*4.1. Materials*

Celluclast was purchased from Novozyme (Nordisk, Bagsvaerd, Denmark). Dulbecco's Modified EagleMedium (DMEM), fetal bovine serum (FBS), and penicillin-streptomycin were purchased from Life Technologies Corporation (Grand Island, NY, USA). Fucoidan standard, dextran sulfate, and chondroitin 6-sulfate molecular weight standards and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), acridine orange, 2 7-dichlorodihydrofluorescein diacetate (DCFH2-DA), propidium iodide (PI), trifluoroacetic acid, ethidium bromide, o-Toluidine blue, Hoechst 33342, agarose, low melting agarose, and sodium dodecyl sulfate were purchased from Sigma-Aldrich (St Louis, MO, USA). Polyvinylidin-fluorid (PVDF) membranes were obtained from Millipore (Schwallbach, Germany). All organic solvents used in this study were of the HPLC grade and purchased from Daejung Chemicals & Metals (Gyeonggi-do, S. Korea).

#### *4.2. Collection and Extraction of Fucoidan Rich Fraction*

Following up on the preliminary screening [25], *Sargassum polycystum* samples for the mass extraction were collected from the south-west coast of Sri Lanka. After washing with tap water, the samples were lyophilized and ground into a powder. The algae powder (350 g) was suspended in a solution of 95% ethanol for depigmentation (repeated three times). Depigmented powder was suspended in a solution of 10% formaldehyde in ethanol for 8 h at 37 ◦C. After filtration, the powder was washed twice with 95% ethanol and dried at 45 ◦C in a drying oven and lyophilized to remove any remaining moisture and ethanol. The powder (300 g) was then suspended in sterilized distilled water, and the pH was adjusted to 4.5 using 1 M HCl. Celluclast was added to the suspension, reaching a concentration of 0.5% of the substrate concentration. The mixture was incubated with continuous agitation at 50 ◦C for 24 h while regulating the pH at 4.5. After the digestion, the mixture was filtered through cheesecloth, and the filtrate was centrifuged to remove any particles. Celluclast was heat deactivated by incubating the supernatant at 100 ◦C for 10 min. The supernatant pH was adjusted to 8.0. Alcalase (0.1%, for 8 h at 50 ◦C) was used to hydrolyze the proteins. Alcalase was heat-inactivated by the same method above. Then the mixture was acidified to a pH of 4.0 using HCl and gradually mixed with a solution of saturated CaCl2, facilitating the precipitation of alginate as calcium alginate. The mixture was then centrifuged, obtaining the supernatant. The supernatant was neutralized by using NaOH and lyophilized to reduce the water content to 1/4th of the initial extraction volume and mixed with four volumes of 95% ethanol to precipitate the polysaccharides.
