Relationship between antithrombotic activities of fucans and their structure

A low molecular weight fucan fraction extracted from the brown seaweed Asco phyllum nodosum was previously shown to exhibit dose-related venous antithr ombotic activity with an ED80 of about 20 mg/kg, 2 h after a single subcuta neous injection HCII (Colliec et al. [1991] Thromb Res 64:143-154; Mauray e t al. [1995] Thromb Haemast 74:1280-1285). Its activity was comparable to t hat of a low molecular weight heparin (Dalteparin(R)). This fucan fraction is one of several, with a range of different structure parameters, prepared by degradation of the whole native fucan. These low molecular weight fract ions were compared using a Wessler stasis thrombosis model in rabbits and b y determination of their in vitro and ex vivo anticoagulant activities. Int ravenous administrations of these fractions reduced thrombosis in a dose-de pendent manner. Partial removal of sulfate groups and/or partial degradatio n lead to a significant decrease in their anticoagulant and antithrombotic activities. The integrity of the regular pattern of sulphation of the fucoi dan is necessary for antithrombotic activity. (C) 2001 Wiley-Liss. Inc.