Atividade antitrombótica dos polissacarídeos sulfatados da alga marinha vermelha Gelidiella acerosa (FORSSKAL) FELDMANN & G. HAMEL coletada nas praias dos municípios de Flexeiras e Paracuru do litoral cearense

Abstract

The interest in the isolation of sulfated polysaccharides from seaweed with anticoagulant and antithrombotic activities are justified by events of thrombosis, the adverse effects of heparin, a widely used drug in the prevention and treatment of thromboembolic diseases. Adding to that sulfated polysaccharides (PS) has attracted a wide interest in various fields of medical sciences. The aim of this study was to evaluate the antithrombotic activity of PS obtained from red seaweed Gelidiella acerosa, collected from natural beds of algae in the State of Ceará (beaches of Flecheiras and Pacaruru). Total sulfated polysaccharides (PST) from both beaches was extracted sodium acetate buffer (pH 6.0) containing cysteine and EDTA (5mM) and crude papain, fractionated by ion exchange chromatography on DEAEcellulose column with acetate buffer eluindo 50m M pH 5.0, containing different concentrations of NaC1 (0.25, 0.50, 0.75, 1.00 and 1.25 M). Ga fractions obtained were characterized by gel electrophoresis on 0.5% agarose and then determined their chemical composition. The antithrombotic activity has been evaluated using an experimental model of venous thrombosis in rats weighing between 200 and 250 g (CEPA-UF'C 58 / 2007). Proceeds from the PST were 1.43 and 1.41% and Flecheiras Paracuru respectively. The chromatographic profiles showed the separation into five different fractions of sulfated (Gal, Gall, GAEL GaIV and GaV), eluted with concentrations of 0.25, 0.50, 0.75, 1.00 and 1.25 M salt, respectively, and revealed by electrophoresis, molecular characteristics similar in the densities of negative charge and degree of sulfation. Yet the chemical composition of total carbohydrates (TC) in the PST and Ga fractions obtained for both locations (Flecheiras and Paracuru) showed percentages ranging from 1.8 to 97.0% and 2.1-80.0% CT, respectively, with respect to SL (Sulfate Free) ranging from 0.4 to 42.4% and 10.1 to 40.5%, respectively, where the fractions Gall and GaIV showed higher levels (SL and TL) to both locations. The fractions were tested for their anticoagulant activity in vitro by the APTT. However, only a fraction GaIV had a slight increase in clotting time at a dosage of 1.0 mg.kg-1, and then assessed in a model of venous thrombosis, where the fraction of both beaches were able to inhibit thrombosis in a significant and dose-dependent (p <0.05). The major effects of inhibition of thrombus were 83.4 and 94.4% (Flecheiras and Paracuru, respectively) at a dose of 1.0 mg.kg-1 of body weight. Therefore, the PS isolated from red alga G. acerosa may be considered an interesting source of new antithrombotic agents to be explored.