2. Vitamin E ( Tocopherol )
Vitamin E = Tocopherol
Tocos = child birth
Pheros = to bear anti-infertility Vitamin
Ol = OH (Alcohol)
Infertile animal + vitamin E conception of animal
Vitamin E = anti-infertility Vitamin (because of Antioxidant Property)
Structure of Vitamin E was elucidated by Paul Karr ( Noble prize-1937)
3. Chemistry of Vitamin E
• Vitamin E : a name given to a group of Tocopherols and Tocotrienols.
1. Vitamin E = Tocopherols derivatives of Tocol (Chromane ring) with
an isoprenoid side chain (3 units )
2. 8 derivatives of Tocopherols identified as α,β,γ,δ Tocopherol etc.
3. Tocol (Chromane ring) present in all 8 derivatives naturally occurring
sources of vitamin E ) along with an isoprenoid chain (3 units )
4. Tocotrienols have 1-50% activity of activity of Tocopherols
5. OH group of Tocol is responsible for antioxidant property of Vitamin E
6. Vitamin E acts as scavenger and gets oxidized to quinone form by
free radicals and protects Polyunsaturated fatty acids (PUFA ) from
peroxidation reactions
4. Structure of of Vitamin E Tocopherols and Tocotrienols
isoprenoid side chain
Tocol
5. Chemistry of Vitamin E
Type of Vitamin E Chemistry of Vitamin E
Alpha (α) Tocopherol 5,7,8 Trimethyl Tocol (The Most Active Form )
Beta (β) Tocopherol 5,8 Dimethyl Tocol
Gamma (γ) Tocopherol 7,8 Dimethyl Tocol
Delta( δ) Tocopherol 8 Methyl Tocol
Vitamin E = Tocopherols derivatives of Tocol (Chromane ring )along with an
isoprenoid side chain (3 units )
7. Properties of Vitamin E
Properties of Vitamin E are
1. Yellow oil
2. Heat stable
3. Alkali labile
4. Oxidation labile
5. Low molecular weight (453 Dalton)
6. Absorbs UV light (292nm)
7. Optically active
8. Forms salts with OH group of chromone ring (at 6 th position)
8. Dietary Sources of Vitamin E
Dietary Sources of Vitamin E are
1. Cotton seed oil
2. Sunflower oil
3. Corn oil
4. Soya bean
5. Cabbage
6. Wheat germ oil
Fish liver oil is devoid of Vitamin E.
11. Tocopherol content of some animal and vegetable foods
Product total tocopherol
as -tocopherol
(mg/100g)
Beef liver 0.9-1.6
Veal lean 0.9
Herring 1.8
Mackerel 0.2-2.7
Crab,
frozen
5.9
Milk 0.02-0.15
Cheese 0.40
Egg yolk 3.0
Egg 0.5-1.5
Product total tocopherol
as -tocopherol
(mg/100g)
Cabbage 2-3
Spinach 0.2-6.0
Beans 1-4
Lettuce 0.2-0.8
Peas 4-6
Tomato 0.9
Carrots 0.2
onion 0.3
Potato 0.12
Mushrooms 0.08
12. Category Recommended Dietary Allowance of Vitamin E
Male 10 mg/day (15 IU/day)
Female 8 mg/day (12 IU/day)
Pregnancy 10 mg/day (15 IU/day)
Lactation 12 mg/day (18 IU/day)
Recommended Dietary Allowance of Vitamin E
Recommended Dietary Allowance of Vitamin E is 10 mg/day . This is
available in a normal diet.
10mg of Tocopherol= 15 International Units
Requirement Vitamin E increases with higher intake of PUFA
Food and nutrition board have suggested an -tocopherol : PUFA ratio of 0.6
mgs -tocopherol per 1g PUFA
13. Metabolism of Vitamin E :1
Absorption, Transport and Storage
DIETARY VITAMIN E
Absorption by diffusion in Small Intestine along with other lipids as micelles
Chylomicrons formation along with other lipids , Apolipoprotein A 1 and B 48 and their
Exocytosis from intestinal mucosal cells
Chylomicrons enter lager veins via thoracic duct
Blood heart adipose tissue / Muscles liver
Storage of vitamin E : in adipose tissue /Muscles take lager proportion of dietary vitamin E
from Chylomicrons for storage
Bile salts
Transport
Absorption
Chylomicrons
Secretion of Chylomicrons into lymphatic vessels
14. Metabolism Of Vitamin E:2
• In liver vitamin E is incorporated into Lipoproteins LDL and VLDL and then
transported to target tissues.
• Target tissues :Muscles ,RBC ,Lungs , Liver
• Catabolism of Vitamin E : ( action of Lipoprotein Lipase Vitamin E+
Lipoproteins )
• During catabolism chromone ring and isoprenoid side chain is oxidized
and excreted in bile after conjugation with Glucuronic acid
• No excretion in urine
18. Reference intervals of serum or plasma vitamin E
Category Reference intervals of serum or plasma vitamin E
mg/dl μmols /L
Premature neonates 0.1 - 0.5 2.3 - 11.6
Children 0.3 - 0.9 7 - 21
Adults 0.5 - 1.8 12- 42
Blood levels of Vitamin E in breast fed infant is more than bottle fed infant.
Mammary transfer of Vitamin E is more than placental transfer .
19. Biochemical Functions of vitamin E
1. Prevents sterility and closely associated with reproductive functions
( maintains germinal epithelium of gonads)
2. Essential for membrane structure and integrity of cell: a membrane antioxidant
(vitamin E –lipophilic in nature) ,stored in a cell membrane along with lipoproteins and
lipids prevents lipid peroxidation
3.Protects RBC from hemolysis by free radicals
4. Enhances activity of δ aminolaevulinic acid (ALA) synthase and ALA dehydratase
Enhances heme synthesis
5.Required for cellular respiration through electron transport chain
( stabilizes coenzyme Q)
Biochemical Functions of vitamin E are related with its antioxidant property
20. Biochemical Functions of vitamin E
6.Prevents oxidation of vitamin A and carotenes
7. Required for storage of creatine in skeletal muscle
8.Needed for optimal absorption by intestinal cells (of amino acids / lipids)
9.Protects liver from damage by free radicals (prevents hepatic necrosis)
10.Useful in treatment of atherosclerosis* ,nocturnal muscle cramps ,cataract and
breast cancers.
Biochemical Functions of vitamin E are related with its antioxidant property
* Vitamin E prevents oxidation of LDL (oxidation of LDL have been implicated to promote heart diseases)
21. Biochemical Functions of vitamin E
11 . vitamin E acts synergistically with Selenium which is a cofactor of antioxidant
enzyme Glutathione peroxidase that destroys free radicals .
*Vitamin E can spare requirement of Selenium ,and vice versa.
12.Aging process ( cumulative effect of free radicals) is slowed down.
Biochemical Functions of vitamin E are related with its antioxidant property
*
22. Invitro function of vitamin E
13 . Trace amount of vitamin E ( hydroquinone),Gallic acid and alpha naphthol are
added in commercial preparation of fat and oils to prevent oxidative rancidity.
Function of vitamin E related with its antioxidant property
*
23. Rancidity :fat/oil undergoes oxidation –producing undesired /dangerous
metabolites-imparting unpleasant odor to stored fat/oils .Certain factors aggravate
oxidation of fat /oils eg exposure to light ,oxygen & bacteria/fungi .
24. Antioxidant property of vitamin E
Free radicals are generated during metabolic processes
Free radicals : OHº, Oº , CCl3 º ,Clº,H2O2
Free radicals have tendency to snatch electrons as posses unpaired electrons
Free radicals target polyunsaturated fatty acids (PUFA) from cell membrane
Free radicals induce destructive chain forming hydroxy & peroxy radicals
Destructive Chain continues membrane damage cell death
Vitamin E donates electron from OH group of chromane ring and stops peroxidation
changes in cell membrane
25.
26. ANTIOXIDANT PROPERTY OF VITAMIN E
❖ Vitamin E prevents oxidative changes in
1. Mitochondrial membrane and facilitates electron transport ( stabilize coenzyme Q ),
oxidative phosphorylation
2. Vitamin A and Carotenes
3. RBC membrane* (prevents hemolytic anemia )
4. Muscular membrane * (prevents muscular dystrophy)
5. Hepatocyte membrane * (prevents hepatic necrosis)
6. Germinal epithelium of gonads ( helps in reproductive function )
*Tissue with high oxygen consumption and Vitamin E prevents peroxide formation
27. Causes of Vitamin E Deficiency
Causes of Vitamin E Deficiency
1. Dietary deficiency
2. Sprue
3. Obstructive jaundice (unavailability of bile salts)
4. Pancreatitis
5. Steatorrhea
6. Hypolipoproteinemia
28. Symptoms of Vitamin E Deficiency
Symptoms of Vitamin E Deficiency are
➢increased fragility of RBC
➢neurological changes
• Retrolental fibroplasia (RLF):a neuropathy observed in premature infants
with low birth weight due to poor placental transfer of Vitamin E .
Symptoms of Vitamin E Deficiency in human beings are very mild. .
31. Hypervitaminosis E
Hypervitaminosis E : toxicity at doses above 1000 IU
• Administration of Vitamin E 300mg per day for 23 years no
toxic effects observed = LEAST TOXIC fat soluble vitamin
