Antioxidant enzyme systems

Figure 27.12. Lung intracellular antioxidant enzyme systems. The three major systems Superoxide dismutase, catalase, and the glutathione redox cycle are shown. (See text for details.)...

Antioxidants are naturally present in many foodstuffs and are of great importance as inactivators of radical formation. Some antioxidative enzyme systems are produced in the human body and are supposed to play an important role in the cellular defense against oxidative damage (Langseth, 1995). 

Reactive Oxygen Species Antioxidant Enzyme Systems... 

With its active ingredient proanthocyanidins, it is a potent antioxidant 50x more powerfnl than vitamin E and 20x more than vitamin C. It recycles vitamin C, regenerates vitamin E, and increases the endogenous antioxidant enzyme system [110]. 

Meat products have to be stabilised in some cases, as meat lipids contain no natural antioxidants or only traces of tocopherols. Most muscle foods contain, however, an efficient multi-component antioxidant defence system based on enzymes, but the balance changes adversely on storage. The denaturation of muscle proteins is the main cause of the inbalance as iron may be released from its complexes, catalysing the lipid oxidation. Salting contributes to the negative effects of storage, as it enhances oxidation. Using encapsulated salt eliminates the deleterious effect of sodium chloride. 

The efficient removal of O2 and H2O2 vvill diminish OH formation and therefore antioxidant defence systems have evolved to limit their accumulation. Enzymic and low molecular weight antioxidants exist to scavenge free radicals as self-protection mechanisms. Some proteins exhibit antioxidant properties because they chelate transition-metal catalysts. The significance of antioxidants in relation to inflammatory joint disease is discussed below. 

Selenium is an essential trace element in the human body. This nutrient is an important part of antioxidant enzymes that protect cells against the effects of free radicals that are produced during normal oxygen metabolism. Selenium is also essential for normal functioning of immune system and thyroid gland. 

---