title: Ethanol extract of Bupleurum falcatum and saikosaponins inhibit neuroinflammation via inhibition of NF-κB.
abstract: BACKGROUND
  The root of Bupleurum falcatum L. (BF) has been used in traditional Korean and Chinese medicines for over 2000 years to treat infections, fever, and chronic liver diseases. Among the many active compounds in BF ethanol extract (BFE), saikosaponins exert pharmacological activities including anti-inflammatory effects. Activated microglial cells release a variety of pro-inflammatory substances, leading to neuronal cell death and neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. The aim of the present study was to investigate the mechanism of the anti-neuroinflammatory effects of BFE using lipopolysaccharide (LPS)-stimulated microglial cells and LPS-intraperitoneal injected C57BL/6 mice.
  
  
  METHODS
  Dried roots of BF were extracted with 70% ethanol (tenfold volume) on a stirring plate for 24h at room temperature to prepare BFE. Pure saikosaponins (SB3, SB4, and SD) were prepared by solvent extraction and column chromatography fractionation. BV2 murine microglial cells were treated with BFE or saikosaponins for 4h and stimulated with LPS. Generation of nitric oxide (NO), inflammatory cytokines, and reactive oxygen species (ROS) from activated microglial cells were monitored. The effects of BFE on NF-κB activation were determined using RT-PCR, reporter assay, and immunostaining. The in vivo effects of BFE were also assessed by immunohistochemical staining of tissue sections from LPS-injected mouse brains.
  
  
  RESULTS
  Treatment with BFE or saikosaponins dose-dependently attenuated LPS-induced production of NO, iNOS mRNA, and ROS by 30-50%. They reduced LPS-mediated increases in the mRNA levels of IL-6, IL-1β, and TNF-α by approximately 30-70% without affecting cell viability, and decreased LPS-mediated NF-κB activity via reducing p65/RELA mRNA, transcriptional activity, and nuclear localization of NF-κB. BFE also reduced LPS-induced activation of microglia and astrocytes in the hippocampus and substantia nigra of LPS-injected mice.
  
  
  CONCLUSIONS
  Our data suggest that BFE may be effective for reducing neuroinflammation-mediated neurodegeneration through suppressing NF-κB-mediated inflammatory pathways.
authors.affiliation: Neurodegeneration Control Research Center, Department of Physiology, College of Medicine, Kyung Hee University, Seoul 130-731, Republic of Korea.
authors.forename: Wook Ha
authors.initials: WH
authors.lastname: Park
authors.affiliation: Neurodegeneration Control Research Center, Department of Physiology, College of Medicine, Kyung Hee University, Seoul 130-731, Republic of Korea.
authors.forename: Sora
authors.initials: S
authors.lastname: Kang
authors.affiliation: Neurodegeneration Control Research Center, Department of Physiology, College of Medicine, Kyung Hee University, Seoul 130-731, Republic of Korea.
authors.forename: Ying
authors.initials: Y
authors.lastname: Piao
authors.affiliation: Neurodegeneration Control Research Center, Department of Physiology, College of Medicine, Kyung Hee University, Seoul 130-731, Republic of Korea.
authors.forename: Christine Jeehye
authors.initials: CJ
authors.lastname: Pak
authors.affiliation: Department of Oriental Pharmaceutical Science, College of Pharmacy, Kyung Hee University, Seoul 130-731, Republic of Korea.
authors.forename: Myung Sook
authors.initials: MS
authors.lastname: Oh
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Jinwoong
authors.initials: J
authors.lastname: Kim
authors.affiliation: Neurodegeneration Control Research Center, Department of Physiology, College of Medicine, Kyung Hee University, Seoul 130-731, Republic of Korea.
authors.forename: Min Seo
authors.initials: MS
authors.lastname: Kang
authors.affiliation: Neurodegeneration Control Research Center, Department of Physiology, College of Medicine, Kyung Hee University, Seoul 130-731, Republic of Korea. Electronic address: ykpak@khu.ac.kr.
authors.forename: Youngmi Kim
authors.initials: YK
authors.lastname: Pak
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use*; D029972:Bupleurum; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use*; D000431:Ethanol / Q000494:pharmacology / Q000627:therapeutic use*; D007249:Inflammation / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use; D018517:Plant Roots; D012503:Saponins / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D000893:Anti-Inflammatory Agents; D004365:Drugs, Chinese Herbal; D016328:NF-kappa B; D012503:Saponins; D000431:Ethanol; D009828:Oleanolic Acid; C025759:saikosaponin D
keywords: Anti-inflammatory effects; Astrocytes; Bupleurum falcatum; Microglia; Neuroinflammation; Saikosaponin