title: Inhibitory effects of p-cresol and p-hydroxy anisole dimers on expression of the cyclooxygenase-2 gene and lipopolysaccharide-stimulated activation of nuclear factor-κB in RAW264.7 cells.
abstract: OBJECTIVE
  Phenolic compounds, particularly dihydroxybiphenyl-related compounds, possess efficient anti-oxidative and anti-inflammatory activity. We investigated the anti-inflammatory activity of 2,2'-dihydroxy-5,5'-dimethylbiphenol (p-cresol dimer), 2,2'-dihydroxy-5,5'-dimethoxybiphenol (pHA dimer), p-cresol, p-hydroxyanisole (pHA) and 2-t-butyl-4-hydroxyanisole (BHA).
  
  
  METHODS
  The cytotoxicity of the investigated compounds against RAW264.7 cells was determined using a cell counting kit (CCK-8). Their inhibitory effects on cyclooxygenase-2 (Cox2) mRNA expression stimulated by lipopolysaccharide (LPS) were determined using northern blot analysis, and their inhibition of LPS-stimulated nuclear factor-kappa B (Nf-κb) activation was evaluated using enzyme-linked immunosorbent assay-like microwell colorimetric transcription factor activity assay. The molecular orbital energy was calculated on the basis of density function theory BLYP/6-31G*.
  
  
  RESULTS
  The cytotoxicity of the compounds declined in the order pHA dimer > p-cresol dimer > BHA > p-cresol > pHA. The inhibitory effect on Cox2 expression and Nf-κb activation was enhanced by p-cresol dimer and pHA dimer, particularly the former, suggesting potent anti-inflammatory activity, whereas p-cresol and pHA showed weak activity, and BHA no activity. Both p-cresol dimer and pHA dimer were highly electronegative, as determined by quantum chemical calculations.
  
  
  CONCLUSIONS
  Dimerization of p-cresol and pHA enhances their anti-inflammatory activity. p-Cresol dimer and pHA dimer, particularly the former, are potent anti-inflammatory agents.
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.affiliation: Division of Oral diagnosis, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, Sakado-City, Saitama, Japan.
authors.forename: Akifumi
authors.initials: A
authors.lastname: Kawata
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Chiyoda-Ku, Tokyo, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Ito
authors.affiliation: Division of Oral diagnosis, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, Sakado-City, Saitama, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Katayama
authors.affiliation: Division of Oral diagnosis, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, Sakado-City, Saitama, Japan.
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Fujisawa
mesh_terms: D000818:Animals; D000840:Anisoles / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D002460:Cell Line; D003408:Cresols / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D000840:Anisoles; D003408:Cresols; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; C032538:4-cresol; C009760:mequinol; D051546:Cyclooxygenase 2
keywords: Cox2; Nf-κb; RAW264.7 cells; antioxidative activity; cytotoxicity; p-Cresol dimer; p-hydroxy anisole dimer; quantum molecular properties