Antioxidants spinning

Polyakov, N. E., A. I. Kruppa et al. (2001b). Carotenoids as antioxidants Spin trapping, EPR and optical studies. Free Rad. Biol. Med. 31 43-52. 

The reaction of eq. 16.9 will regenerate the antioxidant Arj-OH at the expense of the antioxidant At2-OH. Despite the fact that such regeneration reactions are not simple electron transfer reactions, the rate of reactions like that of eq. 16.9 has been correlated with the E values for the respective Ar-0. Thermodynamic and kinetic effects have not been clearly separated for such hierarchies, but for a number of flavonoids the following pecking order was established in dimethyl formamid (DMF) by a combination of electrolysis for generating the a-tocopherol and the flavonoid phenoxyl radicals and electron spin resonance (ESR) spectroscopy for detection of these radicals (Jorgensen et al, 1999) ... 

ANDERSEN M L, ouTTRUP H and SKIBSTED L H (2000) Potential antioxidants in beer assessed by ESR spin trapping, J Agric Food Chem, 48, 3106-11. 

GARDNER p T, MCPHAIL D B and DUTHIE G G (1998) Electron spin resonance spectroscopic assessment of the antioxidant potential of teas in aqueous and organic media, J Sci Food Agric, 76, 257-62. 

Gregor, W. Grabner, G. Adelwohrer, C. Rosenau, T. Gille, L. Antioxidant properties of natural and synthetic chromanol derivatives study by fast kinetics and electron spin resonance spectroscopy. J. Org. Chem. 2005, 70(9), 3472-3483. 

The scavenging ability toward O2 can also be measured by using electron spin resonance (ESR) spectrometry. The 02 anion is trapped with 5,5-dimethyl-1-pyrroline TV-oxidc (DMPO), and the resultant DMPO-OH adduct is detected by ESR using manganese oxide as internal standard. Noda and others (1997) used this technique to evaluate antioxidant activities of pomegranate fruit extract and its anthocyanidins (delphinidin, cyanidin, and pelargonidin). 

Skladanowski, A., and Konopa, J., 1993, Adriamycin and daunomycin induce programmed ceU death (apoptosis) in tumor ceUs. Biochem. Pharmacol. 46 375-382 Slater, A.F.G., Nobel, C.S.L, Maelaro, E., Bustamante, J., Kimland, M., and Orrenius, S., 1995, Nitrone spin traps and a nitroxide antioxidant inhibit a common pathway in thymocyte apoptosis. Biochem. J. 306 771-778 Snyder, R., Jowa, L., Witz, G., Kalf, G., and Rushmore, T., 1987, Formation ofreactive metabolites from benzene. Arch. Toxicol. 60 61-64. 

The expression of several genes is induced or repressed by hemopexin-mediated heme transport. Most of these are simple responses of the cell to the increased heme (or iron derived from heme) in the cell. For example, HO-1 is induced (15, 88), ferritin levels rise (14, 61, 89), the transferrin receptor is down-regulated (15), and hemopexin mRNA itself is induced (A. Smith, unpublished). However, MT-1 is also induced, apparently to prepare the cell for oxidative stress thus, in addition to sequestering heme in a low-spin, non-oxidatively active form, hemopexin also indirectly exerts antioxidant effects by inducing MT-1 (16, 61, 90). 

Mainly during the last decade structural information regarding flavonoids associated with other molecules has been reported. High-resolution H magic angle spinning (MAS) NMR spectroscopy has been used to investigate the structural basis for the antioxidative effects of... 

Popular EPR-based assays of antioxidant activity include the DPPH assay, in which the ability of compounds to quench (by H-atom transfer) the 1,1-diphenyl-2-picrylhydrazyl radical is used to rank their antioxidant activity. This method has been applied widely to the analysis of dietary antioxidants and extracts from medicinal plants.213 219 Extensive use has also been made of assays based on the competition between spin traps and test compounds for reaction with enzymatically-generated 02 and, in the presence of a metal catalyst, the OH rad-... 

A number of studies have examined the antioxidant activities of chitosan from various sources. Park et al. (2004a) prepared three kinds of partially deacetylated hetero-chitosans such as 90% deacetylated, 75% deacetylated, and 50% deacetylated chitosan from crab chitin, and their antioxidant properties were measured using electron spin resonance spectrometry. Park and coworkers found that their antioxidant activities were dependent on the DD, and the 90% deacetylated chitosan showed the highest free radical scavenging activities. Yen et al. (2008) also found that a sample with more amino groups at the C-2 position showed the highest antioxidant activity. Tomida et al. (2009) examined the protective effects of seven different MW chitosans on plasma protein from oxidation by peroxyl radicals. In the ability to protect plasma protein from... 

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