Superoxide scavenging activity assay

Chemiluminescent assay for superoxide-scavenging activity of aldehyde-modified HSA... 

Also in the superoxide anion scavenging assay in the phenazine methosulfate/NADH-nitroblue tetrazolium system, garcinol exhibited potent superoxide anion scavenging activity almost comparable to that of gallic acid and stronger than that of (+)-catcchin [60]. 

Four polysaccharide fractions (PAVF 1,11-a and III) were extracted from the fruit calyx of Physalis alkekengi var. francheti and their chemical compositions were determined. The crude polysaccharide fractions (FCPs) and all purified fractions (PAVF I, Il-a and III) were evaluated for their antioxidant activity by using hydroxyl radical assay (.OH), superoxide radical assay and DPPH assay. All tested compoxmds showed a dose-dependent radical-scavenging activity. Among all, PAVF I had the best scavenger activity on DPPH radical, hydroxyl radical and superoxide anion, and its activity was more pronounced than Vc used as the standard [116]. 

For some stictic acid derivates, Lohezic-Le Devehat et al. (2007) found moderate antiradical activity in the l,l-diphenyl-2-picrylhydrazyl (DPPH) assay and very high superoxide anion scavenging activity. 

Alcohol extractives retarded the oxidation of linoleic acid in vitroThe six compounds isolated from Coix hull possessed free radical scavenging activity in the DPPH assay/ The methanolic extract of the seed also inhibited the production of nitric oxide and superoxide ions in activated macrophages in vitro, which supports the anti-inflammatory effect of job s tears/ ... 

Superoxide dismutase will scavenge the Of formed and will therefore inhibit the reduction of the dianisidine radical by Of. Consequently the dianisidine radical will dismute to yield the divalently oxidized dianisidine. In the presence of superoxide dismutase this reaction is augmented (Fig. 6). The possibility that Of could reduce the final product of dianisidine oxidation and reverse the change in absorbance at 460 nm was tested and was excluded. The assay has been used to determine the rate constant for purified swordfish liver copper/zinc superoxide dismutase (Bannister et al., 1979) and could be applied to crude extracts. The assay was also found applicable to polyacryalmide gels (Misra and Fridovich, 1977c). Gels soaked in riboflavin plus dianisidine, and subsequently illuminated, developed stable brown bands. Peroxidases are also stained by this procedure due to the photochemical production of hydrogen peroxide. However, the development of bands due to peroxidase activity is much slower than the development of bands due to dismutase activity. 

The antioxidant activity of alizarin was established in four different assays (1) suppression of light emission in the p-iodophenol enhanced chemiluminescent assay, (2) scavenging of superoxide anion (02 -) in a hypoxanthine-xanthine oxidase system, (3) protection of rat liver microsomes from lipid peroxidation by ADP/iron(II) ions, and (4) protection of bromobenzene-intoxicated mice from liver injury in vivo [141]. Alizarin was compared with Trolox (water soluble vitamin E), the flavonoid baicalin and green tea proanthocyanidins. In assay (1) the activity of alizarin was 76% of that of Trolox. In assay (2) the inhibition of 02 -induced chemiluminescence was 40%, 32%, 23% and 14% for Trolox, alizarin, green tea polyphenols and baicalin respectively. Alizarin was not significantly active in the lipid peroxidation assay but after baicalin the most active compound in the in vivo assay. This shows again the difficulty in the evaluation of antioxidant activity and the differences between in vitro and in vivo assays [141]. 

In order to monitor SOD activity routinely, assays that require only instrumentation typical of a chemical or biochemical laboratory were set up. The assays consist of a reaction mixture that generates superoxide anion and a coupled redox reaction that scavenges the superoxide ion. The latter reaction is usually followed spectrophoto-metrically. The addition of superoxide dismutase destroys superoxide and inhibits the coupled reaction. The specific activity of the enzyme is determined on the basis of the amount of protein required to slow down to 50% the first-order coupled reaction, i.e., one enzymatic unit is the amount of protein that reduces the rate to 50% and the specific activity corresponds to the number of units per milligram of protein. 

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