Fucoidan and sodium alginate were extracted from the Tunisian brown seaweed Cystoseira sedoides, with good yields. The samples were characterized by colorimetric, spectroscopic (FTIR) and chromatographic (SEC/ MALS/VD/DRI) methods. The quantitative estimation of the mannuronic acid/guluronic acid ratio (M/G ratio) of alginate was performed by FT-IR spectroscopy. It has been found that sodium alginate from C. sedoides contain more mannuronic acid (63%) than guluronic acid (37%). The isolated fucoidan was examined for in vitro antioxidant properties using various antioxidant assays. The sulfated polysaccharide exhibited important DPPH radical-scavenging activity (77% inhibition at a concentration of 5 mg/mL) and a considerable ferric reducing potential. An effective chelating activity was also recorded for the extracted fucoidan. Furthermore, the gastroprotective activity was determined for sodium alginate using HCl/EtOH induced gastric ulcers in rats. With a dose of 50 mg/kg, sodium alginate from C. sedoides showed a significant decrease (87%) in the intensity of gastric mucosal damages compared to a control group.
H. Hadj Ammar, J. Hafsa, D. Le Cerf, A. Bouraoui, H. Majdoub
Cystoseira sedoides, Polysaccharides, SEC/MALS/VD/DRI, Antioxidant activity, Gastroprotective activity