Effect of Astilbe koreana on ultraviolet B (UVB)-induced inflammatory response in human keratinocytes

The EtOH extract from the rhizomes of Astilbe koreana (Saxifragaceae) exhibited potent antioxidant activity in our recent study. Since the oxidative stress is known to be involved in the inflammatory response after ultraviolet B (UVB) exposure, the ability of the A. koreana extract to inhibit UVB-induced prostaglandin E2 (PGE2) and nitric oxide (NO) production was examined. UVB irradiation (35 mJ/cm2) increased PGE2 and NO production, which were significantly decreased by pre-administration of the A. koreana extract in a dose-dependent manner. The A. koreana extract also preserved cellular antioxidant capacity after UVB irradiation, which was determined by glutathione (GSH) content. UVB irradiation enhanced the formation of ROS in the keratinocytes, which was determined using a 2,7'-dichlorofluorescein diacetate (DCFH-DA), a redox sensitive dye. The levels of intracellular reactive oxygen species (ROS) were also significantly reduced by pre-treatment of the A. koreana extract in a dose-dependent manner measured 9 h after UVB irradiation. The results suggest that the A. koreana extract may have a protective effect on the UVB-injured keratinocytes by inhibiting PGE2 and NO production, possibly through the inhibition of intracellular ROS accumulation.