Nitrogen species, scavenging

Figure 10.1 Ward cascade showing the cooperation between cytoprotective enzymes and antioxidants for scavenging of reactive oxygen and reactive nitrogen species.

A problem In the analysis of these data Is the potential masking of some sources of variability by other correlated variables which may be difficult to quantify. For example, the potential meteorological Influences of atmospheric dispersion and mixing, scavenging differences between warm and cold clouds, variable rates of oxidation of sulfur and nitrogen species, and the dilution effect of variable rain volume may mask source-receptor chemical relationships. A particular problem Is that meteorological data and source-receptor locations share directional dependence. 

With emission source chemical signatures and corresponding aerosol or rainwater sample measurements PLS can be used Co calculate a chemical element mass balance (CEB). Exact emission profiles for the copper smelter and for a power plant located further upwind were not available for calculation of source contributions to Western Washington rainwater composition. This type of calculation Is more difficult for rainwater Chan for aerosol samples due Co atmospheric gas to particle conversion of sulfur and nitrogen species and due Co variations In scavenging efficiencies among species. Gatz (14) has applied Che CEB to rainwater samples and discussed Che effect of variable solubility on the evaluation of Che soil or road dust factor. 

Several mechanisms of antioxidant action have been proposed. The presence of antioxidants may result in the decreased formation of the reactive oxygen and nitrogen species in the first place. Antioxidants may also scavenge the reactive species or their precursors. Vitamin E is an example of this latter behavior in its inhibition of lipid oxidation by reaction with radical intermediates generated from polyunsaturated fatty acids. Some antioxidants can bind the metal ions needed to catalyze the formation of the reactive oxidants. Other antioxidants can repair oxidative damage to biomolecules or can influence enzymes that catalyze repair mechanisms. 

The most widely recognized property of tea catechins is their antioxidant property that results from their ability to scavenge reactive oxygen and nitrogen species and... 

Antioxidant activity Scavenging of reactive oxygen species (ROS) and reactive nitrogen species (RNS) " ... 

The conditions to induce strand breaks, oxidation and deamination of DNA require high concentrations of reactive nitrogen oxide species or NO which may not be physiologically relevant (Laval et al. 1997). In vivo, antioxidants and reactive nitrogen oxide species scavengers, such as ascorbate and reduced glutathione, are abundant decreasing the chance that these chemical species directly modify DNA. 

Stevens JF, Miranda CL, Wolthers KR, Schimerlik M, Deinzer ML, Buhler DR (2002) Identification and in vitro biological activities of hop proanthocyanidins inhibition of nNOS activity and scavenging of reactive nitrogen species. J Agric Food Chem 50 3435-3443... 

Chain-breaking antioxidant activity, chemical scavenging of reactive oxygen and nitrogen species... 

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