Galactosaminoglycans: Medical Applications and Drawbacks

Galactosaminoglycans (GalAGs) are sulfated glycans composed of alternating N-acetylgalactosamine and uronic acid units. Uronic acid epimerization, sulfation patterns and fucosylation are modifications observed on these molecules. GalAGs have been extensively studied and exploited because of their multiple biomedical functions. Chondroitin sulfates (CSs), the main representative family of GalAGs, have been used in alternative therapy of joint pain/inflammation and osteoarthritis. The relatively novel fucosylated chondroitin sulfate (FCS), commonly found in sea cucumbers, has been screened in multiple systems in addition to its widely studied anticoagulant action. Biomedical properties of GalAGs are directly dependent on the sugar composition, presence or lack of fucose branches, as well as sulfation patterns. Although research interest in GalAGs has increased considerably over the three last decades, perhaps motivated by the parallel progress of glycomics, serious questions concerning the effectiveness and potential side effects of GalAGs have recently been raised. Doubts have centered particularly on the beneficial functions of CS-based therapeutic supplements and the potential harmful effects of FCS as similarly observed for oversulfated chondroitin sulfate, as a contaminant of heparin. Unexpected components were also detected in CS-based pharmaceutical preparations. This review therefore aims to offer a discussion on (1) the current and potential therapeutic applications of GalAGs, including those of unique features extracted from marine sources, and (2) the potential drawbacks of this class of molecules when applied to medicine.