Anticoagulant, antioxidant and antitumor activities of heterofucans from the seaweed Dictyopteris delicatula

Abstract

In the present study, six families of sulfated polysaccharides were obtained from seaweed Dictyopteris delicatula by proteolytic digestion, followed by acetone fractionation and molecular sieving on Sephadex G-100. Chemical analyses demonstrated that all polysaccharides contain heterofucans composed mainly of fucose, xylose, glucose, galactose, uronic acid, and sulfate. The fucans F0.5v and F0.7v at 1.0 mg/mL showed high ferric chelating activity (∼45%), whereas fucans F1.3v (0.5 mg/mL) showed considerable reducing power, about 53.2% of the activity of vitamin C. The fucan F1.5v presented the most prominent anticoagulant activity. The best antiproliferative activity was found with fucans F1.3v and F0.7v. However, F1.3v activity was much higher than F0.7v inhibiting almost 100% of HeLa cell proliferation. These fucans have been selected for further studies on structural characterization as well as in vivo experiments, which are already in progress.

Figure 1.

Anticoagulant activity of sulfated polysaccharides from Dictyopteris delicatula. Results were expressed as ratios obtained by dividing the clotting time achieved with the anticoagulant by the time achieved with the control. Hep—Heparin; Cle—Clexane^® (Enoxaparin). Each value is the mean ± SD of three determinations (n = 6). ^a indicates a significant difference when compared with Clexane^® control; ^b indicates a similar APTT ratio when compared with Clexane^® control.

Figure 2.

Antioxidant activity of sulfated polysaccharides from Dictyopteris delicatula. (A) Chelating effect; (B) Power reducing assay. Each value is the mean ± SD of three determinations. ^a,b,c,d Distinct letters indicates a significant difference between sulfated polysaccharides when compared at each concentration (p < 0.05).

Figure 3.

Influence of sulfated polysaccharides from Dictyopteris delicatula on inhibition of cell proliferation of HeLa cells after 72 h incubation: (A) Antiproliferative activity of sulfated polysaccharides at concentration of 2.0 mg/mL; (B) Dose-dependent effect of sulfated polysaccharides. Each value is the mean ± SD of seven determinations. Different letters indicates a significant difference between concentrations of individual sulfated polysaccharides (p < 0.05); the asterisk indicates a significant difference between different sulfated polysaccharides at same concentration (p < 0.05).