Atividade anticoagulante in vitro de galactanas sulfatadas obtidas da alga verde Udota flabellum (J.Ellis & Solander) M.Howe

Abstract

The main known anticoagulant drug is the sulfated polysaccharide named heparin. However, the use of heparin can cause side effects such as the development of thrombocytopenia, arterial embolism, bleeding complications. Therefore, new anticoagulants that have fewer side effects than heparin are being sought. Many seaweeds are known to synthesize sulfated polysaccharides with anticoagulant activity. Therefore, in this paper, sulfated polysaccharide-rich extracts were obtained from 22 tropical seaweeds (4 red, 11 brown, and 7 green) found in northeastern Brazil and evaluated as anticoagulant agents. Fifteen extracts had anticoagulant activity, including all extracts of green seaweeds. Udotea flabellum extract was the most potent, requiring only 3 µg to double the plasma coagulation time in the activated partial thromboplastin time (APTT) test. A similar result was obtained with 1 µg of heparin. Two sulfated homogalactans F-I (130 kDa) and F-II (75 kDa) with high anticoagulant activity were obtained from this extract using several bio-guided purification steps. Their anticoagulant activities were close to that of heparin. F-I and F-II (0.5–10 μg/mL) were not able to directly inhibit thrombin. In the presence of antithrombin, F-I (0.5 μg/mL) was more effective than heparin (0.5 μg/mL) in inhibiting thrombin, while F-II showed similar effects as heparin. Taken together, the results provide strong evidence for the anticoagulant potential of sulfated homogalactans from U. flabellum.