Effects of An Hot Water Extract of Saccharina japonica on Skin Moisture in Ultraviolet B-exposed Human Keratinocytes

This study evaluated the effect of Saccharina japonica hot water extract (SJH) on the skin moisture in ultraviolet B (UVB)-exposed HaCaT keratinocytes. SJH significantly reduced the intracellular reactive oxygen species (ROS) production via the activation of nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signalling in UVB-exposed HaCaT keratinocytes. Also, SJH significantly reduced the mRNA expression and/or production of inflammatory cytokines (interleukin (IL)-25, IL-33, thymic stromal lymphopoietin (TSLP), IL-6, IL-8, tumor necrosis factor (TNF)-α) and chemokines (macrophagederived chemokine (MDC) and thymus and activation regulated chemokine (TARC)) with the inactivation of MAPK signaling pathway in UVB-exposed HaCaT keratinocytes. In addition, SJH significantly increased the production of hyaluronic acid (HA) by regulating the protein expression levels of skin barrier (occludin, zonula occludens (ZO)-1, claudin-1, -4, -7 and -2) and skin moisture (lympho-epithelial kazal-type-related inhibitor (LEKT1), kallikrein (KLK)-5, protease activated receptor (PAR)-2, phospholipase (PLA)-2, involucrin and filaggrin) molecules in UVB-exposed HaCaT keratinocytes. These results suggest that SJH can effectively improve the skin moisture with the inhibition of oxidative stress, inflammation and dysfunction of skin barrier caused by UVB exposure in HaCaT keratinocytes.