Abstract
The increasing demand for heparin (HEP) has led to a search for alternative sources of natural anticoagulants. This study aimed to evaluate the anticoagulant activity of sulfated polysaccharides (SP) isolated from a Halymenia rhodophyceae genus native to the coast of Ceará, Brazil. Total SP were obtained by consecutive digestions with papain in 0.1 M sodium acetate buffer (pH 5.0) containing 5 mM cysteine and 5 mM EDTA, followed by ion-exchange chromatography on DEAE-cellulose column. The obtained fractions were concentrated by lyophilization and submitted to 0.5% agarose gel electrophoresis. Anticoagulant activity was evaluated by the activated partial thromboplastin time (APTT) using plasma from rabbits and a standard HEP (100 IU mg-1) curve. The extractions (53.96%) showed marked differences during the fractionation and in the degree of purification of SP. The species SP showed higher activity anticoagulant than that of HEP. However, the APTT of the fractions changed sharply among the extractions, expressing itself in a dose-dependent manner and increasing from 110.40 (1st extraction) to 143.10 IU mg-1 (3rd extraction). The results suggest that the anticoagulant activity of SP isolated from Halymenia sp. was promoted by inhibition of the intrinsic and/or common pathway of the coagulation cascade. The changes on APTT possibly will be elucidated through the mechanisms of action involved in coagulation and structural characterization of these compounds. Therefore, the red alga Halymenia sp. is a good source of heparinoids, and studies are suggested on the cultivation of this species and on the protection of natural algae banks.
Highlights
Introdução As algas são organismos fotossintetizantes de grande valor ecológico e que são utilizadas pelo homem há décadas (LEVRING et al, 1969; GREENWELL; LAURENS, 2008; NEORI et al, 1998)
This study aimed to evaluate the anticoagulant activity of sulfated polysaccharides (SP) isolated from a Halymenia rhodophyceae genus native to the coast of Ceará, Brazil
The results suggest that the anticoagulant activity of SP isolated from Halymenia sp. was promoted by inhibition of the intrinsic and/or common pathway of the coagulation cascade
Summary
As algas foram lavadas com água destilada, desidratadas ao sol, cortadas em pequenos pedaços e armazenadas em frascos para posterior extração dos PS. Inicialmente, os PST (10 mg) foram dissolvidos em tampão AcNa 0,1 M e submetidos à cromatografia de troca iônica em coluna de DEAEcelulose equilibrada e percolada com o tampão de extração (AcNa 0,1 M) até a completa remoção dos polissacarídeos não-retidos, seguido do fracionamento dos PS por eluição com o mesmo tampão, contendo NaCl em diferentes concentrações (0,25; 0,50; 0,75; 1,00; 1,25; 1,50; 1,75 e 2,00 M), utilizando-se um coletor de frações (FRAC-920) com fluxo ajustado para 60 mL h-1. As frações de PS obtidas foram dialisadas exaustivamente contra água destilada, concentradas por liofilização e armazenadas até a realização dos ensaios
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