Impacts of antioxidants on hydroxyl radical production from individual and mixed transition metals in a surrogate lung fluid
Inhalation of ambient particulate matter causes morbidity and mortality in humans. One hypothesized mechanism of toxicity is the particle-induced formation of reactive oxygen species (ROS) – including the highly damaging hydroxyl radical ( OH) – followed by inflammation and a variety of diseases. Wh...
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Published in | Atmospheric environment (1994) Vol. 45; no. 40; pp. 7555 - 7562 |
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Main Authors | , |
Format | Journal Article Conference Proceeding |
Language | English |
Published |
Kidlington
Elsevier Ltd
01.12.2011
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Inhalation of ambient particulate matter causes morbidity and mortality in humans. One hypothesized mechanism of toxicity is the particle-induced formation of reactive oxygen species (ROS) – including the highly damaging hydroxyl radical (
OH) – followed by inflammation and a variety of diseases. While past studies have found correlations between ROS formation and a variety of metals, there are no quantitative measurements of
OH formation from transition metals at concentrations relevant to 24-hour ambient particulate exposure. This research reports specific and quantitative measurements of
OH formation from 10 individual transition metals (and several mixtures) in a cell-free surrogate lung fluid (SLF) with four antioxidants: ascorbate, citrate, glutathione, and uric acid. We find that Fe and Cu can produce
OH under all antioxidant conditions as long as ascorbate is present and that mixtures of the two metals synergistically increase
OH production. Manganese and vanadium can also produce
OH under some conditions, but given that their ambient levels are typically very low, these metals are not likely to chemically produce significant levels of
OH in the lung fluid. Cobalt, chromium, nickel, zinc, lead, and cadmium do not produce
OH under any of our experimental conditions. The antioxidant composition of our SLF significantly affects
OH production from Fe and Cu: ascorbate is required for
OH formation, citrate increases
OH production from Fe, and both citrate and glutathione suppress
OH production from Cu. MINTEQ ligand speciation modeling indicates that citrate and glutathione affect
OH production by changing metal speciation, altering the reactivity of the metals. In the most realistic SLF (i.e., with all four antioxidants), Fe generates approximately six times more
OH than does the equivalent amount of Cu. Since levels of soluble Fe in PM are typically higher than those of Cu, our results suggest that Fe dominates the chemical generation of
OH from deposited particles in the lungs.
►Of 10 metals tested, Fe and Cu produce the most
OH in a surrogate lung fluid. ►Antioxidant composition significantly affects
OH production from metals. ►Glutathione and citrate alter
OH production by changing metal speciation. ►Mixtures of Fe and Cu synergistically produce
OH |
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Bibliography: | http://dx.doi.org/10.1016/j.atmosenv.2010.12.021 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1352-2310 1873-2844 |
DOI: | 10.1016/j.atmosenv.2010.12.021 |