Macrophage-stimulating activities of a novel low molecular weight saccharide fragment prepared from ascophyllan with alginate lyase

From sea to sea: Edible, hydrostable, and degradable straws based on seaweed-derived insoluble cellulose fibers and soluble polysaccharides

The widespread use of disposable plastic straws has caused a long-lasting environmental problem. Potential alternatives for plastic straws are far from satisfactory due to the low utility, poor water stability, and non-ideal natural degradability. In this work, an edible, hydrostable, and degradable straw was developed from the economically significant seaweed. Seaweed-derived insoluble cellulose fibers were used as the building block of the straw, and the soluble polysaccharide extracts were explored as the natural glue through the chelation with Ca2+. Repeated freeze-thawing was introduced to strengthen the molecular interactions, which further improved its mechanical stability and hydrostability. The straw exhibited remarkable natural degradability in open environments, particularly in marine-mimicking conditions. By incorporating pH-sensitive food pigments, the straws could indicate acid-base property of a beverage or even discriminate the freshness of milk. The versatile seaweed-derived straw adhered to the biocycle concept of "from sea to sea" to alleviate the burden of white pollution on oceans.

Structural characterization of a fucoidan from Ascophyllum nodosum and comparison of its protective effect against cellular oxidative stress with its analogues

In the present study, a fucoidan fraction (ANP-3) was isolated from Ascophyllum nodosum, and the combined application of desulfation, methylation, HPGPC, HPLC-MSn, FT-IR, GC-MS, NMR, and Congo red test elucidated ANP-3 (124.5 kDa) as a triple-helical sulfated polysaccharide constituted by →2)-α-Fucp3S-(1→, →3)-α-Fucp2S4S-(1→, →3,6)-β-Galp4S-(1→, →3,6)-β-Manp4S-(1→, →3,6)-β-Galp4S-(1→，→6)-β-Manp-(1→, →3)-β-Galp-(1→, α-Fucp-(1→, and α-GlcAp-(1→ residues. To better understand the relationship between the fucoidan structure of A. nodosum and protective effects against oxidative stress, two fractions ANP-6 and ANP-7 were used as contrast. ANP-6 (63.2 kDa) exhibited no protective effect against H2O2-induced oxidative stress. However, ANP-3 and ANP-7 with the same molecular weight of 124.5 kDa could protect against oxidative stress by down-regulating reactive oxygen species (ROS) and malondialdehyde (MDA) levels and up-regulating total antioxidant capability (T-AOC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities. Then metabolites analysis indicated that arginine biosynthesis and phenylalanine, tyrosine, and tryptophan biosynthesis metabolic pathways and metabolic biomarkers such as betaine were involved in the effects of ANP-3 and ANP-7. The better protective effect of ANP-7 compared to that of ANP-3 could be attributed to its relatively higher molecular weight, sulfate substitution and →6)-β-Galp-(1→ content, and lower uronic acid content.

In vitro fermentation of seaweed polysaccharides and tea polyphenol blends by human intestinal flora and their effects on intestinal inflammation

A combination of polysaccharides and tea polyphenols can enhance immune activity synergistically, depending on the type and structure of polysaccharides, but the mechanism remains unknown. This study is aimed to investigate the regulating effects of different seaweed polysaccharide (ι-carrageenan, agarose) and tea polyphenol blends on intestinal flora and intestinal inflammation using an in vitro ascending-transverse-descending colon fermentation system and RAW264.7 cell model. The results showed that seaweed polysaccharides in the presence of tea polyphenol were almost completely degraded at transverse colon fermentation for 36 h. Agarose significantly enhanced the butyric acid production content by increasing the abundance of Lachnospiraceae, whereas agarose and tea polyphenol blends did not have a synergistic effect. On the contrary, ι-carrageenan and tea polyphenol blends synergistically increased the abundance of beneficial bacteria (e.g., Bacteroidetes and Bifidobacterium) and promoted the production of short-chain fatty acids (SCFAs), such as isobutyric acid. Such changes tended to alter the impacts of different seaweed polysaccharides and tea polyphenol blends on intestinal inflammation. Among them, ι-carrageenan and tea polyphenol blends were the most effective in inhibiting lipopolysaccharide-induced NO, ROS, IL-6, and TNF-α production in RAW264.7 cells, indicating the alleviated intestinal inflammation. The results suggest that the seaweed polysaccharide and tea polyphenol blends have prebiotic potential and can benefit intestinal health.

Two Ascophyllum nodosum Fucoidans with Different Molecular Weights Inhibit Inflammation via Blocking of TLR/NF-κB Signaling Pathway Discriminately

The present study aimed to clarify the potential mechanism of fucoidans found in Ascophyllum nodosum on anti-inflammation and to further explore the relationship between their structures and anti-inflammation. Two novel fucoidans named ANP-6 and ANP-7 and found in A. nodosum, were separated and purified and their structures were elucidated by HPGPC, HPLC, GC-MS, FT-IR, NMR, and by the Congo red test. They both possessed a backbone constructed of →2)-α-L-Fucp4S-(1→, →3)-α-L-Fucp2S4S-(1→, →6)-β-D-Galp-(1→, and →3,6)-β-D-Galp4S-(1→ with branches of →2)-α-L-Fucp4S-(1→ and →3)-β-D-Galp-(1→. Moreover, ANP-6 and ANP-7 could prevent the inflammation of the LPS-stimulated macrophages by suppressing the NO production and by regulating the expressions of iNOS, COX-2, TNF-α, IL-1β, IL-6, and IL-10. Their inhibitory effects on the TLR-2 and TLR-4 levels suggest that they inhibit the inflammation process via the blocking of the TLR/NF-κB signal transduction. In addition, ANP-6, with a molecular weight (63.2 kDa), exhibited stronger anti-inflammatory capabilities than ANP-7 (124.5 kDa), thereby indicating that the molecular weight has an influence on the anti-inflammatory effects of fucoidans.

