The effect of glycosaminoglycans and proteoglycans on lipid peroxidation (Review)

Recent investigations show that glycosaminoglycans (GAGs) and proteoglycans (PGs) have the ability to affect lipid peroxidation, one the best characte rized forms of free radical mediated biological damage. A protective effect of these extracellular matrix (ECM) components has been demonstrated in va rious experimental systems, including fatty acids and liposomes, where oxid ation was induced by transition metals, including copper and iron. The effe ct was specific and dependent on the type and structural features of GAGs a nd PGs. The mechanism of peroxidation inhibition was likely to be dependent , at least to a large extent, on the sequestration of transition metals by GAG chains. Thus, it is conceivable that GAGs in the ECM and in the pericel lular space may contribute to protecting cells against free radical damage. It is of particular interest that in certain tissues (cornea and aorta) ag ing was associated with a decrease of content of the GAGs which were most e ffective as anti-oxidant. This suggests that age-induced modifications of E CM composition in certain tissues may increase the susceptibility to oxidat ive stress. The investigation on the effect of GAGs on lipoprotein oxidatio n led to apparently conflicting results. An interesting reconciliation is p ossible, according to which GAGs exerted their protective effect under expe rimental conditions not compatible with the formation of lipoprotein-GAG co mplexes; rather, lipoproteins exhibited increased susceptibility to metal-c atalyzed oxidation (MCO), possibly due to structural modifications of the p article after binding to GAGs or PGs. This process is likely to occur in th e intimal matrix of arteries.