Composition of Glycosaminoglycans in Elasmobranchs including Several Deep-Sea Sharks: Identification of Chondroitin/Dermatan Sulfate from the Dried Fins of <i>Isurus oxyrinchus</i> and <i>Prionace glauca</i>

<div><p>Shark fin, used as a food, is a rich source of glycosaminoglyans (GAGs), acidic polysaccharides having important biological activities, suggesting their nutraceutical and pharmaceutical application. A comprehensive survey of GAGs derived from the fin was performed on 11 elasmobranchs, including several deep sea sharks. Chondroitin sulfate (CS) and hyaluronic acid (HA) were found in <i>Isurus oxyrinchus</i>, <i>Prionace glauca</i>, <i>Scyliorhinus torazame</i>, <i>Deania calcea</i>, <i>Chlamydoselachus anguineus</i>, <i>Mitsukurina owatoni</i>, <i>Mustelus griseus</i> and <i>Dasyatis akajei</i>, respectively. CS was only found from <i>Chimaera phantasma</i>, <i>Dalatias licha</i>, and <i>Odontaspis ferox</i>, respectively. Characteristic disaccharide units of most of the CS were comprised of C- and D-type units. Interestingly, substantial amount of CS/dermatan sulfate (DS) was found in the dried fin (without skin and cartilage) of <i>Isurus oxyrinchus</i> and <i>Prionace glauca</i>. ¹H-NMR analysis showed that the composition of glucuronic acid (GlcA) and iduronic acid (IdoA) in shark CS/DS was 41.2% and 58.8% (<i>Isurus oxyrinchus</i>), 36.1% and 63.9% (<i>Prionace glauca</i>), respectively. Furthermore, a substantial proportion of this CS/DS consisted of E-, B- and D-type units. Shark CS/DS stimulated neurite outgrowth of hippocampal neurons at a similar level as DS derived from invertebrate species. Midkine and pleiotrophin interact strongly with CS/DS from <i>Isurus oxyrinchus</i> and <i>Prionace glauca</i>, affording <i>K_d</i> values of 1.07 nM, 6.25 nM and 1.70 nM, 1.88 nM, respectively. These results strongly suggest that the IdoA-rich domain of CS/DS is required for neurite outgrowth activity. A detailed examination of oligosaccharide residues, produced by chondroitinase ACII digestion, suggested that the IdoA and B-type units as well as A- and C-type units were found in clusters in shark CS/DS. In addition, it was discovered that the contents of B-type units in these IdoA-rich domain increased in a length dependent manner, while C- and D-type units were located particularly in the immediate vicinity of the IdoA-rich domain.</p>