What are the functions of antioxidant?

In biological systems, various biochemical defense mechanism involving enzymes, trace minerals and antioxidant vitamins protect the cellular components from oxidative damage.

Antioxidants are regarded to be safe and healthy in general and to protect cells and tissues from all kinds of environmental and endogenous attacks. In food systems, naturally occurring antioxidants impart a certain amount of protection against oxidation. Antioxidants are a group of chemicals effective in extending the shelf life of a wide variety of food products.

Although there are numerous sources of free radicals, there are also several naturally occurring compounds that can inactivate these reactive molecules. Antioxidants have the capacity to lower the free radical burden. Free radical reactions can be broken into three stages: initiation, propagation and termination. Antioxidants can affect the generation of free radicals during any of these stages.

Food antioxidants utilize several mechanisms in order to facilitate their actions in the liver including interactions with receptor mediated functions, alteration of specific protein kinase activities, regulation of enzymes expression and activities, direct effects on nucleic acids and nucleoproteins and interaction with oncogenes and oncoproteins.
What are the functions of antioxidant?