Hyaluronic acid and polyglutamic acid are two often compared biopolymers, recognized in skin care for their excellent hydrating properties. Nevertheless, they differ on a number of points, notably on their origin and chemical structure. This article will dive into their differences.
What Are the Differences Between Hyaluronic Acid and Polyglutamic Acid?
- Hyaluronic Acid and Polyglutamic Acid: Different Origins
- Hyaluronic Acid and Polyglutamic Acid: Different Chemical Structures
- Cosmetic Properties of Hyaluronic Acid and Polyglutamic Acid
- Combining Hyaluronic Acid and Polyglutamic Acid
Hyaluronic Acid and Polyglutamic Acid: Different Origins.
Where does hyaluronic acid come from?
This biopolymer was first discovered in the vitreous humor of the bovine eye in 1934 by Karl Meyer and John Palmer. It was subsequently extracted from the cartilage of the snout of the ox and from the crest of the cock. Naturally present in the human body, it is also found around the joints, in the muscles, in the eye... However, the skin and more precisely the dermis remains the main reservoir of this molecule in the human body. Today, the hyaluronic acid present in cosmetic care is generally obtained by biotechnological synthesis from bacteria.
Where does polyglutamic acid (PGA) come from?
This compound was isolated for the first time from the organism of the marine jellyfish. It allows the jellyfish to store water in its fragile tissue and thus avoid dehydration accelerated by the salty water of the ocean. Today, PGA is extracted from a traditional Japanese food, nattô, composed of fermented soybeans. It can also be biosynthesized from glutamic acid using the bacterium Bacillus subtilis. Thus, unlike hyaluronic acid, PGA is not naturally found in the human body.
Hyaluronic Acid and Polyglutamic Acid: Different Chemical Structures.
Hyaluronic acid is a non-branched linear chain of repeating disaccharide units of D-glucuronic acid and an aminoglycan, D-N-acetylglucosamine. Polyglutamic acid is a polymer derived from the amino acid L-glutamic. Its chemical formula is (C5H7NO3)n.
To summarize, hyaluronic acid is formed from a polysaccharide chain, while polyglutamic acid is derived from the polymerization of amino acids.
Cosmetic Properties of Hyaluronic Acid and Polyglutamic Acid.
These two acids are known for their moisturizing properties in skin and hair care. Nevertheless, some nuances are to be brought concerning their mode of functioning and their penetration in the skin:
As a natural constituent of the dermis, hyaluronic acid plays a structural role. It acts as a humectant agent capable of retaining water in the cells. Its mode of action is directly linked to its molecular structure. Indeed, this polymer can bind a hundred or so sulfated proteoglycans to form supramolecular structures. These are then able to establish links with water molecules and ions to maintain the skin's hydration.
Thus, hyaluronic acid has a retention capacity of 1,000 times its weight in water. Moreover, this molecule exists in two molecular weights. High molecular weight hyaluronic acid remains on the surface of the epidermis and creates a protective film that prevents water from evaporating. Low molecular weight hyaluronic acid penetrates deeper into the epidermis, to the base of the corneal structure, to stimulate the production of hyaluronic acid naturally produced by the body.
Polyglutamic acid has a larger molecular size than hyaluronic acid. It does not penetrate deeply but rather remains on the surface. Its moisturizing action is linked to its capacity to form a protective film on the surface of the skin which limits the evaporation of water. This is called a microgel; this structure swells and traps water, thus promoting its retention. Polyglutamic acid is able to retain up to 5,000 times its weight in water.
Combining Hyaluronic Acid and Polyglutamic Acid.
Hyaluronic acid is a compound that has been widely used in skin care for several years now, while polyglutamic acid is a recent active ingredient on the market. However, combining these two molecules offers the skin a hydration boost.
On the one hand, hyaluronic acid acts on the internal cells of the dermis for long-lasting hydration. It contributes in particular to the oxygenation, the toning and the nutrition of the skin. On the other hand, polyglutamic acid forms a protective film on the surface of the stratum corneum that prevents water evaporation.
For example, during your beauty routine, morning and night, you can apply the moisturizing serum with hyaluronic acid first, followed by the plumping serum with polyglutamic acid and red algae extract.
DINI G. & al. Hyaluronic acid in cutaneous intrinsic aging. International Journal of Dermatology (1994).
GOLDMAN D. M. & al. Polyglutamic acid: a novel peptide for skin care. Cosmetics Toiletries Magazine (2007).