Free The Abcs Of Antioxidant Activity Research Paper Example

Antioxidant definition and general function

Antioxidants are chemical compounds which can delay the start or slow the rate of lipid oxidation reaction in food systems. These are substances that oppose oxidation or inhibit reactions promoted by oxygen or peroxides, of which many are being used as preservatives in various products. (Gupta, 2015)
Antioxidants occur in many foods including fruits and vegetables, pasta and cereals, vegetable oils and green tea. The most common antioxidants are vitamin A, C and E, chemicals found in plants like flavonoids and carotenoids, and minerals such as selenium (Eat Right Ontario, 2015).

Antioxidants Classification based on Mechanism of Action

Non-enzymatic antioxidants interfere with chain reactions of free radicals. Non-enzymatic antioxidants comprise of vitamin C and E, plant polyphenols, Selenium, carotenoids, and glutathione. Enzymatic antioxidants function by destroying and eradicating free radicals. This is done by the conversion of oxidative products into hydrogen peroxide, then into water. (Brewer, 2011)
Lipid-soluble antioxidants such as lipoic acid, vitamins E and A, and carotenoids are predominantly found in the cell membranes. Water-soluble antioxidants like vitamin C, glutathione and polyphenols are present in aqueous body fluids, such as blood, the cytosol, and intercellular fluids. Synthetic antioxidants are phenolic types. Differences in their actions are due to their chemical structures, which also influence their volatility, solubility and thermal stability. (Madhavi, 1995)
Figure 1 shows an anti-oxidant molecule donating an electron to a reactive free radical particle effecting its stability. Figure 2 illustrates the conversion of free radicals into a stable oxygen molecule and hydrogen peroxide which is further converted into a water molecule.

Antioxidant Evaluation

In order to evaluate and rank antioxidant activities, several assays were developed. These assays produce helpful data on total radical-trapping capacity, stated as TRAP or total radical-trapping parameter. Oxygen radical absorbance capacity (ORAC) is the most frequently used TRAP assay. It measures both the influence of antioxidant activity on the phase prior to oxidation of the fluorescent protein and the maximum percentage of the inhibition. ORAC is widely applied for evaluating antioxidants both in commercial and academic institutes. (Pinchuk et al., 2012)

Antioxidant Capacity

The total antioxidant capacity or activity is a empty without the consideration for reaction states such as temperature, pressure, reaction medium, reference points, chemical reactivity etc. We must refer to an oxidant specific terms like peroxy radical scavenging capacity, ferric ion reducing capacity, superoxide scavenging capacity, etc. (Gupta, 2011)
In order to understand the amounts of antioxidants that a person consumes when eating particular foods, methods are required to determine these foods’ antioxidant capacities. Barroso et al. (2011) examined the protective effect of antioxidants by analyzing the integrity of DNA nucleobases through an electrochemical approach. Specifically, an adenine-rich oligonucleotide (dA21 ) adsorbed on carbon paste electrodes was used to assess antioxidant capacity in drinks.

Antioxidants and Oil Stability

Antioxidants can improve the stability of various oils. The contribution of a-tocopherol to the stability of olive oil has been researched, with concentrations of 100, 500 and 1000 ppm in purified olive oil. All concentrations of a-tocopherol proved to have an antioxidant effect, with the greatest effect resulting from the 100 ppm concentration. (Blekas et al., 1995).

Antioxidants in the Prevention and Treatment of Cancer

The antioxidants contained in foods are commonly believed to be beneficial for human health, but Saeidnia and Abdollahi (2013) have discussed the debate that exists concerning this idea that antioxidants are beneficial, specifically for the prevention or treatment of cancer. Reactive oxygen species can play a role in carcinogenesis by repeatedly harming DNA, but they also play key roles in signal transduction and gene transcription. Natural antioxidants can be beneficial in chemoprevention, but they may also help detached cancerous cells to survive. The antioxidants may prevent damage to DNA while simultaneously promoting tumor maintenance via cell survival.

References

Barroso M.F., del-los-Santos-Alvarez, N., Lobo-Castanon, M.J., Miranda-Ordieres, A.J.,
Delerue-Matos, C., Oliveira, M.B.P.P., Tunon-Blanco, P. (2011). DNA-based biosensor
for the electrocatalytic determination of antioxidant capacity in beverages. Biosensors
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Blekas, G., Tsimidou, M., Boskou, D. (1995). Contribution of tocopherol to olive oil stability.
Food Chemistry, 52, 289-294.
Brewer, M.S. (2011). Natural Antioxidants: Sources, Compounds, Mechanisms of Action, and
Potential Applications. Comprehensive Reviews in Food Science and Food Safety
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Eat Right Ontario. (2015). Antioxidants. Retrieved from: http://www.eatrightontario.ca/en/Articles/Antioxidants/What-you-need-to-know-about- antioxidants.aspx#.VN0ZQLDF_dI
Frankel, E.D. (2010) Chemistry of Extra Virgin Olive Oil: Adulteration, Oxidative Stability, and Antioxidants. Journal of Agricultural and Food Chemistry 58, 5991-6006.
Gupta, Deepshinkha. (2015) Methods For Determination Of Antioxidant Capacity: A Review
International Journal Of Pharmaceutical Sciences And Research. Vol. 6(2): 546-566. Retrieved from: http://www.researchgate.net/publication/272415666_Methods_For_ Determination_Of_Antioxidant_Capacity_A_Review
Madhavi DL, Deshpande SS, Salunkhe DK. (1995) Food Antioxidants: Technological,
Toxicological and Health Perspectives. New York : CRC Press.
Masters, Thomas. (2013). Antioxidants 101. Retrieved from: http://docsfitnesstips.blogspot.ca/
2013/03/antioxidants-101.html
Pinchuk I., Shoval H., Dotan Y., Lichtenberg D. (2012) Evaluation of antioxidants: Scope,
limitations and relevance of assays. Chemistry and Physics of Lipid, 638– 647. Retrieved from: http://www.researchgate.net/publication/227856537_Evaluation_of_antioxidants_
scope_limitations_and_relevance_of_assays
Saeidnia, S., Abdollahi, M. (2013). Antioxidants: Friends or foe in prevention or treatment of
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Shah, Shweta. (2011). Anti oxidants for Immunity, Aging, Skin and Hair: Vitamin Supplements.
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