Monthly variations of fucoidan content and its composition in the farmed brown alga Saccharina sculpera (Laminariales, Phaeophyceae)

Crude fucoidan was extracted from the Saccharina sculpera from Rongcheng cultivation area in Sanggou Bay in the Yellow Sea of China which was sampled monthly from March to July. The crude fucoidan yield of S. sculpera showed an increase from 2.9% in March to 6.1% dry wt in July as the plant matured. And the content of polysaccharide (from 0.55 to 1.46% dry wt) and sulfate (from 0.37 to 1.62% dry wt) tended to increase from March to July as well. The monosaccharide composition changed constantly in the growing period with an increase of fucose (from 32.15 to 60.85 mol%) and a decrease of galactose (from 21.89 to 9.03 mol%). Analysis results showed that the content of crude fucoidan, polysaccharide, and sulfate in matured season was higher than that of other three species of farmed brown algae Saccharina japonica, Costaria costata, and Undaria pinnatifida in the same waters. These data indicated that S. sculpera was an excellent algal species in fucoidan content. This study on seasonal variations of polysaccharide, sulfate content, and monosaccharide composition provides a practical guidance for determining the optimal opportunity for harvesting the algae in order to standardize preparations of fucoidan for use in the pharmaceutical industry.