title: Comparative inhibitory effects of magnolol, honokiol, eugenol and bis-eugenol on cyclooxygenase-2 expression and nuclear factor-kappa B activation in RAW264.7 macrophage-like cells stimulated with fimbriae of Porphyromonas gingivalis.
abstract: BACKGROUND
  The anti-inflammatory activity of magnolol and related compounds is currently a focus of interest. In the present study, the inhibitory effects of these compounds on cyclooxygenase (COX-2) expression and nuclear factor-kappa B (NF-κB) activation were investigated in RAW264.7 macrophage-like cells stimulated with the fimbriae of Porphyromonas gingivalis, an oral anaerobe.
  
  
  METHODS
  The cytotoxicity of magnolol, honokiol, eugenol and bis-eugenol against RAW264.7 cells was determined using a cell counting kit (CCK-8). The regulatory effect of these compounds on the expression of COX-2 mRNA, stimulated by exposure to the fimbriae was investigated by real-time polymerase chain reaction (PCR). NF-κB activation was evaluated by enzyme-linked immunosorbent assay (ELISA)-like microwell colorimetric transcription factor activity assay (Trans-AM) and western blot analysis. The radical-scavenging activity was determined using the induction period method in the methyl methacrylate-azobisisobutyronitrile (AIBN) polymerization system under nearly anaerobic conditions. The phenolic bond dissociation enthalpy (BDE) and orbital energy were calculated at the density functional theory (DFT) B3LYP/6-31G* level.
  
  
  RESULTS
  The cytotoxicity against RAW264.7 cells declined in the order bis-eugenol>eugenol> honokiol>magnolol, whereas the radical-scavenging activity declined in the order honokiol, bis-eugenol>magnolol> eugenol. Magnolol and honokiol significantly inhibited the fimbria-induced expression of COX-2 at non-cytotoxic concentrations. Both the fimbria-stimulated binding of NF-κB to its consensus sequence and phosphorylation-dependent proteolysis of inhibitor κB-α were markedly inhibited by magnilol and honokiol, whereas eugenol and bis-eugenol did not inhibit COX-2 expression and NF-κB activation. Magnolol and honokiol possessed a high electronegativity (χ) value.
  
  
  CONCLUSIONS
  Magnolol and honokiol exhibit antioxidative activity, low cytotoxicity, and anti-inflammatory activity. These compounds may be capable of preventing chronic inflammatory diseases induced by oral bacteria.
authors.affiliation: Division of Oral Diagnosis, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, Sakado-City, Saitama, Japan. ymura@dent.meikai.ac.jp
authors.forename: Yukio
authors.initials: Y
authors.lastname: Murakami
authors.forename: Akifumi
authors.initials: A
authors.lastname: Kawata
authors.forename: Yuya
authors.initials: Y
authors.lastname: Seki
authors.forename: Teho
authors.initials: T
authors.lastname: Koh
authors.forename: Kenji
authors.initials: K
authors.lastname: Yuhara
authors.forename: Takehisa
authors.initials: T
authors.lastname: Maruyama
authors.forename: Mamoru
authors.initials: M
authors.lastname: Machino
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ito
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kadoma
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Fujisawa
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000008:administration & dosage*; D002452:Cell Count; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D005054:Eugenol / Q000008:administration & dosage; D036781:Fimbriae Proteins / Q000737:chemistry / Q000633:toxicity; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy; D017705:Lignans / Q000008:administration & dosage*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D016966:Porphyromonas gingivalis / Q000737:chemistry; D000498:Allyl Compounds; D010636:Phenols
chemical_list: D000893:Anti-Inflammatory Agents; D001713:Biphenyl Compounds; D051546:Cyclooxygenase 2; D005054:Eugenol; D036781:Fimbriae Proteins; D017705:Lignans; D016328:NF-kappa B; C005498:magnolol; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols