Abstract
The objective of this study was to compare effects of quin2 and EDTA in iron-driven Fenton-type reactions. Seven different assays for detection of strong oxidants were used: the DMSO, deoxyribose, benzoate hydroxylation, and plasmid DNA strand breakage assays, detection of 8-oxo-deoxyguanosine in deoxyguanosine mononucleosides and calf thymus DNA, and electron spin resonance with the spin-trap (4-pyridyl-1-oxide)- N-tertbutylnitrone (4-POBN) in the presence of ethanol or DMSO. With H 2O 2 and Fe 3+, quin2 generally strongly increased the formation of reactive species in all assays, whereas with EDTA the results varied between the assays from barely detectable to highly significant increases compared to H 2O 2 and unchelated Fe 3+. We found that the species produced in the reaction between Fe 3+-quin2 and H 2O 2 behaved like the hydroxyl radical in all assays, whereas with Fe 3+-EDTA no clear conclusion could be drawn about the nature of the oxidant. The effect of quin2 on the formation of oxidants on Fe 2+ autoxidation, varied from generally inhibiting to slightly promoting, depending on the assay used. EDTA had a promoting effect on the amount of oxidant detected by all but one assay. None of the autoxidation systems produced DMSO or ethanol radical adducts with 4-POBN. In the presence of either chelator, H 2O 2, and Fe 2+ DMSO and ethanol radical adducts of 4-POBN were produced. Using the Fe 2+ indicator ferrozine, evidence for direct reduction of Fe 3+-quin2 by H 2O 2 was found. Superoxide anion radical appeared to be less efficient than H 2O 2 as reductant of Fe 3+-quin2 as addition of superoxide dismutase in the ferrozine experiments only decreased the amount of Fe 2+ available for Fenton reaction by 10–20%. The main conclusions from our study are that the reduction of Fe 3+-quin2 can be driven by H 2O 2 and that Fe 2+ in the following oxidation step produces a species indistinguishable from free hydroxyl radical.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
