Structure, biology, evolution, and medical importance of sulfated fucans and galactans

Refined linkage analysis of the sulphated marine polysaccharide fucoidan of Cladosiphon okamuranus with a focus on fucose

Methylation followed by depolymerization and gas chromatography (GC) is an effective methodology for the linkage analysis of polysaccharides, including fucoidan, a sulphated algal polysaccharide. However, this sample material demands attention to experimental details to prevent aberrations in the analytical result. The use of deficient bases for methylation, the presence of water, analyte degradation during hydrolysis, and coelution of the target analytes during gas chromatography create doubts about published results. We therefore investigated critical parameters of the method and carefully optimized the steps of the protocol to ensure the integrity of the results for the fucose monomers. Fucoidan from Cladosiphon okamuranus was used as reference sample to determine the glycosidic bonds, and sulphate positions in the monomer. Fucoidan in protonated form was methylated in a strictly water-free environment using lithium dimsyl as base and methyl iodide for methylation. The methylated polymer was isolated by solid phase extraction, which was crucial to recover also the highly sulfated fraction. Hydrolysis was conducted with trifluoroacetic acid. To separate all target analytes in GC-FID/MS, a stationary phase with high cyanopropyl content (HP-88) was required, as the commonly employed phenyl siloxane phases result in co-elution, which distorts the result severely.

The α-linkage in funoran and agarose could be hydrolyzed by a GH96 family enzyme: Discovery of the α-funoranase

Agarans represent a group of galactans extracted from red algae. Funoran and agarose are the two major types and commercially applied polysaccharides of agaran. Although the glycoside hydrolases targeting β-glycosidic bonds of agaran have been widely investigated, those capable of degrading α-glycosidic bonds of agarose were limited, and the enzyme degrading α-linkages of funoran has not been reported till now. In this study, a GH96 family enzyme BiAF96A_Aq from a marine bacterium Aquimarina sp. AD1 was heterologously expressed in Escherichia coli. BiAF96A_Aq exhibited dual activities towards the characteristic structure of funoran and agarose, underscoring the multifunctionality of GH96 family members. Glycomics and NMR analysis revealed that BiAF96A_Aq hydrolyzed the α-1,3 glycosidic bonds between 3,6-anhydro-α-l-galactopyranose (LA) and β-d-galactopyranose-6-sulfate (G6S) of funoran, as well as LA and β-d-galactopyranose (G) of agarose, through an endo-acting manner. The end products of BiAF96A_Aq were majorly composed of disaccharides and tetrasaccharides. The identification of the activity of BiAF96A_Aq on funoran indicated the first discovery of the funoran hydrolase for α-1,3 linkage. Considering the novel catalytic reaction, we proposed to name this activity as "α-funoranase" and recommended the assignment of a dedicated EC number for its classification.

Marine algae-derived characterized bioactive compounds as therapy for cancer: A review on their classification, mechanism of action, and future perspectives

In 2022, there were around 20 million new cases and over 9.7 million cancer-related deaths worldwide. An increasing number of metabolites with anticancer activity in algae had been isolated and identified, which were promising candidates for cancer therapy. Red algae are well-known for the production of brominated metabolites, including terpenoids and phenols, which have the capacity to induce cell toxicity. Some non-toxic biological macromolecules, including polysaccharides, are distinct secondary metabolites found in many algae, particularly green algae. They possess anticancer activities by inhibiting tumor angiogenesis, stimulating the immune response, and inducing apoptosis. However, the structure-activity relationship between these components and antitumor activity, as well as certain taxa within the algae, remains relatively unstudied. This work is based on the reports published from 2003 to 2024 in PubMed and ISI Web of Science databases. A comprehensive review of the characterized algal anticancer active compounds, together with their structure and mechanism of action was performed. Also, their structure-activity relationship was preliminarily summarized to better assess their potential properties as a natural, safe bioactive product to be used as an alternative for the treatment of cancers, leading to new opportunities for drug discovery.

β-glucans from Euglena gracilis or Saccharomyces cerevisiae effects on immunity and inflammatory parameters in dogs

Considering the differences in molecular structure and function, the effects of β-1,3-glucans from Euglena gracilis and β-1,3/1,6-glucans from Saccharomyces cerevisiae on immune and inflammatory activities in dogs were compared. Four diets were compared: control without β-glucans (CON), 0.15 mg/kg BW/day of β-1,3/1,6-glucans (Β-Y15), 0.15 mg/kg BW/day of β-1,3-glucans (Β-S15), and 0.30 mg/kg BW/day of β-1,3-glucans (Β-S30). Thirty-two healthy dogs (eight per diet) were organized in a block design. All animals were fed CON for a 42-day washout period and then sorted into one of four diets for 42 days. Blood and faeces were collected at the beginning and end of the food intake period and analysed for serum and faecal cytokines, ex vivo production of hydrogen peroxide (H2O2) and nitric oxide (NO), phagocytic activity of neutrophils and monocytes, C-reactive protein (CRP), ex vivo production of IgG, and faecal concentrations of IgA and calprotectin. Data were evaluated using analysis of covariance and compared using Tukey's test (P<0.05). Dogs fed Β-Y15 showed higher serum IL-2 than dogs fed Β-S30 (P<0.05). A higher phagocytic index of monocytes was observed in dogs fed the B-S15 diet than in those fed the other diets, and a higher neutrophil phagocytic index was observed for B-S15 and B-Y15 than in dogs fed the CON diet (P<0.05). Monocytes from dogs fed B-S15 and B-S30 produced more NO and less H2O2 than those from the CON and B-Y15 groups (P<0.05). Despite in the reference value, CRP levels were higher in dogs fed B-S15 and B-S30 diets (P<0.05). β-1,3/1,6-glucan showed cell-mediated activation of the immune system, with increased serum IL-2 and neutrophil phagocytic index, whereas β-1,3-glucan acted on the immune system by increasing the ex vivo production of NO by monocytes, neutrophil phagocytic index, and serum CRP. Calprotectin and CRP levels did not support inflammation or other health issues related to β-glucan intake. In conclusion, both β-glucan sources modulated some immune and inflammatory parameters in dogs, however, different pathways have been suggested for the recognition and action of these molecules, reinforcing the necessity for further mechanistic studies, especially for E. gracilis β-1,3-glucan.

Chemical characterization of polysaccharides from Gracilaria gracilis from Bizerte (Tunisia)

Polysaccharides were extracted from Gracilaria gracilis collected from Manzel Jemil Lake in Bizerte Tunisia, with two different solvents (water and NaOH 0.3 M). Different assays were performed on samples (total sugars, neutral sugars, uronic acids, anhydrogalactose, proteins, sulphates, pyruvates), followed by high performance anion-exchange chromatography (HPAEC) to observe the monosaccharide composition, high pressure size exclusion chromatography with multi-angle laser light scattering (HPSEC-MALS) to obtain the molecular mass, Fourier transform infrared spectroscopy (FTIR), and 1D and 2D nuclear magnetic resonance (NMR) to access to structural data. Results have shown that the polysaccharide extracted from Gracilaria gracilis collected from Manzel Jemil Lake in Bizerte Tunisia, is of agar type but with high molecular mass and some original structural features. Hence, the sample was found to contain 9 % of pyruvate groups and is partly sulphated at the C4 of β-d-galactose and methylated on C2 of anhydro-α-l-galactose. The polymer from G. gracilis from Bizerte thus presents a never described structure that could be interesting for further rheological or biological activities applications.

