Abstract
Sulphated polysaccharides with anti-thrombotic and anti-coagulant activities have been found in various marine biota. In this study, a previously characterised anti-thrombotic and anti-coagulant extract from blacklip abalone was fractionated by anion exchange chromatography (AEC), pooled (on a sulphated polysaccharide basis) and administered to Wistar rats via oral gavage (N = 8) for assessment as an oral therapeutic. To ensure that the preparation had anti-coagulant activity prior to oral administration, it was assessed in rat blood by thromboelastography (TEG) significantly increasing reaction (R) time (or time until clot formation). Following in vitro confirmation of anti-coagulant activity, 40 mg of the preparation was orally administered to rats with blood samples collected at 2, 4, and 6 h post-gavage. Assessment of all blood samples by TEG showed some prolongation of R time from 355 to 380 s after 4 h. Dosing of the post-gavage blood samples with the abalone preparation to confirm anti-thrombotic activity in vitro revealed residual anti-coagulant activity, further suggesting that oral administration did increase anti-coagulant potential in the collected blood but that bioavailability was low. Assessment of tissues and haematological parameters showed no obvious harmful effects of the abalone preparation in animals. In summary, even though oral administration of fractionated and pooled blacklip abalone extract to rats delayed clotting after 4 h, bioavailability of the preparation appeared to be low and may be more appropriate for intravenous administration as an anti-thrombotic or anti-coagulant therapeutic.
Highlights
Thrombosis and related disease states are increasing globally and require anti-thrombotic and anti-coagulant therapy
According to the World Health Organisation (WHO), cardiovascular diseases, including heart disease and stroke related to thrombosis, are the main causes of death globally with predictions that by 2030, almost 3.6 million people will die from these diseases [18]
Heparin-like molecules have been identified form various molluscs, and some have less bleeding side effects compared to heparin [22]
Summary
Thrombosis and related disease states are increasing globally and require anti-thrombotic and anti-coagulant therapy. One of the most widely available intravenous anti-coagulant therapeutics and the second most abundant, naturally-occurring drug after insulin [1], is a potent anti-coagulant because of its unique binding to anti-thrombin III [2]. Mar. Drugs 2017, 15, 240 from these sources are often comprised of more than one type of glycosaminoglycan that can appear as contaminants with detrimental effects [5]. The disaccharide composition of heparin from different sources displays complexity in sulphation that can result in different coagulation, thrombosis, and bleeding. In a study from Brazil, uncontrolled bleeding occurred when porcine intestinal heparin was replaced by bovine intestinal heparin [6]; even though bovine intestinal heparin displayed half the coagulant activity compared to porcine intestinal heparin, the bleeding side effects were similar
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