Nanna Rhein-Knudsen1, Diego Reyes-Weiss1 and Svein Jarle Horn1
1Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432 Ås, Norway
Fucoidans are heterogenous fucose rich polysaccharides that are found in the cell wall of brown seaweeds. Fucoidans have several interesting bioactivities, however, lack of knowledge about the structural elements that are responsible for these activities and the exact chemical compositions are limiting potential applications of fucoidans. Traditionally, fucoidans have been isolated from seaweeds using hot liquid extraction techniques, but depolymerization of the polysaccharide, high amounts of contamination and limited process control are major disadvantages of this extraction technique. In this study we report a new enzymatic extraction technique to produce pure and intact fucoidans from the two brown seaweeds Saccharina latissima and Alaria esculenta. This new extraction protocol uses fungal cellulases together with endo- and exo-acting thermophilic alginate lyases, to degrade the seaweed cell wall components and release the intact fucoidans. The fucoidans obtained by this extraction technique is compared to traditionally extracted fucoidans, in terms of chemical compositions and molecular weights, and are shown to contain significantly higher amounts of fucose, galactose, and sulfate, the main components of fucoidans, while cellulose, laminarin, and alginate contamination is low. Additionally, the enzymatic extracted fucoidans have higher molecular weights, as no degradation of the fucoidan was observed during the enzymatic extraction. The pure and more intact fucoidans extracted by this new method can be used to provide further insights into native fucoidan structures and their biological activities.