Isolation and purification of brown algae fucoidan from Sargassum siliquosum and the analysis of anti-lipogenesis activity

Fucoidans are sulfated polysaccharides of marine origin and they have distinguished biological applications due to their anti-viral, anti-inflammatory, anti-angiogenic, and anti-tumorigenic potential. In this study, fucoidan was extracted from a brown macroalga (Sargassum siliquosum) using microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE). MAE under the condition of 750 W, 10 min, and a liquid/solid ratio of 15 mL/g, showed higher extraction efficiency with a total sugar yield of 6.94% per dry weight. The crude fucoidan obtained with ethanol precipitation was further purified by isoelectric point precipitation and calcium chloride addition (for protein and uronic acid removal), followed by anion-exchange chromatography (AEC) and dialysis. The purity of the polysaccharides content of crude fucoidan increased from 33.3–64.5% with a total sugar recovery of 50.3%. Based on the sugar and sulfate group (the major components of fucoidan), the purity of the final sulfated polysaccharides product is nearly 84.0%, and this purified fucoidan product was found to display biological activities linked to anti-lipogenesis with 28.9% decreased lipid synthesis in contrast to the free-fatty-acid-induced control.