title: Anti-allergic activity of emodin on IgE-mediated activation in RBL-2H3 cells.
abstract: BACKGROUND
  EMODIN (1,3,8-trihydroxy-6-methylanthraquinone) is a Chinese herbal anthraquinone derivative from the rhizome of rhubarb (Rheum palmatum L.) that exhibits numerous biological activities, such as antitumor, antibacterial, antiinflammatory, and immunosuppressive. In the present studies, the anti-allergic activities of emodin were investigated to elucidate the underlying active mechanisms.
  
  
  METHODS
  The inhibitory effects of emodin on the IgE-mediated allergic response in rat basophilic leukemia (RBL-2H3) cells were evaluated by measuring the release of granules and cytokines. The Ca2+ mobilization in RBL-2H3 cells loaded with the Ca(2+)-reactive fluorescent probe Fluo-4 AM was also measured by laser scanning confocal microscope.
  
  
  RESULTS
  Emodin inhibited the release of β-hexosaminidase (β-HEX; IC50 = 5.5 μM) and tumor necrosis factor (TNF)-α (IC50 = 11.5 μM) from RBL-2H3 cells induced by 2,4-dinitrophenylated bovine serum albumin (DNP-BSA) and displayed stronger inhibition of β-HEX release than ketotifen fumarate salt (IC50 = 63.8 μM). Emodin at a concentration of 12.5 μM also inhibited the DNP-BSA-induced influx of extracellular Ca2+ in RBL-2H3 cells.
  
  
  CONCLUSIONS
  These results suggested that emodin likely exhibits anti-allergic activities via increasing the stability of the cell membrane and inhibiting extracellular Ca2+ influx.
authors.affiliation: Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, Department of Pharmacy, College of Life Sciences, China Jiliang University, Hangzhou 310018, China.
authors.forename: Weimin
authors.initials: W
authors.lastname: Wang
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhou
authors.forename: Lu
authors.initials: L
authors.lastname: Liu
authors.forename: Keqin
authors.initials: K
authors.lastname: Zou
mesh_terms: D000818:Animals; D018926:Anti-Allergic Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D004642:Emodin / Q000494:pharmacology*; D007073:Immunoglobulin E / Q000276:immunology*; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D018926:Anti-Allergic Agents; D014409:Tumor Necrosis Factor-alpha; D007073:Immunoglobulin E; D001619:beta-N-Acetylhexosaminidases; D004642:Emodin; D002118:Calcium