By Riya Tyagi
What are the Antioxidants?
An antioxidant can be extended in a nutritional context to include ‘compounds that protect biological system against the potentially harmful effects of processes or reactions that can cause excessive oxidations’.
Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions. Although oxidation reactions are crucial for life, they can also be damaging; plants and animals maintain complex systems of multiple types of antioxidants, such as glutathione, vitamin C, vitamin A, and vitamin E as well as enzymes such as catalase and various peroxidases. Oxidative stress is damage to cell structure and cell function by overly reactive oxygen-containing molecules and chronic excessive inflammation. Antioxidants also have many industrial uses, such as preservatives in food.
Role of Antioxidants in Metabolism
Antioxidants are classified into two broad divisions, depending on whether they are soluble in water or in lipids. These compounds may be synthesized in the body or obtained from the diet. The different antioxidants are present at a wide range of concentrations in body fluids and tissues, while others such as uric acid are more evenly distributed. Some antioxidants are only found in a few organisms and these compounds can be important in pathogens and can be virulence factors.
The relative importance and interactions between these different antioxidants is a very complex question, with the various metabolites and enzyme systems having synergistic and interdependent effects on one another. The action of one antioxidant may therefore depend on the proper function of other members of the antioxidant system. The amount of protection provided by any one antioxidant will also depend on its concentration, its reactivity towards the particular reactive oxygen species being considered, and the status of the antioxidants with which it interacts.
Some compounds contribute to antioxidant defense and prevent them from catalyzing the production of free radicals in the cell. Particularly important is the ability to sequester iron, which is the function of iron binding proteins.
People who eat fruits and vegetables appear to have a lower risk of heart disease, some neurological diseases, and some cancers. Since fruits and vegetables happen to be good sources of nutrients and phytochemicals, this suggests that antioxidant compounds might lower risk against several diseases.
Antioxidants have been investigated as possible treatments for neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease.
Ascorbic acid is a redox catalyst which can reduce, and thereby neutralize, reactive oxygen species such as hydrogen peroxide.