Vitamin E has numerous benefits for the body and skin, notably its antioxidant and anti-inflammatory properties. These characteristics allow it to be included in the composition of many cosmetic skin and hair care products. As a gentle active ingredient, Vitamin E is generally well tolerated by all skin types. But what is its extraction process? Discover this by continuing to read.
How is Vitamin E obtained?
Summary
Published on April 17, 2024, by Pauline, Chemical Engineer — 5 min of reading
Themes:
The brief history of Vitamin E.
The vitamin E is a natural active ingredient first identified in 1922 by Herbert EVANS and Katharine BISHOP. Following studies conducted on rats, these scientists hypothesised the existence of a lipophilic compound essential for foetal development. Two years later, Bennett SURE confirmed this hypothesis and demonstrated that the absence of this compound in the diet of rats led to their sterility. It was then named vitamin E, as the other letters were already taken. It also received the name of tocopherol, from the Greek tokos: offspring and pherein: to bear. The story of vitamin E continued in 1936 when it was first isolated from wheat germ oil by Herbert EVANS and Oliver EMERSON. Its structure was finally determined in 1938 by Erhard FERNHOLZ.
Vitamin E actually refers to a group of eight fat-soluble molecules, meaning they dissolve in fats: 4 tocopherols and 4 tocotrienols. For reasons of stability, alpha-tocopherol is the most commonly used form of Vitamin E in cosmetic products.
The eight natural forms of Vitamin E.
Source: ERKEKOGLU P., SANTOS S. & BLUMENBERG M. Vitamin E in Health and Disease: Interactions, Diseases and Health Aspects. Biochemistry (2021).
Method of obtaining No.1: The extraction of Vitamin E from vegetable oils.
Today, the majority of the vitamin E found in cosmetic products is extracted from vegetable oils. For this process, one or more oils can be used. Most commonly, these are soybean oil and/or sunflower oil, which are very rich in tocopherols. The extraction is carried out using an organic solvent, in which the non-saponifiable elements of vegetable oils such as vitamin E are soluble, while the fatty acids, glycerol and other hydrophilic compounds remain in the aqueous alkaline phase. The most frequently used solvent is hexane, either alone or with a small fraction of a more polar solvent such as ethanol, ethyl acetate or diisopropyl ether. It is also possible to use acetone, diethyl ether or a 2:1 mixture of chloroform-methanol. In the latter case, this is referred to as Folch extraction.
The extraction of vitamin E from vegetable oils is typically carried out using a vortex or equivalent stirring systems . These devices allow for vigorous yet controlled agitation of the solution, which reduces the extraction time. The solvent is then evaporated using a rotary evaporator under reduced pressure. The temperature depends on the solvent used but is often within ranges between 40 and 60°C. Following this, the extracted vitamin E undergoes various purification processes to remove impurities and obtain a purer molecule. Distillation, filtration, and decantation stages are notably involved. Throughout the process, the quality of the vitamin E is tested by several chromatography methods (HPLC, TLC, CEC...).
Method of acquisition no.2: the chemical synthesis of vitamin E.
It is also possible to synthesise vitamin E in a laboratory. However, this method is being used less and less due to its cost and technical complexity. Here are the main steps of this chemical synthesis, noting however that these may slightly vary from one laboratory to another.
Formation of the chromanol ring.
The initial stage of alpha-tocopherol synthesis involves hydroquinone, an aromatic compound also known as 1,4-benzenediol, and isophytol, a natural precursor of tocopherols derived from phytol, a component of plant chlorophyll. These two molecules react together to form a chromanol ring, the fundamental structure of vitamin E.
Alkylation of the chromanol ring.
Once formed, the chromanol ring must be alkylated to introduce the isoprenoid side chains. Among the intermediates commonly used to carry out this reaction, we can mention geranylgeranyl pyrophosphate.
Hydroxylation and Methylation.
In conclusion, successive hydroxylation/methylation reactions are carried out to establish the alcohol group of alpha-tocopherol as well as its carbon chain.
Purification and Isolation.
Once the reactions are completed, alpha-tocopherol is purified and isolated using chromatography techniques such as high-performance liquid chromatography, thin-layer chromatography, or size-exclusion chromatography. The aim is to obtain a product that is as pure as possible, free from reaction by-products.
Sources
ISTASSE L. & al. Chemistry, dietary sources and measurement of vitamin E. Annals of Veterinary Medicine (2003).
NETSCHER T. Synthesis of Vitamin E. Vitamins & Hormones (2007).
Mohammed GUIGA's Thesis. Vitamin E: Metabolism, Physiological Role: Benefits and Risks of Supplementation (2021).
ERKEKOGLU P., SANTOS S. & BLUMENBERG M. Vitamin E in Health and Disease: Interactions, Diseases and Health Aspects. Biochemistry (2021).
