科研之友
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摘要
Generation of reactive oxygen species (ROS) - including superoxide (O-center dot(2)-), hydrogen peroxide (HOOH), and hydroxyl radical ((OH)-O-center dot) - has been suggested as one mechanism underlying the adverse health effects caused by ambient particulate matter (PM). In this study we compare HOOH and (OH)-O-center dot production from fine and coarse PM collected at an urban (Fresno) and rural (Westside) site in the San Joaquin Valley (SJV) of California, as well as from laboratory solutions containing dissolved copper or iron. Samples were extracted in a cell-free, phosphate-buffered saline (PBS) solution containing 50 mu M ascorbate (Asc). In our laboratory solutions we find that Cu is a potent source of both HOOH and (OH)-O-center dot, with approximately 90% of the electrons that can be donated from Asc ending up in HOOH and (OH)-O-center dot after 4 h. In contrast, in Fe solutions there is no measurable HOOH and only a modest production of (OH)-O-center dot. Soluble Cu in the SJV PM samples is also a dominant source of HOOH and (OH)-O-center dot. In both laboratory copper solutions and extracts of ambient particles we find much more production of HOOH compared to (OH)-O-center dot: e.g., HOOH generation is approximately 30-60 times faster than (OH)-O-center dot generation. The formation of HOOH and (OH)-O-center dot are positively correlated, with roughly 3% and 8% of HOOH converted to (OH)-O-center dot after 4 and 24 h of extraction, respectively. Although the SJV PM produce much more HOOH than (OH)-O-center dot, since (OH)-O-center dot is a much stronger oxidant it is unclear which species might be more important for oxidant-mediated toxicity from PM inhalation.
- 出版日期2012-1
