The brown seaweed Cystoseira schiffneri as a source of sodium alginate: Chemical and structural characterization, and antioxidant activities

Sodium alginates were extracted from brown seaweeds (Cystoseira schiffneri) collected a Tunisian island (Kerkennah, Sfax) in different seasons (December, April, July and September). The structural features antioxidant properties of C. schiffneri sodium (CSSA) characterized. Micro-elementary analysis showed the absence nitrogen sulfur alginate fractions. All isolates high uronic acids (47.4–66.4%) ash (24.3–39.4%). ATR-FTIR, NMR circular dichroism data that all CSSA polyguluronate-type. Weight-average molecular weight determined using performance size exclusion chromatography variations ranging 4.49 to 1230 kDa. Thermogravimetric suggested stable until 400 °C except for September, which was observed only be 200 °C. Antioxidant activity measured DPPH• radical-scavenging, reducing power Fe2+chelating ability assays. potential varied significantly with respect season main factor controlling mass.