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We investigated the structure of fucoidan from Hizikia fusiformis. Using DEAE-Sepharose column chromatography, fucoidan was fractionated into four groups. F4, main fraction of fucoidan, contained 38 % (w/w) of ester sulfate and had the simplest sugar component (l-Fuc: d-Gal=7:3). The structure of F4 was discussed using de-sulfation, 2D-NMR and methylation analysis and proposed as % in molar ratio of the hydroxyl group is sulfated.Keywords: fucoidan, Hizikia fusiformis, brown seaweed, de-sulfation, 2D-NMR, methylation *To whom correspondence should be addressed. E-mail: tako@agr.u-ryukyu.ac.jp IntroductionFucoidan, a cell-wall matrix polysaccharide in brown seaweed and some echinoderms, is composed of α-l-fucose and ester sulfate, including minor amounts of d-Gal, d-Man, d-Xyl, d-Glc, d-GlcA and acetic acid. Fucoidans have been extensively investigated because of their various biological activities as an anticoagulant (Chevolot et al., 1999;Doane and Whistler, 1963;Nagumo and Nishino, 1996), antitumor (Itoh et al., 1993), antiviral agent (Baba et al., 1988;Ponce et al., 2003) and inhibitor of Helicobacter pylori infection (Shibata et al., 2003), and these activities differ according to linkage pattern, content of ester sulfate, sugar component and molecular weight (Berteau and Mulloy, 2003). It is also important to elucidate the structure of fucoidans to understand the interactions between their structure and biological activities. Recently, the structure of fucoidan from the brown seaweed has been identified using 2D-NMR or electrospray ionization mass spectrometry (ESI-MS) techniques (Bilan et al., 2002;Chizhov et al., 1999;Daniel et al., 2007), although there is structural diversity.In this study, Hizikia fusiformis, which is utilized for food material mainly in Japan and South Korea, was used for structural elucidation. Various reports have already addressed the preliminary characterization (Nishide et al., 1987;Nishino and Nagumo, 1987;Shiroma et al., 2003) and anticoagulant activity (Dobashi et al., 1989) of fucoidans from H. fusiformis, as well as the structure of a H. fusiformis fucoidan containing a fucose-free core (Li et al., 2006). However, the structure of fucoidan containing high-fucose and ester sulfate has not yet been reported. Here, we discuss the structure of fucoidan containing high-fucose and ester sulfate from H. fusiformis in an acidic extract. Materials and MethodsMaterials H. fusiformis used in this study was harvested in June 2002 from Yonabaru Town, Okinawa, Japan. The collected seaweed was washed with tap water and air-dried in an oven at 40 ℃ for 24 h. The dried seaweed was then powdered using a mixer (MX-620G, Matsushita Electric In-177 dustrial Co., Ltd., Japan).Isolation and fractionation of fucoidan from H. fusiformis The isolation of crude fucoidan was carried out as previously reported (Shiroma et al., 2003). Briefly, dried seaweed (20 g) was suspended in 0.1 M HCl (200 ml) and stirred at room temperature for 6 h. The suspension was filtered with a suction filter, and the fil...

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The polysaccharide was isolated from Hypnea pannosa which was grown in Okinawa, Japan. The yield of the polysaccharide was 17.2%, and the total carbohydrates, pyruvic acid, sulfuric acid and ash contents were 55.2%, 3.8%, 35.2% and 24.3%, respectively.