Ultraviolet B (UVB) radiation, is harmful to the skin, and induces cytokine release from keratinocytes leading to inflammatory skin disorders. Previous studies have shown that chronic exposure to UVB radiation increases tumor necrosis factor (TNF)-α and interleukin (IL)-6 secretion through various signaling pathways, resulting in skin inflammation and increased risk of skin cancer. The present study was undertaken to investigate the protective effects of 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 cytokine production 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 such as IL-6 and TNF-α, but not IL-8, in UVB-irradiated HaCaT cells. These results demonstrate that RWF potentially protects 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 extract constituents. Moreover, we tested the potential application of RWF extracts as a cosmetic treatment by performing human skin primary irritation tests. In these tests, the RWF extracts did not induce adverse reactions. Based on these results, we suggest that RWF extracts be considered anti-inflammatory candidates for pharmaceutical and/or cosmetic applications.
Key words: UVB, Rhododendron weyrichii, IL-6 and TNF-a, kaempferol and astragalin
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