Purpose: The purpose of the present study was to explore the possibility of using sinapic acid as a skin anti-aging cosmetic by demonstrating its antioxidant and anti-inflammatory effects in keratinocytes damaged by ultraviolet (UV) irradiation. Methods: The effects of sinapic acid against oxidative stress were examined in a UVB-induced aging model of human keratinocyte HaCaT cells. The water-soluble tetrazolium salt (WST-1) assay was employed to examine protective effects against UVB. Changes in the concentration of reactive oxygen species (ROS) produced by UVB were measured using 2',7'-dichlorofluorescin diacetate (DCF-DA). Expression of genes associated with anti-oxidant and anti-inflammatory effects were confirmed using quantitative real-time polymerase chain reaction (qRT-PCR). Results: Sinapic acid protected cells from UVB-induced cytotoxicity and reduced ROS produced by UVB irradiation. Expression of genes associated with antioxidant effects including, superoxide dismutase 1 (SOD1), catalase (CAT), glutathione peroxidase 1 (GPX1), nuclear factor (erythroid-derived 2)-like 2 (NRF2), and heme oxygenase 1 (HO1), increased and lipid peroxidation decreased in a dose-dependent manner. The expression of cyclooxygenase 2 (COX2), interleukin 6 (IL6), and interleukin 8 (IL8) genes, which are associated with inflammation, also decreased in a dose-dependent manner. Conclusion: These results suggest that sinapic acid has potential as an anti-aging cosmetic ingredient with anti-oxidant, anti-inflammatory properties against UVB irradiation.

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