Recent Advances in Marine Algae Polysaccharides: Isolation, Structure, and Activities

Abstract

Marine algae have attracted a great deal of interest as excellent sources of nutrients. Polysaccharides are the main components in marine algae, hence a great deal of attention has been directed at isolation and characterization of marine algae polysaccharides because of their numerous health benefits. In this review, extraction and purification approaches and chemico-physical properties of marine algae polysaccharides (MAPs) are summarized. The biological activities, which include immunomodulatory, antitumor, antiviral, antioxidant, and hypolipidemic, are also discussed. Additionally, structure-function relationships are analyzed and summarized. MAPs' biological activities are closely correlated with their monosaccharide composition, molecular weights, linkage types, and chain conformation. In order to promote further exploitation and utilization of polysaccharides from marine algae for functional food and pharmaceutical areas, high efficiency, and low-cost polysaccharide extraction and purification methods, quality control, structure-function activity relationships, and specific mechanisms of MAPs activation need to be extensively investigated.

Keywords: characterization; extraction; marine algae; polysaccharide; structure-function relationship.

Figure 1

Schematic diagram of extraction, purification, characterization, biological activities, and applications of marine algae polysaccharides.

Figure 2

Schematic diagram of saccharide mapping (or enzymatic profile, E1–E3 are glycosidases) aiming to assess biological activities of marine algae polysaccharides. First, active compounds (color square) are digested by selected endo-glycosidases (E1–E3). Then biological activities are determined by in vitro and in vivo tests, as well as toxicity level. Finally, chromatographic profiles of active compounds are performed. This systematic approach could be used for quality assurance of developed products.

Figure 3

Schematic presentation of the immune system activated by marine algae polysaccharides after interaction of several molecular events. (Akt: protein kinase B; CR3: complement receptor 3; ERK1/2: extracellular signal regulated kinase 1/2; GSK3: glycogen synthase kinase 3-β; IFN: interferon; IL: interleukin; JNK1/2: c-Jun N-terminal kinase 1/2; MAPK: mitogen-activated protein kinase; PAK: p21-activated kinase; PI3K: phosphatidylinositol-3 kinase; SR: scavenger receptor; TLR-4: toll-like receptor 4; TNF-α: tumor necrosis factor-α).