Depolymerization of sulfated polysaccharides under hydrothermal conditions

Fermented Gracilaria lemaneiformis polysaccharides alleviate food allergy by regulating Treg cells and gut microbiota

Food allergy has a significant impact on the health and well-being of individuals, affecting both their physical and mental states. Research on natural bioactive compounds, such as polysaccharides extracted from seaweeds, holds great promise in the treatment of food allergies. In this study, fermented Gracilaria lemaneiformis polysaccharides (F-GLSP) were prepared using probiotic fermentation. Probiotic fermentation of Gracilaria lemaneiformis reduces the particle size of polysaccharides. To compare the anti-allergic activity of F-GLSP with unfermented Gracilaria lemaneiformis polysaccharides (UF-GLSP), an OVA-induced mouse food allergy model was established. F-GLSP exhibited a significant reduction in OVA-specific IgE and mMCP levels in allergic mice. Moreover, it significantly inhibited Th2 differentiation and IL-4 production and significantly promoted Treg differentiation and IL-10 production in allergic mice. In contrast, UF-GLSP only reduced OVA-specific IgE and mMCP in the serum of allergic mice. Furthermore, F-GLSP demonstrated a more pronounced regulation of intestinal flora abundance compared to UF-GLSP, significantly influencing the populations of Firmicutes, Bacteroidetes, Lactobacillus, and Clostridiales in the intestines of mice with food allergy. These findings suggest that F-GLSP may regulate food allergies in mice through multiple pathways. In summary, this study has promoted further development of functional foods with anti-allergic properties based on red algae polysaccharides.

Conventional extraction of fucoidan from Irish brown seaweed Fucus vesiculosus followed by ultrasound-assisted depolymerization

Fucoidan has attracted considerable attention from scientists and pharmaceutical companies due to its antioxidant, anticoagulant, anti-inflammatory, anti-tumor, and health-enhancing properties. However, the extraction of fucoidan from seaweeds often involves the use of harsh chemicals, which necessitates the search for alternative solvents. Additionally, the high viscosity and low cell permeability of high molecular weight (Mw) fucoidan can limit its effectiveness in drug action, while lower Mw fractions exhibit increased biological activity and are also utilized as dietary supplements. The study aimed to (1) extract fucoidan from the seaweed Fucus vesiculosus (FV) using an environmentally friendly solvent and compare it with the most commonly used extraction solvent, hydrochloric acid, and (2) assess the impact of ultrasound-assisted depolymerization on reducing the molecular weight of the fucoidan extracts and examine the cytotoxic effect of different molecular weight fractions. The findings indicated that the green depolymerization solvent, in conjunction with a brief ultrasound treatment, effectively reduced the molecular weight. Moreover, a significant decrease in cell viability was observed in selected samples, indicating potential anticancer properties. As a result, ultrasound was determined to be an effective method for depolymerizing crude fucoidan from Fucus Vesiculosus seaweed.

Effects of degradation on the physicochemical and antioxidant properties of carboxymethyl pachymaran

Poria cocos (Schw.) Wolf is a well-known edible and medicinal fungus. The polysaccharide in the sclerotium of P. cocos was extracted and prepared into carboxymethyl pachymaran (CMP). Three different degradation treatments including high temperature (HT), high pressure (HP) and gamma irradiation (GI) were used to process CMP. The changes in physicochemical properties and antioxidant activities of CMP were then comparatively investigated. We found that the molecular weights of HT-CMP, HP-CMP, and GI-CMP decreased from 787.9 kDa to 429.8, 569.5 and 6.0 kDa, respectively. Degradation treatments had no effect on the main chains of →3-β-D-Glcp-(1 → while changed the branched sugar residues. The polysaccharide chains of CMP were depolymerized after high pressure and gamma irradiation treatments. The three degradation methods improved the stability of CMP solution while decreased the thermal stability of CMP. In addition, we found that the GI-CMP with lowest molecular weight had the best antioxidant activity. Our results suggest that gamma irradiation treatment could degrade CMP as functional foods with strong antioxidant activity.

