Protective effect of (2'S)-columbianetin from Corydalis heterocarpa on UVB-induced keratinocyte damage

A salt tolerant plant, Corydalis heterocarpa has been used as a folk medicine to treat travail and spasm. Recent studies have also reported antioxidant and antiinflammatory activities of compounds isolated from C. heterocarpa. In this study, the protective effect of (2'S)-columbianetin isolated from C. heterocarpa on UVB-induced human keratinocyte (HaCaT) damage was investigated. First, the appropriate energy level of UVB irradiation was determined using MTT and LDH assays. And then the protective effect of (2'S)-columbianetin on UVB induced HaCaT damage was evaluated by measuring; the changes in cell viability, LDH release level, ROS generation, cell cycle arrest and MMP expression levels. Finally, the effect of compound on MAPK and AP-1 signaling pathways were studied to understand the underlying signaling mechanisms. Result demonstrated that the presence of (2'S)-columbianetin suppressed the Reactive Oxygen Species (ROS) generation, cell cycle arrest at sub-G1 phase and down regulation of MMP expression in UVB treated HaCaT cells. Furthermore, stress activated signaling pathways (ASK1-MAPK) and AP-1 signaling pathway were regulated by (2'S)-columbianetin treatment. These results suggest that (2'S)-columbianetin could be effectively used to protect human keratinocytes from UVB induced damage.