Antioxidant properties reactive oxygen species

The antioxidant system in humans is a complex network composed by several enzymatic and nonenzymatic antioxidants. In addition to being an antioxidant, lycopene also exerts indirect antioxidant properties by inducing the production of cellular enzymes such as superoxide dismutase, glutathione S-transferase, and quinone reductase that also protect cells from reactive oxygen species and other electrophilic molecules (Goo and others 2007). 

The antioxidant properties of vitamin E are well known and documented [5]. In particular, prevention by a-tocopherol of LDL oxidation has been studied [6]. Although the correlation between the level of LDL oxidation and atherosclerosis is not always evident [7], alternative studies have suggested that a-tocopherol protection against LDL oxidation may be secondary to the inhibition of protein kinase C (PKC). This enzyme seems to be responsible for the release of reactive oxygen species and lipid oxidation [8,9]. 

For about ten years, I have been interested in the antioxidant properties of polyphenol derivatives, i.e., interaction with various reactive oxygen species such as hydroxyl radical (OH0) superoxide (O2 0) as well as their enzymatic source (xanthine oxidase)[53-56]. 

The aerial parts of Eupatorium articulatum L. (Compositae) are widely used in the Andes region of Ecuador for the treatment of inflammatory diseases. The methanolic extract of this species exhibited a significant in vivo anti-inflammatory activity, when tested for its ability to reduce carrageenan-induced inflammation in rat paw oedema, thus supporting the traditional use claimed for this plant. Since the inflammation process is associated to the generation of reactive oxygen species and the induction of lipid peroxidation, the antioxidant properties of the extract were also studied [45]. Significant activity was observed when tested for its ability... 

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... 

Moseley R, Leaver M, Walker M, Waddington RJ, Parsons D, Chen WY, Embery G. Comparison of the antioxidant properties of HYAFF-llp75, AQUACEL and hyaluronan towards reactive oxygen species in vitro. Biomaterials 2002 23 2255-2264. 

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