N-Acetylglucosamine (N-acetyl-D-glucosamine, or GlcNAc,) is a monosaccharide and a derivative of glucose. It is part of a biopolymer in the bacterial cell wall, built from alternating units of GlcNAc and N-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure is called peptidoglycan (formerly called murein). GlcNAc is the monomeric unit of the polymer chitin, which forms the outer coverings of insects and crustaceans. It is the main component of the radulas of mollusks, the beaks of cephalopods, and a major component of the cell walls of most fungi. It is lnsown, that the breakdown of glycosaminoglycans is an important consequence of inflammation at mucosal surfaces, and inhibition of metalloprotease activity may be effective in treating chronic inflammation. GlcNAc directly incorporates into glycosaminoglycans and glycoproteins, as a substrate for tissue repair mechanisms. It was shown, that GlcNAc was promising substance for treatment of chronic inflammatory bowel disease, with a mode of action which is distinct from conventional treatments. In experiments on rabbits with osteoarthritis, was found chondroprotective effects of aminomonosaccharide glucosamine, but no statistically significant difference was found between study groups. It was also investigated for the treatment of Multiple sclerosis, however, as a drug development target, GlcNAc had significant limitations. GlcNAc has poor membrane permeability, requiring high concentrations for biological effects.