Fucosylated chondroitin sulfates from the sea cucumbers Holothuria tubulosa and Holothuria stellati

Two polysaccharides HT and HS were isolated from the sea cucumbers Holothuria tubulosa and Holothuria stellati, respectively. Purification of the natural polymers was performed by consecutive ion-exchange and gel permeation chromatography. The molar ratio of the monosaccharides and sulfate GlcA:GalNAc:Fuc:SO3Na was determined as 12:14:17:57 for HT and 12:12:16:60 for HS indicating that both polysaccharides are fucosylated chondroitin sulfates. Detailed structural characterization of HT and HS was performed using the 1D and 2D NMR spectroscopic methods. The main chain of HT and HS was shown to consist of alternating →4)- β-d-GlcA-(1→ and →3)-β-d-GalNAc-(1→ sequence, where the latter unit was sulfated at O-4 or both at O-4 and O-6. The ratio of GalNAc4S:GalNAc4S6S was determined as 1:4 for HT and 1:4.5 for HS. Three types of sulfated fucosyl branches Fucp2S4S, Fucp3S4S and Fucp4S attached to O-3 of glucuronic acid residues were found in a ratio of 3:3:1 for HT and 2:2:1 for HS.