vitamin e and its clinical applications

Dr. Rohini C Sane

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)

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

Structure of of Vitamin E Tocopherols and Tocotrienols

isoprenoid side chain

Tocol

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 )

Chemistry of derivatives Vitamin E

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)

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.

Dietary Sources of Vitamin E

Product total

tocopherol

(mg/100g)

Cottonseed

oil

80-110

Peanut oil 20-59

Cocoa butter 3-13

Coconut oil 3-8.5

Corn germ oil 87-250**

Corn oil 40-60

Palm oil 2-50

Rapseed oil 50

Olive oil 3-30

Product total

tocopherol

(mg/100g)

Soybean oil 90-280**

Sunflower oil 70

Beef tallow 1.0

Lard 0.2-2.7

Herring oil 1.0

Cheese (45%

fat)

1.0

Butter 1.7-42

margarine 30-100

Tocopherol content of fat and fat products

**Richest

sources of vitamin E

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

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 UnitsRequirement 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

Metabolism of Vitamin E :1Absorption, 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

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

Metabolism Of Vitamin E

Metabolism Of Vitamin E

Metabolism Of Vitamin E

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 .

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

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)

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

*

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

*

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 .

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

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

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

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. .

Symptoms of Vitamin E Deficiency

Symptoms of Vitamin E Deficiency

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

Hypervitaminosis E