Skin‑Healing Properties of Ginsenoside Rd against Ultraviolet‑B‑Induced Photooxidative Stress through Up‑Regulation of Antioxidant Components in HaCaT Keratinocytes

Objectives: This work assesses the antioxidant and protective potentials of Rd against ultraviolet (UV)‑B‑induced skin photooxidative stress in HaCaT keratinocytes. Materials and Methods: Cell viability was detected using 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide assay. Intracellular reactive oxygen species (ROS) were measured using dichlorodihydrofluorescein diacetate. Promatrix metalloproteinase‑2 (proMMP‑2) activity and protein were detected using gelatin zymography and western analysis. Total glutathione (GSH) content and total superoxide dismutase (SOD) activity were spectrophotometrically determined. Results: Rd, at varying concentrations non- toxic to HaCaT keratinocytes, attenuated the UV‑B‑induced ROS generation. Rd at 5, 12, and 30 µM attenuated the UV‑B‑induced proMMP‑2 gelatinolytic activities to 59.3% ± 9.5%, 41.3% ± 9.5%, and 13.1% ± 8.9%, respectively, of those of the non-treated control cells. It could also diminish the UV‑B‑induced proMMP‑2 protein levels. Rd at 5, 12, and 30 µM augmented the UV‑B‑reduced total SOD activities to 1.6 ± 0.2‑, 2.4 ± 0.3‑, and 3.2 ± 0.2‑fold of those of the non-treated control cells, respectively. Rd could up‑regulate the UV‑B‑reduced total GSH. Conclusion: Rd has counteracting properties against elevated ROS and proMMP‑2 and attenuated GSH and SOD under UV‑B irradiation, implying that it possesses a protective activity against photoaging possibly through up‑regulating antioxidant components. These findings suggest that Rd can be considered as a novel natural resource for anti‑photoaging functional cosmetics.