Saturday, May 8, 2010

Mechanism of action of antioxidants


Health medicine - Continue from antioxidants-and-role-of-health.
Mechanism of anti-oxidants work has two functions. The first function is the main function of the anti-oxidant that is as the giver of the hydrogen atom. Antioxidants (AH), which has the main function is often referred to as primary antioxidants. This compound can provide a fast hydrogen atoms to the lipid radical (R *, Roo *) or change it to a more stable form, while the radical derived antioxidants (D *) has a more stable situation than radical lipids.

The second function is a secondary function of anti-oxidants, which slows the rate of auto-oxidation with a variety of mechanisms beyond the auto-oxidation mechanism of chain termination by radical conversion of lipids to form more stable (Gordon, 1990).

Addition of anti-oxidant (AH) primers with low concentrations of lipids can inhibit or prevent auto-oxidation reaction of fats and oils. Addition of these may hinder the oxidation reaction at the initiation and propagation phases (Figure 1). Radicals, anti-oxidants (A *) is formed in the reaction is relatively stable and did not have enough energy to react with other lipid molecules to form new lipid radicals (Gordon, 1990).

Initiation: R * + AH ----> RH + A *
Radical lipide

Propagation: Roo * + AH ---> ROOH + A *

Picture 1. Inhibition of the reaction of primary antioxidant against lipid radicals (Gordon, 1990)

Large concentrations of antioxidants that are added can affect the rate of oxidation. At high concentrations, the antioxidant activity of phenolic groups often disappear even become pro oxidant antioxidants (Figure 2). Effect of concentration on the oxidation rate depends on the structure of the antioxidant, conditions and samples to be tested.

AH + O2 ----> A * + hoo *

AH + ROOH ---> RO * + H2O + A *

Figure 2. Antioxidants act as pro oxidant at higher concentrations (Gordon 1990)

The role of antioxidants in health

The process of aging and degenerative diseases such as cancer, cardiovascular disease, blood vessel blockage that includes hiperlipidemik, atherosclerosis, stroke and high blood pressure and disrupted his body's immune system can be caused by oxidative stress.

Oxidative stress is a state of balance and its total oxidant peroxiding in the body. In this condition, the molecular activity of free radicals or reactive oxygen species (ROS) can cause cellular and genetic damage. Nutrient deficiencies and the existence of Xenobiotic compounds from food or too polluted environment will worsen the situation.

When the Japanese public generally or some Asian communities rarely have problems with a variety of degenerative diseases, this is due to its healthy menu of traditional rich nutrients and bioactive components. These substances have the ability as an antioxidant, which plays an important role in inhibiting the oxidation of chemical reactions, which can damage macro-molecules and can cause various health problems.

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