**4. Materials and Methods**

#### *4.1. Extraction, Purification and Chemical Analysis of Fucoidans (FSF and BBF)*

Brown algae *B. bifurcata* and *F. spiralis* were harvested on the at El Jadida city (Morocco) in December 2017. The extraction and separation of sulfated polysaccharides were performed according to Ermakova et al. [54]. Samples of 25 g of each algae species were depigmented with formaldehyde 2% and then dried for 12 h at ambient temperature. Dried powders were then treated twice with HCl 0.1 M solution during 2 h (at 60 ◦C, 450 rpm). After centrifugation for 20 min at 5000 rpm, the recovered supernatants were neutralized to pH 7.5. Crude fucoidans were obtained with thrice ethanol 96% (3 *v*/*v*) precipitation and then freeze-dried to *B. bifurcata* and *F. spiralis* crude fucoidans powders (BBF and FSF, respectively). All chemical analysis of FSF and BBF was performed using colorimetric assays as described in previous paper [41].

#### *4.2. GC-MS Analysis of FSF and BBF*

Prior to GC-MS analysis, samples of 15 mg of BBF and FSF were hydrolyzed using Trifluoroacetic acid (TFA) under 120 ◦C for 90 min. Monosaccharides generated by this acid hydrolysis were then treated with N,O-Bis (trimethylsilyl) trifluoroacetamide (BSTFA) with 1% Trimethylchlorosilane (TMCS) according to Pierre et al.'s method [55,56]. After evaporation, monosaccharides constituting the fucoidans (FSF and BBF) as well as the standards were injected in GC-MS at 10 g/<sup>L</sup> of dichloromethne.