Structure and Binding Properties to Blood Co-Factors of the Least Sulfated Galactan Found in the Cell Wall of the Red Alga Botryocladia occidentalis

Three different populations of sulfated polysaccharides can be found in the cell wall of the red alga Botryocladia occidentalis. In a previous work, the structures of the two more sulfated polysaccharides were revised. In this work, NMR-based structural analysis was performed on the least sulfated polysaccharide and its chemically modified derivatives. Results have revealed the presence of both 4-linked α- and 3-linked β-galactose units having the following chemical features: more than half of the total galactose units are not sulfated, the α-units occur primarily as 3,6-anhydrogalactose units either 2-O-methylated or 2-O-sulfated, and the β-galactose units can be 4-O-sulfated or 2,4-O-disulfated. SPR-based results indicated weaker binding of the least sulfated galactan to thrombin, factor Xa, and antithrombin, but stronger binding to heparin cofactor II than unfractionated heparin. This report together with our previous publication completes the structural characterization of the three polysaccharides found in the cell wall of the red alga B. occidentalis and correlates the impact of their composing chemical groups with the levels of interaction with the blood co-factors.

The characteristic structure of funoran could be hydrolyzed by a GH86 family enzyme (Aga86A_Wa): Discovery of the funoran hydrolase

Funoran, agarose and porphyran all belong to agaran, and share the similar skeleton. Although the glycoside hydrolase for agarose and porphyran, i.e. agarase and porphyranase, have been extensively studied, the enzyme hydrolyzing funoran has not been reported hitherto. The crystal structure of a previously characterized GH86 β-agarase Aga86A_Wa showed a large cavity at subsite -1, which implied its ability to accommodate sulfate ester group. By using glycomics and NMR analysis, the activity of Aga86A_Wa on the characteristic structure of funoran was validated, which signified the first discovery of funoran hydrolase, i.e. funoranase. Aga86A_Wa hydrolyzed the β-1,4 glycosidic bond between β-d-galactopyranose-6-sulfate (G6S) and 3,6-anhydro-α-l-galactopyranose (LA) unit of funoran, and released disaccharide LA-G6S as the predominant end product. Considering the hydrolysis pattern, we proposed to name the activity represented by Aga86A_Wa on funoran as "β-funoranase" and suggested to assign it an EC number.

Oligomer-guided recognition of two fucan sulfate from Bohadschia argus and inhibition of P-selectin binding to its ligand

Fucan sulfate (FS) from sea cucumber shows intriguing structure and extensive activities. Here, three homogeneous FS (BaFSI - III) were obtained from Bohadschia argus, followed with physicochemical properties analyses including monosaccharide composition, molecular weight, and sulfate content. BaFSI was proposed to carry a unique distribution pattern of sulfate groups as a novel sequence composed of domain A and domain B that formed by different Fuc_S residues, markedly differing from FS reported before, according to the analyses of 12 oligosaccharides and a representative residual saccharide chain. BaFSII possessed a highly regular structure {4-L-Fuc_3S-α1,}_n according to its peroxide depolymerized product. BaFSIII was confirmed as a FS mixture bearing similar structural characteristics with BaFSI and BaFSII by means of mild acid hydrolysis and oligosaccharide analysis. Bioactivity assays showed that BaFSI and BaFSII could potently inhibit P-selectin binding to PSGL-1 and HL-60 cells. Structure-activity relationship analysis showed that molecular weight and sulfation pattern were the essential factors for the potent inhibition. Meanwhile, an acid hydrolysate of BaFSII with a molecular weight about 15 kDa exhibited a comparable inhibition with the native BaFSII. Given the potent activity and highly regular structure of BaFSII, it shows great potential for development as a P-selectin inhibitor.

A novel anti-hyperglycemic sulfated pyruvylated polysaccharide from marine macroalga Hydropuntia edulis

Dipeptidyl peptidase is a crucial enzyme that regulates glucose metabolism by degrading incretins, such as glucagon-like-peptide-1, thereby reducing insulin secretion from the pancreatic β-cells. Consequently, dipeptidyl peptidase-IV inhibitors are an important remedial approach to moderate the hyperglycemic pathophysiology. A pyruvylated polysaccharide characterized as [→3)-4,6-O-(1-carboxyethylidene)-β-D-galp-(2SO3-)-(1→4)-3,6-α-L-AnGalp-(2OMe)-(1→], isolated from the marine macroalga Hydropuntia edulis, showed attenuation potential against dipeptidyl peptidase-IV (IC50 4.44 μM). The structure was elucidated using mass and one/two-dimensional nuclear magnetic resonance spectroscopic analyses of hydrolyzed polysaccharide besides glycosidic linkages obtained from partially methylated alditol acetate derivative. The isolated polysaccharide also revealed potential anti-carbolytic properties against α-amylase/α-glucosidase (IC50 45-47 μM). The results proved the candidacy of pyruvylated polysaccharide isolated from H. edulis as a potential therapeutic lead against hyperglycemia.

The Sea Cucumber Thyonella gemmata Contains a Low Anticoagulant Sulfated Fucan with High Anti-SARS-CoV-2 Actions against Wild-Type and Delta Variants

In this work, we isolated two new sulfated glycans from the body wall of the sea cucumber Thyonella gemmata: one fucosylated chondroitin sulfate (TgFucCS) (17.5 ± 3.5% kDa) and one sulfated fucan (TgSF) (383.3 ± 2.1% kDa). NMR results showed the TgFucCS backbone composed of [→3)-β-N-acetylgalactosamine-(1→4)-β-glucuronic acid-(1→] with 70% 4-sulfated and 30% 4,6-disulfated GalNAc units and one-third of the GlcA units decorated at the C3 position with branching α-fucose (Fuc) units either 4-sulfated (65%) or 2,4-disulfated (35%) and the TgSF structure composed of a tetrasaccharide repeating unit of [→3)-α-Fuc2,4S-(1→2)-α-Fuc4S-(1→3)-α-Fuc2S-(1→3)-α-Fuc2S-(1→]n. Inhibitory properties of TgFucCS and TgSF were investigated using SARS-CoV-2 pseudovirus coated with S-proteins of the wild-type (Wuhan-Hu-1) or the delta (B.1.617.2) strains and in four different anticoagulant assays, comparatively with unfractionated heparin. Molecular binding to coagulation (co)-factors and S-proteins was investigated by competitive surface plasmon resonance spectroscopy. Among the two sulfated glycans tested, TgSF showed significant anti-SARS-CoV-2 activity against both strains together with low anticoagulant properties, indicating a good candidate for future studies in drug development.

