title: Mechanism of the OH radical scavenging activity of nordihydroguaiaretic acid: a combined theoretical and experimental study.
abstract: The antioxidant nordihydroguaiaretic acid (NDGA) is a plant phenolic lignan originally isolated from the creosote bush (Larrea tridentata). It has been shown that NDGA scavenges efficiently hydroxyl radicals ((*)OH). In the present paper the mechanism by which NDGA scavenges (*)OH is addressed performing a combined experimental and theoretical investigation. We found that NDGA protects, in a concentration-dependent way, bovine serum albumin and DNA from the damage induced by (*)OH generated by the Fenton reaction. In addition, the NDGA + (*)OH reaction is predicted to be diffusion-controlled. The first step of this reaction is proposed to occur mainly by a sequential electron proton transfer from NDGA to (*)OH generating a neutral radical of NDGA, which after a second oxidation step gives a diradical that after a cascade sequential complex reaction produces a cyclic compound. This cyclic product is predicted to have a UV-vis spectrum very similar to that of NDGA, making its identification by this technique very difficult. The electrochemical studies performed in water support the formation of a cyclic compound (C2) as the main product of the reaction. It is concluded that NDGA can scavenge at least two (*)OH.
authors.affiliation: Departamento de Química, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, 09340 City, México. agalano@prodigy.net.mx
authors.forename: Annia
authors.initials: A
authors.lastname: Galano
authors.forename: Norma A
authors.initials: NA
authors.lastname: Macías-Ruvalcaba
authors.forename: Omar Noel
authors.initials: ON
authors.lastname: Medina Campos
authors.forename: José
authors.initials: J
authors.lastname: Pedraza-Chaverri
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry; D055664:Electrochemical Techniques; D016166:Free Radical Scavengers / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D032442:Larrea / Q000737:chemistry; D009637:Masoprocol / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D016166:Free Radical Scavengers; D012710:Serum Albumin, Bovine; D017665:Hydroxyl Radical; D009637:Masoprocol; D004247:DNA