, a tubular green seaweed, is a rich source of nutrient, especially sulphated polysaccharides.
Sulphated polysaccharides from U. intestinalis were extracted with distilled water, 0.1 N HCl, and
0.1 N NaOH at 80 ◦C for 1, 3, 6, 12, and 24 h to study the effect of the extraction solvent and time on
their chemical composition and antioxidant activity. Different types of solvents and extraction time had
a significant influence on the chemical characteristics and antioxidant activity (p < 0.05). Monosaccharide
composition and FT-IR spectra analyses revealed that sulphated polysaccharides from all solvent
extractions have a typical sugar backbone (glucose, rhamnose, and sulphate attached at C-2 or C-3 of
rhamnose). Sulphated polysaccharides extracted with acid exhibited greater antioxidant activity than
did those extracted with distilled water and alkali. The results indicated that solvent extraction could
be an efficacious method for enhancing antioxidant activity by distinct molecular weight and chemical
characteristic of sulphated polysaccharides.