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HUN 4221 Exam 2 > Vitamin E > Flashcards

Vitamin E Flashcards

1
Q

Paul Karrer

A

Synthesized Vitamin E

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2
Q

Evans and Bishop

A

Found a factor in vegetable oil that is required in female rats

  • wheat germ oil was found to contain the factor
  • propose name “vitamin E” following vitamin D
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3
Q

Tokos means?

Pherein means?

A

Tokos- childbirth

pherein- to bear or carry

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4
Q

Vitamin E chemistry?

A
  • Lipophilic tail

- chromanol ring

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5
Q

How do tocotrienols differ from tocopherols?

A

Tocotrienols have an unsaturated side chain

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6
Q

What are the two different general forms of Vitamin E?

A

Tocopherols and tocotrienols

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7
Q

What are the different kinds of tocopherols?

A

alpha, beta, gamma, delta

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8
Q

What are the different kinds of tocotrienols?

A

alpha, beta, gamma, delta

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9
Q

Which form of Vitamin E is essential?

A

Alpha-tocopherol

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10
Q

What is the only form of Vitamin E that will reverse Vitamin E deficiency?

A

Alpha-tocopherol

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11
Q

What are the major food sources of Vitamin E?

A

Vegetable oils, margarine, mayonaise, wheat germ, nuts, seeds

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12
Q

What is alpha-tocopherol transfer protein (alpha-TTP)?

A

Specific for alpha-tocopherol Finds alpha-tocopherol and transfers it from liver to lipoproteins VLDL-> LDL -> HDL

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13
Q

What form of Vitamin E is used in our bodies?

A

Alpha-tocopherol, everything else is excreted in bile

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14
Q

Why are Vitamin E forms not inter convertible?

A

Because their plasma concentrations are dependent on the affinity of hepatic alpha-TTP for them

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15
Q

What is the transport protein for Vitamin E?

A

It does not have one

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16
Q

If it does not have a transport protein, How is alpha-tocopherol exported into the plasma?

A

Secreted from liver under the control of alpha-TTP and then into the plasma as component of VLDL.

17
Q

A genetic defect in what protein may lead to vitamin E def?

A

Alpha-TTP

18
Q

How is vitamin E taken up by cells?

A
  • Lipoprotein lipase mediated lipoprotein catabolism
  • Lipoprotein receptors
  • Membrane lipid transporters
19
Q

How is Vitamin E stored?

A

Adipose tissue

20
Q

How is Vitamin E excreted?

A

Fecal

21
Q

What is the function of Vitamin E?

A

Antioxidant ONLY

-lipid-soluble chain-breaking antioxidant

22
Q

How does Vitamin E function as an antioxidant?

A
  • Neutralizes lipid peroxyl radicals, which are involved in oxidation of lipids (lipid peroxidation) serves as a reducing agent for lipid peroxyl radicals
  • Protects poly unsaturated fatty acids within phospholipids of biological membranes and in plasma lipoproteins
23
Q

What are the three steps to lipid peroxidation?

A

Inititation, propogation, termination

24
Q

What happens in initiation?

A

Unsaturated fatty acid -> carbon centered radical -> lipid peroxy radical (LOOdot) (COOdot)

25
Q

What initiates another round of peroxidation (propogation)?

A

Lipid peroxyl radical

26
Q

What happens in propogation?

A

Lipid peroxyl radical is looking for an electron so it attacks the hydrogen off an unsaturated fatty acid and becomes a stable lipid peroxide (LOOH)
But now the unsaturated fatty acid becomes a carbon centered radical and needs an electron so it takes it off of oxygen again and creates another lipid peroxyl radical and starts the process over again.

27
Q

What happens in termination?

A

Vitamin E comes in and gives the lipid peroxyl radical an electron so that it stops taking electrons from fatty acids and creating more radicals.
This causes Vitamin E to become a radical but it is relatively stable and will not react with another unsaturated fatty acid.

28
Q

After termination how is Vitamin E regenerated?

A

Vitamin E gets an electron from Vitamin C.

29
Q

Where is Vitamin E found in cells?

A

Lipid membranes

30
Q

Vitamin E def

A

Oxidative damage of tissues, membrane damage of cells and sub-cellular organelles

  • oxidative species damage structural and functional compounds
  • neurological abnormalities
  • muscular function
  • membrane instability leading to hemolytic anemia
31
Q

What is hemolytic anemia?

A

Red blood cells burst because membranes can’t take radical damage anymore

32
Q

Who can have Vitamin E def?

A
  • Premature babies of very low birth weight
  • People with fat malabsoprtion
  • Ataxia with vitamin e def (AVED)
33
Q

What is Ataxia with Vitamin E Def?

A

Rare neurodegenerative disease, caused by mutations in the gene for alpha-tocopherol transfer protein (alpha-TTP)
you could increas plasma levels with high doses of vitamin e but it does not reverse the damage.

34
Q

What is the RDA for Vitamin E?

A

15mg

35
Q

1 mg of alpha-tocopherol is equivalent to how much IU?

A

1.49

36
Q

What high doses of Vitamin E cause?

A

Increases risk of
-bleeding by reducing bodys ability to form clots
-bleeding in the brain (hemmorhagic stroke)
-vitamin e antagonizes vitamin k-dependent coagulation
(APPLIES TO ALL FORMS OF SYNTHETIC VITAMIN E)

HUN 4221 Exam 2 (7 decks)

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