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Structural Biochemistry/Chemistry of important organic molecules in Biochemistry/Vitamin E

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Overview of Vitamin E

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Vitamin E is a name collectively for a group of fat-soluble compounds that contain antioxidant distinctive activities. It can be found in vegetable oils, nuts, seeds, green vegetables like broccoli, or taken as a dietary supplement. Vitamin E exists in 8 chemical forms; alpha, beta, and delta-tocopherol and alpha-, beta-, gamma-, and delta-tocotrienol. In general, Vitamin E is a fat-soluble antioxidant that prevents the production of ROS formed during the process of the oxidation of fat. Scientists are currently investigating whether vitamin E could help prevent or slow the chronic diseases associated with free radicals.

Deficiency in vitamin E can cause nerve and muscle damage to the point of loss of feeling in arms and legs, muscle weakness, and vision problems. It can also result in a weakened immune system. Vitamin E deficiency can be linked to diseases like Crohn's disease, cystic fibrosis as these are diseases where fat is not properly absorbed/digested. It can also be linked to a few genetic diseases like abetalipoproteinemia.

The most common forms of Vitamin E in a natural diet is γ-tocopherol followed by α-Tocopherol. [1]

http://www.uic.edu/classes/phar/phar332/Clinical_Cases/vitamin%20cases/vitamin%20E/vit-E.gif

Function

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Vitamin E has many important biological functions which include:[2]

  1. Vitamin E is an antioxidant.
  2. Enzymatic Activities
  3. Gene Expression
  4. Neurological Functions
  5. Cell Signaling
  6. Protects Lipids and Prevents Oxidation of Polyunsaturated Fatty Acids

Forms

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Vitamin E has 8 forms split between two types - Tocopherols and Tocotrienols. These forms are then named with prefixes such as alpha, beta, gamma, and delta. Among these forms, α-Tocopherol is the most studied as it is the form which humans consume and require. [3]

α-Tocopherol

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Alpha Tocopherol appears to mainly serve as an antioxidant in humans. As alpha-tocopherol is a fat soluble molecule it takes on the role of preventing free radicals from destroying (through oxidation) fats in the body. As fats are essential for cell membranes, this is very important for our bodies hence why it is a Vitamin.

Other functions that alpha-tocopherol has include inhibiting the activity of protein kinase C. Protein kinase C is an important molecule for cell-signaling. Alpha-tocopherol also affects the activity of enzymes in immune and inflammatory cells.

γ-Tocopherol

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Gamma Tocopherol is the most common form of Vitamin E in a North American diet. However, its function is not as well known as alpha tocopherol and surprisingly its concentration levels in the bloodstream is around 1/10th of alpha-tocopherol. It would appear that the reason for this is that alpha-tocopherol lowers gamma-tocopherol levels. Through limited studies, it has been suggested that gamma-tocopherol may act as an antioxidant as well. However, gamma-tocopherol is also suspected to increase risk of developing prostate cancer. More research on Gamma Tocopherol needs to be conducted at this point.

References

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1. "Vitamin E." — Health Professional Fact Sheet. N.p., n.d. Web. 07 Dec. 2012.

  1. ↑ Jane Higdon, "Vitamin E", Micronutrient Information Center, Linus Pauling Institute, Oregon State University
  2. ↑ Azzi (2007). "Molecular mechanism of alpha-tocopherol action". Free radical biology & medicine 43 (1): 16–21. doi:10.1016/j.freeradbiomed.2007.03.013. PMID 17561089.
  3. ↑ Jane Higdon, "Vitamin E", Micronutrient Information Center, Linus Pauling Institute, Oregon State University

2. "Dietary Supplement Fact Sheet:Vitamin E". NIH Office of Dietary Supplements. http://ods.od.nih.gov/factsheets/VitaminE-QuickFacts/?print=1

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