine release from keratinocytes leading toinflammatory skin disorders. Previous studies have shown that chronic exposure to UVB radiation increases tumornecrosis factor (TNF)-α and interleukin (IL)-6 secretion through various signaling pathways, resulting in skininflammation and increased risk of skin cancer. The present study was undertaken to investigate the protective effectsof Rhododendron weyrichii flower (RWF) extracts against UVB damage of immortalized human keratinocytes(HaCaT). To determine the anti-inflammatory effects of RWF, we examined UVB-induced proinflammatory cytokineproduction in HaCaT cells in the presence or absence of RWF extract, using enzyme-linked immunosorbent assay(ELISA). The results indicated that the RWF extract inhibited the production of proinflammatory molecules suchas IL-6 and TNF-α, but not IL-8, in UVB-irradiated HaCaT cells. These results demonstrate that RWF potentiallyprotects against UVB-induced skin inflammation. In addition, using high-performance liquid chromatography (HPLC)fingerprinting, kaempferol (0.335 ppm) and astragalin (2.569 ppm) were identified and quantified as RWF extractconstituents. Moreover, we tested the potential application of RWF extracts as a cosmetic treatment by performinghuman skin primary irritation tests. In these tests, the RWF extracts did not induce adverse reactions. Based on theseresults, we suggest that RWF extracts be considered anti-inflammatory candidates for pharmaceutical and/or cosmeticapplications.