Vitamin E

Absorption

10-33% of deuterium labelled vitamin E is absorbed in the small intestine. Absorption of Vitamin E is dependant upon absorption of the fat in which it is dissolved. For patients with poor fat absorption, a water soluble form of vitamin E may need to be substituted such as tocopheryl polyethylene glycol-1000 succinate.
In other studies the oral bioavailability of alpha-tocopherol was 36%, gamma-tocotrienol was 9%. The time to maximum concentration was 9.7 hours for alpha-tocopherol and 2.4 hours for gamma-tocotrienol.

Toxicity

There is no data available for effects in pregnancy, breast feeding, hepatic impairment, or renal impairment. However, it appears that the process of vitamin E elimination is strict and self regulating enough that vitamin E toxicity is exceedingly rare. Studies showing adverse effects from excess vitamin E generally involve people consuming more than 1000mg/day for weeks to months.

Description

(+)-α-Tocopherol is one of eight components of vitamin E and, while not the most abundant, it is the most biologically active. It occurs naturally in many foods, especially in plant oils such as wheat germ, canola, sunflower, and safflower.
In 1936, Herbert M. Evans*, Oliver H. Emerson, and Gladys A. Emerson at the University of California, Berkeley, reported the first isolation of α-tocopherol, from wheat germ. Vitamin E was already known, and these authors established that α-tocopherol is its active component. Between 1938 and 1943, the same team published seven papers on the compound’s role in nutrition.
Also in 1938, Erhard Fernholz at Merck (Rahway, NJ) described the structure of α-tocopherol, which he deduced from its degradation products. The same year, three other research groups reported syntheses of the molecule: Paul Karrer et al. at the University of Zurich, Franz Bergel et al. at the University of Manchester (UK), and Lee Irvin Smith et al. at the University of Minnesota (Minneapolis). Five years later, Smith and Joseph A. Sprung followed up with an improved synthesis.
The main biological function of vitamin E/α-tocopherol is as a fat-soluble antioxidant. The US National Academy of Medicine’s adult daily dietary recommendation for vitamin E is 15 mg; individuals with deficiencies are often prescribed the vitamin as a supplement. Vitamin E is also added to commercial fats and oils as an antioxidant.
During this National Chemistry Week, “The Healing Power of Chemistry”, keep in mind how α-tocopherol keeps your body safe.

Chemical properties

light yellow liquid

Chemical properties

VITAMIN E is sometimes referred to as the antisterility vitamin, factor X (an earlier designation), chemically vitamin E is alphatocopherol. Active analogues and related compounds include: dl-α-Tocopherol; 1-α-tocopherol; esters (succinate, acetate, phosphate), and β, ζ 1, ζ 2- tocopherols. The principal physiological forms are D-a-tocopherol, tocopheronolactone, and their phosphate esters.

Originator

Doppelherz,Queisser Pharma,Germany

The Uses of Vitamin E

α-Tocopherol is the most bioactive of the naturally occurring forms of Vitamin E. Richest sources are green vegetables, grains, and oils, particularly palm, safflower and sunflower oils.

The Uses of Vitamin E

vitamin E, antioxidant

The Uses of Vitamin E

Use in insect cell culture applications as an antioxidant.

What are the applications of Application

(+)-α-Tocopherol is a fat-soluble antioxidant

Background

In 1922, vitamin E was demonstrated to be an essential nutrient. Vitamin E is a term used to describe 8 different fat soluble tocopherols and tocotrienols, alpha-tocopherol being the most biologically active. Vitamin E acts as an antioxidant, protecting cell membranes from oxidative damage. The antioxidant effects are currently being researched for use in the treatment of diseases causing bone loss, cardiovascular diseases, diabetes mellitus and associated comorbidities, eye diseases, inflammatory diseases (including skin conditions), lipid disorders, neurological diseases, and radiation damage. Though this research is so far inconclusive, vitamin E remains a popular supplement and is generally considered safe by the FDA.

Indications

Vitamin E supplementation is indicated for treatment of vitamin E deficiency which can occur in cystic fibrosis, cholestasis and severe liver disease, abetalipoproteinemia or simply poor diet.

Definition

ChEBI: An alpha-tocopherol that has R,R,R configuration. The naturally occurring stereoisomer of alpha-tocopherol, it is found particularly in sunflower and olive oils.

