Antioxidant properties superoxide anion

Superoxide anion scavenging activity of the enzymatically synthesized poly(catechin) was evaluated. Poly(catechin), synthesized by HRP catalyst, greatly scavenged superoxide anion in a concentration-dependent manner, and almost completely scavenged at 200 p.M of a catechin unit concentration. The laccase-catalyzed synthesized poly(catechin) also showed excellent antioxidant property. Catechin showed pro-oxidant property in concentrations lower than 300 jlM. These results demonstrated that the enzymatically synthesized poly(catechin) possessed much higher potential for superoxide anion scavenging, compared with intact catechin. 

Kim, Y.J. et al.. Superoxide anion scavenging and xanthine oxidase inhibition of (-l-)-catechin-aldehyde polycondensates. Amplification of the antioxidant property of (-l-)-catechin by polycondensation with aldehydes. Biomacromolecules, 5, 547, 2004. 

Oxidative stress appears to have a central role in the induction of apoptosis following the exposure of cells to a range of cytotoxic insults. Anti-apoptotic properties of the antioxidant, 4b,5,9b,10-tetrahydroindeno[l,2-b]indole, in Jurkat T cells subjected to a number of cytotoxic insults. Peroxide and superoxide anion production following UV treatment showed that indole derivative was found to only partially inhibit superoxide anion production and exhibited strong inhibition of caspase-3 activation in UV [115]. 

The lung also possesses nonenzymatic antioxidants such as vitamin E, beta-carotene, vitamin C, and uric acid. Vitamin E is lipid-soluble and partitions into lipid membranes, where it is positioned optimally for maximal antioxidant effectiveness. Vitamin E converts superoxide anion, hydroxyl radical, and lipid peroxyl radicals to less reactive oxygen metabolites. Beta-carotene also accumulates in cell membranes and is a metabolic precursor to vitamin A. Furthermore, it can scavenge superoxide anion and react directly with peroxyl-free radicals, thereby serving as an additional lipid-soluble antioxidant. Vitamin C is widely available in both extracellular and intracellular spaces where it can participate in redox reactions. Vitamin C can directly scavenge superoxide and hydroxyl radical. Uric acid formed by the catabolism of purines also has antioxidant properties and primarily scavenges hydroxyl radical and peroxyl radicals from lipid peroxidation. 

Interactions between lycopene and oxygen radicals can be considered second-order rate reactions. Lycopene is less efficient, and electron transfer is observed in both directions (Conn et al., 1992). The potential reduction of the antioxidant property of lycopene is related to the formation of the superoxide radical anion, CV (Palozza, 1998). 

Oxidative cellular damage by reactive oxygen species such as superoxide anion, hydroperoxy and hyassociated with various human chronic diseases, e.g. cancers, inflammation, arthritis, atherosclerosis and also with the process of ageing. Claims that diet and increased intake of nutrients exhibiting antioxidative activity have a preventative effect on chronic diseases have increased in recent years. In this context, polyphenolic compounds such as tannins, flavonoids, coumarins, lignans and caffeic acid derivatives, which are abundantly contained in a large number of medicinal plants, foods and beverages, are of particular interest for human health care because of the antioxidative properties widely found in plant phenolics. The antioxidative activity of tannins has been extensively studied in various in vitro and in vivo experimental systems and summarized in reviews [96, 97]. Such activity includes the inhibition of lipid peroxidation induced by NADPH-ADP and ascorbic acid-ADP in rat liver microsomes and mitochondria, respectively... 

---