From seaweed to superfood: Next-generation fucoidan extraction, structural and bioactivity evaluation for sustainable...

Sulfated fucoidan was extracted from Sargassum sp. using hydrothermal (HT), microwave-assisted extraction (MAE), and ultrasonic-assisted extraction (UAE) methods, each with distinct environmental and bioactivity profiles. Hydrothermal extraction yielded the highest amount of fucoidan (105.64 ± 2.14 mg/g) at 140 °C for 40 min. The extraction methods significantly influenced fucoidan's physicochemical composition and bioactivity, with antioxidant potential in the order MAE > UAE > HT. Notably, the hydrothermal extract (140-40-Pure) exhibited the strongest α-glucosidase inhibition (96 %, IC₅₀ 346.32 μg/mL) via mixed-type inhibition, while MAE and UAE extracts demonstrated superior prebiotic activity, supporting Lactobacillus plantarum and L. kefiri growth in vitro. Despite yielding lower quantities, UAE extracts showed consistent bioactivity and superior structural composition. Environmentally, UAE stands out as the greenest extraction method, with lower CO₂ emissions, reduced energy and solvent usage, and minimized processing time, aligning with SDGs-3. This research highlights the UAE's potential for scalable, eco-friendly production of bioactive fucoidans with diverse applications in the nutraceutical and pharmaceutical industries.