ABSTRACT
Several bioactive sulfated galactans have been isolated from the tunic of different species of ascidians. The biological activity of this kind of polysaccharides has been related with the presence and position of sulfate groups, and by the chemical composition of this kind of polysaccharides. A sulfated galactan (1000RS) was isolated from the tunic of the Brazilian ascidia Microcosmus exasperatus through proteolytic digestion, ethanol precipitation, dialysis and freeze-thaw cycles. Homogeneity and molecular weight were estimated by using size exclusion chromatography. Monosaccharide composition and type of linkage were assessed by Gas chromatography coupled to mass spectrometry and the sulfate content was quantified through gelatin/BaCl2 method. These experiments along with NMR and FTIR analysis allowed to claim that the galactan backbone is mainly composed of 4-linked α-l-Galp units. In addition, they permitted to establish that some of the galactose residues are sulfated at the 3-position. This sulfated polysaccharide, which has an average molecular mass of 439.5kDa, presents anticoagulant effect in a dose-dependent manner through the inhibition of the intrinsic coagulation pathway.
Subject(s)
Blood Coagulation/drug effects , Galactans/chemistry , Galactans/pharmacology , Sulfates/chemistry , Urochordata/chemistry , Animals , Dose-Response Relationship, Drug , Humans , MethylationABSTRACT
Aims: The anticoagulant effect and cytotoxicity of a high molecular weight polysaccharide fraction (1000RS) obtained from the tunic of the ascidia Microcosmus exasperatus were evaluated. Methods: Anticoagulant properties of 1000RS was evaluated by activated Partial Thromboplastin Time (aPTT), Thrombin Time (TT), Prothrombin Time (PT), anti-factor Xa and lupic anticoagulant (dRVVT) assays. Cytotoxicity was tested on murine hematopoietic cells using MTT assay. Results: This galactose rich fraction showed to be a potential anticoagulant due to its inhibitory effect on the intrinsic coagulation pathway. At the same time, anticoagulant doses of this fraction have no effect on cellular viability, which means that it can be used as a therapeutic agent. Conclusion: In vitro anticoagulant effect of 1000RS occurs at innocuous doses, however, it still need to be tested using in vivo models and its cytotoxicity evaluated in normal human cell lines
Objetivos: El efecto anticoagulante y la citotoxicidad de una fracción de polisacáridos de alto peso molecular (1000RS), obtenida de la túnica de la ascidia Microcosmus exasperatus, fueron evaluados. Métodos: La actividad anticoagulante de 1000RS fue evaluada mediante los ensayos de tiempo de tromboplastina parcial activado (TTPa), tiempo de trombina (TT), tiempo de protrombina (TP), anti factor Xa y anticoagulante lúpico (dRVVT). La citotoxicidad sobre las células hematopoyéticas murinas, fue evaluada usando el método del MTT. Resultados: Esta fracción rica en galactosa mostró ser un anticoagulante potencial debido a su efecto inhibidor de la vía intrínseca de la coagulación. Así mismo, las dosis anticoagulantes de esta fracción no afectan la viabilidad celular, lo cual ratifica su potencial como agente terapéutico. Conclusión: El efecto anticoagulante in vitro de 1000RS ocurre a dosis inocuas, sin embargo, este debe ser evaluado en modelos in vivo, así como su citotoxicidad sobre células humanas normales
