Advances in Research on the Bioactivity of Alginate Oligosaccharides

Abstract

Alginate is a natural polysaccharide present in various marine brown seaweeds. Alginate oligosaccharide (AOS) is a degradation product of alginate, which has received increasing attention due to its low molecular weight and promising biological activity. The wide-ranging biological activity of AOS is closely related to the diversity of their structures. AOS with a specific structure and distinct applications can be obtained by different methods of alginate degradation. This review focuses on recent advances in the biological activity of alginate and its derivatives, including their anti-tumor, anti-oxidative, immunoregulatory, anti-inflammatory, neuroprotective, antibacterial, hypolipidemic, antihypertensive, and hypoglycemic properties, as well as the ability to suppress obesity and promote cell proliferation and regulate plant growth. We hope that this review will provide theoretical basis and inspiration for the high-value research developments and utilization of AOS-related products.2 of 26 the 4 C 1 conformation and are linked by β-1,4-glycosidic bond, while in pG, all G residues are in the 1 C 4 conformation and are linked by an α-1,4-glycosidic bond. These features are responsible for the differences in their higher-order structure. For example, pG exhibits an egg-box-like conformation and usually forms stiffer 2-fold screw helical chains when dissolved in water, while pM forms belt chains through intra-molecular hydrogen bonds. Due to these dissimilarities, pM and pG, as well as their derivatives, will exhibit different activities [12].As the most abundant marine biomass and low-cost material, alginate has been extensively used in the food and medical industries. The widespread utilization is also driven by its favorable chemical properties and versatile activities. However, the applications of alginate have been greatly limited due to its high molecular weight and low bioavailability. Therefore, the degradation of high molecular weight polysaccharides into low molecular weight poly-or oligosaccharides is considered of great significance for improving their bioavailability, increasing the body's absorption of drugs, and fully utilizing the efficacy of polysaccharides. Recently, the degradation products of alginate, i.e., alginate oligosaccharides (AOS), have attracted increasing attention due to their biological activities and excellent solubility in water [13]. AOS can be depolymerized by different degradation methods, including enzymatic degradation, acid hydrolysis, and oxidative degradation [14]. Alginate lyases have been isolated from a wide range of organisms, including algae, marine invertebrates, and marine and terrestrial microorganisms, which can degrade alginate into unsaturated oligosaccharides by β-elimination [15,16]. Moreover, due to differences in degradation patterns, G content (G/M ratio), molecular weight, and spatial conformation of degradation products, AOS possess a variety of biological activities. They have anti-tumor properties [17], counteract oxidation [8], regulate immune respo...

Antioxidant and cytotoxic activities of sulfated polysaccharides from five different edible seaweeds

“…Comparing the polysaccharides of terrestrial plant origin, seaweed polysaccharides constitute unique monomers like galactose, mannose, fucose, xylose etc. with varying degree of sulfation in their sugar residues [40] that influence the structure and biological properties of polymer isolated from each seaweed species [41]. This sulfate group of sugar moieties is found responsible for exhibiting anionic charge to the polymers [27,39,40].…”

Alginate Oligosaccharide Ameliorates D-Galactose-Induced Kidney Aging in Mice through Activation of the Nrf2 Signaling Pathway

“…Chronic administration of D-gal may cause physiological states similar to those observed during natural aging, such as cell metabolism disorders and injury [ 12 ]. Alginate oligosaccharide (AOS) is a degradation product of alginate that has been extensively studied due to its wide range of pharmacological activities and beneficial effects [ 13 , 14 ]. Previous studies have shown that AOS has a variety of biological activities, such as antioxidant [ 15 ], antitumor [ 16 ], and immunomodulatory effects [ 17 ].…”

Marine Natural Products: Promising Candidates in the Modulation of Gut-Brain Axis towards Neuroprotection

“…From the mechanistic point, alginate has targeted oxidative pathways (e.g., ROS) and neuroinflammation (e.g., TLR4) to protect neuronal damages. So, regulation of GM and neuronal dysregulated pathways by alginate pave the road in attaining a promising gut-brain axis [ 203 ].…”