Reaction modeling reactive oxygen species

During the ferroxidation reaction, a blue color with an absorption maximum of 650 run appears. This persists in oxygen-limited conditions and decays as iron oxidation proceeds. " In frog H-chain ferritin, resonance Raman studies indicate a similar absorption is associated with an Fe(III)-tyrosinate. Harrison and Treffty have considered these and other studies and attribute the transient color to formation of a /x-l,2-peroxodiferric intermediate, which decays to a more stable /x-oxodiferric species as occurs in methane monooxygenase, ribonucleotide reductase, and model compounds. Protein radicals distinct from reactive oxygen species have been observed that have been attributed to damage caused by Fenton chemistry. ... 

This chapter reviews past studies of other investigators and presents previously unpublished laboratory studies relating to photochemical reactions of halocarbons in aquatic environments. Kinetics considerations relevant to the modeling of halocarbons in natural waters are briefly considered. Then direct and indirect photoreactions that provide sinks for halocarbons are examined with consideration of the effects of sorption onto dissolved NOM and suspended sediments. Photoreductive dehalogenation is emphasized. Finally, the role of photochemically produced reactive oxygen species in the production of halocarbons in the aquatic environment is discussed. The main emphasis is on field and laboratory studies that provide predictive capability and a mechanistic understanding of the processes. 

In addition to their broncho dilatory action in asthma, P-agonistically active substances of diphe-nolic structure offer radical scavenging properties toward reactive oxygen species as shown in a model system by electron paramagnetic resonance spectroscopy and photometric approaches (Zwicker et al. 1998). The substances under study showed activity in superoxide radical scavenging under aprotic and protic conditions as well. The efficiency of the reaction decreased in the order fenoterol > salbuta-mol > reproterol > terbutaline > oxyfedrine when 5,5-dimethyl-l-pyrroline-N-oxide (DMSO) was used as an aprotic solvent. In an aqueous system, the rate constants decreased in the order fenoterol > reproterol > salbutamol. 

The voltammetric method uses the process of oxygen electroreduction (ER O ) as modeling reaction. This process is similar to oxygen reduction in tissues and plant extracts. It proceeds at the working mercury film electrode (MFE) in several stages with formation of the reactive oxygen species (ROS), such as O and HO [6] ... 

Chuyen, N.V. Ijichi, K. Moteki, K. On the formation and scavenging of reactive oxygen species by Amino-carbonyl reaction products in model and food systems. Nippon Kagaku Kaishi. 1996, 70, 20. 

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