title: Baicalein, an active component of Scutellaria baicalensis, protects against lipopolysaccharide-induced acute lung injury in rats.
abstract: BACKGROUND
  Baicalein (BE), a phenolic flavonoid extracted mainly from the root of Scutellaria baicalensis Georgi, a Chinese herb, is traditionally used in oriental medicine. Several studies have demonstrated that BE exerts many beneficial effects including anti-inflammatory and antioxidant activities. However, its effect on acute lung injury (ALI) and the molecular mechanisms involved remain unclear and warrant further investigation. The aim of the study is to investigate whether BE improves lipopolysaccharide (LPS, intratracheally, i.t.)-induced ALI in rats, and further study the underlying mechanisms of its activity.
  
  
  METHODS
  Rats were administrated with LPS (5mg/kg/body weight, i.t.) through a 24-gauge catheter to establish the ALI model. The effects of BE on the levels of pro-inflammatory cytokines, nitrite/nitrate in bronchoalveolar lavage fluid, and the expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and nuclear factor-kappa B (NF-κB) activation as well as the histopathological changes were evaluated.
  
  
  RESULTS
  Results showed that BE (20mg/kg, i.p.) treatment markedly attenuated LPS-induced lung edema, elevation of the levels of IL-1β, TNF-α, IL-6, CINC-3, and nitrite/nitrate in bronchoalveolar lavage fluid accompanied by a remarkable improvement of lung histopathological symptoms. The LPS-enhanced inflammatory cell infiltration and myeloperoxidase activity, O2(-) formation and the expression of inducible nitric oxide synthase and nitrotyrosin in lungs were all attenuated by BE. Notably, BE could augment Nrf2/HO-1 cascade, but inhibited NF-κB activation in LPS-instilled lungs that was strongly reversed by blocking HO-1 activity.
  
  
  CONCLUSIONS
  This study is the first to demonstrate that BE protects against LPS-induced ALI in rats. The underlying mechanisms may include inhibition of NF-κB-mediated inflammatory responses and upregulation of Nrf2/HO-1 pathway, which ultimately alleviates the pathological symptoms of ALI.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Tri-Service General Hospital, Taipei, Taiwan.
authors.forename: Chen-Liang
authors.initials: CL
authors.lastname: Tsai
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Lin
authors.affiliation: Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung, Taiwan; Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Wang
authors.affiliation: Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan; Department of Biotechnology, Asia University, Taichung, Taiwan; China Medical University Hospital, China Medical University, Taichung, Taiwan. Electronic address: tcchou48@mail.tcu.edu.tw.
authors.forename: Tz-Chong
authors.initials: TC
authors.lastname: Chou
mesh_terms: D055371:Acute Lung Injury / Q000473:pathology / Q000517:prevention & control*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001992:Bronchoalveolar Lavage Fluid; D004195:Disease Models, Animal; D004487:Edema / Q000188:drug therapy / Q000473:pathology; D044950:Flavanones / Q000302:isolation & purification / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity; D008297:Male; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D031364:Scutellaria baicalensis / Q000737:chemistry*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000893:Anti-Inflammatory Agents; D044950:Flavanones; D008070:Lipopolysaccharides; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; C006680:baicalein; D051547:Heme Oxygenase-1
keywords: Acute lung injury; Baicalein; Heme oxygenase-1; Inflammation; Lipopolysaccharide