RESUMO: As algas marinhas são fontes naturais de macromoléculas conhecidas como polissacarídeos sulfatados. Esta classe de compostos atraiu o interesse das Ciências Farmacêuticas devido às suas propriedades farmacológicas como anticoagulante, antiplaquetária e antitrombótica. Portanto, este estudo tem como objetivo avaliar o potencial anticoagulante de polissacarídeos sulfatados extraídos de algas de Penicillus capitatus. Os polissacarídeos sulfatados extraídos foram purificados, parcialmente caracterizados e sua atividade anticoagulante foi avaliada. O processo de extração seguido pela precipitação com etanol resultou em cinco frações. Entre as frações analisadas, F44 foi a maior concentração de polissacarídeos sulfatados. Após a purificação, as frações F23 e F44 mostraram atividade anticoagulante in vitro em um teste de tempo de tromboplastina parcialmente ativada e tempo de protrombina. Seu mecanismo preferencial é baseado nas interações entre trombina e fator Xa. Estudos adicionais sobre a estrutura farmacológica são necessários para testar a viabilidade do uso como agente terapêutico.

ABSTRACT: Marine algae are natural sources of macromolecules known as sulfated polysaccharides. This class of compounds has attracted the interest of Pharmaceutical Sciences due to its pharmacological anticoagulant, antiplatelet and antithrombotic properties. Therefore, this study evaluated the anticoagulant potential of sulfated polysaccharides extracted from the algae Penicillus capitatus. The extracted sulfated polysaccharides were purified, partially characterized and their anticoagulant activity was evaluated. The extraction process followed by ethanol precipitation resulted in five fractions. Among the analyzed fractions, F44 contained highest concentration of sulfated polysaccharides. After the purified fraction F23, F44 displayed in vitro anticoagulant activity in a time testing for activated partial thromboplastin time and prothrombin time. The preferential mechanism effect was based on interactions between thrombin and factor Xa. Additional studies on structure pharmacological are required to test the viability of the use of sulfated polysaccharides as therapeutic agents.

Marine sulfated polysaccharides (MSP), such as sulfated fucans (SF), sulfated galactans (SG) and glycosaminoglycans (GAG) isolated from either algae or invertebrate animals, are highly anionic polysaccharides capable of interacting with certain cationic proteins, such as (co)-factors of the coagulation cascade during clotting-inhibition processes. These molecular complexes between MSP and coagulation-related proteins might, at first glance, be assumed to be driven mostly by electrostatic interactions. However, a systematic comparison using several novel sulfated polysaccharides composed of repetitive oligosaccharides with clear sulfation patterns has shown that these molecular interactions are regulated essentially by the stereochemistry of the glycans (which depends on a conjunction of anomericity, monosaccharide, conformational preference, and glycosylation and sulfation sites), rather than just a simple consequence of their negative charge density (mainly the number of sulfate groups). Here, we present an overview of the structure-function relationships of MSP, correlating their structures with their potential anticoagulant and antithrombotic actions, since pathologies related to the cardiovascular system are one of the major causes of illness and mortality in the world.

Os polissacarídeos sulfatados (PSs) de algas vermelhas têm sido relatados mundialmente como agentes anticoagulantes e antitrombóticos. Entretanto, nenhuma descrição de atividade antitrombótica tem sido relacionada com os PSs de algas verdes. A clorofícea Caulerpa cupressoides possui três frações de PSs (PS1; PS2 e PS3). Dessa forma, objetivou-se investigar os efeitos da fração PS2 sobre a atividade da trombina por antitrombina e usando um modelo experimental de trombose venosa em ratos. O ensaio de inibição da trombina foi avaliado usando a antitrombina (AT) na presença de PS2 e a atividade antitrombótica foi investigada em ratos, usando a tromboplastina como o estímulo trombogênico. Os efeitos anticoagulantes de PS2 devem-se provavelmente à sua potência de inibir a trombina mediada pela AT (IC50 ~ 10,0µg mL-1) e esse mecanismo de interação é diferente, comparado ao de outros polissacarídeos de Caulerpa estudados. PS2 exibiu efeitos antitrombóticos nas doses de 1,0 e 2,0mg kg-1 peso corpóreo, mas em doses mais elevadas (>2,0mg kg-1 peso corpóreo) esse polissacarídeo exibe efeitos pró-trombóticos. Também não foi observado nenhum efeito hemorrágico (2,0mg kg-1). Assim como ocorre com os PSs de algas vermelhas, os resultados indicam que os PSs de algas verdes também possuem atividades biológicas distintas in vivo.

Red algae sulfated polysaccharides (SPs) have been widely described as anticoagulant and antithrombotic agents; however no description of antithrombotic activity regarding green algae SPs has been reported. Caulerpa cupressoides (Chlorophyta) has three different SPs fractions (SP1, SP2 and SP3). We investigated the effects of SP2 on thrombin activity by antithrombin and in an experimental model of venous thrombosis in rats. The inhibition of thrombin assay was evaluated using antithrombin (AT) in the presence of SP2 and the antithrombotic activity was investigated in rats with thromboplastin as the thrombogenic stimulus. The anticoagulant effects of SP2 are suggested be due to the potentiation of thrombin inhibition by antithrombin (IC50 ~ 10.0µg mL-1) and this mechanism of interaction is different when compared to other studied Caulerpa polysaccharides. SP2 exhibited antithrombotic effects at doses of 1.0 and 2.0mg kg-1 body weight, but at higher doses (>2.0mg kg-1 body weight) this polysaccharide revert the antithrombotic property. No hemorrhagic effect (2.0mg kg-1) was observed. As occurs with red algae SPs, these results indicate that green algae SPs are also capable of exhibiting different in vivo properties.