Hyaluronic Acid (HA), also known as hyaluronan or glass acid, is a glycosaminoglycan composed of alternating disaccharide units of glucuronic acid and N-acetylglucosamine.
HA is one of the fundamental components of human skin and the most widely distributed acidic glycosaminoglycan in the human body. It is extensively present in connective tissues, epithelial tissues, and neural tissues, serving as a natural biomolecule in the skin with strong hydrophilic properties. In solution, HA can retain water approximately 500–1000 times its own weight, providing exceptional moisturizing effects and making it an ideal Natural Moisturizing Factor (NMF).
HA is widely used in pharmaceuticals, food and health supplements, medical aesthetics, cosmetics, and various new material fields.
The bioactivity and efficacy of HA are directly related to its relative molecular weight (Mr). HA of different molecular weights may exhibit entirely opposite biological activities.
High Molecular Weight HA (Mr > 2,000,000 Daltons) pssesses excellent viscoelasticity, moisturizing properties, anti-inflammatory effects, and lubrication functions. It is used in ophthalmic surgery viscoelastic agents and intra-articular injection treatments.
Medium Molecular Weight HA (Mr between 1,000,000 and 2,000,000 Daltons) eibits good moisturizing, lubricating, and drug-sustained release effects. It is widely used in cosmetics, eye drops, skin burn healing, and post-surgical anti-adhesion applications.
Low Molecular Weight HA (Mr between 10,000 and 80,000 Daltons) and HA Oligosaccharides (Mr < 10,000 Daltons) donstrate anti-tumor effects, promote wound healing, stimulate bone and blood vessel formation, and exhibit immunomodulatory properties.
Enhances Skin Moisturization
High molecular weight HA forms a hydrating film on the skin's surface, creating a barrier that prevents moisture loss, which is one of its primary functions in cosmetics.
HA exhibits the strongest hygroscopicity at low relative humidity (below 33%) and the weakest at high relative humidity (above 75%). This characteristic makes it particularly suitable for skincare products that need to adapt to varying seasonal and environmental humidity levels, such as dry winters or humid summers.
HA's moisturizing effect is not influenced by surrounding environmental conditions or relative humidity, offering intelligent hydration.
Additionally, studies by Yu Hui et al. have found that long-term use of HA can increase the skin's natural moisture content, improve the skin barrier function, and effectively reduce Transepidermal Water Loss (TEWL).Nourishes the Skin
HA is an intrinsic biomolecule of the skin, with over half of the body's HA content located in the epidermis and dermis. The skin's hydration level is directly correlated with its HA content. A decrease in HA leads to reduced moisture in skin tissue cells and intercellular spaces, shrinking the gel-like matrix primarily composed of HA. This causes cells to become tightly packed, collagen to dehydrate and harden, ultimately resulting in rough skin, loss of elasticity, and the formation of wrinkles.
When HA forms a hydration film over skin, it can not only retain moisture, but can also soften the stratum corneum of skin, thereby further enhancing the absorption and utilization of active substances by the stratum corneum of the skin; After HA penetrates into the epidermis layer of the skin, it maintains water in the skin, which is conducive to the transmission of skin nutrients and the discharge of metabolic wastes, so as to achieve the effects of nourishing and beautifying the skin.
Preventing and Repairing Skin Damage
Free radicals are generated when the skin is exposed to ultraviolet rays, and sun exposure can cause skin redness, burning, peeling, etc. Combined with CD44, which is on the surface of epidermal cells, HA promotes the differentiation of epidermal cells, and scavenges reactive oxygen species, which promotes skin regeneration at the injured site. In addition, the latest in vitro experiments show that HA also has a good repairing effect on ethanol-induced skin cell apoptosis.
Antibacterial and Anti-inflammatory for Skin
The hydration film formed by HA over skin surface can separate bacteria and show an anti-inflammatory effect. In addition, protein and HA are combined in the skin matrix to form a protein complex, which is abundant in the intercellular spaces. It can form gel to bind cells, ensuring the normal metabolism and water-holding function of cell tissues and preventing harmful substances invasion, which further prevents and treats various infections, and provides certain protection for the skin.
HA in the human body will gradually disappear as age grows, causing the skin to lose its ability to store water and become dull, aging, and wrinkling. The application of skin care products containing HA can increase skin elasticity and tension, and help restore the skin's normal oil-water balance, as well as improve skin metabolism and poor skin conditions, making skin soft, smooth, elastic, and showing healthy natural beauty!
