Generate reactive oxygen species

Taking into account all of the abovementioned studies, one is compelled by the evidence to conclude that, at least under conditions of ischaemia/reperfiision, the brain certainly has the capacity to generate reactive oxygen species and that these reactive oxygen species are likely to play an important role in the pathology that results from... 

Certain bifunctional metal chelating agents have been used to investigate protein interactions by virtue of their ability to generate reactive oxygen species that affects protein structure in the immediate vicinity of their modification site. The following sections discuss two applications of such chelate labels, one of which cleaves peptide bonds while the other one causes covalent crosslinks to occur between interacting protein structures. 

Many organic and inorganic compounds, fibers, and particles are capable of damaging nucleic acids by generating reactive oxygen species via the reduction of dioxygen. These stimuli include different classes of organic compounds, classic prooxidants (anticancer antibiotics, various quinones, asbestos fibers, and so on), and even antioxidants, which can be oxidized in the presence of transition metal ions. 

Nitric oxide and peroxynitrite contribute to oxidative damage 569 Production of eicosanoids from polyunsaturated fatty acids such as arachidonic acid may generate reactive oxygen species 570 Brain antioxidant defenses modify ischemia-reperfusion injury 570 Reactive oxygen species may modify both the excitotoxic and the apoptotic components of ischemic brain damage 570... 

Some metabolites, most commonly aromatic hydroxylamines and quinone-type metabolites, can undergo redox cycling and generate reactive oxygen species, especially... 

The aim of the work was evaluation of the ability of photoexcited fullerene C60 and synthesized fullerene C60-containing composites to generate reactive oxygen species (ROS) and to perform comparative analysis of the state of the cells of two types (normal ones - thymocytes, and malignant ones - the cells of ascite Erhch carcinoma [EAC] and leucosis L1210) by such indexes as viability, content of LPO products, MTT test, and DNA fragmentation upon incubation in the presence of photoexcited fullerene C60. 

Garcia-Ruiz, C., Colell, A., Paris, R., and Femandez-Checa, J. C., 2000, Direct interaction of GD3 ganghoside with mitochondria generates reactive oxygen species followed by mitochondrial permeabihty transition, cytochrome c release, and caspase activation. Faseb J14 847-858. 

P19 It has become evident that fine particulate matter has the ability to generate reactive oxygen species (ROS) (10, 11). This is striking... 

Aminolevulinic acid (ALA HCl, Levulan Kerastick) is indicated for the treatment of nonhyperkeratotic actinic keratosis of the face and scalp. It has two components, an alcohol solution vehicle and ALA HCl as a dry solid. The two are mixed prior to application to the skin. When applied to human skin, ALA is metabolized to protoporphyrin, which accumulates and on exposure to visible light produces a photodynamic reaction that generates reactive oxygen species (ROS).The ROS produce cytotoxic effects that may explain therapeutic efficacy. Local burning and stinging of treated areas of skin due to photosensitization can occur. 

Another example is paraquat, which can accept an electron from donors such as NADPH, becoming a stable free radical, which is not chemically reactive. However, it will generate reactive oxygen species by donating an electron to available oxygen (see chap. 7). 

Hydroquinones, for example, can form semiquinone radicals and then quinones in a two-step oxidation reaction. The semiquinone radical is potentially reactive but so also is the quinone, which can easily form an electrophile. Furthermore, quinones can also take part in redox cycling by accepting electrons and so generate reactive oxygen species. 

Basta G., Lazzerini G., Del Turco S., Ratto G. M., Schmidt A. M., and De Caterina R. (2005). At least 2 distinct pathways generating reactive oxygen species mediate vascular cell adhesion molecule-1 induction by advanced glycation end products. Arterioscler. Thromb. Vase. Biol. 25 1401-1407. 

Nitrilotriacetic acid (NTA) is a constituent of various domestic and hospital detergents and is a common water contaminant. NTA forms water-soluble chelate complexes with various metal ions, including iron, at neutral pH. Its iron complex, Fe-NTA, is a known potent nephrotoxic agent. The renal toxicity is assumed to be caused by the elevation of serum free-iron concentration following the reduction of Fe-NTA at the luminal side of the proximal tubule, which generates reactive oxygen species and leads to enhancement of lipid peroxidation. 

Although structurally and spectrally similar, the differing redox and photophysical properties of the various lanthanide(III) texaphyrin complexes allow their use in such disparate areas as PDT, direct cancer treatment, and both X-ray and chemotherapy enhancement protocols. Both compounds 1 and 2 generate reactive oxygen species (ROS), albeit via mechanistically distinct pathways (vide infra). The ROS are thought to be responsible, at least in part, for the observed biological activity of MGd and MLu [22],... 

The structurally similar, but magnetically distinct, lanthanide(III) texaphyrin complexes, MLu and MGd both generate reactive oxygen species (ROS), albeit via different mechanisms. Photoirradiation of MLu causes excitation from the singlet ground state to the triplet state (Fig. 3). 

Seo JH, Ahn Y, Lee SR, Yeol YC, Chung HK. 2005. The major target of the endogenously generated reactive oxygen species in response to insulin stimulation is phosphatase and tensin homolog and not phosphoinositide-3 kinase (PI-3 kinase) in the PI-3 kinase/Akt pathway. Mol Biol Cell 16 348-357. 

It is not known how much of the oxygen consumption of the cell is turned over to generating reactive oxygen species, but the figure is thought to be between 2% (Chance et al. 1979) and 0.2% (St-Pierre et al. 2002 Staniek and Nohl 2000). The cell has very efficient scavenging mechanisms, and so these figures may be underestimates. 

Reoxidation of reduced flavin coenzymes is the major source of oxygen radicals in the body, and riboflavin is also capable of generating reactive oxygen species nonenzymically. As protection against this, there is very strict control over the body content of riboflavin. Absorption is limited, and any in excess of requirements is rapidly excreted. 

---