Action mechanism of anti-wrinkle effect of Rhamnus yoshinoi methanol extract in human dermal fibroblast and keratinocyte cell lines

Rhamnus yoshinoi is a deciduous broad-leaf bush and endemic species widely found in Korea. Recently, we reported that R. yoshinoi methanol extract (RYME) had excellent antioxidant activity and inhibition of collagenase and elastase activity in cell-free system. In this study, we investigated the ability of RYME to control the mRNA and protein expression levels of the known skin wrinkle-related factors in cultured human dermal fibroblast and keratinocyte cell lines. Treatment with 100 or 200 μg/mL RYME strongly blocked the UVB-induced downregulation of type 1 collagen mRNA expression (p < 0.001) and partially blocked the UVB-induced upregulation of MMP-3 mRNA expression in HaCaT human keratinocytes (p < 0.05 or p < 0.001). Treatment with RYME at 100 μg/mL considerably decreased MMP-1 mRNA expression in UVB-exposed HaCaT cells (p < 0.01). In HaCaT cells, RYME exhibited the potential to improve UV light-induced skin wrinkles. Moreover, RYME selectively inhibited the UVB-induced ERK-1/2 protein phosphorylation in CCD-986sk human dermal fibroblasts at 80 and 160 μg/mL. UV-induced ERK-1/2 protein phosphorylation is one of the major mechanisms of the generation of UV-induced skin wrinkles. Therefore, it is likely that the anti-skin wrinkling effect of RYME could be attributable to selective inhibition of UV induced ERK-1/2 protein phosphorylation.