Vitamin E

Question 1

Paul Karrer

Answer 1

Synthesized Vitamin E

Question 2

Evans and Bishop

Answer 2

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

Question 3

Tokos means?

Pherein means?

Answer 3

Tokos- childbirth

pherein- to bear or carry

Question 4

Vitamin E chemistry?

Answer 4

• Lipophilic tail

- chromanol ring

Question 5

How do tocotrienols differ from tocopherols?

Answer 5

Tocotrienols have an unsaturated side chain

Question 6

What are the two different general forms of Vitamin E?

Answer 6

Tocopherols and tocotrienols

Question 7

What are the different kinds of tocopherols?

Answer 7

alpha, beta, gamma, delta

Question 8

What are the different kinds of tocotrienols?

Answer 8

alpha, beta, gamma, delta

Question 9

Which form of Vitamin E is essential?

Answer 9

Alpha-tocopherol

Question 10

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

Answer 10

Alpha-tocopherol

Question 11

What are the major food sources of Vitamin E?

Answer 11

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

Question 12

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

Answer 12

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

Question 13

What form of Vitamin E is used in our bodies?

Answer 13

Alpha-tocopherol, everything else is excreted in bile

Question 14

Why are Vitamin E forms not inter convertible?

Answer 14

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

Question 15

What is the transport protein for Vitamin E?

Answer 15

It does not have one

Question 16

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

Answer 16

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

Question 17

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

Answer 17

Alpha-TTP

Question 18

How is vitamin E taken up by cells?

Answer 18

• Lipoprotein lipase mediated lipoprotein catabolism
• Lipoprotein receptors
• Membrane lipid transporters

Question 19

How is Vitamin E stored?

Answer 19

Adipose tissue

Question 20

How is Vitamin E excreted?

Answer 20

Fecal

Question 21

What is the function of Vitamin E?

Answer 21

Antioxidant ONLY

-lipid-soluble chain-breaking antioxidant

Question 22

How does Vitamin E function as an antioxidant?

Answer 22

• 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

Question 23

What are the three steps to lipid peroxidation?

Answer 23

Inititation, propogation, termination

Question 24

What happens in initiation?

Answer 24

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

Question 25

What initiates another round of peroxidation (propogation)?

Answer 25

Lipid peroxyl radical

Question 26

What happens in propogation?

Answer 26

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.

Question 27

What happens in termination?

Answer 27

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.

Question 28

After termination how is Vitamin E regenerated?

Answer 28

Vitamin E gets an electron from Vitamin C.

Question 29

Where is Vitamin E found in cells?

Answer 29

Lipid membranes

Question 30

Vitamin E def

Answer 30

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

Question 31

What is hemolytic anemia?

Answer 31

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

Question 32

Who can have Vitamin E def?

Answer 32

- Premature babies of very low birth weight - People with fat malabsoprtion - Ataxia with vitamin e def (AVED)

Question 33

What is Ataxia with Vitamin E Def?

Answer 33

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.

Question 34

What is the RDA for Vitamin E?

Answer 34

15mg

Question 35

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

Answer 35

1.49

Question 36

What high doses of Vitamin E cause?

Answer 36

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)