Epiphytic common core bacteria in the microbiomes of co-located green (Ulva), brown (Saccharina) and red (Grateloupia, Gelidium) macroalgae

BACKGROUND

Macroalgal epiphytic microbial communities constitute a rich resource for novel enzymes and compounds, but studies so far largely focused on tag-based microbial diversity analyses or limited metagenome sequencing of single macroalgal species.

RESULTS

We sampled epiphytic bacteria from specimens of Ulva sp. (green algae), Saccharina sp. (brown algae), Grateloupia sp. and Gelidium sp. (both red algae) together with seawater and sediment controls from a coastal reef in Weihai, China, during all seasons. Using 16S rRNA amplicon sequencing, we identified 14 core genera (consistently present on all macroalgae), and 14 dominant genera (consistently present on three of the macroalgae). Core genera represented ~ 0.7% of all genera, yet accounted for on average 51.1% of the bacterial abundances. Plate cultivation from all samples yielded 5,527 strains (macroalgae: 4,426) representing 1,235 species (685 potentially novel). Sequencing of selected strains yielded 820 non-redundant draft genomes (506 potentially novel), and sequencing of 23 sampled metagenomes yielded 1,619 metagenome-assembled genomes (MAGs), representing further 1,183 non-redundant genomes. 230 isolates and 153 genomes were obtained from the 28 core/dominant genera. We analyzed the genomic potential of phycosphere bacteria to degrade algal polysaccharides and to produce bioactive secondary metabolites. We predicted 4,451 polysaccharide utilization loci (PULs) and 8,810 biosynthetic gene clusters (BGCs). These were particularly prevalent in core/dominant genera.

CONCLUSIONS

Our metabolic annotations and analyses of MAGs and genomes provide new insights into novel species of phycosphere bacteria and their ecological niches for an improved understanding of the macroalgal phycosphere microbiome. Video Abstract.

A propitious role of marine sourced polysaccharides: Drug delivery and biomedical applications

Numerous compounds, with extensive applications in biomedical and biotechnological fields, are present in the oceans, which serve as a prime renewable source of natural substances, further promoting the development of novel medical systems and devices. Polysaccharides are present in the marine ecosystem in abundance, promoting minimal extraction costs, in addition to their solubility in extraction media, and an aqueous solvent, along with their interactions with biological compounds. Certain algae-derived polysaccharides include fucoidan, alginate, and carrageenan, while animal-derived polysaccharides comprise hyaluronan, chitosan and many others. Furthermore, these compounds can be modified to facilitate their processing into multiple shapes and sizes, as well as exhibit response dependence to external conditions like temperature and pH. All these properties have promoted the use of these biomaterials as raw materials for the development of drug delivery carrier systems (hydrogels, particles, capsules). The present review enlightens marine polysaccharides providing its sources, structures, biological properties, and its biomedical applications. In addition to this, their role as nanomaterials is also portrayed by the authors, along with the methods employed to develop them and associated biological and physicochemical properties designed to develop suitable drug delivery systems.

Glycosaminoglycans from the Starfish Lethasterias fusca: Structures and Influence on Hematopoiesis

Crude anionic polysaccharides extracted from the Pacific starfish Lethasterias fusca were purified by anion-exchange chromatography. The main fraction LF, having MW 14.5 kDa and dispersity 1.28 (data of gel-permeation chromatography), was solvolytically desulfated and giving rise to preparation LF-deS with a structure of dermatan core [→3)-β-d-GalNAc-(1→4)-α-l-IdoA-(1→]n, which was identified according to NMR spectroscopy data. Analysis of the NMR spectra of the parent fraction LF led to identification of the main component as dermatan sulfate LF-Derm →3)-β-d-GalNAc4R-(1→4)-α-l-IdoA2R3S-(1→ (where R was SO3 or H), bearing sulfate groups at O-3 or both at O-2 and O-3 of α-l-iduronic acid, as well as at O-4 of some N-acetyl-d-galactosamine residues. The minor signals in NMR spectra of LF were assigned as resonances of heparinoid LF-Hep composed of the fragments →4)-α-d-GlcNS3S6S-(1→4)-α-l-IdoA2S3S-(1→. The 3-O-sulfated and 2,3-di-O-sulfated iduronic acid residues are very unusual for natural glycosaminoglycans, and further studies are needed to elucidate their possible specific influence on the biological activity of the corresponding polysaccharides. To confirm the presence of these units in LF-Derm and LF-Hep, a series of variously sulfated model 3-aminopropyl iduronosides were synthesized and their NMR spectra were compared with those of the polysaccharides. Preparations LF and LF-deS were studied as stimulators of hematopoiesis in vitro. Surprisingly, it was found that both preparations were active in these tests, and hence, the high level of sulfation is not necessary for hematopoiesis stimulation in this particular case.

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.

Immunopotentiating Activity of Fucoidans and Relevance to Cancer Immunotherapy

Fucoidans, discovered in 1913, are fucose-rich sulfated polysaccharides extracted mainly from brown seaweed. These versatile and nontoxic marine-origin heteropolysaccharides have a wide range of favorable biological activities, including antitumor, immunomodulatory, antiviral, antithrombotic, anticoagulant, antithrombotic, antioxidant, and lipid-lowering activities. In the early 1980s, fucoidans were first recognized for their role in supporting the immune response and later, in the 1990s, their effects on immune potentiation began to emerge. In recent years, the understanding of the immunomodulatory effects of fucoidan has expanded significantly. The ability of fucoidan(s) to activate CTL-mediated cytotoxicity against cancer cells, strong antitumor property, and robust safety profile make fucoidans desirable for effective cancer immunotherapy. This review focusses on current progress and understanding of the immunopotentiation activity of various fucoidans, emphasizing their relevance to cancer immunotherapy. Here, we will discuss the action of fucoidans in different immune cells and review how fucoidans can be used as adjuvants in conjunction with immunotherapeutic products to improve cancer treatment and clinical outcome. Some key rationales for the possible combination of fucoidans with immunotherapy will be discussed. An update is provided on human clinical studies and available registered cancer clinical trials using fucoidans while highlighting future prospects and challenges.

