What are the benefits of polyglutamic acid on the skin?

Thepolyglutamic acid or PGA is a water-soluble peptide derived from the polymerisation of glutamic acid extracted from the fermentation of soybean seeds. This compound combats skin dehydration at various levels.

Firstly, it forms a microscopic film on the surface of the epidermal tissue, referred to as a microgel . This molecular arrangement swells upon contact with water and traps H2O molecules. Through this mechanism, the PGA is capable of retaining up to 5,000 times its weight in water. In comparison, hyaluronic acid can retain up to 1,000 times its weight in water. A 2014 study revealed that PGA had a more hydrating effect than hyaluronic acid.

Next, PGA enhances the production of molecules that make up the Natural Moisturising Factor (NMF). As a reminder, in the stratum corneum, water is retained by hygroscopic substances that form duringthe epidermal differentiation process. Thus, several studies have demonstrated the ability of polyglutamic acid to boost the production of some of these molecules, including pyrrolidone carboxylic acid (PCA), lactic acid, and urocanic acid.

Finally, PGA limits the activity of the hyaluronidase, the enzyme responsible for the reduction of hyaluronic acid present in the dermal tissue. As a reminder, hyaluronic acid is a molecule predominantly produced by the fibroblasts of the dermis (deep layer of the skin) that acts like a sponge and retains water. It thus ensures the hydration of the skin and gives it its plump and bouncy appearance. Over the years, not only does its content decrease but its quality also changes . Thus, by the age of 50, the stock of hyaluronic acid has halved. This drastic drop leads to an atrophy of the fat pockets located in the depth of the dermis, causing the appearance of wrinkles and fine lines on the skin's surface. By inhibiting the activity of the hyaluronidase enzyme, polyglutamic acid therefore prevents skin dehydration and the appearance of signs of ageing.

Note : While PGA aids in maximising the hydration of the epidermis, its high molecular weight prevents it from acting in depth. Its action is limited to the superficial layers of the skin. Low molecular weight hyaluronic acid is more recommended for deep skin hydration.

The ageing of the skin is due to intrinsic factors, such as a decrease in the rate of cell renewal, a change in the composition of the dermis and the molecules that constitute it (hyaluronic acid, collagen...) and the loss of fatty and muscular tissue which no longer plays its supporting role. Extrinsic factors that depend on the lifestyle of the individual can greatly accelerate the process (poor diet, smoking, excessive alcohol consumption, sun exposure, stress, lack of sleep...). In response to this, wrinkles deepen, the skin becomes drier, pigment spots may appear, as well as dilated vessels. Furthermore, the epidermis changes, it thickens or thins depending on the individual.

The first wrinkles that appear around the age of thirty are most often dehydration wrinkles (generally around the eyes and/or on the forehead). Thepolyglutamic acid helps to slow down this process thanks to its hydrating action, described in the previous paragraph. Furthermore, astudy has demonstrated the ability of polyglutamic acid to enhance the skin's elasticity in a more significant way than collagen and hyaluronic acid when applied topically.