Sulfation pattern of the fucose branch is important for the anticoagulant and antithrombotic activities of fucosylated chondroitin sulfates

BackgroundThe aim is to compare the structures, anticoagulant and antithrombotic activities of two fucosylated chondroitin sulfates isolated from sea cucumbers Isostichopus badionotus (fCS-Ib) and Pearsonothuria graeffei (fCS-Pg), which were known to have different sulfation patterns on the fucose branches.MethodsThe structures of fCSs were identified using 2D NMR. Anticoagulant activities were measured by activated partial thromboplastin time (APTT) and thrombin time (TT), and inhibition of factors IIa, Xa and XIIa was assessed in vitro. Antithrombotic activity was determined ex vivo by measuring the length and weight of the thrombus generated.ResultsThe two fCSs had identical chondroitin sulfate E backbones and similar fucose branches, but different sulfation patterns of the fucose branches. The fucose branch in fCS-Ib was mainly 2,4-O-sulfated whereas that in fCS-Pg was mainly 3,4-O-sulfated. In vitro assay indicated that fCS-Pg possessed much lower potency than fCS-Ib in prolonging APTT/TT and in inhibition of thrombin. However, they both exhibited similar inhibitory effects on factor X activation by intrinsic tenase complex, and on thrombus generation. Furthermore, both fCSs significantly activated factor XII, which has been proved to be associated with adverse clinical events associated with heparin contaminated by oversulfated chondroitin sulfate.ConclusionThe 2,4-O-sulfated fucose branch is the key structural factor of fCSs for prolonged APTT/TT and inhibition of thrombin, whereas the inhibitory effect of fCSs on factor X, XII activation and thrombus generation was attributed to the overall structure of fCS polysaccharide.General importanceBoth fCSs have well defined structures and can be readily quality-controlled, and therefore may be potential alternatives for heparin as anticoagulant and antithrombotic drugs.

► Fuc2,4S branches are the key for prolonged APTT/TT and inhibition of thrombin.
► FXa, FXIIa and thrombus generation are affected by stereotype structures of fCSs.
► fCS-Pg has high antithrombotic but low anticoagulant activity.
► fCS-Ib has both high anticoagulant activity and antithrombotic activity.
► Both two fCSs have well repeated unit and can be readily quality controlled.