Inhibitory effects of a low-molecular-weight sulfated fucose-containing saccharide on α-amylase and α-glucosidase prepared from ascophyllan

To find natural and safe anti-diabetic foods or potential drugs, low-molecular-weight saccharide fragments LMWAs-H (M_w 33.48 kDa) and LMWAs-L (M_w 6.71 kDa) from the sulfated polysaccharide ascophyllan of Ascophyllum nodosum using alginate lyase (EC 4.2.2.3) were investigated. The results revealed that LMWAs-H possessed potent inhibition activity against α-glucosidase or α-amylase in a concentration-dependent manner, which were higher than native ascophyllan or LMWAs-L. LMWAs-H exhibited a stronger inhibitory activity against α-glucosidase than α-amylase because it differently affects the conformational structures of these enzymes. Structural analysis revealed LMWAs-H to be →4)-α-L-Fucp-(1 → 4)-α-L-Fucp-(1 → 3)-β-D-Xylp-(1 → 3)-α-L-Fucp4S(1→ as main chain, and T-α-D-Glcp-(1→ and →3)-β-D-ManpA_red residues were attached to the ends of main chain as non-reducing- and reducing-end residues, respectively. The 4-deoxy-L-erythro-hex-4-enuronosyluronate linked the O-4 position of →3,4)-β-D-ManpA_red residue as side branches. Our results suggest that LMWAs-H is the main active structural motif responsible for the enzymes-inhibiting activities, which is probably derived from the fucose-containing branches of ascophyllan. Our findings reveal that the strong inhibition of LMWAs-H on α-glucosidase but mild inhibition on α-amylase is highly related to its structural properties, suggesting its desirable characteristics as an anti-diabetic agent.

Evolving strategies for marine enzyme engineering: recent advances on the molecular modification of alginate lyase

Alginate, an acidic polysaccharide, is formed by β-d-mannuronate (M) and α-l-guluronate (G). As a type of polysaccharide lyase, alginate lyase can efficiently degrade alginate into alginate oligosaccharides, having potential applications in the food, medicine, and agriculture fields. However, the application of alginate lyase has been limited due to its low catalytic efficiency and poor temperature stability. In recent years, various structural features of alginate lyase have been determined, resulting in modification strategies that can increase the applicability of alginate lyase, making it important to summarize and discuss the current evidence. In this review, we summarized the structural features and catalytic mechanisms of alginate lyase. Molecular modification strategies, such as rational design, directed evolution, conserved domain recombination, and non-catalytic domain truncation, are also described in detail. Lastly, the application of alginate lyase is discussed. This comprehensive summary can inform future applications of alginate lyases.

Immunomodulatory effects of polysaccharides from marine algae for treating cancer, infectious disease, and inflammation

A significant rise in the occurrence and severity of adverse reactions to several synthetic drugs has fueled considerable interest in natural product-based therapeutics. In humans and animals, polysaccharides from marine microalgae and seaweeds have immunomodulatory effects. In addition, these polysaccharides may possess antiviral, anticancer, hypoglycemic, anticoagulant, and antioxidant properties. During inflammatory diseases, such as autoimmune diseases and sepsis, immunosuppressive molecules can serve as therapeutic agents. Similarly, molecules that participate in immune activation can induce immune responses against cancer and infectious diseases. We aim to discuss the chemical composition of the algal polysaccharides, namely alginate, fucoidan, ascophyllan, and porphyran. We also summarize their applications in the treatment of cancer, infectious disease, and inflammation. Recent applications of nanoparticles that are based on algal polysaccharides for the treatment of cancer and inflammatory diseases have also been addressed. In conclusion, these applications of marine algal polysaccharides could provide novel therapeutic alternatives for several diseases.

Structural characterization and pro-angiogenic property of a polysaccharide isolated from red seaweed Bangia fusco-purpurea

In this study, we evaluated the structural characteristics and novel biological activity of polysaccharide purified from red seaweed Bangia fusco-purpurea (BFP). Methylation, GC/MS, and NMR analyses suggested that the proposal repeating structure of BFP was →3)-β-D-Galp-(1→, →3)-β-D-Galp6S-(1 → 4)-α-D-Galp-(1→, →4)-α-D-Galp-(1 → 4)-α-L-AnGalp-(1 → 3)-β-D-Galp-(1→, and →4)-α-D-Galp-(1 → at a molar ratio of 13: 1: 1: 1. Interestingly, BFP exhibited significant cell migration- and tube formation-promoting activities toward human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner via increasing the N-cadherin expression and decreasing the E-cadherin expression. Furthermore, ERK and p38 mitogen-activated protein kinase (MAPK) specific inhibitors exhibited potent inhibitory effects on BFP-induced cell migration but not JNK MAPK inhibitor, suggesting ERK and p38 MAPK signaling pathways were mainly involved in BFP-induced cell migration. Moreover, vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitor significantly inhibited BFP-induced cell migration and tube formation in HUVECs, suggesting VEGF receptors of HUVECs were involved in the pro-angiogenesis activity of BFP. This is the first report that a sulfated polysaccharide possessing a pro-angiogenic effect was obtained from red seaweed. Our findings are expected to promote the practical use of red seaweed B. fusco-purpurea and its polysaccharide in the development of the in vitro and ex vivo vascular endothelial cell-based cell therapy products.