Graphical abstract

۱٫ Introduction

۲٫ Materials and methods

۳٫ Results and discussion

۴٫ Conclusions

Acknowledgments

References

Abstract

The interest in bioactive compounds from natural sources, such as marine organisms, has increased considerably in recent years. Among these compounds, sulfated polysaccharides from seaweed exhibit a broad spectrum of biological activities. Sulfated polysaccharides from green algae are still poorly investigated. For this reason, in this study, using unusual methodologies, such as extraction conditions, FACE, and RAMAN, we investigated the structural features of F50UL and F70UL sulfated polysaccharides from Ulva lactuca L. and their distinct in vitro anticoagulant and in vivo antithrombotic activities. Sulfated polysaccharides of U. lactuca were obtained by enzymatic proteolysis with ALCALASE® and fractionated by acetone precipitation. F50Ul and F70Ul sulfated polysaccharides with higher yield were partially chemically characterized by Fluorophore-assisted carbohydrate electrophoresis (FACE) and RAMAN spectroscopy analysis and submitted to an in vitro screening by APTT, PT, TT, and anti-factor Xa and IIa tests. The venae cavae ligature experimental model for the analysis of in vivo antithrombotic activity of F50Ul and F70Ul sulfated polysaccharides were also performed. The U. lactuca L. sulfated polysaccharides characterization by FACE and RAMAN showed a typical ulvans structure that contains as principal component rhamnose, but other monosaccharides (uronic acid, glucose, and galactose) are present. F50Ul (0.1–۱٫۰ μg/μl) showed anticoagulant activity in vitro. However, F70Ul that has a similar composition did not present these effects. Also, only F50Ul sulfated polysaccharides (≥۵ μg/g) showed a great in vivo antithrombotic concentration-dependent and time-dependent activity. In summary, we demonstrate the use of unusual extraction and characterization analysis procedures for U. lactuca L. sulfated polysaccharides and the ability of F50Ul to reduce the weight of thrombus in rats probably by the association with factors Xa and IIa inhibition. These results provide strong evidence of the anticoagulant potential of these sulfated polysaccharides isolated from Ulva lactuca L.

Introduction

According to the World Health Organization, cardiovascular diseases are the major cause of death worldwide. An approximate calculation has shown that over 23.6 million people will die due to cardiovascular diseases until 2030. It is associated with heart and blood vessels disorders and includes coronary heart disease, hypertension, stroke (cerebrovascular), rheumatic heart and peripheral vascular diseases [1]. Arterial thrombosis is one of the most common causes of death in the world due to either instability or rupture of an atherosclerotic plaque resulting in localized clot formation and blockage of blood flow with subsequent myocardial infarction (heart attack) or stroke [2].

The physiologic action of the hemostatic system removes fibrin deposits from vessels and maintains the circulating blood in a fluidic state. In cases of vessel injury, the tissue factor on adventitial cells, such as adventitial fibroblasts and smooth muscle cells activates the clotting system with a complex series of enzymatic reactions involving coagulation proteins, culminating in the activation of thrombin, which converts fibrinogen to fibrin. Thus, it forms a stable clot and prevents excessive blood loss. While hemostatic clots are localized to the vessel wall and do not impair blood flow, the thrombotic clots result in impairment of blood flow and even complete occlusion of the vessel [2]. In this case, anticoagulation therapy is required for inhibition of blood clotting using appropriate drugs, i.e., warfarin or heparin [3].