Antioxidant activity of crude fucoidan extract from brown seaweeds (Phaeophyceae), Sargassum sp. and Turbinaria sp.

Seaweed is one of the highly commercial aquatic commodities, accounting for 51.3% of total marine and coastal aquaculture production. As much as 99.5% of seaweed production is concentrated in Asia, especially in East and Southeast Asian countries, one of which is Indonesia. The wide diversity of seaweeds has not been fully optimizing their potential to provide maximum economic benefits. This study aimed to determine the characteristics of crude extracts of fucoidan using two different solvents and to analyze the antioxidant activity of crude extracts of fucoidan using different solvents. The research method included the preparation of raw materials, extraction with distilled water and 2% CaCl2 at 85 °C for 4 h, followed by quality analyses. Total sugar using the phenol-sulphate method obtained higher results in distilled water (67.88%). The total sulphate analysis showed higher results with 2% CaCl2 (19.60%). The total phenol analysis yielded higher results with 2% CaCl2 (978.20%). The antioxidant activity of the crude fucoidan were 312.01 ppm (distilled water), 193.52 ppm (distilled water), 54.653 μg/mL ascorbic acid/g extract (CaCl2 2%, 128.38 mol Fe2+/g (CaCl2 2%).