Structure and anti-influenza A (H1N1) virus activity of three polysaccharides from Eucheuma denticulatum

Three polysaccharides (EW, EH and EA) were prepared from a red alga Eucheuma denticulatum by sequential extraction with cold water, hot water and sodium hydroxide water solution. Their monosaccharide compositions, relative molecular mass and structural characterization were determined by gas chromatography, high performance 1iquid chromatography, fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy methods. EW was hybrid ?/??/??-carrageenan (70 ?/17??/13??-carrabiose), EH was mainly ?-carrageenan, and EA was mainly ??-1,4-Glucan (88%) but mixed with small amount of ?-carrageenan (12%). The relative molecular mass of EW, EH and EA was 480, 580 and 510 kDa, respectively. The anti-influenza A (H1N1) virus activity of these three polysaccharides was evaluated using the Madin-Darby canine kidney cells model. EW showed good anti-H1N1 virus activity, its IC₅₀ was 276.5 ??g mL^?1, and the inhibition rate to H1N1 virus was 52% when its concentration was 250 ??g mL^?1. The IC₅₀ of ?-carrageenan EH was 366.4 ??g mL^?1, whereas EA showed lower anti-H1N1 virus activity (IC₅₀>430 ??g mL^?1). Available data obtained give positive evidence that the hybrid carrageenan EW from Eucheuma denticulatum can be used as potential anti-H1N1 virus inhibitor in future.