Hibiscus syriacus (H. syriacus) as the national flower of Korea has been used as the herbal medicine in Asia. In this study, we evaluated the anti-inflammatory effect of 70% ethanol extracts from the root of Hibiscus syriacus (RHS-E70) and elucidated the potential signaling pathway in LPS-stimulated RAW264.7 cells. RHS-E70 dose-dependently suppressed NO production by inhibiting iNOS and IL-β expression in LPS-stimulated RAW264.7 cells. RHS-E70 inhibited the phosphorylation and degradation of IκB-α, which contributed to the inhibition of p65 nuclear accumulation and NF-κB activation. Furthermore, RHS-E70 suppressed the phosphorylation of ERK1/2 and p38, which results in the inhibition of ATF2 phosphorylation and subsequent nuclear accumulation. These results indicate that RHS-E70 may exert antiinflammatory activity by inhibiting NF-κB and MAPK/ATF2 signaling. From these findings, RHS-E70 has potential to be a candidate for the development of chemopreventive or therapeutic agents for the inflammatory diseases.

Abstract
 Introduction
 Materials and methods
  Materials
  Sample preparation
  Cell culture and treatment
  Cell viability assay
  Measurement of NO production
  Isolation of cytosol and nucleus fraction
  SDS-PAGE and Western blot analysis
  Reverse transcriptase-polymerase chain reaction (RT-PCR)
  Transient transfection and luciferase activity
  Statistical analysis
 Results and Discussion
  Effect of RHS-E70 on LPS-mediated NO production,and expression of iNOS and IL-1β in LPS-stimulatedRAW264.7 cells
  Inhibitory of RHS-E70 on NF-κB signaling activation inLPS-stimulated RAW264.7 cells
  Inhibitory of RHS-E70 on MAPK/ATF2 signaling inLPS-stimulated RAW264.7 cells
 References

• Ha Na Kim(Department of Medicinal Plant Resources, Andong National University)
• Su Bin Park(Department of Medicinal Plant Resources, Andong National University)
• Gwang Hun Park(Forest Medicinal Resources Research Center, National Institute of Forest Science)
• Hyun Ji Eo(Forest Medicinal Resources Research Center, National Institute of Forest Science)
• Jeong Ho Song(Forest Medicinal Resources Research Center, National Institute of Forest Science)
• Hae Yun Kwon(Forest Tree Improvement Division, Forest Bioresources Department, National Institute of Forest Research)
• Jin Boo Jeong(Department of Medicinal Plant Resources, Andong National University, Agricultural Science and Technology Research Institute, Andong National University) Corresponding author