title: Effects of luteolin, quercetin and baicalein on immunoglobulin E-mediated mediator release from human cultured mast cells.
abstract: BACKGROUND
  Flavonoids have a variety of activities including anti-allergic activities, and are known to inhibit histamine release from human basophils and murine mast cells.
  
  
  OBJECTIVE
  The effects of luteolin, a flavone, on the immunoglobulin (Ig) E-mediated allergic mediator release from human cultured mast cells (HCMCs) were investigated and compared with those of baicalein and quercetin.
  
  
  METHODS
  HCMCs were sensitized with IgE, and then treated with flavonoids before challenge with antihuman IgE. The amount of released mediators was determined as was mobilization of intracellular Ca2+ concentration, protein kinase C (PKC) translocation and phosphorylation of intracellular proteins were detected after anti-IgE stimulation.
  
  
  RESULTS
  Luteolin, baicalein and quercetin inhibited the release of histamine, leukotrienes (LTs), prostaglandin D2 (PGD2), and granulocyte macrophage-colony stimulating factor (GM-CSF) from HCMC in a concentration-dependent manner. Additionally, the three flavonoids inhibited A23187-induced histamine release. As concerns Ca2+ signalling, luteolin and quercetin inhibited Ca2+ influx strongly, although baicalein did slightly. With regard to PKC signalling, luteolin and quercetin inhibited PKC translocation and PKC activity strongly, although baicalein did slightly. The suppression of Ca2+ and PKC signallings might contribute to the inhibition of mediator release. The activation of extracellular signal-regulated kinases (ERKs) and c-Jun NH2-terminal kinase (JNK), that were activated just before the release of LTs and PGD2 and GM-CSF mRNA expression in IgE-mediated signal transduction events, were clearly suppressed by luteolin and quercetin. In contrast, the flavonoids did not affect the activation of p38 mitogen-activated protein kinase (p38 MAPK) pathway.
  
  
  CONCLUSIONS
  These results indicate that luteolin is a potent inhibitor of human mast cell activation through the inhibition of Ca2+ influx and PKC activation.
authors.affiliation: Department of Pharmacology, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kimata
authors.forename: M
authors.initials: M
authors.lastname: Shichijo
authors.forename: T
authors.initials: T
authors.lastname: Miura
authors.forename: I
authors.initials: I
authors.lastname: Serizawa
authors.forename: N
authors.initials: N
authors.lastname: Inagaki
authors.forename: H
authors.initials: H
authors.lastname: Nagai
mesh_terms: D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D004347:Drug Interactions; D044950:Flavanones; D005419:Flavonoids / Q000276:immunology / Q000494:pharmacology*; D006636:Histamine Release / Q000187:drug effects*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology / Q000494:pharmacology*; D047311:Luteolin; D008407:Mast Cells / Q000502:physiology* / Q000648:ultrastructure; D011493:Protein Kinase C / Q000502:physiology; D011794:Quercetin / Q000276:immunology / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D044950:Flavanones; D005419:Flavonoids; D007073:Immunoglobulin E; C006680:baicalein; D011794:Quercetin; D011493:Protein Kinase C; D047311:Luteolin; D002118:Calcium