Structure Analysis And Bioactivities Of Fucoidans From Two Species Of Brown Algae

Researches on the polysaccharides from two species of brown algae, Kjellmaniella crassifolia and Sargassum thunbergii were rarely concerned. In this study, polysaccharides were extracted from K. crassifolia and S. thunbergii by dilute hydrochloric acid and hot water, respectively. Chemical analysis showed that these polysaccharides consisted of fucose mainly, accompanying with galactose, mannose and glucuronic acid. Electrospray ionization mass spectrometry(ESI-MS) showed that the desulfated fucoidan from K. crassifolia was composed of sulfated fucooligosaccharides and sulfated galactofucooligosaccharides. The backbones of these oligosaccharides were 3-linked and the sulfation pattern was at C4. The desulfated fucoidanfrom S. thunbergii has the same compositions and structure features. In addition, it was important to note that the galactofucan consisted of a backbone of either alternating Gal and Fuc or alternating(Gal)n and(Fuc)n. Moreover, the samples, obtained by acid hydrolysis, contained glucuronomanno-oligosaccharides, glucurono-oligosaccharides and fucoglucurono-oligosaccharides, suggesting that it contained glucuronomannan, glucuronan and fucoglucuronan.The activities of polysaccharides from K. crassifolia and S. thunbergii against the hemolytic activity of both the classical and alternative complement pathways were determined. The results showed that the crude polysaccharides from two algae exhibited good anti-complement activity in concentration dependent manner. In addition, the degraded and desulfated polysaccharides displayed lower activities, indicating that molecular weight and sulfate had an effect on the activity.Anti-liver cancer activities of polysaccharides from different extractions, locations and fraction components were determined. In addition, the activities of polysaccharides with different molecular weight, sulfate content and UA content were also tested. It was shown that polysaccharides, extracted by dilute hydrochloric acid, dilute sodium carbonate and hot water, showed slightly differences in the chemical composition, however, they showed different activities. Polysaccharide extracted by water had the highest activity. Polysaccharides, obtained from different locations, also had little difference in the chemical composition and the activity. Polysaccharides with different molecular weight exhibited no differences at the high concentration(1 mg/mL), while showed evident differences at the concentration of lower than 1 mg/mL. After fractionation on the DEAE-Bio Gel Agarose FF gel, all fractions showed less activity, presuming that the activity was attributed to synergy.The activities of desulfated and over-sulfated polysaccharides were lower than the native polysaccharide’s, indicating that sulfate influence the activity. Compared with the decarboxylated polysaccharide, the native polysaccharide had better activity, suggesting that uronic acid was related to the activity.