Ultraviolet B (UVB) exposure is a risk factor for skin damage resulting in oxidative stress, inflammation, and cell death. The purpose of this study was to investigate the physicochemical properties of Platycodon grandiflorum (PG) to improve its biological activities using a three-step steaming process. We investigated the protective effects of PG and steamed PG extracts on human dermal fibroblasts (HDFs) against UVB radiation-induced oxidative stress and inflammation as well as the underlying mechanisms. The antioxidant potential of the PG extracts was evaluated by measuring the 2,2-diphenyl-1- picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) scavenging activity. ABTS and DPPH were shown by the 0, 30, and 70% ethanol extracts of 2S-PG and 3S-PG (IC50, 28~45 and 27~30 μg/mL, respectively). Treatment of UVB-irradiated cells with steamed PG (25~400 μg/mL) did not affect their viability. The streamed PG extract suppressed UVB-induced generation of reactive oxygen species (ROS). In addition, streamed PG extract reduced cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) protein expression in UVB-irradiated HDF, regulating nuclear factor (NF)-κB expression. These findings suggest that steamed PG extract may be potentially effective against inflammation associated with UVB-induced oxidation stress.

Abstract
 Introduction
 Materials and Methods
  1. Sample preparation
  2. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay
  3. 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid(ABTS) scavenging assay
  4. Cell culture and treatment
  5. Cell viability assay
  6. Quantitation of intracellular ROS
  7. Western blot assay
  8. Statistical analysis
 Results and Discussion
  1. Antioxidant effect of S-PG samples
  2. Effects of S-PG on cell viability of UVB radiationdamagedHDF cells
  3. Effect of S-PG on intracellular ROS generation in UVBradiation-damaged HDF cells
  4. Effect of PG samples on protein expression UVBradiation-damaged HDF cells
 References

• Ji Yeon Lee(Dept. of Herbal Crop Research, National Institute of Horticultural & Herbal Science, Dept. of Food Science and Biotechnology, Chungbuk National University)
• Jeong-Yong Park(Dept. of Herbal Crop Research, National Institute of Horticultural & Herbal Science, Dept. of Food Science and Biotechnology, Chungbuk National University)
• Dae Young Lee(Dept. of Herbal Crop Research, National Institute of Horticultural & Herbal Science)
• Hyung Don Kim(Dept. of Herbal Crop Research, National Institute of Horticultural & Herbal Science)
• Geum-Soog Kim(Dept. of Herbal Crop Research, National Institute of Horticultural & Herbal Science)
• Seung Eun Lee(Dept. of Herbal Crop Research, National Institute of Horticultural & Herbal Science)
• Kyung Hye Seo(Dept. of Herbal Crop Research, National Institute of Horticultural & Herbal Science) Corresponding author