Free radical scavenging system

Asayama, K., Kooy, N.W. and Burr, I.M. (1986). Effect of vitamin E deficiency and selenium deficiency on insulin reserve and free radical scavenging systems in islets decrease of islet manganosuperoxide dismutase. J. Lab. Clin. Med. 107, 459-463. 

Perumal, A.S., Gopal, V.B., Tordzro, W.K., Cooper, T.B. and Cadet, J.L. (1992). Vitamin E attenuates the toxic effects of 6-hydrooxydopamine on free radical scavenging systems in rat brain. Brain Res. Bull. 29, 699-701. 

W.C. Stallings, C. Bull, J.A. Fee, M.S. Lah, and M.L. Ludwig, in Molecular Biology of Free Radical Scavenging Systems (J. Scandalios, Ed.) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, p. 193 (1992). 

K. Asada, in Molecular Biology of Free Radical Scavenging Systems, p. 173, Cold Spring Harbor Laboratory Press, New York (1992). 

Using various free radical scavenging systems. Jolly et al. (1984), Burton (1985), Ambrosio et al. (1986), Bolli et al. (1987) and Bhatnagar (1995) have shown a link between myocardial ischaemia and reperfusion injury and the generation of various toxic free radical species. Sharma et al. (1994) in an electron paramagnetic resonance study found ascorbyl free radical as a real-time marker of free radical generation in briefly ischaemic and reper-fused dog hearts. Only Uraize et al. (1987) were unable to limit the size of myocardial necrosis after 40 min of ischaemia by superoxide dismutase. 

In a study of different free radical scavenging systems, it was observed that the jambolan skin had significant antioxidant activity, which was attributed in part to antioxidant vitamins, phenolics or tannins, and anthocyanins (Baneijee etal., 2005). 

The antioxidant activity of the four phytochemicals isolated from rosemary were assayed in a DPPH free radical scavenge system. Carnosic acid, camosol and rosmarinic acid showed concentration-dependent scavenging ability. These phytochemicals were more potent than vitamin C and vitamin E. The 50% DPPH... 

A simplified experimental system results when free radical scavengers such as nitric oxide, iodine, or oxygen are added to the samples before... 

Lebedev, A.V., Ivanova, M.V., and Levitsky, D.O., Echinochrome, a naturally occurring iron chelator and free radical scavenger in artificial and natural membrane systems. Life Sci., 76, 863, 2005. 

Sanchez-Moreno C. 2002. Review Methods used to evaluate the free radical scavenging activity in foods and biological systems. Food Sci Technol Int 8(3) 121—137. 

From chemical point of view, efficient free radical scavengers must contain substituents with the very weak C—H, O—H, or S—H bonds, from which reactive free radicals are able to abstract a hydrogen atom. It can be seen that the antioxidants discussed above (ascorbic acid, a-tocopherol, ubihydroquinones, glutathione, etc) fall under this category. However, many other compounds manifest free radical scavenging activity in in vitro and in vivo systems. 

No information is available on the adverse health effects of hexachloroethane in humans. Animal studies revealed that hexachloroethane primarily causes liver and kidney toxicity. Effects on the nervous system and lungs have also been reported. The mechanism by which these effects are mediated is not well characterized. Reductive metabolism by cytochrome P-450 and production of a free radical intermediate have been suggested as factors in hexachloroethane-induced hepatotoxicity (Nastainczyk et al. 1982a Thompson et al. 1984 Town and Leibman 1984). Accordingly, one possible approach may be to reduce free radical injury. To that end, oral administration of N-acetylcysteine can be used as a means of reducing free radical injury. Also, oral administration of vitamin E and vitamin C may be of value since they are free radical scavengers. 

Section 2 deals with reactions involving only one molecular reactant, i.e. decompositions, isomerisations and associated physical processes. Where appropriate, results from studies of such reactions in the gas phase and condensed phases and induced photochemically and by high energy radiation, as well as thermally, are considered. The effects of additives, e.g. inert gases, free radical scavengers, and of surfaces are, of course, included for many systems, but fully heterogeneous reactions, decompositions of solids such as salts or decomposition flames are discussed in later sections. Rate parameters of elementary processes involved, as well as of overall reactions, are given if available. 

For treatment by the ZPU, a waste stream must be in the vapor phase at near-ambient pressure, at a temperature of less than 400°F, and relatively free of particulate matter. Each compound in the waste stream has unique requirements for destruction. Many compounds are destroyed with a low application of energy, while others require a stronger application. The dose required for a specific combination of contaminants must be determined experimentally. Moisture may either enhance or reduce system effectiveness depending on the mixture. Compounds that act as free-radical scavengers or reducing agents may diminish the process efficiency. Concentrations of vapors that produce temperatures above 400°F in the reaction chamber through exothermic reaction must be diluted to keep the temperature below 400°F. 

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