Current heparin-based treatment for thromboembolic disorder mainly relies on the heterogeneous unfractionated (UF) or low molecular weight (LMW) heparins that are either extracted from natural animal source or degraded forms of such extractions. UF and LMW heparins therapy faces the challenges in product quality control owing to the non-uniformity of the animal sources. In contrast, the synthetic homogenous ultralow molecular weight (ULMW) heparins bear multiple advantages over the aforementioned two forms in terms of pharmacokinetics (such as, longer circulation half-life and low IC50 value) and product quality control. One of the examples, among others, is the currently marketed Arixtra�, a densely sulfated pentasaccharide developed on the basis of natural antithrombin-binding activating domain of UF heparin. However, one prominent issue associated with Arixtra is that there is still no antidote currently available to efficiently neutralize their anticoagulant activity in the case of overdose or after surgical procedures.Herein, we demonstrate a chemoenzymatic synthetic technique to prepare the biotinylated ULMW heparin (i. e. hexasaccharide) using chemically synthesized biotinylated glucuronic acid as initiating point of polymerization, followed by actions of a series of recombinant heparin sulfate biosynthetic enzymes. Such enzymatic approach, which is more environmental friendly and did not use organic solvents during the synthesis, dramatically shortens the overall synthetic steps (i.e. total 10 steps) as compared with the chemical synthesis (around 50 steps) that is currently used for preparation of Arixtra. The in vitro bioassay study has shown that final constructed biotinylated ULMW heparin has comparable anticoagulant activity to Arixtra, more significantly, it could be irreversibly neutralized by non-toxic avidin protein while Arixtra could not. Therefore, the biotinylated heparin we prepared could potentially substitute the ULMW heparin as a novel neutralizable anticoagulant agent.

Development of neutralizable homogeneous biotinylated heparin as a novel anticoagulant

247th National Meeting (2014)

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