Comparative Analyses of Fucoidans from South African Brown Seaweeds That Inhibit Adhesion, Migration, and Long-Term Survival of Colorectal Cancer Cells

Human colorectal cancer (CRC) is a recurrent, deadly malignant tumour with a high incidence. The incidence of CRC is of increasing alarm in highly developed countries, as well as in middle to low-income countries, posing a significant global health challenge. Therefore, novel management and prevention strategies are vital in reducing the morbidity and mortality of CRC. Fucoidans from South African seaweeds were hot water extracted and structurally characterised using FTIR, NMR and TGA. The fucoidans were chemically characterised to analyse their composition. In addition, the anti-cancer properties of the fucoidans on human HCT116 colorectal cells were investigated. The effect of fucoidans on HCT116 cell viability was explored using the resazurin assay. Thereafter, the anti-colony formation potential of fucoidans was explored. The potency of fucoidans on the 2D and 3D migration of HCT116 cells was investigated by wound healing assay and spheroid migration assays, respectively. Lastly, the anti-cell adhesion potential of fucoidans on HCT116 cells was also investigated. Our study found that Ecklonia sp. Fucoidans had a higher carbohydrate content and lower sulphate content than Sargassum elegans and commercial Fucus vesiculosus fucoidans. The fucoidans prevented 2D and 3D migration of HCT116 colorectal cancer cells to 80% at a fucoidan concentration of 100 µg/mL. This concentration of fucoidans also significantly inhibited HCT116 cell adhesion by 40%. Moreover, some fucoidan extracts hindered long-term colony formation by HCT116 cancer cells. In summary, the characterised fucoidan extracts demonstrated promising anti-cancer activities in vitro, and this warrants their further analyses in pre-clinical and clinical studies.

Relevance of the Extraction Stage on the Anti-Inflammatory Action of Fucoidans

The anti-inflammatory action of fucoidans is well known, based on both in vitro and some in vivo studies. The other biological properties of these compounds, their lack of toxicity, and the possibility of obtaining them from a widely distributed and renewable source, makes them attractive novel bioactives. However, fucoidans’ heterogeneity and variability in composition, structure, and properties depending on seaweed species, biotic and abiotic factors and processing conditions, especially during extraction and purification stages, make it difficult for standardization. A review of the available technologies, including those based on intensification strategies, and their influence on fucoidan composition, structure, and anti-inflammatory potential of crude extracts and fractions is presented.

Efficient adsorption of dyes from aqueous solution using a novel functionalized magnetic biochar: Synthesis, kinetics, isotherms, adsorption mechanism, and reusability

In this study, a novel adsorbent, dodecylbenzene sulfonic acid (DBSA) functionalized magnetic biochar (DBSA-Fe₃O₄@BC), was synthesized and used to efficiently remove dyes from aqueous solution. The results indicated that DBSA-Fe₃O₄@BC exhibited an excellent adsorption capacity for Rhodamine B (RhB), and the maximum adsorption capacity for RhB at 298 K was 367.67 mg/g, which was approximately 2.3-1.2 folds than that of BC, dodecylsulfonic acid functionalized biochar (DSA@BC), DBSA@BC, Fe₃O₄@BC, and DSA-Fe₃O₄@BC. The possible adsorption mechanisms for RhB adsorption by DBSA-Fe₃O₄@BC included pore filling, electrostatic attraction, H bond, and surface complexation. Importantly, structural control presented that the simultaneous introduction of alkyl and phenyl groups significantly enhanced RhB adsorption by DBSA-Fe₃O₄@BC through hydrophobic and π-π interaction. Combined ethanol (EtOH) desorption and H₂O₂ oxidation regeneration, DBSA-Fe₃O₄@BC remained high-performance for RhB adsorption after six cycles (97.44%), indicating its outstanding reusability. In summary, DBSA-Fe₃O₄@BC exhibited a prospective application for dyeing wastewater treatment.

