| Summary: | Fucosylated chondroitin sulfates (FCSs) <b>PC</b> and <b>HH</b> were isolated from the sea cucumbers <i>Paracaudina chilensis</i> and <i>Holothuria hilla</i>, respectively. The purification of the polysaccharides was carried out by anion-exchange chromatography on a DEAE-Sephacel column. The structural characterization of the polysaccharides was performed in terms of monosaccharide and sulfate content, as well as using a series of nondestructive NMR spectroscopic methods. Both polysaccharides were shown to contain a chondroitin core [→3)-β-<span style="font-variant: small-caps;">d</span>-GalNAc (N-acethyl galactosamine)-(1→4)-β-<span style="font-variant: small-caps;">d</span>-GlcA (glucuronic acid)-(1→]<sub>n</sub>, bearing sulfated fucosyl branches at O-3 of every GlcA residue in the chain. These fucosyl residues were different in their pattern of sulfation: <b>PC</b> contained Fuc2<i>S</i>4<i>S</i> and Fuc4<i>S</i> in a ratio of 2:1, whereas <b>HH</b> included Fuc2<i>S</i>4<i>S</i>, Fuc3<i>S</i>4<i>S</i>, and Fuc4<i>S</i> in a ratio of 1.5:1:1. Moreover, some GalNAc residues in <b>HH</b> were found to contain an unusual disaccharide branch Fuc4<i>S</i>-(1→2)-Fuc3<i>S</i>4<i>S</i>-(1→ at O-6. Sulfated GalNAc4<i>S</i>6<i>S</i> and GalNAc4<i>S</i> units were found in a ratio of 3:2 in <b>PC</b> and 2:1 in <b>HH</b>. Both polysaccharides demonstrated significant anticoagulant activity in a clotting time assay, which is connected with the ability of these FCSs to potentiate the inhibition of thrombin and factor Xa in the presence of anti-thrombin III (ATIII) and with the direct inhibition of thrombin in the absence of any cofactors.
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