Selective 2-desulfation of tetrasaccharide-repeating sulfated fucans during oligosaccharide production by mild acid hydrolysis

Sulfated fucans (SFs) from echinoderms, such as sea cucumbers and sea urchins, present linear and regular sulfation patterns within defined oligosaccharide building blocks. The high molecular weights of these polymers pose a problem in advanced structure-activity relationship studies for which derived oligosaccharides are more appropriate tools for investigation. However, enzymes capable of specifically depolymerizing SFs, fucanases, are not very common. Scarce abundance and unknown catalytic activities are additional barriers to exploiting fucanases. Oligosaccharide production by controlled chemical reactions such as mild acid hydrolysis then becomes a convenient strategy. As a consequence, physicochemical studies are necessary to understand the structural modifications caused on SFs by this chemical hydrolysis. Hence, in this work, we subjected three tetrasaccharide-repeating SFs from sea cucumbers, Isostichopus badionotus (IbSF), Holothuria floridana (HfSF), and Lytechinus variegatus (LvSF) to mild acid hydrolysis for oligosaccharide production. Interestingly, selective 2-desulfation reaction was observed in all three SFs. Through our study, we indicate that selective 2-desulfation is a common and expected phenomenon in oligosaccharide production by mild acid hydrolysis of SFs, including those composed of tetrasaccharide-repeating units.

A novel therapeutic effect of mannitol-rich extract from the brown seaweed Sargassum ilicifolium using in vitro and in vivo models

BACKGROUND

Wound healing is an active, complex, integrated series of cellular, physiological, and biochemical changes initiated by the stimulus of injury in a tissue. The present study was performed to investigate the potential wound healing abilities of Sargassum ilicifolium crude extracts (CE) that were characterized by 1H NMR and FTIR Spectrometric measurements.

MATERIALS AND METHODS

Seaweed samples were collected from southern coastal sites of Sri Lanka. To determine the cytotoxicity and proliferation of S. ilicifolium CE were used for the MTT and alamarBlue assays respectively. The scratch and exclusion wound models were used to HaCaT and HDF cells to assess the cell proliferation and migration. RAW 264.7 cells (macrophages) were used to evaluate Nitric Oxide (NO) production and phagocytosis activities. Moreover, Fifteen, 8-week-old, female, New Zealand rabbits were selected and divided into five groups: excision skin wounds (10.40 ± 0.60 mm) were induced in groups I, II, and III. Rabbits in groups I and IV were given S. ilicifolium CE (orally, 100 mg/kg day, two weeks), whereas groups II and V were given equal amounts of distilled water. Wound healing properties were measured and wound tissue samples were collated, formalin-fixed, wax-embedded, stained (Hematoxylin and Eosin; Van Gieson) and examined for the healing process.

RESULTS

Anti-inflammatory and wound healing activities were observed in RAW 264.7, HDF and HaCaT cells treated with S. ilicifolium aqueous extracts when compared to the control groups. S. ilicifolium extracts concentration 8 - 4 μg/μL, (P<0.05) had remarkable the highest proliferative and migratory effects on RAW 264.7, HDF and HaCaT cells when compared with the control. RAW 264.7 cell proliferation and/or migration were higher in S. ilicifolium extracts (4 μg/μL, 232.8 ± 10.07%) compared with the control (100 %). Scratch wound healing were remarkably enhanced in 24 h, 48 h (P<0.05) when treated with S. ilicifolium on HaCaT cells. Rabbits treated with the CE of S. ilicifolium showed a significantly increased wound healing activities (P<0.05) within three days with a close wound area of 57.21 ± 0.77 % compared with control group (26.63 ± 1.09 %). Histopathology, aspartate aminotransferase and alanine aminotransferase levels evidenced no toxic effects on seaweed treated groups. Histopathological results also revealed that the healing process was significantly faster in the rabbit groups which were as treated with CE of S. ilicifolium orally with the evidence of enhanced early granulation tissue (connective tissue and angiogenesis) and significant epithelization compared to the control.

CONCLUSIONS

Cell proliferation and migration are significantly faster when treated with S. ilicifolium aqueous extracts. Moreover, there are no toxic effect of S. ilicifolium aqueous extracts on RAW 264.7, HDF and HaCaT cell lines. In this study, it is revealed that S. ilicifolium has potential remedial agent; D-Mannitol for skin wound healing properties that by promote keratinocyte and fibroblast proliferation and migration. These findings show that S. ilicifolium have promising wound healing properties.

Structure elucidation and antitumor activity of a water soluble polysaccharide from Hemicentrotus pulcherrimus

Sea urchin nowadays serves as a delicacy around the world, and its gonads accumulate abundant polysaccharides before gametogenesis. However, the structure and bioactivity of these polysaccharides remain less well understood. Herein, a water soluble polysaccharide (HPP-1S) with a molecular weight of 2.996 × 10⁷ Da was purified from the gonads of Hemicentrotus pulcherrimus. Chemical, spectroscopic and oligosaccharide sequencing analyses revealed that HPP-1S was a highly homogeneous polysaccharide featuring a linear backbone of 1,4-linked α-d-glucose with 1,6-α-d-glucose and 1,6-α-D-glucuronic acid side chains grafted on the backbone in an alternating pattern. In vitro, HPP-1S can arrest the cell cycle at G2/M and sub-G1 phases, and induce apoptosis in Hela cells potentially by increasing expression ratio of Bax/Bcl-2. In vivo, HPP-1S exhibited obvious antitumor efficacy in Hela xenograft-bearing nude mice with low toxicity. These findings indicated that HPP-1S might serve as a potential low toxic antitumor agent.

Research Progress on the Protective Effect of Brown Algae-Derived Polysaccharides on Metabolic Diseases and Intestinal Barrier Injury

In the human body, the intestine is the largest digestive and immune organ, where nutrients are digested and absorbed, and this organ plays a key role in host immunity. In recent years, intestinal health issues have gained attention and many studies have shown that oxidative stress, inflammation, intestinal barrier damage, and an imbalance of intestinal microbiota may cause a range of intestinal diseases, as well as other problems. Brown algae polysaccharides, mainly including alginate, fucoidan, and laminaran, are food-derived natural products that have received wide attention from scholars owing to their good biological activity and low toxic side effects. It has been found that brown algae polysaccharides can repair intestinal physical, chemical, immune and biological barrier damage. Principally, this review describes the protective effects and mechanisms of brown algae-derived polysaccharides on intestinal health, as indicated by the ability of polysaccharides to maintain intestinal barrier integrity, inhibit lipid peroxidation-associated damage, and suppress inflammatory cytokines. Furthermore, our review aims to provide new ideas on the prevention and treatment of intestinal diseases and act as a reference for the development of fucoidan as a functional product for intestinal protection.

