Vitamin E

Question 1

evans and bishop

Answer 1

identify a factor in
vegetable oil that is required for production
in rats, also in wheat germ. Proposes
“Vitamin E”. Tokos-childbirth, pherin- to bear
or carry—tocopherol.

Question 2

Kerrer

Answer 2

vitamin E

synthesized.

Question 3

Human Requirement

Answer 3

α-tocopherol is the
only form to meet RDA. Forms are not
convertible

Question 4

food

Answer 4

vegetable oils,

margarine, mayonnaise, wheat germ, nuts

Question 5

α- Tocopherol Transfer protein

Answer 5

transfer of α-
tocopherol from liver to lipoproteins. Plasma
concentrations dependent on the affinity. Other
forms are absorbed and delivered to liver in
chylomicrons but poorly packaged in lipoproteins for
transport. Relates back to structure.

Question 6

Binding to α-TTP

Answer 6

Requires it to be in the form

of RRR- α-tocopherol

Question 7

Transport

Answer 7

Does not have a specific transport
protein. Liver exports α-tocopherol into plasma
as VLDL. Genetic defect in synthesis of α-TTP
leads to deficiency.

Question 8

Cellular uptake

Answer 8

Lipoprotein lipase-mediated catabolism. Lipoprotein

receptors. Membrane lipid transporters.

Question 9

Storage & Excretion

Answer 9

Storage is in adipose (>90%). Excretion is fecal.

Question 10

Forms

Answer 10

8 different forms. 4
tocopherols & 4
tocotrienols. Trienols have 3
double bonds in chain

Question 11

RDA

Answer 11

1 mg/ 1.49 IU

Question 12

UL

Answer 12

> 1000 mg (bleeding in
brain/ can’t form clots b/c antagonized Vit. K)
Applies to all synthetic forms.

Question 13

Antioxidant function-

Answer 13

lipid soluble chain-breaking antioxidant.
Neutralizes lipid peroxyl radicals, involved in the oxidation of lipids
(lipid peroxidation). Protects PUFA within phospholipids of biological
membranes and in plasma lipoproteins.

Question 14

Lipid peroxidation

Answer 14

In initiation, propagation and termination.
Donates a hydrogen to the lipid peroxyl radical to form lipid
peroxide and a vitamin E radical. Chain reaction is terminated
because the Vitamin E radical is relatively stable and will not react
with an adjacent unsaturated fatty acid.

Question 15

Symptoms-

Answer 15

oxidative damage of tissues, membrane damage of
cells/ sub-cellular organelles, damage of structural and functional
compounds, neurological abnormalities, muscular function,
membrane instability  hemolytic anemia. VERY RARE. Babies with
VLBW. Fat malabsorption disorders. Ataxia with Vitamin E disorder.

Question 16

Antioxidant Function

Answer 16

Structure of Vit. E-phenolic ring
 Donation of hydrogen to free radicals. When lipid
peroxides are oxidized to peroxy radical (ROO-)…
Faster with E than PUFA