The reaction of hyaluronic acid and its monomers, glucuronic acid and N-acetylglucosamine, with reactive oxygen species

Synovial fluid is a similar to 0.15% (w/v) aqueous solution of hyaluronic a cid (HA), a polysaccharide consisting of alternating units of GlcA and GlcN Ac. In synovial fluid of patients suffering from rheumatoid arthritis, HA i s thought to be degraded either by radicals generated by Fenton chemistry ( Fe2+/H2O2) or by NaOCl generated by myeloperoxidase. We investigated the co urse of model reactions of these two reactants in physiological buffer with HA, and with the corresponding monomers GlcA and GlcNAc. meso-Tartaric aci d, arabinuronic acid, arabinaric acid and glucaric acid were identified by GC-MS as oxidation products of glucuronic acid. When GlcNAc was oxidised, e rythronic acid, arabinonic acid, 2-acetamido-2-deoxy-gluconic acid, glyceri c acid, erythrose and arabinose were formed. NaOCl oxidation of HA yielded meso-tartaric acid; in addition, arabinaric acid and glucaric acid were obt ained by oxidation with Fe2+/H2O2. These results indicate that oxidative de gradation of HA proceeds primarily at glucuronic acid residues. meso-Tartar ic acid may be a useful biomarker of hyaluronate oxidation since it is prod uced by both NaOCl and Fenton chemistry. (C) 1999 Elsevier Science Ltd. All rights reserved.