Chondroitin 4-sulphate exhibits inhibitory effect during Cu2+-mediated LDL oxidation

Chondroitin 4-sulphate (C4S), a basic component of the extracellular matrix of the artery wail, inhibited copper-induced low density lipoprotein (LDL) oxidation by prolonging the lag time and reducing the rate of propagation, LDL oxidation was assessed by monitoring conjugated dienes and low level chemiluminescence, A possible initial key reaction in LDL oxidation, the reduction of copper(II) to copper(I) by LDL, was decreased in the presence of C4S. Moreover, C4S protected tryptophan residues of C4S in the early stage of LDL oxidation and during the subsequent propagation phase, The presence of the sulphate group in position 4 of N-acetylgalactosaminyl residues of C4S is crucial for protective activity, In Fact, the structurally related chondroitin 6-sulphate, also present in tissues, had no effect an LDH. oxidation. These data suggest that C4S mag contribute to protest LDL against oxidation in arterial intima. (C) 1997 Federation of European Biochemical Societies.