Efficient catalytic degradation of alkanes in soil by a novel heterogeneous Fenton catalyst of functionalized magnetic biochar

In this study, sodium dodecyl sulfate (SDS) functionalized magnetic biochar (SDS-Fe@BC) was successfully prepared. Compared to other traditional heterogeneous Fenton catalysts, more total petroleum hydrocarbons (TPH) (3499.40 mg kg^-1) was adsorbed from soil to the surface of SDS-Fe@BC through hydrophobic interaction between alkyls in alkanes and SDS-Fe@BC, which formed an efficient interface oxidation system. In SDS-Fe@BC-mediated heterogeneous Fenton system, 10,191.41 mg kg^-1 (88.10%) TPH was degraded in the presence of 400 mM H₂O₂, which was 1.38-5.67 folds than that of H₂O₂ alone, Fe²⁺, zero valent iron (ZVI), Fe₃O₄, pristine biochar (BC), and Fe@BC. Moreover, all individual alkanes were efficiently degraded (>75%), and the higher the initial amount of individual alkane, the more the degradative amount in the SDS-Fe@BC/H₂O₂ system. Additionally, TPH degradation was highly related to the mass ratio of SDS/Fe@BC, H₂O₂ concentration, SDS-Fe@BC dosage, and initial pH in the SDS-Fe@BC/H₂O₂ system, and the optimal values were 1:5, 400 mM, 50 mg g^-1, and pH 7, respectively. Radical quenching experiments revealed that hydroxyl radicals (•OH) generated on the surface of SDS-Fe@BC was the dominated reactive oxidative species (ROS) responsible for alkanes degradation. After five cycles, SDS-Fe@BC still remained a high catalytic activity for alkanes degradation (73.21%), showing its excellent reusability. This study proved that the SDS-Fe@BC can be used as a potential heterogeneous Fenton catalyst for petroleum-contaminated soil remediation.

Hydrothermal systems to obtain high value-added compounds from macroalgae for bioeconomy and biorefineries

The search of sustainable and environmentally friendly alternatives to obtain compounds for different industrial sectors has grown exponentially. Following the principles of biorefinery and circular bioeconomy, processes in which the use of natural resources such as macroalgae biomass is prioritized are required. This review focuses on a description of the relevance, application and engineering platforms of hydrothermal systems and the operational conditions depending on the target as an innovative technology and bio-based solution for macroalgae fractionation in order to recover profitable products for industries and investors. In this sense, hydrothermal treatments represent a promising alternative for obtaining different high value-added compounds from this biomass; since, the different variations in terms of operating conditions, gives great versatility to this technology compared to other types of processing, allowing it to be adapted depending on the objective, whether it is working under sub/super critical conditions, thus expanding its field of application.

Health effects of dietary sulfated polysaccharides from seafoods and their interaction with gut microbiota

Various dietary sulfated polysaccharides (SPs) have been isolated from seafoods, including edible seaweeds and marine animals, and their health effects such as antiobesity and anti-inflammatory activities have attracted remarkable interest. Sulfate groups have been shown to play important roles in the bioactivities of these polysaccharides. Recent in vitro and in vivo studies have suggested that the biological effects of dietary SPs are associated with the modulation of the gut microbiota. Dietary SPs could regulate the gut microbiota structure and, accordingly, affect the production of bioactive microbial metabolites. Because of their differential chemical structures, dietary SPs may specifically affect the growth of certain gut microbiota and associated metabolite production, which may contribute to variable health effects. This review summarizes the latest findings on the types and structural characteristics of SPs, the effects of different processing techniques on the structural characteristics and health effects of SPs, and the current understanding of the role of gut microbiota in the health effects of SPs. These findings might help in better understanding the mechanism of the health effects of SPs and provide a scientific basis for their application as functional food.

Comparison of hydrothermal depolymerization and oligosaccharide profile of fucoidan and fucosylated chondroitin sulfate from Holothuria floridana

To minimize undesired pharmacological activities and improve the bioavailability, the fucoidan and fucosylated chondroitin sulfate (FCS) from Holothuria floridana were depolymerized under hydrothermal conditions and the mechanism underlying hydrothermal depolymerization was proposed. Our results demonstrated that fucoidan and FCS from Holothuria floridana were able to be gradually depolymerized without desulfation at 100-121 °C by control of pH at 5-6 to obtain controlled molecular weight. It was the first time to find that pH also plays a key role on the hydrothermal depolymerization of fucoidan and FCS. The monosaccharide composition, FT-IR and NMR analysis showed that the structure of the optimized hydrothermal depolymerized fucoidan and FCS remained almost unchanged. By comparison, FCS was more difficult to be depolymerized than fucoidan under the same hydrothermal condition. The oligosaccharide profile in depolymerized fucoidan and FCS by HILIC-MS analysis further revealed that FCS was depolymerized with preferential cleavage of β-1 → 4 glycosidic linkage and decarboxylation on glucuronic acid during hydrothermal treatment, which was quite different with the random fracture type of fucoidan due to their different structure. These results indicated that hydrothermal depolymerization and action mechanism of fucoidan and FCS from sea cucumber were quite different for their different structure.

