Assessment of nutritional value and antioxidant activity of polysaccharide extracts from brown seaweed Sarga

Abstract

In this study, crude polysaccharides were extracted from brown seaweed Sargassum flavicans with three extraction solvents including hot-water (SF1), 0.1N HCl (SF2), and 90% aqueous ethanol (SF3). The extracts were then analyzed for chemical composition and antioxidant activity. The results showed that among three extraction solvents, 0.1N HCl extract exhibited higher yield (41.1%), followed by hot-water (24.5%) and 90% aqueous ethanol solvent (12.8%). The color of these freeze-dried extracts changed from brown (SF1 and SF2) to brown green (SF3). The crude protein concentrations were 3.6, 6.1, and 5.2% for SF1, SF2, and SF3, respectively. Extract SF2 had higher concentration of total phosphorus (0.34%) than that of SF1 (0.17%). Total phlorotannin concentrations of extracts were in the range of 0.27-0.47%. Also, extract SF2 had the highest percentage of sulfate content (3.5%). The free radical scavenging activity, ferrous ion chelating activity, and ferric reducing power of extracts were increased with increasing of concentrations of polysaccharides. Polysaccharide was extracted by 0.1N HCl (SF2) showed the highest antioxidant activity. These results indicated that the polysaccharide extracts of brown seaweed S. flavicans possessed a good antioxidant activity.