Bioactive Polysaccharides from Seaweeds

Abstract

Bioactive compounds with diverse chemical structures play a significant role in disease prevention and maintenance of physiological functions. Due to the increase in industrial demand for new biosourced molecules, several types of biomasses are being exploited for the identification of bioactive metabolites and techno-functional biomolecules that are suitable for the subsequent uses in cosmetic, food and pharmaceutical fields. Among the various biomasses available, macroalgae are gaining popularity because of their potential nutraceutical and health benefits. Such health effects are delivered by specific diterpenes, pigments (fucoxanthin, phycocyanin, and carotenoids), bioactive peptides and polysaccharides. Abundant and recent studies have identified valuable biological activities of native algae polysaccharides, but also of their derivatives, including oligosaccharides and (bio)chemically modified polysaccharides. However, only a few of them can be industrially developed and open up new markets of active molecules, extracts or ingredients. In this respect, the health and nutraceutical claims associated with marine algal bioactive polysaccharides are summarized and comprehensively discussed in this review.

Keywords: Macroalgae; bioactive agents; biomolecules; polysaccharides; seaweeds.

Figure 1

Bioactive compounds from marine seaweeds.

Figure 2

Algal polysaccharides classification.

Figure 3

Applications of bioactive algal polysaccharides.

Figure 4

Structures of fucoidans extracted from brown seaweeds of the Fucales order. (A) Fucoidan of Fucus serratus (and Ascophyllum nodosum) composed of a main chain of (1→3)- and (1→4)-α-l-Fucp with short branches of α-l-Fucp-(1→4)-α-l-Fucp and α-l-Fucp-(1→3)-α-l-Fucp in O-4 of α-(1→3)-l-Fucp and sulfate groups in O-2 and/or O-4 positions. (B) Fucoidan extracted from Fucus evanescens consisting of a main skeleton of (1→3)- and (1→4)-α-l-Fucp highly substituted by sulfate groups at O-2 and/or O-3 positions.

Figure 5

Structures of fucoidans from brown seaweeds of the Laminariales order. (A) Fucoidan from Laminaria saccharina composed of a main chain of (1→3)-α-l-Fucp branched at O-2 and O-4 of α-l-Fucp by terminal residues and sulfate groups. (B) Fucoidan obtained from Chorda filum consisting of a (1→3)-α-l-Fucp main backbone highly ramified at O-2 by terminal residues and substituted by sulfate groups at O-2 and/or O-4positions.

Figure 6

Structures of (A) laminaribioses and (B) gentiobioses.

Figure 7

Structure of alginates. G: guluronate or l-GulpA; M: mannuronate or d-ManpA.

Figure 8

Structures of (A) μ-carrageenans, (B) κ-carrageenans, (C) ν-carrageenans, (D) λ-carrageenans and (E) ι-carrageenans.

Figure 9

Representation of agarose.

Figure 10

Structures of (A) porphyrans and (B) funorans. R: CH₃ or SO₃⁻.

Figure 11

Structures of ulvans. A₃S: ulvanobiuronate-3-sulfate type A,; B₃S: ulvanobiuronate-3-sulfate type B; U₃S: ulvanobiose-3-sulfate type A; U_2’S₃S: ulvanobiose-2,3-disulfate type B.

Figure 12

Damage induced by reactive oxygen species (ROS).

Figure 13

Potentials of marine-derived algae polysaccharide (SP)-based engineered cues to induce cell death of tumor cells (apoptosis).

Figure 14

Signaling pathways involved in natural killer cell (NK cells) activation by bioactive algal polysaccharides.

Figure 15

Signaling pathways involved in macrophage activation by algal-sulfated polysaccharides.