Active oxygenating species

FIGURE S.47 The role of glutathione and metabolic pathways involved In the protection of tissues against Intoxication by electrophiles, oxidants and active oxygen species. (Used with permission.)... 

Marsh, J. P., and Mossman, B. L (1991) Role of asbestos and active oxygen species in. ictiva-rion. and expression of ornirhinc decarboxylase in hamster tracheal epithelial cells. Cancer Ra. 51(1), 167-173. 

Nakano, M. (1998). Detection of active oxygen species in biological systems. Cell. Mol. Neurobiol. 18 565-579. 

Suzuki, N., etal. (1991). Studies on the chemiluminescent detection of active oxygen species 9-acridone-2-sulfonic acid, a specific probe for superoxide. Agric. Biol. Chem. 55 1561-1564. 

Suzuki, N., et al. (1991). Chemiluminescent detection of active oxygen species, singlet molecular oxygen and superoxide, using Cypridina luciferin analogs. Nippon Suisan Gakkaishi 57 1711-1715. 

Tawa, R., and Sakurai, H. (1997). Determination of four active oxygen species such as H2O2, OH, OJ and 02 by luminol-and CLA-chemiluminescence methods and evaluation of antioxidative effects of hydroxybenzoic acid. Anal. Lett. 30 2811-2825. 

In the luminescence systems that require a peroxide or an active oxygen species in addition to molecular oxygen (the scaleworm, the tube worm Chaetopterus, the clam Pholas, the squid Symplecto-teuthis), their in vitro luminescence reactions reported are much slower and inefficient compared to their bright in vivo luminescence. The true, intrinsic activation factor in their in vivo luminescence should be determined, and the detailed mechanisms of oxidation should be elucidated. 

ALR air-lift reactor AOS active oxygen species C constant in Eq. (13)... 

RAO G N and berk b c (1992) Active oxygen species stimulate vascular smooth muscle cell growth and proto-oncogene expression Circulation Research 70, 593-9. 

Under aqueous conditions, flavonoids and their glycosides will also reduce oxidants other than peroxyl radicals and may have a role in protecting membranal systems against pro-oxidants such as metal ions and activated oxygen species in the aqueous phase. Rate constants for reduction of superoxide anion show flavonoids to be more efficient than the water-soluble vitamin E analogue trolox (Jovanovic et al, 1994), see Table 16.1. 

Handehnan, G.J., Carotenoids as scavengers of active oxygen species, in Handbook of Antioxidants, Cadenas, E. and Packer, L., Eds., Marcel Dekker, New York, 1996, 259. 

Wende R, F-H Bernhardt, K Pfleger (1989) Substrate-modulated reactions of putidamonooxin the nature of the active oxygen species formed and its reaction mechanism. Eur J Biochem 81 189-197. 

Characterization of the oxidized and reduced catalyst surfaces and the active oxygen species. 

Results discussed above show in several lines a distinct biomimetic-type activity of iron complexes stabilized in the ZSM-S matrix. The most important feature is their unique ability to coordinate a very reactive a-oxygen form which is similar to the active oxygen species of MMO. At room temperature a-oxygen provides various oxidation reactions including selective hydroxylation of methane to methanol. Like in biological oxidation, the rate determining step of this reaction involves the cleavage of C-H bond. 

Relatively detailed study has been done for the reaction pathways over Au/Ti02 catalysts mainly because of simplicity in catalytic material components. The rate of PO formation at temperatures around 323 K does not depend on the partial pressure of C3H6 up to 20vol% and then decreases with an increase, while it increases monotonously with the partial pressure of O2 and H2 [57]. A kinetic isotope effect of H2 and D2 was also observed [63]. These rate dependencies indicate that active oxygen species are formed by the reaction of O2 and H2 and that this reaction is rate-determining [57,63,64]. 

Injury to cells and tissues may enhance the toxicity of the active oxygen species by releasing intracellular transition metal ions (such as iron) into the surrounding tissue from storage sites, decompartmentalized haem proteins, or metalloproteins by interaction with delocalized proteases or oxidants. Such delocalized iron and haem proteins have the capacity to decompose peroxide to peroxyl and alkoxyl radicals, exacerbating the initial lesion. 

Kobayashi, K., Sakuma, H. and Arakawa, T. (1991). Role of leukotrienes in damage caused by active oxygen species in cultured gastric mucosal cells. Gastroenterology 100, A99. 

Oka, S., Ogino, K., Hobara, T., Yoshimura, S., Yanai, H., Okazaki, Y., Takemoto, T., Ishiyama, H., Imaizumi, T., Yamasaki and Kanbe, T. (1990a). Role of active oxygen species in diethyldithiocarbamate-induced gastric ulcer in the rat. Experientia 46, 281-283. 

Farber, J.L., Kyle, M.E. and Coleman, J.B, (1990). Biology of disease mechanisms of cell injury by activated oxygen species. Lab. Invest. 62, 670-679. 

ElSisi, A.E.D., Earnest, D.L. and Sipes, LG. (1993b). Vitamin-A potentiation of carbon tetrachloride hepatotoxicity-role of liver macroph es and active oxygen species. Toxicol. Appl. Pharmacol. 119, 295-301. 

Monny, C. and Michelson, A.M. (1982). Fixation of aromatic hv drocarbons to proteins and DNA mediated by superoxide radicals and other activated oxygen species. Biochimie 64, 451-453. 

In acidic media, the reactivity of ethanol on Au electrodes is much lower than in alkaline media. The main product of the oxidation of ethanol on Au in an acidic electrolyte was found to be acetaldehyde, with small amounts of acetic acid [Tremiliosi-FiUio et al., 1998]. The different reactivities and the product distributions in different media were explained by considering the interactions between the active sites on Au, ethanol, and active oxygen species absorbed on or near the electrode surface. In acidic media, surface hydroxide concentrations are low, leading to relatively slow dehydrogenation of ethanol to form acetaldehyde as the main oxidation pathway. In contrast, in alkaline media, ethanol, adsorbed as an ethoxy species, reacts with a surface hydroxide, forming adsorbed acetate, leading to acetate (acetic acid) as the main reaction product. 

Observations The preliminary treatment of the cholinesterase-containing material with allelochemical (or other compound, e.g. active oxygen species, ozone free radicals and peroxides, formed in allelopathic relations) is for 30 min, then a substrate acetylcholinesterase is added to the reaction medium and final reaction of hydrolysis is for 1 h. 

Laccase is one of the main oxidizing enzymes responsible for polyphenol degradation. It is a copper-containing polyphenoloxidase (p-diphenoloxidase, EC 1.10.3.2) that catalyzes the oxidation of several compounds such as polyphenols, methoxy-substituted phenols, diamines, and other compounds, but that does not oxidize tyrosine (Thurston, 1994). In a classical laccase reaction, a phenol undergoes a one-electron oxidation to form a free radical. In this typical reaction the active oxygen species can be transformed in a second oxidation step into a quinone that, as the free radical product, can undergo polymerization. 

Cypridina luciferin analogs are widely used for several analytical applications (determination of substrates, enzymes, active oxygen species such as superoxide), but they are mainly related to CL [241, 242],... 

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