title: Hydroxyl radical is produced via the Fenton reaction in submitochondrial particles under oxidative stress: implications for diseases associated with iron accumulation.
abstract: Mitochondrial dysfunction and reactive oxygen species (ROS) are often implicated in diseases involving oxidative stress and elevated iron. As mitochondria produce ATP by oxidative phosphorylation, ROS by-products are generated from the electron transport chain. Although superoxide and hydrogen peroxide have been thoroughly investigated, little evidence documents hydroxyl radical (HO(*)) production in mitochondria. In order to determine whether HO(*) is generated under oxidative stress conditions by a Fenton-type mechanism, bovine heart submitochondrial particles were examined for HO(*) in the presence and absence of iron ligands, antioxidant enzymes and HO(*) scavengers. HO(*) was measured as 2,3- and 2,5-dihydroxybenzoic acid (DHBA), using HPLC with electrochemical detection. The iron ligand desferrioxamine significantly decreased DHBAs, indicating that HO(*) generation required iron redox-cycling. In addition, results from exogenous SOD and catalase, exogenous hydrogen peroxide, and HO(*)-scavenger studies support a Fenton-type reaction mechanism. The results indicate that increased HO(*) levels occur in mitochondria under oxidative stress and that the HO(*) levels can be modulated with antioxidant enzymes and iron ligands. Our findings together with reports on iron accumulation in degenerative diseases highlight the importance of developing mitochondrial-targeted antioxidants for the therapeutic intervention of diseases associated with mitochondrial dysfunction and oxidative stress.
authors.affiliation: Department of Chemistry, Central Washington University, Ellensburg, Washington 98926, USA. cthomas@cwu.edu
authors.forename: Carin
authors.initials: C
authors.lastname: Thomas
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Mackey
authors.forename: Amy A
authors.initials: AA
authors.lastname: Diaz
authors.forename: David P
authors.initials: DP
authors.lastname: Cox
mesh_terms: D000818:Animals; D002396:Catechols / Q000737:chemistry; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D062385:Hydroxybenzoates; D017665:Hydroxyl Radical / Q000737:chemistry* / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013367:Submitochondrial Particles / Q000378:metabolism*
chemical_list: D002396:Catechols; D062385:Hydroxybenzoates; D017382:Reactive Oxygen Species; D017665:Hydroxyl Radical; C009135:2,3-dihydroxybenzoic acid