title: Electron spin resonance studies and theoretical quantum calculations of free radicals generated from anthracenetrione by electrochemical and microsomal reduction.
abstract: The ESR spectra of radicals obtained by electrolytic reduction of 4,4-dimethylanthracene-1,9,10 (4H)-trione (1) and the regioisomeric quinones 8-acetyloxymethyl-4,4,5-trimethyl- (2), and 5-acetyloxy-methyl-4,4,8-trimethyl-(4H)-1,9,10-anthracenetrione (3) were measured in DMSO and analyzed by quantum chemical calculations. The electrochemistry of these compounds was characterized using cyclic voltammetry, in DMSO and DMF solvents and compared with nifurtimox. The quinones were also reduced by microsomal NADPH-cytochrome P-450 reductase and the corresponding radicals species were also detected by ESR spectroscopy. AMI, INDO, and ADF calculations were performed to obtain the optimized geometries, theoretical hyperfine constants, and spin distributions, respectively. Density functional theory was used to rationalize the reduction potential of these compounds.
authors.affiliation: Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago. colea@uchile.cl
authors.forename: C
authors.initials: C
authors.lastname: Olea-Azar
authors.forename: F
authors.initials: F
authors.lastname: Mendizábal
authors.forename: J
authors.initials: J
authors.lastname: Alarcón
authors.forename: R
authors.initials: R
authors.lastname: Briones
authors.forename: B K
authors.initials: BK
authors.lastname: Cassels
authors.forename: T
authors.initials: T
authors.lastname: Delgado-Castro
authors.forename: R
authors.initials: R
authors.lastname: Araya-Maturana
mesh_terms: D000873:Anthracenes / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry* / Q000378:metabolism; D008433:Mathematics; D008861:Microsomes / Q000737:chemistry* / Q000201:enzymology; D015394:Molecular Structure; D009251:NADPH-Ferrihemoprotein Reductase / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D012997:Solvents / Q000737:chemistry
chemical_list: D000873:Anthracenes; D005609:Free Radicals; D012997:Solvents; D009251:NADPH-Ferrihemoprotein Reductase; D004121:Dimethyl Sulfoxide