Physicochemical Characterization of Fucoidans from Sargassum henslowianum C.Agardh and Their Antithrombotic Activity In Vitro

Sargassum fucoidan is a kind of sulfated heteropolysaccharide with a variety of biological activities. The aim of this study was to investigate the extraction, purification, physicochemical characterization and in vitro antithrombotic activity of fucoidan from Sargassum henslowianum C.Agardh. Hot-water-assisted ultrasound was used to extract fucoidan (F). Fucoidan was purified by DEAE cellulose 52 (F1), Vc-H2O2 (FD1) and Superdex 75 gel (FDS1). The physical and chemical properties of fucoidans were analyzed by chemical composition, monosaccharide composition, average molecular weight (Mw) and FTIR. The sulfate contents of F, F1, FD1 and FDS1 were 11.45%, 16.35% and 17.52%, 9.66%, respectively; the Mw was 5.677 × 105, 4.393 × 105, 2.176 × 104 and 6.166 × 103, respectively. The results of monosaccharide composition showed that the four fucoidans contained l-fucose, d-galactose, l-mannose, d-xylose, l-rhamnose and d-glucose, but the mass fraction ratio was different. The results of FTIR showed that fucoidan contained characteristic peaks of sugar and sulfate. In vitro, F1, FD1 and FDS1 could alleviate HUVEC damage induced by adrenaline (Adr). F1, FD1 and FDS1 decreased vWF and TF and increased the ratio of t-PA/PAI-1 in Adr-induced HUVEC.

Biomaterials and Bioactive Natural Products from Marine Invertebrates: From Basic Research to Innovative Applications

Aquatic invertebrates are a major source of biomaterials and bioactive natural products that can find applications as pharmaceutics, nutraceutics, cosmetics, antibiotics, antifouling products and biomaterials. Symbiotic microorganisms are often the real producers of many secondary metabolites initially isolated from marine invertebrates; however, a certain number of them are actually synthesized by the macro-organisms. In this review, we analysed the literature of the years 2010–2019 on natural products (bioactive molecules and biomaterials) from the main phyla of marine invertebrates explored so far, including sponges, cnidarians, molluscs, echinoderms and ascidians, and present relevant examples of natural products of interest to public and private stakeholders. We also describe omics tools that have been more relevant in identifying and understanding mechanisms and processes underlying the biosynthesis of secondary metabolites in marine invertebrates. Since there is increasing attention on finding new solutions for a sustainable large-scale supply of bioactive compounds, we propose that a possible improvement in the biodiscovery pipeline might also come from the study and utilization of aquatic invertebrate stem cells.

Variability of Bacterial Homopolysaccharide Production and Properties during Food Processing

Various homopolysaccharides (HoPSs) can be produced by bacteria: α- and β-glucans, β-fructans and α-galactans, which are polymers of glucose, fructose and galactose, respectively. The synthesis of these compounds is catalyzed by glycosyltransferases (glycansucrases), which are able to transfer the monosaccharides in a specific substrate to the medium, which results in the growth of polysaccharide chains. The range of HoPS sizes is very large, from 10⁴ to 10⁹ Da, and mostly depends on the carbon source in the medium and the catalyzing enzyme. However, factors such as nitrogen nutrients, pH, water activity, temperature and duration of bacterial culture also impact the size and yield of production. The sequence of the enzyme influences the structure of the HoPS, by modulating the type of linkage between monomers, both for the linear chain and for the ramifications. HoPSs' size and structure have an effect on rheological properties of some foods by their influence on viscosity index. As a consequence, the control of structural and environmental factors opens ways to guide the production of specific HoPS in foods by bacteria, either by in situ or ex situ production, but requires a better knowledge of HoPS production conditions.

Synthesis of low-molecular weight fucoidan derivatives and their binding abilities to SARS-CoV-2 spike proteins

Fucoidan derivatives 10-13, whose basic sugar chains are composed of repeating α(1,4)-linked l-fucopyranosyl residues with different sulfation patterns, were designed and systematically synthesized. A structure-activity relationship (SAR) study examined competitive inhibition by thirteen fucoidan derivatives against heparin binding to the SARS-CoV-2 spike (S) protein. The results showed for the first time that 10 exhibited the highest inhibitory activity of the fucoidan derivatives used. The inhibitory activity of 10 was much higher than that of fondaparinux, the reported ligand of SARS-CoV-2 S protein. Furthermore, 10 exhibited inhibitory activities against the binding of heparin with several mutant SARS-CoV-2 S proteins, but was found to not inhibit factor Xa (FXa) activity that could otherwise lead to undesirable anticoagulant activity.

Solid-State NMR Investigations of Extracellular Matrixes and Cell Walls of Algae, Bacteria, Fungi, and Plants

Extracellular matrixes (ECMs), such as the cell walls and biofilms, are important for supporting cell integrity and function and regulating intercellular communication. These biomaterials are also of significant interest to the production of biofuels and the development of antimicrobial treatment. Solid-state nuclear magnetic resonance (ssNMR) and magic-angle spinning-dynamic nuclear polarization (MAS-DNP) are uniquely powerful for understanding the conformational structure, dynamical characteristics, and supramolecular assemblies of carbohydrates and other biomolecules in ECMs. This review highlights the recent high-resolution investigations of intact ECMs and native cells in many organisms spanning across plants, bacteria, fungi, and algae. We spotlight the structural principles identified in ECMs, discuss the current technical limitation and underexplored biochemical topics, and point out the promising opportunities enabled by the recent advances of the rapidly evolving ssNMR technology.

Bioactive Carbohydrate Polymers-Between Myth and Reality

Polysaccharides are complex macromolecules long regarded as energetic storage resources or as components of plant and fungal cell walls. They have also been described as plant mucilages or microbial exopolysaccharides. The development of glycosciences has led to a partial and difficult deciphering of their other biological functions in living organisms. The objectives of glycobiochemistry and glycobiology are currently to correlate some structural features of polysaccharides with some biological responses in the producing organisms or in another one. In this context, the literature focusing on bioactive polysaccharides has increased exponentially during the last two decades, being sometimes very optimistic for some new applications of bioactive polysaccharides, notably in the medical field. Therefore, this review aims to examine bioactive polysaccharide, taking a critical look of the different biological activities reported by authors and the reality of the market. It focuses also on the chemical, biochemical, enzymatic, and physical modifications of these biopolymers to optimize their potential as bioactive agents.

Structural and kinetic analyses of holothurian sulfated glycans suggest potential treatment for SARS-CoV-2 infection

Certain sulfated glycans, including those from marine sources, can show potential effects against SARS-CoV-2. Here, a new fucosylated chondroitin sulfate (FucCS) from the sea cucumber Pentacta pygmaea (PpFucCS) (MW ∼10-60 kDa) was isolated and structurally characterized by NMR. PpFucCS is composed of {→3)-β-GalNAcX-(1→4)-β-GlcA-[(3→1)Y]-(1→}, where X = 4S (80%), 6S (10%) or nonsulfated (10%), Y = α-Fuc2,4S (40%), α-Fuc2,4S-(1→4)-α-Fuc (30%), or α-Fuc4S (30%), and S = SO3-. The anti-SARS-CoV-2 activity of PpFucCS and those of the FucCS and sulfated fucan isolated from Isostichopus badionotus (IbFucCS and IbSF) were compared with that of heparin. IC50 values demonstrated the activity of the three holothurian sulfated glycans to be ∼12 times more efficient than heparin, with no cytotoxic effects. The dissociation constant (KD) values obtained by surface plasmon resonance of the wildtype SARS-CoV-2 spike (S)-protein receptor-binding domain (RBD) and N501Y mutant RBD in interactions with the heparin-immobilized sensor chip were 94 and 1.8 × 103 nM, respectively. Competitive surface plasmon resonance inhibition analysis of PpFucCS, IbFucCS, and IbSF against heparin binding to wildtype S-protein showed IC50 values (in the nanomolar range) 6, 25, and 6 times more efficient than heparin, respectively. Data from computational simulations suggest an influence of the sulfation patterns of the Fuc units on hydrogen bonding with GlcA and that conformational change of some of the oligosaccharide structures occurs upon S-protein RBD binding. Compared with heparin, negligible anticoagulant action was observed for IbSF. Our results suggest that IbSF may represent a promising molecule for future investigations against SARS-CoV-2.

