Superoxide dismutase increased activity

Recently, several studies have found that black tea and green tea offered protection against oxidative damage to red blood cells induced by a variety of inducers, such as hydrogen peroxide, primaquine, 2,2 -azo-fc (2-amidinopropane) dihydrochloride (AAPH), phenylhydrazine, copper-ascorbic acid, and the xanthine/xanthine oxidase system. Recently, we found that oral feeding of green tea leaves to rats resulted in enhanced superoxide dismutase (SOD) activity in serum and catalase activity in liver and an increased concentration of glutathione in the liver. ... 

PHY is metabolized to eseroline which is further hydroxylated to form catechol and its oxidative product rubreserine (o-quinone). Eseroline causes damage to neuronal ceUs. hi another investigation, the changes in antioxidant enzymes were studied in brain regions in response to chronic infusion of PHY (34.5 jig/kg/hr) in rats that were sacrificed at the end of days 1, 7, and 12 of infusion. PHY infusion increased superoxide dismutase (SOD) activity in brain stem (122 and 123% of control) and in striatum (119 and 117% of control) on days 7 and 12, respectively. PHY infusion depressed catalase activity in the brain stem, while glutathione peroxidase activity increased in the brain stem (153 and 151% of control) and in cortex (114 and 138% of control) on days 7 and 12 of PHY infusion, respectively. This study suggests... 

Marttila, R.J., Lorentz, H. and Rinne, U.K. (1988) Oxygen toxicity protecting enzymes in Parkinson s disease. Increase of superoxide dismutase-like activity in the substantia nigra and basal nucleus. ]. Neurol. Sci. 86 321-331... 

In these VX aerosol inhalation studies. Western blot analyses showed that xanthine oxidoreductase, an enzyme-producing superoxide, is activated in response to VX inhalation exposure at 343 mg x min/m. VX inhalation also triggered IL-6 expression in rat Ixmg tissue. In VR-exposed rats, lung lavage assays showed decreased GSH concentration and superoxide dismutase (SOD) activity, which indicates a local oxidative stress environment. Western blot analyses of Ixmg tissue 6h post-expo-sure demonstrated an increased expression of xanthine oxidase, increased IL-ip expression, and activation of phosphorylation of p38 and Akt suggesting stimulation of inflammatory mechanisms. 

Carrillo, M.C., Kanai, S., Sato, Y., Nokubo, M., Ivy, G.O. and Kitani, K. (1993). The optimal dosage of (-) deprenyl for increasing superoxide dismutase activities in several brain regions decreases with age in male Fischer 344 rats. Life Sci. 52, 1925-1934. 

The mitochondrial dysfunctionality seen in manganese neurotoxicity might be related to the accumulation of reactive oxygen species (Verity, 1999). Mitochondrial Mn superoxide dismutase (MnSOD) is found to be low or absent in tumour cells and may act as a tumour suppressor. It is induced by inflammatory cytokines like TNF, presumably to protect host cells. In a rat model, iron-rich diets were found to decrease MnSOD activity, although a recent study reported that in rat epithelial cell cultures iron supplementation increased MnSOD protein levels and activity, but did not compromise the ability of inflammatory mediators like TNF to further increase the enzyme activity (Kuratko, 1999). 

Observations Table 1 shows the activity of the antioxidant enzymes of tomato roots after 72 h of exposure of allelochemical stress caused by S. deppei. Catalase (CAT) activity increases by 1.5 fold Ascorbate Peroxidase (APX) decreases 2.3 fold Glutathione reductase (GR) activity does not change with the treatment and Superoxide dismutase (SOD) decreases 1.3 fold. 

The basis of this assay was first used to measure the activity of superoxide dismutase (SOD) using a xanthine/xanthine oxidase 02"-generating system. O2 generated via this enzyme will reduce feni (oxidised)-cytochrome c, but SOD (which has a much higher affinity for O2" than cytochrome c) will prevent this reduction. Babior, Kipnes and Cumutte (1973) modified this technique to provide a specific assay to measure O2 production by activated neutrophils. Thus, 02" reduces cytochrome c (measured by an absorbance increase at 550 nm), but this reduction will be blocked by the addition of exogenous SOD (Fig. 5.10). 

Figure 5.10. Cytochrome c reduction by 02 Production of 02 from activated neutrophils may be assayed using cytochrome c. Oxidised (Fe3+) cytochrome c can be reduced by 02" to form Fe2+-cytochrome c, which absorbs at 550 nm thus, in a mixture of activated neutrophils and cytochrome, absorption increases at 550 nm are due to 02 production. Superoxide dismutase (SOD) has a higher affinity for 02 than does cytochrome c thus, the addition of SOD to activated neutrophil suspensions will prevent the reduction of cytochrome c. SOD-inhibitable cytochrome c reduction is therefore a direct measure of the rate of 02 formation.

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