hüaluroonhapet

Hyaluronic acid (HA), also known as hyaluronan, is a naturally occurring, non-sulfated glycosaminoglycan distributed widely in connective, epithelial, and neural tissues. It consists of repeating disaccharide units of D-glucuronic acid and N-acetyl-D-glucosamine, and is particularly abundant in the extracellular matrix.

HA is essential for tissue hydration, lubrication, and resilience. Its ability to bind large amounts of water helps maintain cell and tissue turgor in the skin, joints, and eyes. It also participates in cell signaling, wound healing, and inflammatory processes, interacting with receptors such as CD44 and RHAMM.

Biosynthesis and turnover are dynamic. HA is produced at the inner surface of the plasma membrane by hyaluronan synthases HAS1–HAS3 and released into the extracellular space. It is degraded by hyaluronidases and oxidative processes. Molecular weight varies widely; high-molecular-weight HA tends to be anti-inflammatory, while low-molecular-weight fragments can promote inflammation and repair signaling.

Occurrence and significance. In humans, HA is synthesized endogenously and present in skin, synovial fluid, eyes, and the umbilical cord. Levels decrease with age and in certain diseases, contributing to reduced hydration and tissue elasticity.

Applications. Medically, HA is used in intra-articular injections for osteoarthritis, as a viscoelastic agent in ophthalmic surgery, and in wound dressings. In cosmetics, it is used in dermal fillers and topical moisturizers to improve hydration and plumpness. HA-based products vary in molecular weight and crosslinking, affecting performance and duration.

Safety and regulation. HA is generally well tolerated, with occasional local reactions. Quality control is important to avoid contaminants; some formulations may cause swelling or bruising at injection sites.