Gradual degradation of fucoidan from Fucus vesiculosus and its effect on structure, antioxidant and antiproliferative activities

The fucose-containing sulfated polysaccharides (syn. fucoidans) from brown algae exhibit a wide range of bioactivities and are therefore considered promising candidates for health-supporting and medical applications. During the past three decades, research on isolation, molecular characterization, and screening of in vitro and in vivo pharmacological activities has significantly increased. Until now, however, fucoidans are only used as ingredients in cosmetics and food supplements, especially due to the proclaimed antioxidant activities of fucoidan. One obstacle to medical applications is the usually high molecular mass of native fucoidans, as it is associated with unfavorable biopharmaceutical properties and possibly undesired effects. Therefore, it seems reasonable to develop fucoidan derivatives with reduced size. So far, in this study, fucoidan from Fucus vesiculosus was gradually degraded from M_w 38.2 down to 4.9 kDa without concomitant desulfation. Compared to hydrothermal treatment, the degradation with H₂O₂ showed to be more efficient and additionally eliminated the antioxidant and antiproliferative activities of the genuine fucoidan. This confirmed our previous hypothesis that rather co-extracted compounds like terpenoids and polyphenols than the fucoidan itself exhibit these effects.

A Novel Heterogalactan from Antrodia camphorata and Anti-Angiogenic Activity of Its Sulfated Derivative

A heterogalactan, named ACW0, was extracted from Antrodia camphorata and purified by anion exchange and gel permeation chromatography. It was composed of galactose (94.98%), traces of mannose (2.41%), and fucose (2.61%), with its molecular weight estimated to be 13.5 k Da. The polysaccharide ACW0 was shown to be a mannofucogalactan with a backbone chain of α-d-1,6-linked Gal, attached by a non-reducing terminal α-d-Man and α-l-Fuc on C-2 of nearly every six α-d-1,6-linked Gal residues. A sulfated polysaccharide, ACW0-Sul was achieved by the chlorosulfonic acid-pyridine method. Compared with the native polysaccharide, ACW0-Sul could disrupt tube formation and migration as well as cell growth of human microvascular endothelial cells (HMEC-1) dose-dependently. Further studies revealed that phosphorylation of Extracellular Regulated Protein Kinases (Erk) and Focal Adhesion Kinase (FAK) were significantly inhibited by ACW0-Sul. These results suggested that ACW0-Sul could be a potent candidate for anti-angiogenic agent development.

Navicula sp. Sulfated Polysaccharide Gels Induced by Fe(III): Rheology and Microstructure

A sulfated polysaccharide extracted from Navicula sp. presented a yield of 4.4 (% w/w dry biomass basis). Analysis of the polysaccharide using gas chromatography showed that this polysaccharide contained glucose (29%), galactose (21%), rhamnose (10%), xylose (5%) and mannose (4%). This polysaccharide presented an average molecular weight of 107 kDa. Scanning electron microscopy (SEM) micrographs showed that the lyophilized Navicula sp. polysaccharide is an amorphous solid with particles of irregular shapes and sharp angles. The polysaccharide at 1% (w/v) solution in water formed gels in the presence of 0.4% (w/v) FeCl₃, showing elastic and viscous moduli of 1 and 0.7 Pa, respectively. SEM analysis performed on the lyophilized gel showed a compact pore structure, with a pore size of approximately 150 nm. Very few studies on the gelation of sulfated polysaccharides using trivalent ions exist in the literature, and, to the best of our knowledge, this study is the first to describe the gelation of sulfated polysaccharides extracted from Navicula sp.