Since the first description of sulfated polysaccharides from seaweeds, these compounds have been tested for biological activities in different mammalian systems. They have shown several biological/pharmacological activities, including anticoagulant activity. These activities were related to the structural and the chemical composition of the polysaccharides. In an addition, the structure of these polymers varies among species and sometime among different part of the seaweed. Thus each sulfated polysaccharides purified is a unique compound with unique structural features and thus a potential new drug. We have obtained sulfated polysaccharides from the green seaweed Codium isthmocladium by proteolytic digestion, followed by separation into five fractions (0.3, 0.5, 0.7, 0.9 and 1.2) by sequential acetone precipitation. The chemical analyses have demonstrated that all fractions are composed mainly to sulfated polysaccharides. The anticoagulant activity of these fractions was determined by activated partial thromboplastin time (aPTT) and prothrombin test (PT) using citrate normal human plasma. No one fraction has shown anticoagulant activity by PT test. Furthermore, all of them have shown anticoagulant activity by aPTT test. These results indicated that the sites of actions of these sulfated polysaccharides are mainly in the intrinsic via of the coagulation cascade. Agarose gel electrophoresis in 1,3-diaminopropane acetate buffer, pH 9.0, stained with 0.1% toluidine blue showed the presence of two or three bands in several fractions while the fraction 0.9 showed a single spot. The acid polysaccharides from the 0.9 acetone fraction were separated into two new fractions eluted respectively with 2.0 and 3.0 M NaCl. These compounds showed a molecular weight of 6.4 and 7.4 kDa respectively and the chemical analyses showed they are sulfated homogalactans. aPPT test demonstrated the fractions 2,0 and 3,0M have high anticoagulant activity. To prolong the coagulation time to double the baseline value in the aPTT, the required concentration of sulfated galactan 2.0M (10mg) was similar to low molecular heparin Clexane®, whereas only 1mg of sulfated galactan 3.0M was needed to obtain the same effect. These results suggest that these fractions (2,0 and 3,0M of NaCl) have a potential application as an anticoagulant drug.
Supported by CNPq, CAPES and FAPERN