Sulfated polysaccharides (fucoidan) from the brown seaweed Silvetia compressa (J. Agardh) E. Serrão, T.O. Cho, S.M. Boo & Brawley

Abstract

The aim of this study was to characterize the yield and chemical compositions of sulfated polysaccharides (SP) from the brown seaweed Silvetia compressa collected off the Pacific coast of Baja California, Mexico. SP yield was evaluated from basal and apical tissues and fruiting bodies. Chemical heterogeneity was evaluated by ethanol fractionation and anion-exchange chromatography and characterized by FTIR spectra. Geographic differences in yield (11–12.1%) and sulfate content (15–16%) were minimal. Basal thallus had a higher yield, while fruiting bodies contained more fucose and sulfates. The SP of S. compressa are composed of variable amounts of fucose, sulfates, and uronic acids (fucoidan type). The heterogeneity of SP was demonstrated by fractionation with ethanol at 50% which yields a soluble fraction, composed of fucose with high sulfate content devoid of uronic acids. Similarly, the anion-exchange chromatography separated fractions composed of molecules differing in fucose content. FTIR spectra showed characteristic signals for SP: a strong peak at 1240–1250 cm−1 (S=O), a peak at 840–850 cm−1 (axial sulfate C-4), and peaks at 1625 and 1417 cm−1 (carboxylic group of uronic acids). These results indicate that SP of S. compressa correspond to a fucoidan-type polysaccharides with sulfates occurring mainly on C-4 of the fucose units and containing low amounts of uronic acids.