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 ginsenosides 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.