Manufacturing Process

Manufacturing process for Vitamin E, that is, α-tocopherol (5,7,8-trimethyltocol) in the past has been accomplished primarily by reacting trimethylhydroquinone (TMHQ) with isophytol (3,7,11,15-tetramethylhexadec-1-en-3-ol) or phytol (3,7,11,15-tetramethylhexadec-2-en-1-ol) in a condensation reaction. The reaction is well known and has been practiced for many years (StallaBourdillon, Ind. Chim. Belg., 35, 13 (1970); "The Vitamins" Vol. 5, pages 168- 223, Academic Press, New York, 1967). The Synthesis of Vitamin E includes these steps as follows: Rearrangement to C15 Acetylene; Saponification of the C20 Dienol Acetate to Dehydrophytol;Condensation of Dehydrophytol with TMHQ to yield Dehydro-Vitamin E.

Therapeutic Function

Antioxidant

General Description

α-Tocopherol is synthesized from γ-tocopherol by the action of enzyme γ-tocopherol methyltransferase. It is the major form of Vitamin E in human plasma. It is present in sunflower seed oil.

Health Hazard

The physiological functions of vitamin E substances include: (1) bio logical antioxidant; (2) normal growth maintenance; (3) protects unsaturated fatty acids and membrane structures; (4) aids intestinal absorption of unsaturated fatty acids; (5) maintains normal muscle metabolism; (6) maintains integrity of vascular system and central nervous system; (7) detoxifying agent; and (8) maintains kidney tubules, lungs, genital structures, liver, and red blood cell membranes.
In livestock and laboratory animals, a deficiency of vitamin E substances may cause degeneration of reproductive tissues, muscular dystrophy, encephalomalacia, and liver necrosis. Considerable research is required to fully determine supplementation of livestock diets unless typical symptoms of a deficiency appear. Symptoms have appeared where there are selenium deficiencies in the soil and where there are excessive levels of nitrates in the soil. “White muscle” is the term used to describe a condition of muscular dystrophy in cattle.

Biochem/physiol Actions

α-Tocopherol is essential for the photosynthesis in Synechocystis sp. strain PCC 6803. Supplementation with α-Tocopherol decreases lipid peroxidation and platelet aggregation. It inhibits protein kinase C and may play key role in gene regulation.

Pharmacokinetics

Vitamin E is a collective term used to describe 8 separate fat soluble antioxidants, most commonly alpha-tocopherol. Vitamin E acts to protect cells against the effects of free radicals, which are potentially damaging by-products of the body's metabolism. Vitamin E deficiency is seen in persons with abetalipoproteinemia, premature, very low birth weight infants (birth weights less than 1500 grams, or 3? pounds), cystic fibrosis, and cholestasis and severe liver disease. Preliminary research suggests vitamin E may help prevent or delay coronary heart disease and protect against the damaging effects of free radicals, which may contribute to the development of chronic diseases such as cancer. It also protects other fat-soluble vitamins (A and B group vitamins) from destruction by oxygen. Low levels of vitamin E have been linked to increased incidence of breast and colon cancer.

Safety Profile

Experimental reproductive effects. Mutation data reported. When heated to decomposition it emits acrid smoke and irritating fumes.

Metabolism

Alpha and gamma tocopherol are undergo beta oxidation and a process mediated by cytochrome P450s such as CYP4F2, CYP3A4, and CYP3A5. These processes convert alpha and gamma tocopherol to alpha-CEHC (2,5,7,8-tetramethyl-2-(2’-carboxyethyl)-6-hydroxychroman) and gamma-CEHC (2,7,8-trimethyl-2-(2’-carboxyethyl)-6-hydroxychroman) respectively, however the full process is not known.

Purification Methods

Vitamin E is a viscous yellow oil which is distilled at high vacuum. It has max at 294nm (E1cm 1% 71). It is oxygen and light sensitive and is best stored as its stable D--acetate [58-95-7] which is purified by evaporative distillation at b 180-200o(bath temperature)/0.7mm, and has [] D 25 +3.3o (c 5.1, EtOH). It forms needles at -30o and has m 26.5-27.5o, [] D 25 +0.25o (c 10, CHCl3). [NMR: Cohen et al. Helv Chim Acta 6 4 1158 1981, Burton & Ingold Acc Chem Res 1 9 194 1986, Karrer et al. Helv Chim Acta 2 1 520 1938, Robeson J Am Chem Soc, 64 1487 1942, 65 1660 1943.] Of the eight isomers the D--isomer is the most active. [See W. Friedrich “Vitamins” Walter de Guyter Publ, Berlin 1988.] [Beilstein 17/4 V 168.]