Procédé d'obtention du rétinol.

How is retinol produced?

Retinol, a derivative of Vitamin A, has been used for around thirty years to effectively combat skin sagging and wrinkles. However, its extraction process remains somewhat opaque.

What exactly is Retinol?

The term "retinol" originates from the fact that vitamin A plays a role in vision, specifically in the retina of the eye. Interestingly, in ancient times, Egyptians used to apply beef liver compresses, which contain retinol, to the eyes of the blind to treat blindness. However, it was not until 1931 that retinol was first isolated from mackerel liver oil by a Swiss chemist. In 1943, retinol was recognised as effective in reducing acne due to its action on cell renewal. It unclogs pores and regulates sebum production.

Later on, retinol becomes the star of cosmetic active ingredients in the fight against signs of ageing. It helps to counteract the degradation of the skin's support fibres. It has the ability to stimulate the production of collagen, hyaluronic acid, elastin, as well as the activity of fibroblasts for smoother, firmer and more elastic skin. Moreover, retinol is recognised for its antioxidant virtues that prevent premature ageing of skin cells. It also has an effect on the skin's melanin production, helping to reduce the appearance of brown spots that can appear with age.

It should be noted that skincare products containing retinol can be irritating to the skin and are generally not recommended for sensitive skin types.

Retinol can be derived from a 100% chemical reaction or from biosynthesis, as detailed below.

The synthesis of retinol.

Pure retinol is a molecule obtained through chemical synthesis. This compound can easily be degraded by the oxygen present in the ambient air, hence the need to carry out its synthesis under controlled conditions (low temperature and inert atmosphere).

A 1994 article highlights the industrial synthesis of retinol by four different companies.

  1. Synthesis of beta-ionone from acetone and isobutene. Beta-ionone is a chemical compound with the formula C13H20O, belonging to the terpene family. As an interesting side note, the β-ionone is the main molecule responsible for violet aromas in wines.

  2. The beta-ionone is then transformed into retinol. For this step, three different chemical reactions are possible. Two methods involve organic chemistry reactions known as the Grignard and Julia reactions. The third method is a Wittig reaction. Three parameters must be considered during these reactions: cyclisation, stereoselectivity (with 16 possible stereoisomers) and stability related to the polyene system.

The biosynthesis of retinol.

This method of acquisition involves a precursor known as β-carotene or provitamin A. It is a carotenoid (plant pigment) with the chemical formula C40H56. This molecule presents itself in the form of a carbon chain made up of eight isoprene units, with a series of eleven conjugated double bonds. It can absorb indigo-blue light and therefore appear orange as in a carrot.

The biosynthesis of retinol from β-carotene involves the following steps:

  1. Reaction with a primary enzyme and formation of an epoxide (a chemical function featuring a bridged oxygen on a single carbon-carbon bond) at the central double bond of β-carotene.

  2. Hydrolysis (reaction with a water molecule H2O) of this epoxide to form two hydroxyl groups (2 -OH functions) at the centre of the molecule.

  3. Reduction of hydroxyls into aldehydes (carbonyl group C=O located at the end of the carbon chain), via NADH (Nicotinamide adenine dinucleotide hydride, a coenzyme derived from vitamin B3). At this point, a cleavage of the molecule occurs, resulting in retinal (C20H28O), a compound also approved for use in cosmetics with proven regenerative properties.

  4. Reduction of Retinal (C20H28O) to Retinol (C20H30O) via a second enzyme.

Discover our treatments containing retinol.

To combat skin ageing and prevent skin sagging, the wrinkle & fine lines serum contains 0.3% retinol. It is formulated with 99% natural origin ingredients. It is particularly suitable for mature skin. We advise against its use on sensitive and reactive skin.

The neck and décolletage serum is composed of retinol (0.2%) and borage oil, known for its firming properties. This treatment smooths the skin of the neck and décolletage. It can also be used locally on other parts of the body.

Our firming face cream with 0.2% retinol and tsubaki oil is enriched with tightening agents to combat the appearance of wrinkles and make the skin more plump. It stimulates the production of collagen and elastin fibres to prevent signs of skin ageing.

The Firming Tonic Lotion contains 0.1% retinol and Damask rose extract. It is applied after skin cleansing, to rebalance the skin's pH and delay the appearance of wrinkles. It is composed of 99% natural origin ingredients.

The wrinkle and blemish serum combines the densifying action of retinol (0.3%) with the anti-bacterial action of bakuchiol (1%) to reduce the appearance of wrinkles and correct blemishes. Synthesised by endemic Australian plants, the plant polypeptides it contains are capable of working in synergy with retinol to promote the synthesis of type I collagen. They thus help to reduce the depth of wrinkles and densify the skin. These peptides also contribute to maintaining a thick epidermis, which plays its role as a shield against the external environment.

Note: As retinol is photosensitive, it is advised not to expose oneself to the UV rays of the sun after using one of these treatments. The use of retinol is preferably done in the evening. The following morning, ensure to apply a sunscreen with an SPF suitable for your skin type.

Sources:

  • Ludivine Chaurand, LE RETINOL, UQACC, (2016).

  • WANG L. H. Simultaneous determination of retinal, retinol and retinoic acid (all-trans and 13-cis) in cosmetics and pharmaceuticals at electrodeposited metal electrodes. Analytica Chimica Acta (2000).

  • KAFI & al. Improvement of naturally aged skin with vitamin a (retinol). Archives of Dermatology (2007).

  • QUAN. T. & al. Molecular basis of retinol anti-aging properties in naturally aged human skin in vivo. International Journal of Cosmetic Science (2016).

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