Chemical Characterization of Fucoidan from Commercially Cultured Nemacystus decipiens (Itomozuku)

抄録

  Fucoidan was isolated from Nemacystus decipiens KUCKUCK which is commercially cultured at the rate of about 2,000 t/year in fields of the Okinawa Islands, in Japan. The yield of fucoidan extracted by 0.1 M HCl was 0.5% (W/W) based on the wet algae. The total carbohydrate, sulfuric acid, ash, and moisture in fucoidan was 65.8, 30.8, 22.3, and 3.8%, respectively. Fucose and galactose were identified by liquid chromatography. The molar ratio of the sugar residues in the fucoidan was estimated to be L-fucose:D-galactose:sulfuric acid=1.0:0.05:1.0. The optical rotation of the fucoidan (0.4%) showed a value of −0.315° at 60°C, then it decreased a little with decreasing temperature. The infrared spectrum of isolated fucoidan is in agreement with that of standard fucoidan. The molecular mass of fucoidan was estimated to be 2.4×10⁵. The ¹H- and ¹³C-NMR spectral data suggest that fucoidan is mainly composed of L-fucopyranose, 2-mono-O-sulfo-L-fucopyranose, 4-mono-O-sulfo-L-fucopyranose, and 2,4-di-O-sulfo-L-fucopyranose.