Silica-based purification and desalting of fucoidan

Algal fucoidans are promising molecules for carbon sequestration evaluation and have therapeutic potential due to their bioactive properties. The extraction, purification, characterization and quantification of fucoidan is important, both in biomedical as well as in environmental research. Common fucoidan purification methods require subsequent dialysis steps to remove salts prior to downstream analyses and applications. Here, we present a combined purification and desalting procedure for fucoidan, which is based on a solid-phase extraction (SPE) principle using a silica-containing column like those found in common DNA purification kits. We find that a mini spin column from a commercial DNA kit can recover >1 milligram of fucoidan and remove molar scale salts in a single step. Also, the SPE technique shows the potential to recover and separate fucoidan oligosaccharides based on their size, which is useful in glycan structure determination and bioactivity analyses. Finally, we demonstrate that SPE allows the extraction of fucoidan from seawater collected over kelp forests in the North Sea. Thus, the SPE method is convenient for simultaneous purification, desalting and concentration of fucoidan from both preparative and environmental samples. While fucoidan is the focus in this study, we find that the method is also suitable for purification of other anionic glycans such as ulvan, pectin and carrageenans.