Photoprotective effect of libanoridin isolated from Corydalis heterocarpa on UVB stressed human keratinocyte cells.

Ultraviolet-B (UVB) irradiation acts primarily on the epidermal basal cell layer of the skin, inducing harmful biological effects. In this study, we have investigated the effect of libanoridin isolated from Corydalis heterocarpa against UVB-induced damage in human keratinocyte (HaCaT) cells and the molecular mechanism underlying those effects. Treatment with libanoridin inhibited the cell cytotoxicity and LDH induced by UVB exposure at 40 mJ/cm(2). Additionally, expression levels of type IV collagenases (MMP-2, MMP-9) were decreased by libanoridin. Furthermore, MMP tissue inhibitors were enhanced followed by treatment with libanoridin. Moreover, UVB-induced activation of phosphorylation of three MAPKs such as JNK, ERK, p38 and AP-1 transcription factor were decreased by treatment with libanoridin. Our present study demonstrates that libanoridin has the abilities to inhibit UVB-induced cellular damage via ASK1-MAPK and AP-1 signalling pathways. Therefore, libanoridin may be used as an effective natural compound to prevent skin damage due to UVB exposure.