Photoprotective properties of 20(S)-protopanaxatriol, an aglycone of ginseng saponins: Protection from ultraviolet-B radiation-induced oxidative stress in human epidermal keratinocytes

Ginsenosides are responsible for diverse pharmacological properties ascribed to ginseng, a plant used in traditional medicine. Ginsenosides are classified into three categories: Protopanaxadiol, protopanaxatriol (PPT) and oleanolic acid. As an aglycone of PPT-type ginsenosides, PPT exists in two stereoisomeric forms, 20(S)-PPT and 20(R)-PPT. The 20(S)-PPT stereoisomer is a major metabolic product of PPT-type ginsengosides produced in the gastrointestinal tract. In the present study, 20(S)-PPT suppressed the elevation of reactive oxygen species in HaCaT cells following irradiation with ultraviolet (UV)-B. In addition, 20(S)-PPT inhibited UV-B-induced gelatinase activities of matrix metalloproteinase-2 and -9 in HaCaT cells, and suppressed UV-B-induced expression and secretion of these proteins. Accordingly, 20(S)-PPT restored the total glutathione levels in UV-B-irradiated keratinocytes. Taken together, these data indicated that 20(S)-PPT may possess photoprotective properties that combat the effects of UV-B radiation.