Reactive oxide species

DIPLOCK A T, CHARLEUX J L, CROZIER-WILLI G, KOK F J, RICE-EVANS C, ROBERFROID M, STAHL W, VINA-RIBES J. (1998) Functional food science and defence against reactive oxidative species. /Airir. 80 S77-112. 

The use of chemiluminescence techniques therefore raises two questions. Firstly, what is the nature of the intracellular chemiluminescence Secondly, what reactive oxidant species are detected by this technique ... 

The H202 so produced is also a reactive oxidizing species capable of causing cellular damage, so it too needs to be removed by catalase at the expense of glutathione (GSH), thus ... 

Diplock, A.T., Charleux, J.-L., Crozier-Willi, G., Bung, P., Kok, F.J., Rice-Evans, C.A., Rober-froid, M., Stahl, W., and Vina-Ribes, J., Functional food science and defence against reactive oxidative species, Br. J. Nutr., 80, S77, 1998. 

Short-Lived Species in Fluid Solution. - In fluid solution, radical cations derived from saturated hydrocarbons are highly reactive oxidizing species and the rates of their bimolecular reactions are often determined by the frequency of diffusion collisions in solutions. It is known that the reactions of primary radical... 

A Cr(VI)-catalyst complex has been proposed as the reactive oxidizing species in the oxidation of frans-stibene with chromic acid, catalysed separately by 1,10-phenanthroline (PHEN), oxalic acid, and picolinic acid (PA). The oxidation process is believed to involve a nucleophilic attack of the olefinic bond on the Cr(VI)-catalyst complex to generate a ternary complex.31 PA- and PHEN-catalysed chromic acid oxidation of primary alcohols also is proposed to proceed through a similar ternary complex. Methanol- reacted nearly six times slower than methanol, supporting a hydride transfer mechanism in this oxidation.32 Kinetics of chromic acid oxidation of dimethyl and diethyl malonates, in the presence and absence of oxalic acid, have been obtained and the activation parameters have been calculated.33 Reactivity in the chromic acid oxidation of three alicyclic ketoximes has been rationalized on the basis of I-strain. Kinetic and activation parameters have been determined and a mechanism... 

A mechanism involving a diperoxomolybdenum(VI) species as the reactive oxidizing species has been proposed.128... 

One of the most intriguing reactions in the chytochrome P450 catalysis is the transfer of second electron and dioxygen activation, which appears to be a key step of the entire process. The chemical nature of reactive oxidizing species appears in the coordination sphere of heme iron and the mechanism of hydroxylation of organic compounds, saturated hydrocarbons in particular, is a much debated question in the field of the cytochrome P450 catalysis. To solve this problem, an entire arsenal of modern experimental and theoretical methods are employed. The catalytic pathway of cytochrome P450cam from Pseudomonas putida obtained on the basis of X-ray analysis at atomic resolution is presented in Fig. 3.10. 

The situation is even more complex in the case of the interaction between reactive oxidizing species (ROS) and the HIF system (for review see References 103, 104). Quantifying the role of ROS, such as superoxide, is difficult because of their reactivity and ability to affect many cellular processes. Good evidence suggests that under stress conditions ROS can regulate HIF, possibly via interaction with the HIF hydroxylases (see e.g.. References 94, 105, and 106), but the molecular mechanisms are unclear, as is the relevance of ROS regulation of HIF under normal physiological conditions. 

It is known that exposure to reactive oxidation species and subsequent DNA damage can be linked to diseases, such as cancer and rheumatoid arthritis, and to aging. " Volk et al used MP2 theory and DFT to study the oxidized cytosine product, 5-hydrox5mracil. Oxidized cytosine products have been shown to be major chemical precursors in DNA for GC to AT transition mutations.In related work, Volk et al studied the highly mutagenic 5-formyluracil which results from oxidation of the th5unine methyl group. 

Oxidation is an important catalytic phenomenon, and many industrially and scientifically interesting reactions can be characterized as oxidations. Section 5.5 focuses on chemically catalyzed oxidation reactions. The present section, however, focuses on elementary steps in biocatalytic oxidation reactions. Thus, special emphaisis is placed on elementary principles used by biocatalysts to generate powerful and reactive oxidizing species capable of performing oxidation reactions under mild reaction conditions. Biocatalytic oxidation reactions can vary from simple electron transfer redox reactions to peroxidase-, monooxygenase-, dioxygenase- and oxidase-type of reactions, the basic principles of which will be outlined in this section. 

Bromide and iodide also can be oxidized by reactive oxidizing species tha are produced photochemically (ref. 57 and references therein). The resultin halide radicals may react with NOM to produce halocarbons, although fe field or laboratory studies have examined these reactions. 

Ferroquine possesses planar chirality due to the non-symmetrical 1,2-substitution of the ferrocene entity, and the pure enantiomers (+)35 and (—)35 were obtained by enzymatic resolution using the Candida rugosa lipase as a biocatalyst. The enantiomeric purity levels exceed 98%. However, the two optical isomers display identical activity in vitro at the nanomolecular level. In vivo, however, either of the enantiomers alone is less active than the racemic mixture against both chloroquine-sensitive and chloroquine-resistant strains. In addition, (4-)35 displays better curative effects than (—)35, suggesting different pharmacokinetic properties. The reasons for the enhanced behavior of racemic ferroquine have not yet been elucidated. It is still not clear whether 35 is oxidized by the parasite to give the ferricinium ion, thus initiating Fenton-type reactivity. Such a hypothesis is reasonable, given that reactive oxidative species can escalate in cancer cells due to the malfunction of mitochondria. ... 

Tlie ability to respond to oxidative stress is a critical determinant of life-span. Tlie production of oxidants and the scavenging of reactive oxidant species involve cellular strategies for detection and detoxification of reactive oxygen species and are linked to longevity [520] 4 3 jjgjg mutations with links to stress resistance in multicellular organisms... 

Intermediates detected during the photocatalytic degradation of halogenated aromatic compounds have been typically hydroxylated stractures and this gives indirect evidence of hydroxyl radicals as the primary reactive oxidant species (13, 14). Such hydroxylated intermediates are also formed when halogenated aromatics are reacted with known precursors of hydroxyl radicals. 

Studying the use of microspheres encapsulated with glucose oxidase (GOX) for MDR cancer treatment [115], We found that cancer cells can be extensively killed by the reactive oxidative species generated by the encapsulated GOX enzyme. The most appealing feature of this therapy is that the GOX-mediated cytotoxic effect is essentially unaffected by the MDR phenotype (Fig. 4). Further studies will be conducted to optimize this strategy. 

In our experiments we generally use peroxynitrite and other reactive oxidant species to induce DNA damage- Oiu- data are mainly obtained in thymocytes where peroxynitrite-induced poly-ADP-ribosylation involves multilevel mitochondrial-nuclear cross-talk (Fig. 3) involving both the formation of and the biological response to ONA dama ng species. 

Figure 4.36 Proposed mechanism for the formation of the reactive oxidizing species, the Fe v=o intermediate, generated in a typical 2-electron oxidation process characteristic for 20G oxygenases.

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