title: Fenton-like reaction catalyzed by the rare earth inner transition metal cerium.
abstract: Cerium (Ce) is a rare earth metal that is not known to have any biological role. Cerium oxide materials of several sizes and shapes have been developed in recent years as a scaffold for catalysts. Indeed even cerium oxide nanoparticles themselves have displayed catalytic activities and antioxidant properties in tissue culture and animal models. Because of ceria's ability to cycle between the +3 and +4 states at oxygen vacancy sites, we investigated whether cerium metal would catalyze a Fenton-like reaction with hydrogen peroxide. Indeed, cerium chloride did exhibit radical production in the presence of hydrogen peroxide, as assessed by relaxation of supercoiled plasmid DNA. Radical production in this reaction was also followed by production of radical cation of 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS). Radical scavengers and spin traps were capable of competing with ABTS for radicals produced in this cerium dependent Fenton-like reaction. Electron paramagnetic resonance experiments reveal both hydroxyl radical and superoxide anion in a reaction containing cerium and hydrogen peroxide. Based on these results we propose that cerium is capable of redox-cycling with peroxide to generate damaging oxygen radicals.
authors.affiliation: Department of Molecular Biology and Microbiology, University of Central Florida, Burnett School of Biomedical Science, College of Medicine, 4000 Central Florida Blvd., Bldg. 20 Room 124, Orlando, Florida 32816-2364, USA.
authors.forename: Eric G
authors.initials: EG
authors.lastname: Heckert
authors.forename: Sudipta
authors.initials: S
authors.lastname: Seal
authors.forename: William T
authors.initials: WT
authors.lastname: Self
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry; D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D002839:Chromans / Q000737:chemistry; D004249:DNA Damage; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D019097:Spin Trapping; D013451:Sulfonic Acids / Q000737:chemistry
chemical_list: D052160:Benzothiazoles; D002839:Chromans; C045076:Fenton's reagent; D005609:Free Radicals; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D002563:Cerium; D006861:Hydrogen Peroxide; D007501:Iron; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid