Hyaluronan

Hyaluronic acid

Haworth projection
Identifiers
CAS Number	9004-61-9 Y 31799-91-4 (potassium salt) N 9067-32-7 (sodium salt) N
ECHA InfoCard	100.029.695
UNII	S270N0TRQY Y
Properties
Chemical formula	(C14H21NO11)n
Solubility in water	Soluble (sodium salt)
Pharmacology
ATC code	D03AX05 (WHO) M09AX01 (WHO), R01AX09 (WHO), S01KA01 (WHO)
Hazards
S-phrases	S22, S24/25 (sodium salt)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	> 2400 mg/kg (mouse, oral, sodium salt) >4000 mg/kg (mouse, subcutaneous, sodium salt) 1500 mg/kg (mouse, intraperitoneal, sodium salt)
Related compounds
Related compounds	D-Glucuronic acid and N-acetyl-D-glucosamine (monomers)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Hyaluronic acid (HA; conjugate base hyaluronate), also called hyaluronan, is an anionic, nonsulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. It is unique among glycosaminoglycans in that it is nonsulfated, forms in the plasma membrane instead of the Golgi apparatus, and can be very large, with its molecular weight often reaching the millions. One of the chief components of the extracellular matrix, hyaluronan contributes significantly to cell proliferation and migration, and may also be involved in the progression of some malignant tumors.

The average 70 kg (154 lb) person has roughly 15 grams of hyaluronan in the body, one-third of which is turned over (degraded and synthesized) every day. Hyaluronic acid is also a component of the extracellular capsule, and is believed to play a role in virulence.

Until the late 1970s, hyaluronic acid was described as a "" molecule, a ubiquitous carbohydrate polymer that is part of the extracellular matrix. For example, hyaluronic acid is a major component of the synovial fluid, and was found to increase the viscosity of the fluid. Along with lubricin, it is one of the fluid's main lubricating components.

Hyaluronic acid is an important component of articular cartilage, where it is present as a coat around each cell (chondrocyte). When aggrecan monomers bind to hyaluronan in the presence of HAPLN1 (Hyaluronanic acid and proteoglycan link protein 1), large, highly negatively charged aggregates form. These aggregates imbibe water and are responsible for the resilience of cartilage (its resistance to compression). The molecular weight (size) of hyaluronan in cartilage decreases with age, but the amount increases.