Fucoidans from brown seaweed Sargassum swartzii: extraction method, cytotoxic activity and structural studies

Abstract

The brown seaweed Sargassum swartzii was extracted with hydrochloric acid solution, dialyzed through a IK MWCO membrane and precipitated by Cetavlon to yield polysaccharides. The polysaccharides were dissolved in calcium chloride solution, precipitated in ethonol for obtaining the crude fucoidan (F-SS). The crude fucoidan was fractionated with. sodium chloride solution of 0.5, 1.0, 1.5, 2.0 and 2.5 M yielding six fucoidonfractions F05, F10, F15. F20, F25. respectively. The composition offucoidan fractions including monosaccharides. sulphate, uronic acids and total carbohydrate was analyzed. The distribution of molecular weight of the fucoidan fractions was studied. Ninety percents of both F20 and F25 fractions have the average molecular weight of over 100 kDa. Fraction F-20 showed significant activity against human Rhahdosarcoma cells with an IC₅₀ value of 16.6 µg/mL. and lung cancer cells of 13.4 µg/mL. Fucoidan F25 wasagainst only lung small cancer cells with IC₅₀ value of 13.8 µg/mL