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Metabolism Exam 4 > Vitamin E > Flashcards

Vitamin E Flashcards

1
Q

What molecules are forms of vitamin E

A

Tocopherols and tocotrienols; activity as alpha-tocopherol

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2
Q

What is the difference between tocopherols and tocotrienols

A

Tocotrienols have double bonds

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3
Q

What are the R groups of alpha-tocopherol

A

Methyl groups (CH3)

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4
Q

What is the most potent form of vitamin E

A

alpha-tocopherol

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5
Q

How many sterioisomers does alpha-tocopherol have

A

8

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6
Q

What is the most potent sterioisomer form

A

RRR

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7
Q

What is the RDA for vitamin E

A

15mg/22.5IU

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8
Q

What are food sources of vitamin E

A

Sunflower seeds, almonds, sunflower oil

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9
Q

How is vitamin E absorbed

A

Lipid-soluble; follow the route of lipids

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10
Q

Vitamin E is not often eaten in free form; what is this bound molecule called

A

Alpha-tocopherol ester (bound to fatty acids)

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11
Q

What enzyme cleaves the ester from its bound molecule

A

Esterase

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12
Q

Where does esterase come from

A

Pancreas

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13
Q

Where does vitamin E go once absorbed

A

Chylomicrons; small amount to HDL

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14
Q

What cleaves vitamin E (and fatty acids) from chylomicrons

A

Lipoprotein lipase

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15
Q

What is a major excretion source of vitamin E

A

Bile (GI tract)

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16
Q

What are major carriers of vitamin E in blood (once cleaved from chylomicron)

A

Lipoproteins

17
Q

What are two common molecules bound to alpha-tocopherol esters in synthetic forms of vitamin E

A

Tocopherol-acetate and tocopherol-succinate

18
Q

What is vitamin E’s claim to fame

A

Antioxidant

19
Q

What is formed after oxidation of vitamin E (alpha-tocopherol)

A

Alpha-tocopheroxyl radical (free radical, unstable)

20
Q

What stabilizes alpha-tocopheroxyl radical

A

Oxidation (donates electron) or another antioxidant such as vitamin C (back to alpha-tocopherol-recycled)

21
Q

What is formed alpha-tocopheroxyl radical is stabilized

A

8a-peroxy-alpha-tocopherol, alpha-tocopheryl quinone or tocopherol radical dimers

22
Q

How is vitamin E expressed in RDA

A

Alpha-tocopherol equivalents

23
Q

What is 1 IU of synthetic vitamin E esters

A

0.45mg RRR alphaTE

24
Q

What is 1 IU of synthetic “natural” vitamin E

A

0.67 RRR alphaTE

25
Q

What is the RDA for vitamin E based on IU

A

15mg alphaTE OR 30mg synthetic

26
Q

Which oils are highest in alpha-tocopherol

A

Wheat germ oil and walnut oil

Metabolism Exam 4 (5 decks)

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