The benefits of red algae for the skin.

Thered algae, or Rhodophytes, are marine algae primarily found in Europe (Atlantic Ocean, English Channel, North Sea). From these species, a sulfated polysaccharide is extracted, which is used to thicken formulas and give them a gel-like consistency, the carrageenan.

This biopolymer is prevalent in both the cosmetic and food industries. Traditionally extracted from the speciesChondrus crispus (also known as Irish moss), carrageenan is now primarily derived from the species Kappaphycus alvarezii, Eucheuma denticulatum or even Furcellaria lumbricalis, which are very common in Scandinavian waters.

Firstly, the carrageenan extracted from red seaweed possesses excellent propertiesas a humectant, allowing it to retain water in the superficial layers of the skin, thereby reducing insensible water loss. Also known as transepidermal water loss, this natural physiological phenomenon is due to the osmotic pressure difference between the various layers of the skin, as well as the surrounding air. To compensate for this, hydration is essential for all skin types. Properly hydrating the skin with a care product enriched with carrageenan can thus prevent the feelings of tightness that go hand in hand with dry skin or even the fine lines of dehydration.

Next, carrageenan is capable of stimulating the synthesis of hyaluronic acid in the epidermis. As a reminder, hyaluronic acid is a biomolecule that ensures skin hydration and gives it its plump and bouncy appearance. Over the years, its content decreases and its quality also changes. Each decade, we lose about 6% of hyaluronic acid. This drastic drop leads to atrophy of the fat pockets located deep in the dermis, resulting in the appearance of wrinkles and fine lines on the skin's surface. Even though hyaluronic acid is present in larger quantities in the dermis, its synthesis rate is higher in the epidermis than in the dermis. Thus, by stimulating its epidermal synthesis, carrageenan helps to maintain plump skin for as long as possible.

Furthermore, red algae extract limits imperfections on the skin's surface. Indeed, studies have shown thebactericidal activityof carrageenan against Staphylococcus epidermidis and theEnterococcus faecalis, two microorganisms implicated in the development ofacne and its associated inflammatory reactions.

Finally, the red algae extract helps to stimulate the synthesis of ceramides which strengthens the skin's barrier and limits insensible water loss. As a reminder, ceramides are lipids organized into dense and structured layers that form the intercellular cement.

To boost your skin's hydration, the plumping serum contains both red algae extract and polyglutamic acid. The red algae extract is derived from an oligofurcellaran, obtained by depolymerization of a sulfated furcellaran (galactose and anhydrogalactose) from the species Furcellaria lumbricalis.

Following depolymerization, the oligofurcellaran is rehydrated with a solution enriched in sea salts. This final addition of marine trace elements, particularly potassium, induces a reorganization of the polymer into a double helix, endowing it with excellent hygroscopic properties.

• KANAAN H. M. & et al. Anticoagulant and antibacterial properties of polysaccharides from the red algae Corallina collected from the Lebanese coast. Journal of Applied Pharmaceutical Science (2014).

• HUANG N. & al. Potential Use of Seaweed Bioactive Compounds in Skincare: A Review. Marine Drugs (2019).