Fucoidan of Sargassum echinocarpum was extracted using the UAE method. This method produced a fucoidan extract with a yield of 2.82-3.93% and antioxidant activity of 44.57-98.77 ppm at different temperatures and extraction times. The total sulphate, fucose, phenolic, protein, and uronic acid contents were 5.50-6.24%, 17.22-63.22%, 14.66-78.20 mgGAE/g, 0-14.42 mg/g, and 191.43-353.76 mg/g, respectively. Furthermore, extraction treatment with UAE also affected the topology and morphology of the fucoidan extract. The analysis results showed the presence of monosaccharides such as galactose 1.37%, mannose 0.642%, and xylose 2.86%, while glucose and rhamnose were not detected. The extract also had the same absorption band as the fucose and fucoidan standard (F. vesiculosus) as well as a similar basic skeletal structure. Based on the experimental results, the fucoidan extract had excellent antioxidant properties.
Keywords: Antioxidant; Sargassum echinocarpum; fucoidan.