In order to search for sulfated polysaccharides in different invertebrate connective tissues and to examine their biological activities, we have isolated three types of polysaccharides from the body wall of the three sea cucumbers Holothuria edulis, Apostichopus japonicas and Holothuria nobilis. The physicochemical properties and anticoagulant activities of these polysaccharides were examined and compared. The chemical composition analysis and nuclear magnetic resonance (NMR) analysis indicate that two types of polysaccharides, sulfated fucan and fucosylated chondroitin sulfate (FuCS), were found in all of the three species and in addition a neutral glycan was observed in H. edulis. The neutral α-glucan was firstly obtained from sea cucumber. The same type of polysaccharides from different species of sea cucumbers have similar physicochemical properties and anticoagulant activities, but those of different types of glycans are significantly different, possibly due to their different monosaccharide compositions, electric charges and average molecular weights. The FuCSs have stronger anticoagulant activities than the sulfated fucans, although the molecular sizes of the FuCSs are lower than those of the sulfated fucans, whereas the neutral glucan has no activity, as expected from the absence of sulfate. Thus, anticoagulant activities of the different type of polysaccharides are likely to relate to monosaccharide composition and sulfate content. Preliminary analysis suggests that the sulfation patterns of the FuCSs may result in the difference in anticoagulant activities. Our data could help elucidate the structure-activity relationship of the sea cucumber polysaccharides.

Significance: Selective inhibition of the intrinsic coagulation pathway is a promising strategy for developing safer anticoagulants without serious bleeding consequences. We prepared and identified a series of oligosaccharides as inhibitors of the intrinsic tenase, which is the final and rate-limiting enzyme complex in the intrinsic coagulation pathway and is an attractive but less explored target for anticoagulants due to the lack of a pure selective inhibitor. Analysis of these purified oligosaccharides reveals the precise structure of fucosylated glycosaminoglycan. Among these oligosaccharides, nonasaccharide is the minimum fragment that retains potent anticoagulant activity by selective inhibition of the intrinsic tenase while avoiding adverse effects and, thus, it may pave the way for the development of better treatments for thromboembolic diseases.