In vitro and in vivo evaluation of the wound healing properties and safety assessment of two seaweeds (Sargassum ilicifolium and Ulva lactuca)

Seaweeds have been regarded as a reservoir of biologically active molecules that are important in the pharmaceutical industry. The aim of the present study was to explore the wound healing properties and to assess the safety of the seaweed Sargassum ilicifolium and Ulva lactuca. Enhanced cell proliferation and cell migration activities were observed in L929 cells treated with S. ilicifolium extract compared to U. lactuca extract treated cells and the control group. In-vivo experiments were conducted using five groups (10 in each) of Albino mice (BALB/c). Mice in group I and group II were treated (Orally, 100 mg/kg BW/day) with aqueous extracts of S. ilicifolium and U. lactuca, respectively for 14 days. Treatment group III received a topical application of the aqueous extract of S. ilicifolium (25% w/w) and ointment base (75% w/w) (2 g/kg BW/day, for 14 days). Group IV (Control) received an equal amount of distilled water, orally and mice in group V kept without wounds. The extract from S. ilicifolium showed stronger wound healing properties than the one from Ulva lactuca. Histopathological findings also revealed that the healing process was significantly enhanced in the mice group treated orally with S. ilicifolium aqueous extract. These findings show that S. ilicifolium species possess promising wound healing properties in-vitro and in-vivo.

Oversulfated dermatan sulfate and heparinoid in the starfish Lysastrosoma anthosticta: Structures and anticoagulant activity

Crude anionic polysaccharides extracted from the Pacific starfish Lysastrosoma anthosticta were separated by anion-exchange chromatography into fractions LA-F1 and LA-F2. The main fraction LA-F1 was solvolytically desulfated giving rise to preparation LA-F1-DS with a structure of dermatan core [→3)-β-d-GalNAc-(1→4)-α-l-IdoA-(1→]_n. Reduction of LA-F1 afforded preparation LA-F1-RED composed mainly of the repeating disaccharide units →3)-β-d-GalNAc4R-(1→4)-α-l-Ido2S3S-(1→, where R was SO₃- or H. Analysis of the NMR spectra of the parent fraction LA-F1 led to determine the main component as the oversulfated dermatan sulfate LA-Derm bearing sulfate groups at O-2 and O-3 of α-l-iduronic acid, as well as at O-4 of some N-acetyl-d-galactosamine residues. The minor fraction LA-F2 contained a mixture of LA-Derm and heparinoid LA-Hep, the latter being composed of the fragments →4)-α-d-GlcNS3S6S-(1→4)-α-l-IdoA2S3S-(1→ and →4)-α-d-GlcNS3S-(1→4)-α-l-IdoA2S3S-(1→. The presence of 2,3-di-O-sulfated iduronic acid residues is very unusual both for natural dermatan sulfate and heparinoid. Preparations LA-F1, LA-F2 and LA-F1-RED demonstrated significant anticoagulant effect in vitro.

Functional foods and bioactive ingredients harnessed from the ocean: current status and future perspectives

With an increase in life expectancy and decrease of quality-of-life couple with the high prevalence of diseases, diet is expected to play a key function in sustaining human health. Nutritionists, food technologists and medical experts are working in synergy to cater for the increasing demand of food with associated therapeutic benefits, commonly known as functional food, that may improve well-being and reduce the risk of diseases. Interestingly, the marine ecosystem, due to its abundant and phenomenal biodiversity of marine organisms, constitutes a vital source of a panoply of healthy foods supply for the thriving functional food industry. Marine organisms such as seaweeds, sea cucumbers, sponges, and mollusks amongst others are sources of thousands of biologically active metabolites with antioxidant, anti-parasitic, antiviral, anti-inflammatory and anticancer properties. Given the growing number of research and interest to probe into the therapeutic roles of marine products, this review was designed to provide a comprehensive summary of the therapeutic properties of marine organisms (macroalgae, sea cucumbers and fish among others) which are consumed worldwide, in addition to their potentials and as sources of functional ingredients for developing novel food and fostering wellness. The gap between research development and actual commercialization, and future prospects of marine-based products also summarized to some extent.

Structural sequencing and anti-inflammatory, anti-lung cancer activities of 1,4-α/β-sulfomalonoglucan in Antrodia cinnamomea

Antrodia cinnamomea is a precious Polyporaceous fungus with various bioactivities. This study reports the chemical identification and biological activities of sulfomalonoglucan, a sulfated polysaccharide (SPS), from the sodium sulfate enriched medium of the title fungus. The SPS-containing fraction was separated by gel filtration chromatography (GFC) to give the title SPS (denoted as Na10_SPS-F3). By analyzing the evidence for key inter-glycosidic linkages in the 1D and 2D NMR spectroscopic data, one possible repeat unit was proposed as: Na10_SPS-F3 inhibited the secretion of tumor necrosis factor (TNF-α) and interleukin (IL)-6 after lipopolysaccharide (LPS) stimulation in RAW264.7 macrophages. Mechanistically, Na10_SPS-F3 downregulated TGFRII also attenuated the LPS-induced IκB-α degradation. Moreover, Na10_SPS-F3 inhibited lung cancer cell H1975 EGFR/ERK signaling. This is the first paper reporting a 3-O-sulfomalonyl glucan (Na10_SPS-F3) with eight 1,4-β-Glc moieties connected with ten 1,4-α-Glc moieties from Antrodia cinnamomea and its anti-inflammatory and anti-cancer activities.

