Catalyze free radical production

The substantia nigra and globus pallidus are rich in iron yet cerebrospinal fluid has very little iron-binding capacity (H2). Moreover, any injury to the CNS may result in the release of iron, which by Fenton/Haber-Weiss chemistry, catalyzes free radical production. Iron has also been shown to accelerate the production of CNS lipofuscin (increased in Alzheimer s disease), while various antioxidants (vitamin E, GSH, selenium) reduce its concentration (E5). 

The dipeptide carnosine (jS-alanyl-histidine) is able to develop antioxidative properties, at least in vitro [9]. The dipeptide, however, does not enhance the metal-catalyzed free radical production, as does histidine. The high concentrations of this metabolite enable it to act as an antioxidant and as an anti-glycox-idation compound. This makes it an interesting substance in several age-related studies [10]. 

Kennedy, C.H. and R.P. Mason (1990). A reexamination of the cytochrome P-450-catalyzed free radical production from a dihydropyridine. Evidence of trace transition metal catalysis. J. Biol. Chem. 265, 11425-11428. 

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. 

Lipid Peroxidation and Free Radical Production Catalyzed by LOXs... 

LIPID PEROXIDATION AND FREE RADICAL PRODUCTION CATALYZED BY LOXs... 

It has been found that the 3-hydroxy-3-methylglutaryl-CoA (HMG CoA) inhibitors statins (atorvastatin, pravastatin, and cerivastatin), widely prescribed cholesterol-lowering agents, are able to inhibit phorbol ester-stimulated superoxide formation in endothelial-intact segments of the rat aorta [64] and suppress angiotensin II-mediated free radical production [65]. Delbose et al. [66] found that statins inhibited NADPH oxidase-catalyzed PMA-induced superoxide production by monocytes. It was suggested that statins can prevent or limit the involvement of superoxide in the development of atherosclerosis. It is important that statin... 

Alternate Crosslinking Modes. In addition to the crosslinking modes previously described, (co)polymers containing 1 and 2 may be cured by other means. For example, under appropriate acidic conditions with limited availability of active hydrogen species cyclic hemiamidals 2 will lose ROH to form the enamide 9 (Scheme 5). This has been demonstrated on model systems, e.g., 2 where vinyl is replaced by methyl ). The product, N-acetylpyrroline, has in turn been converted to nonvolatile products (oligomers) under free radical catalysis. These systems may thus be considered for application in the UV/EB or catalyzed free radical cure field. 

As a consequence, metal chelation is an alternative antioxidant strategy based on sequestering metal ions to prevent metal-catalyzed free radical formation [Brown et al., 1998 Guo et al., 1996 Morel et al., 1998]. To have an antioxidant action by metal chelation, a compound should be (i) able to complex the metal and yield a stable product, and (ii) the resultant complex should be a poor catalyst for the free radical generating reactions where the metal is involved. 

As the two one-electron redox potentials involved are close to 1V, many aromatic compounds can be oxidized to a radical cation. This is a common source of free radical production during intoxication with xenobiotics [31]. The large difference in redox potential between the two couples O2/H2O2 and H2O2/H2O provides a thermodynamic driving force for H2O2 dismutation catalyzed by catalase ... 

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