Journal article
Iron and dioxygen chemistry is an important route to initiation of biological free radical oxidations: an electron paramagnetic resonance spin trapping study
Free radical biology & medicine, Vol.26(11), pp.1447-1456
1999
DOI: 10.1016/S0891-5849(99)00002-7
PMID: 10401608
Abstract
Iron can be a detrimental catalyst in biological free radical oxidations. Because of the high physiological ratio of [O
2]/[H
2O
2] (≥10
3), we hypothesize that the Fenton reaction with pre-existing H
2O
2 is only a minor initiator of free radical oxidations and that the major initiators of biological free radical oxidations are the oxidizing species formed by the reaction of Fe
2+ with dioxygen. We have employed electron paramagnetic resonance spin trapping to examine this hypothesis. Free radical oxidation of: 1) chemical (ethanol, dimethyl sulfoxide); 2) biochemical (glucose, glyceraldehyde); and 3) cellular (L1210 murine leukemia cells) targets were examined when subjected to an aerobic Fenton (Fe
2+ + H
2O
2 + O
2) or an aerobic (Fe
2+ + O
2) system. As anticipated, the Fenton reaction initiates radical formation in all the above targets. Without pre-existing H
2O
2, however, Fe
2+ and O
2 also induce substantial target radical formation. Under various experimental ratios of [O
2]/[H
2O
2] (1-100 with [O
2] ≈ 250 μM), we compared the radical yield from the Fenton reaction vs. the radical yield from Fe
2+ + O
2 reactions. When [O
2]/[H
2O
2] < 10, the Fenton reaction dominates target molecule radical formation; however, production of target-molecule radicals via the Fenton reaction is minor when [O
2]/[H
2O
2] ≥ 100. Interestingly, when L1210 cells are the oxidation targets, Fe
2++ O
2 is observed to be responsible for formation of nearly all of the cell-derived radicals detected, no matter the ratio of [O
2]/[H
2O
2]. Our data demonstrate that when [O
2]/[H
2O
2] ≥ 100, Fe
2++ O
2 chemistry is an important route to initiation of detrimental biological free radical oxidations.
Details
- Title: Subtitle
- Iron and dioxygen chemistry is an important route to initiation of biological free radical oxidations: an electron paramagnetic resonance spin trapping study
- Creators
- Steven Yue Qian - Free Radical Research Institute, The University of Iowa, Iowa City, IA, USAGarry R Buettner - Free Radical Research Institute, The University of Iowa, Iowa City, IA, USA
- Resource Type
- Journal article
- Publication Details
- Free radical biology & medicine, Vol.26(11), pp.1447-1456
- DOI
- 10.1016/S0891-5849(99)00002-7
- PMID
- 10401608
- NLM abbreviation
- Free Radic Biol Med
- ISSN
- 0891-5849
- eISSN
- 1873-4596
- Publisher
- Elsevier Inc
- Language
- English
- Date published
- 1999
- Academic Unit
- Radiation Oncology
- Record Identifier
- 9984047614302771
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