title: Hydroxyl radical scavenging effects of guaiacol used in traditional dental pulp sedation: reaction kinetic study.
abstract: Guaiacol, which is a phenolic compound with a methoxy group and used in traditional dental pulp sedation, has the property of inducing cell proliferation. To clarify these mechanisms of guaiacol, this study examined the hydroxyl radical (*OH) scavenging effects of guaiacol in vitro. Generation of *OH was carried out by the Fenton reaction using mixture of ascorbic acid, H2O2, and Fe(III)-EDTA, and *OH was detected by measuring the *OH-mediated production of degradation products of deoxyribose, which reacts with 2-thiobarbituric acid (TBA) and is relatively stable for a long time. At concentrations of 10(-10) M to 10(-3) M, guaiacol inhibited the TBA reactive substance (TBA-RS) formation in a dose-dependent manner. Phenol and formaldehyde were also found to inhibit the TBA-RS formation, but their inhibitory activities were lower than that of guaiacol. The concentrations of guaiacol, phenol, and formaldehyde needed to cause 50% inhibition of TBA-RS formation were approximately 5 x 10(-6), 5 x 10(-5), and 2 x 10(-3) M, respectively. In this reaction system, guaiacol showed no chelating reaction with ferrous ion and did not directly react with H2O2. Guaiacol also exhibited radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical, but its scavenging activity was lower than that toward *OH. These results suggest that guaiacol is a potent scavenger of reactive oxygen radicals and that its radical scavenging activity may be associated with its effect on cell proliferation.
authors.affiliation: Department of Pharmacology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Mimurai
authors.forename: Kinya
authors.initials: K
authors.lastname: Yazaki
authors.forename: Kohei
authors.initials: K
authors.lastname: Sawaki
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ozawa
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Kawaguchi
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry; D049109:Cell Proliferation / Q000187:drug effects; D016292:Procedural Sedation; D003782:Dental Pulp; D003855:Deoxyribose / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry*; D006139:Guaiacol / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics
chemical_list: D005290:Ferric Compounds; D016166:Free Radical Scavengers; D017665:Hydroxyl Radical; D003855:Deoxyribose; D006139:Guaiacol; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid