Effects of ginseng saponins isolated from red ginseng on ultraviolet B-induced skin aging in hairless mice

It is well-known that chronic ultraviolet B (UVB) exposure at low-dose causes skin photoaging including increases in skin thickness and wrinkle formation and reduction in skin elasticity. This study examined the effects of total saponins and ginsenoside Rb1 isolated from Red Ginseng roots on skin thickness, elasticity, and wrinkle formation caused by long-term, low-dose UVB irradiation in hairless mice. The topical application of total ginseng saponins (10 pg or 100 ng/mouse) and ginsenoside Rb1 (100 fg, 10 pg, or 1 ng/mouse) significantly inhibited increases in skin thickness and wrinkle formation and the reduction in skin elasticity induced by long-term UVB irradiation. Furthermore, we examined the histological effects of total saponins and ginsenoside Rb1 in the skin of UVB-irradiated hairless mice. The increases in apoptotic, Ki-67-, and 8-hydroxy-2′-deoxyguanosine-positive cells induced by UVB exposure were prevented by the topical application of total saponins and ginsenoside Rb1. Furthermore, total saponins and ginsenoside Rb1 prevented the disruption of collagen fibers induced by the long-term UVB irradiation. Ginsenoside Rb1 (100 fg, 10 pg, and 1 ng/ml) increased the Bcl-2 expression level in UVB-treated human keratinocytes. The protective effect of ginsenoside Rb1 on UVB-mediated apoptosis may be due to the up-regulation of Bcl-2 expression. These results suggest that the protective effect of ginsenoside Rb1 on skin photoaging induced by chronic UVB exposure may be due to the increase in collagen synthesis and/or the inhibition of matrix metalloproteinase expression in dermal fibroblasts.