Two structurally similar fucosylated chondroitin sulfates from the holothurian species Stichopus chloronotus and Stichopus horrens

Abstract Two fucosylated chondroitin sulfates SC and SH were isolated from the holothurian species Stichopus chloronotus and Stichopus horrens , respectively. The molar ratio of monosaccharides and sulfate (GalNAc:GlcA:Fuc:SO 3 Na) was suggested as ∼1:1:1:4 for both polysaccharides. Really this theoretical ratio was slightly distorted by the presence of some fucan sulfate in both preparations (about 2% in SH and 10% in SC ), which could not be separated probably due to coincidence with the main components in charge density and molecular weight. The 1D and 2D NMR spectroscopic methods were applied for the detailed structural characterization of SC and SH , which were found to have similar structures. The main chain of SC and SH was shown to be composed of the repeating disaccharide units →4)-β- d -GlcA-(1 → 3)-β- d -GalNAc-(1→ sulfated at O-4 or both at O-4 and O-6 of the N-acetyl-galactosaminyl residues. The ratio of mono- and disulfated GalNAc residues was determined as 1:9 for SC and SH . Only one type of branches linked to O-3 of glucuronyl residues, namely fucosyl 2,4-disulfate residues, were found in both polysaccharides. Therefore polysaccharides SC and SH are two new examples of highly regular fucosylated chondroitin sulfates.