*3.2.5 Laminarins*

Laminarins are found in brown algae, belong to a linear sulfated polysaccharide that soluble in water and 22–49% of the dry algal mass. Laminarins are known as a β sulfated glucan consists of a 3:1 ratio of β (1 → 3) and β (1 → 6) with a molecular weight of 5 kDa and (1 → 3)-β-d-glucopyranose residues [37]. Laminarin structure depends on algae species, growth period, and growth condition, while molecular weight is affected by the polymerization degree. Laminarin could be M chains or G chains, corresponding to the terminal 1-O-substituted D-mannitol or glucose, respectively, depends on the sugar type at the reducing end of laminarin [38]. Numerous studies showed that laminarins as a potential bioactive ingredient in cancer treatment basing on antioxidant activity and inhibition (melanoma cells, colon cancer, and anti-metastatic). The structure, molecular weight, monosaccharide unit number, degree polymerization, and branching length of laminarin control their antioxidant activity [39, 40]. For example, laminarins (15 and 06 kDa) possess antioxidant activity (7.5 and 79.7%), respectively. DPPH scavenging activity of purified laminarin (10 kDa) corresponds to 87.57%. The antioxidant activity of laminarin is basing on the interaction between carbonyl groups and transition metal ions (Cu2+ or Fe2+) and carbonyl groups [39]. Laminarins also exhibit the ability to the inhibition of lipid peroxidation. Laminarins also play a role in the inhibition of chain initiation, peroxide decomposition, and binding of transition metal ions.
