Antioxidant, cytotoxic and hemolytic effects of sulfated galactans from edible red alga Hypnea musciformis

Polysaccharides, galactans, obtained from edible red seaweed Hypnea musciformis were characterized by molecular weight and infrared spectroscopy analysis and were evaluated for antioxidant activity in vitro and for their effects on cell viability. The main components were galactose and sulfate presenting low protein contamination. These sulfated galactans (F1.0) showed a polydisperse profile, and signs in infrared analysis were attributed to a sulfate ester S = O bond, the presence of a 3,6-anhydrogalactose C-O bond, nonsulfated beta-d-galactose, and a C-O-SO4 bond in galactose C4. The NMR analysis showed signals at about 95 and 92 attributed to anomeric carbon of 4-linked 3,6-anhydro-alpha-d-galactopyranose residue of kappa-carrageenans and 4-linked 3,6-anhydro-alpha-d-galactopyranose2-sulfate of iota-carrageenans. Sulfated galactan F1.0 showed strong antioxidant activity under lipid peroxidation assay where F1.0 at 8 mg mL(-1) promoted 57.92% peroxidation inhibition and displayed the scavenging activity on hydroxyl radicals in a dose-dependent manner leading to 32.5% scavenging of these radicals when 5 mg mL(-1) of sulfated galactan F1.0 was used. The sulfated galactan fraction also exhibited strong inhibition on the H2O2-induced hemolysis model. Sulfated galactan F1.0 displayed low cytotoxic action in 3 T3 cells and moderate antitumoral action in HeLa cells. These results suggest that sulfated galactan F1.0 from H. musciformis has antioxidant potential, which is a great effect for a compound used as food and in the food industry.