## 4 Discussion
The signal at 4.505 ppm (f \(\beta\)-d-Galactose (G) was linked to 3,6-\(\alpha\)-l-anhydroglacatose in the sulfated polysaccharide from _M. oxysporum_[65]. The fucoidan from _S. siliquosum_ possesses (1\(\rightarrow\)3)-linked or (1\(\rightarrow\)4)-linked l-fucose residues as the backbone structure [66]. A similar study on _Ecklonia maxima_ shows that the signal at 1.10 ppm is linked to the C6 methyl protons of L-fucose. The peaks in the range of 3.4-4.0 ppm denote the sugar residues [67]. The AFM is a single molecular spectroscopic technology to detect the conformational changes in morphological structures of polysaccharides and molecular assembling. AFM provides visualization of different types of sulfatedpolysaccharides [68]. In a similar study, AFM was employed to analyze _S. plagiophyllum_[33]. The AFM image shows a three-dimensional view of the spherical shape with its polydispersity nature [69]. The SEM image of F2-fucoidan shows a worm-like structure in _S. plagiophyllum_[33]. The SEM image of crude seaweed polysaccharide shows the irregular shape of _Sargassum longifolium_, which is highly undesirable for biomedical applications [70]. The antioxidant properties of isolated fucoidans were investigated by their physical differences related to molecular weights. The extraction analysis revealed the chemical composition of sulfated polysaccharides in _Fucus evanescens_ and the amount of polyphenols in different extraction methods [71]. Fucoidan isolated from marine brown algae had the highest DPPH scavenging, reducing ability, and overall antioxidant activity in 1000 \(\upmu\)g/mL of _Sargassum polycystum_ (61.2, 67.56, and 65.3%) [49]. In a previous study, the IC\({}_{50}\) of the DPPH scavenging activity of fucoidan extracted from _L. japonica_ was found to be 3.7 mg/mL [72]. The DPPH scavenging activity was associated with a hydrogen atom or electron transfer reaction from the sulfate group to the free radical. Higher sulfate content corresponded to a higher antioxidant activity [56]. The sulfate group, activating the hydrogen atom of the anomeric carbon to adsorb the antioxidants exhibited the scavenging ability of _Sargassum thunbergii_[73]. The sulfated polysaccharides derived from _Dictyota menstrualis_ and _Dyctiota metrensi_ showed the maximum hydroxyl radical scavenging activity inhibition at 8.7 and 7.5%, while the superoxide radical scavengers from _Dictyota cercivornis_ and _Dictyota deliculata_ showed the highest scavenging activity at 29 and 32%, respectively [40]. _L. nigrescens_ and _L. trabeculata_ showed the highest scavenging activity in the superoxide and hydroxyl group experiments [74]. The polyphenols found in the seaweed extracts exhibit antioxidant activity. The free radical scavenging properties of sulfated polysaccharides were isolated from _S. myriocystum_[75]. The ABTS scavenging ability of _Monostroma oxysporum_ exhibited higher scavenging activity (25.37-76.81%) at various concentrations than the standard BHT and l-ascorbic acid [57]. Previous study results demonstrated that the inhibitory impact of sulfated polysaccharide on the formation of these radicals was higher in _Laminaria japonica_[72]. The reducing power is generally associated with the presence of reductones, which has been shown to exert antioxidant activity by breaking the free radical chain by donating a hydrogen atom. The difference in the antioxidant activity of seaweed polysaccharides might be attributed to the influence of various factors, such as the structure, molecular weight (MW), and chemical composition [30]. The antioxidant activity having higher polyphenol contents in the soluble fraction has a tendency to precipitate. The highly effective polyphenol and flavonoid compounds with their hydroxyl group are present because of the potential scavenging free radicals' activity [76]. The compounds with anticoagulant properties are evaluated using different assays, such as APPT and PT [77].