Sulfated polysaccharide ascophyllan from Padina tetrastromatica enhances healing of burn wounds by ameliorating inflammatory responses and oxidative damage

Sulfated polysaccharide ascophyllan from marine brown algae has been identified to have burn wound healing properties. Thus, we examined the effects of ascophyllan fraction (AF3) on the inflammatory response and oxidative damage in burn wounds. Full-thickness burn wounds in rats were then treated twice per day with topical AF3 ointment (5%), while control groups were treated with 10% povidone-iodine (positive control) and petroleum jelly-based ointment (negative control). The activity of cyclooxygenase-2 and myeloperoxidase and levels of C-reactive protein, nitric oxide, and proinflammatory cytokines (tumor necrosis factor-α, interleukin-6, and interleukin-1β) were observed to have significantly decreased in peripheral blood mononuclear cells, serum, and wound tissue of the group treated with AF3 ointment on day 8 after wounding. The expression of inducible nitric oxide synthase, endothelial nitric oxide synthase, and vascular endothelial growth factor at the mRNA level was determined to be upregulated in the wound tissue of the AF3 ointment-treated group. After treatment with AF3 ointment, the antioxidant enzyme activity and level of reduced glutathione were upregulated, whereas the content of thiobarbituric acid reactive substances decreased. Treatment of burn wounds using 5% AF3 ointment decreases oxidative damage associated with inflammation deceptively via inhibition of inflammatory enzymes, regulation of proinflammatory cytokines, upregulation of angiogenesis, and activity of antioxidant enzymes.

Interactions of fibroblast growth factors with sulfated galactofucan from Saccharina japonica

A total 68 types of marine algae oligosaccharides and polysaccharides were prepared and used to study the structure-activity relationship of oligosaccharides and polysaccharides in their interactions with fibroblast growth factors (FGF) 1 and 2. Factors considered include different types of algae, extraction methods, molecular weight, sulfate content and fractions. In the case of low molecular weight polysaccharide (SJ-D) from Saccharina japonica and its fractions eluting from anion exchange column, both 1.0 M NaCl fraction (SJ-D-I) and 2.0 M NaCl fraction (SJ-D-S) had stronger binding affinity than the parent SJ-D, suggesting that sulfated galactofucans represented the major tight binding component. Nuclear magnetic resonance showed that SJ-D-I was a typical sulfated galactofucan, composed of four units: 1, 3-linked 4-sulfated α-L-fucose (Fuc); 1, 3-linked 2, 4-disulfated α-L-Fuc; 1, 6-linked 4-sulfated β-D-Gal and/or 1, 6-linked 3, 4-sulfated β-D-Gal. Modification by autohydrolysis to oligosaccharides and desulfation decreased the FGF binding affinity while oversulfation increased the affinity. The solution-based affinities of SJ-D-I to FGF1 and FGF2 were 69 nM and 3.9 nM, suggesting that SJ-D-I showed better preferentially binding to FGF1 than a natural ligand, heparin, suggesting that sulfated galactofucan might represent a good regulator of FGF1.

Sargassum fusiforme Fucoidan Alleviates High-Fat Diet-Induced Obesity and Insulin Resistance Associated with the Improvement of Hepatic Oxidative Stress and Gut Microbiota Profile

Sargassum fusiforme fucoidan (SFF) exhibits diverse biological activities. Insulin resistance (IR) implicated in type 2 diabetes (T2D) has become an epidemic health issue worldwide. In this study, we investigated whether SFF can improve insulin sensitivity in high-fat diet (HFD)-fed mice. Our present data showed that SFF significantly reduced fasting blood glucose and IR index along with improved glucose tolerance. Impaired phosphorylation of Akt was also restored by SFF. Furthermore, SFF decreased the levels of MDA and 4-HNE-modified protein and increased GSH/GSSG ratio as well as elevated antioxidant enzymes and activated Nrf2 signaling. SFF also increased the abundance and diversity of gut microbiota in the obese mice, as well as improved intestinal integrity and inflammation. Our findings suggested that SFF ameliorated HFD-induced IR through activating the Nrf2 pathway, remodeling gut microbiota, and reducing intestinal inflammation, thus providing a novel perspective into the treatment strategy on metabolic disease.

Inhibition of glucuronomannan hexamer on the proliferation of lung cancer through binding with immunoglobulin G

The anti-lung cancer activity of oligosaccharides derived from glucuronomannan was investigated. The inhibition of A549 cell proliferation by glucuronomannan (Gn) and its oligomers (dimer (G2), tetramer (G4) and hexamer (G6)) were concentration dependent. In vivo activities on the A549-derived tumor xenografts showed the tumor inhibition of G2, G4 and G6 were 17 %, 40 % and 46 %, respectively. Organ coefficients in nude mice showed an increase in the kidney with G4, the brain with G6, and the spleen with G6. An advanced tandem mass tag labeled proteomics approach was performed. A significant differential expression was found in 59 out of the 4371 proteins, which involved the immune system. Surface plasmon resonance (SPR) studies revealed G6 was strongly bound to immunoglobulin G. This suggests that glucuronomannan hexamer inhibits the proliferation of lung cancer through its binding to immunoglobulin.

Immunomodulatory Effects of a Low-Molecular Weight Polysaccharide from Enteromorpha prolifera on RAW 264.7 Macrophages and Cyclophosphamide- Induced Immunosuppression Mouse Models

The water-soluble polysaccharide EP2, from Enteromorpha prolifera, belongs to the group of polysaccharides known as glucuronoxylorhamnan, which mainly contains glucuronic acid (GlcA), xylose (Xyl), and rhamnose (Rha). The aim of this study was to detect the immunomodulatory effects of EP2 on RAW 264.7 macrophages and cyclophosphamide (CYP)-induced immunosuppression mouse models. The cells were treated with EP2 for different time periods (0, 0.5, 1, 3, and 6 h). The results showed that EP2 promoted nitric oxide production and up-regulated the expression of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α, in a time-dependent manner. Furthermore, we found that EP2-activated iNOS, COX2, and NLRP3 inflammasomes, and the TLR4/MAPK/NF-κB signaling pathway played an important role. Moreover, EP2 significantly increased the body weight, spleen index, thymus index, inflammatory cell counts, and the levels of IL-1β, IL-6, and TNF-α in CYP-induced immunosuppression mouse models. These results indicate that EP2 might be a potential immunomodulatory drug and provide the scientific basis for the comprehensive utilization and evaluation of E. prolifera in future applications.

The Effect of Water-Soluble Polysaccharide from Jackfruit (Artocarpus heterophyllus Lam.) on Human Colon Carcinoma Cells Cultured In Vitro

Various phytochemical studies have revealed that jackfruit (Artocarpus heterophyllus Lam.) is rich in bioactive compounds, including carotenoids, flavonoids, volatile acids, tannins, and lectins. The aim of the study was to analyze the biological activity of water-soluble polysaccharide (WSP) isolated from jackfruit and to assess its immunomodulatory, cytotoxic, and anti-oxidative effects on human colon carcinoma cells in vitro. The neutral red (NR) uptake assay revealed no toxic influence of the polymer on the viability of tumor cells (HT29 and SW620). After 24 h and 48 h of incubation, the cellular viability was not lower than 94%. The metabolic activity of the cells (MTT) at the compound concentration of 250 µg/mL was higher than 92% in comparison to the control. WSP (250 µg/mL) exerted no significant effect on the morphology of the cells was determined by May-Grünwald-Giemsa staining. WSP changed nitric oxide (NOx) production by the tumor cells depending on the time of incubation and prior 2-h stimulation of the cells with E. coli 0111:B4 LPS. It significantly stimulated IL-1β production by the tumor cells. The IL-6 level increased but that of IL-10 decreased by a WSP concentration-dependent manner. No such effect was detected in SW620. The WSP had antioxidant properties. In conclusion, water-soluble polysaccharide isolated from A. heterophyllus exhibits significant biological activity towards many types of both normal and cancerous cells. Therefore, it may be considered as a useful agent in the protection of human health or in functional and dietary nutrition.

