Structural elucidation and protective role of a polysaccharide from Sargassum fusiforme on ameliorating learning and memory deficiencies in mice

A fucoidan, Sargassum fusiforme polysaccharide 65 (SFPS65) A, was isolated from a brown alga (S. fusiforme). SFPS65A had an estimated molecular weight of 90 kDa and showed [alpha](D)(20) - 74.3288 (c 0.05, H2O). SFPS65A is composed of fucose, galactose, xylo se, glucose, glucuronic acid, and manno se in the ratio of 19.23:9.58:6.64:1:6.52:2.57. The structural features of SFPS65A were investigated using composition analysis, methylation analysis, infrared spectrum, nuclear magnetic resonance spectroscopy, and electrospray ionization quadruple time-of-flight tandem mass spectroscopy. Results showed that SFPS65A has a main chain composed of -> 3)-beta-L Fucp (1 -> 3,4)-beta-L-Fucp (1 -> 3,4)-beta-L-Fucp (1 -> and connected with -> 3,4)-alpha-D-GlcAp-(1 ->, -> 4)-beta-D-Xylp-(1 ->, -> 4)-alpha-D-Galp-(1 ->, -> 3,6)-alpha-D-Manp-(1 -> alternately. The branches at 0-3 of the fucosyl residue and 0-3 of the hexosyl residues may include sulfate, -> 4)-beta-L-Fucp- (1 ->, beta-D-Xylp-(1 ->, and beta-D-Xylp-(1 ->. SFPS65A exhibited an activity on Alzheimer's disease in vivo in the pharmacological experiments by increasing the cognitive abilities of scopolamine-, ethanol-, and sodium nitrite-treated mice against memory deficits. (C) 2015 Elsevier Ltd. All rights reserved.