A comparative study of sulphated polysaccharide effects on advanced glycation end-product uptake and scavenger receptor class A level in macrophages

Advanced glycation end-products, especially toxic advanced glycation end-products derived from glyceraldehyde (advanced glycation end-product-2) and glycolaldehyde (advanced glycation end-product-3), are biologically reactive compounds associated with diabetic complications. We previously demonstrated that toxic advanced glycation end-products were internalised into macrophage-like RAW264.7 cells through scavenger receptor-1 class A (CD204). Toxic advanced glycation end-product uptake was inhibited by fucoidan, a sulphated polysaccharide and antagonistic ligand for scavenger receptors, suggesting that sulphated polysaccharides are emerging candidates for treatment of advanced glycation end-product-related diseases. In this study, we compared the effects of six types of sulphated and non-sulphated polysaccharides on toxic advanced glycation end-product uptake in RAW264.7 cells. Fucoidan, carrageenan and dextran sulphate attenuated toxic advanced glycation end-product uptake. Fucoidan and carrageenan inhibited advanced glycation end-product-2-induced upregulation of SR-A, while advanced glycation end-product-3-induced upregulation of scavenger receptor-1 class A was only suppressed by fucoidan. Dextran sulphate did not affect scavenger receptor-1 class A levels in toxic advanced glycation end-product-treated cells. Chondroitin sulphate, heparin and hyaluronic acid failed to attenuate toxic advanced glycation end-product uptake. Heparin and hyaluronic acid had no effect on scavenger receptor-1 class A levels, while chondroitin sulphate inhibited advanced glycation end-product-3-induced upregulation of scavenger receptor-1 class A. Taken together, fucoidan and carrageenan, but not the other sulphated polysaccharides examined, had inhibitory activities on toxic advanced glycation end-product uptake and toxic advanced glycation end-product-induced upregulation of scavenger receptor-1 class A, possibly because of structural differences among sulphated polysaccharides.

Diversity of Sulfated Polysaccharides From Cell Walls of Coenocytic Green Algae and Their Structural Relationships in View of Green Algal Evolution

Seaweeds biosynthesize sulfated polysaccharides as key components of their cell walls. These polysaccharides are potentially interesting as biologically active compounds. Green macroalgae of the class Ulvophyceae comprise sulfated polysaccharides with great structural differences regarding the monosaccharide constituents, linearity of their backbones, and presence of other acidic substituents in their structure, including uronic acid residues and pyruvic acid. These structures have been thoroughly studied in the Ulvales and Ulotrichales, but only more recently have they been investigated with some detail in ulvophytes with giant multinucleate (coenocytic) cells, including the siphonous Bryopsidales and Dasycladales, and the siphonocladous Cladophorales. An early classification of these structurally heterogeneous polysaccharides was based on the presence of uronic acid residues in these molecules. In agreement with this classification based on chemical structures, sulfated polysaccharides of the orders Bryopsidales and Cladophorales fall in the same group, in which this acidic component is absent, or only present in very low quantities. The cell walls of Dasycladales have been less studied, and it remains unclear if they comprise sulfated polysaccharides of both types. Although in the Bryopsidales and Cladophorales the most important sulfated polysaccharides are arabinans and galactans (or arabinogalactans), their major structures are very different. The Bryopsidales produce sulfated pyruvylated 3-linked β-d-galactans, in most cases, with ramifications on C6. For some species, linear sulfated pyranosic β-l-arabinans have been described. In the Cladophorales, also sulfated pyranosic β-l-arabinans have been found, but 4-linked and highly substituted with side chains. These differences are consistent with recent molecular phylogenetic analyses, which indicate that the Bryopsidales and Cladophorales are distantly related. In addition, some of the Bryopsidales also biosynthesize other sulfated polysaccharides, i.e., sulfated mannans and sulfated rhamnans. The presence of sulfate groups as a distinctive characteristic of these biopolymers has been related to their adaptation to the marine environment. However, it has been shown that some freshwater algae from the Cladophorales also produce sulfated polysaccharides. In this review, structures of sulfated polysaccharides from bryopsidalean, dasycladalean, and cladophoralean green algae studied until now are described and analyzed based on current phylogenetic understanding, with the aim of unveiling the important knowledge gaps that still exist.

Prospect of Polysaccharide-Based Materials as Advanced Food Packaging

The use of polysaccharide-based materials presents an eco-friendly technological solution, by reducing dependence on fossil resources while reducing a product's carbon footprint, when compared to conventional plastic packaging materials. This review discusses the potential of polysaccharides as a raw material to produce multifunctional materials for food packaging applications. The covered areas include the recent innovations and properties of the polysaccharide-based materials. Emphasis is given to hemicelluloses, marine polysaccharides, and bacterial exopolysaccharides and their potential application in the latest trends of food packaging materials, including edible coatings, intelligent films, and thermo-insulated aerogel packaging.

Degraded fucoidan fractions and β-1,3-glucan sulfates inhibit CXCL12-induced Erk1/2 activation and chemotaxis in Burkitt lymphoma cells

Fucoidans are natural polysaccharides with pronounced antitumoral activities. Their modes of action include the antagonization of the chemokine CXCL12, which plays a central role in tumor development and metastasis. However, the usually high molecular mass (M_w) of fucoidans represents an obstacle to their medical application. We therefore investigated two series of degraded fucoidan fractions with regard to their CXCL12 binding and inhibition of CXCL12-induced effects in Raji cells. In addition, semisynthetic β-1,3-glucan sulfates were examined to get more information about the impact of M_w and degree of sulfation (DS). Degradation of the fucoidans from Saccharina latissima (S.l.-SP; 481-77.0 kDa) and Fucus vesiculosus (F.v.-SP; 38.2-20.6 kDa) did not affect the respective binding capacity to CXCL12. Both the M_w independence and the DS dependence were confirmed by the β-1,3-glucan sulfates having significantly higher affinity to CXCL12. The chemokine binding resulted in reduced CXCL12-induced Erk1/2 signaling and chemotaxis of Raji cells which was also independent of the M_w. Solely the oxidatively degraded fucoidan fraction displayed a significantly reduced chemotaxis inhibition. In conclusion, degradation of fucoidans to obtain biopharmaceutically more favorable M_w is possible without impairing their activities targeting CXCL12. Moreover, the β-1,3-glucan sulfates should also be considered as promising candidates for further development.