Physicochemical and Biological Characterization of Fucoidan from Fucus vesiculosus Purified by Dye Affinity Chromatography

Functionalization of poly (lactic-co-glycolic acid) nano‑calcium sulphate and fucoidan 3D scaffold using human bone marrow mesenchymal stromal cells for bone tissue engineering application

This study aimed to functionalize a novel porous PLGA (Poly lactic-co-glycolic acid) composite scaffold in combination with nano‑calcium sulphate (nCS) and/or fucoidan (FU) to induce osteogenic differentiation of human bone marrow stromal cells. The composite scaffolds (PLGA-nCS-FU, PLGA-nCS or PLGA-FU) were fabricated and subjected to characterization using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Energy Dispersive X-Ray (EDX). The biocompatibility and osteogenic induction potential of scaffolds on seeded human bone marrow derived mesenchymal stromal cells (hBMSCs) were studied using cell attachment and alamar blue cell viability and alkaline phosphatase (ALP), osteocalcin and osteogenic gene expression, respectively. The composition of different groups was reflected in FTIR, XRD and EDX. The SEM micrographs revealed a difference in the surface of the scaffold before and after FU addition. The confocal imaging and SEM micrographs confirmed the attachment of cells onto all three composite scaffolds. However, the AB assay indicated a significant increase (p < 0.05) in cell viability/proliferation seeded on PLGA-nCS-FU on day 21 and 28 as compared with other combinations. A 2-fold significant increase (p < 0.05) in ALP and OC secretion of seeded hBMSCs onto PLGA-nCS-FU was observed when compared with other combinations. A significant increase in RUNX2, OPN, COL-I and ALP genes were observed in the cells seeded on PLGA-nCS-FU on day 14 and 28 as compared with day 0. In conclusion, the incorporation of both Fucoidan and Nano‑calcium sulphate with PLGA showed a promising improvement in the osteogenic potential of hBMSCs. Therefore, PLGA-nCS-FU could be the ideal candidate for subsequent pre-clinical studies to develop a successful bone substitute to repair critical bone defects.

Fucoidan's Molecular Targets: A Comprehensive Review of Its Unique and Multiple Targets Accounting for Promising Bioactivities Supported by In Silico Studies

Fucoidan is a class of multifunctional polysaccharides derived from marine organisms. Its unique and diversified physicochemical and chemical properties have qualified them for potential and promising pharmacological uses in human diseases, including inflammation, tumors, immunity disorders, kidney diseases, and diabetes. Physicochemical and chemical properties are the main contributors to these bioactivities. The previous literature has attributed such activities to its ability to target key enzymes and receptors involved in potential disease pathways, either directly or indirectly, where the anionic sulfate ester groups are mainly involved in these interactions. These findings also confirm the advantageous pharmacological uses of sulfated versus non-sulfated polysaccharides. The current review shall highlight the molecular targets of fucoidans, especially enzymes, and the subsequent responses via either the upregulation or downregulation of mediators' expression in various tissue abnormalities. In addition, in silico studies will be applied to support the previous findings and show the significant contributors. The current review may help in understanding the molecular mechanisms of fucoidan. Also, the findings of this review may be utilized in the design of specific oligomers inspired by fucoidan with the purpose of treating life-threatening human diseases effectively.

Natural fucoidans inhibit coronaviruses by targeting viral spike protein and host cell furin

Fucoidans are a class of long chain sulfated polysaccharides and have multiple biological functions. Herein, four natural fucoidans extracted from Fucus vesiculosus, F. serratus, Laminaria japonica and Undaria pinnatifida, were tested for their HCoV-OC43 inhibition and found to demonstrate EC50 values ranging from 0.15 to 0.61 µg/mL. That from U. pinnatifida exhibited the most potent anti-HCoV-OC43 activity with an EC50 value of 0.15 ± 0.02 µg/mL, a potency largely independent of its sulfate content. Comparison of the gene expression profiles of fucoidan-treated and untreated cells infected with HCoV-OC43 revealed that fucoidan treatment effectively diminished HCoV-OC43 gene expressions associated with induced chemokines, cytokines and viral activities. Further studies using a highly fucoidan-resistant HCoV-OC43 determined that fucoidan inhibited HCoV-OC43 infection via interfering with viral entry and led to the identification of the specific site on the N-terminal region of spike protein, that located adjacent to the host cell receptor binding domain, targeted by the virus. Furthermore, in a SARS-CoV-2 pseudovirus neutralization assay, fucoidan also blocked SARS-CoV-2 entry. In vitro and in vivo, fucoidan decreased SARS-CoV-2 viral loads and inhibited viral infection in Calu-3 or Vero E6 cells and SARS-CoV-2 infected hamsters, respectively. Fucoidan was also found to inhibit furin activity, and reported furin inhibitors were found to inhibit viral infection by wild type HCoV-OC43 or SARS-CoV-2. Accordingly, we conclude that fucoidans inhibit coronaviral infection by targeting viral spike protein and host cell furin to interfere with viral entry.

Bioactivity of Fucoidan-Rich Extracts from Fucus vesiculosus against Rotavirus and Foodborne Pathogens

Marine algae are sources of bioactive components with defensive properties of great value against microbial infections. This study investigated the bioactivity of extracts from brown algae Fucus vesiculosus against rotavirus, the worldwide leading cause of acute gastroenteritis in infants and young children. Moreover, one of the extracts was tested against four foodborne bacteria: Campylobacter jejuni, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes, and the non-pathogenic: E. coli K12. In vitro tests using MA104 cells revealed that both whole algae extracts and crude fucoidan precipitates neutralized rotavirus in a dose-responsive manner. The maximum neutralization activity was observed when the rotavirus was incubated with 100 μg mL-1 of the hydrochloric acid-obtained crude fucoidan (91.8%), although crude fucoidan extracted using citric acid also demonstrated high values (89.5%) at the same concentration. Furthermore, molecular weight fractionation of extracts decreased their antirotaviral activity and high molecular weight fractions exhibited higher activity compared to those of lower molecular weight. A seaweed extract with high antirotaviral activity was also found to inhibit the growth of C. jejuni, S. Typhimurium, and L. monocytogenes at a concentration of 0.2 mg mL-1. Overall, this study expands the current knowledge regarding the antimicrobial mechanisms of action of extracts from F. vesiculosus.

Development and characterization of a fucoidan-based nanoemulsion using Nigella sativa oil for improvement of anti-obesity activity of fucoxanthin in an obese rat model

The anti-obesity activity of encapsulated fucoxanthin in fucoidan-based nanoemulsion was investigated. Then, high-fat diet (HFD) induced-obese rats were fed along with different treatments including administration of encapsulated fucoxanthin (10 mg/kg and 50 mg/kg/day), fucoidan (70 mg/kg), Nigella sativa oil (250 mg/kg), metformin (200 mg/kg), and free form of fucoxanthin (50 mg/kg) by oral gavage daily for 7 weeks. The study discovered that fucoidan-based nanoemulsions with a low and high dose of fucoxanthin had droplet size in the range of 181.70-184.87 nm and encapsulation efficacy of 89.94-91.68 %, respectively. Also exhibited 75.86 % and 83.76 % fucoxanthin in vitro release. The TEM images and FTIR spectera confirmed the particle size and encapsulation of fucoxanthin, respectively. Moreover, in vivo results revealed that encapsulated fucoxanthin reduced body and liver weight compared with a HFD group (p < 0.05). Biochemical parameters (FBS, TG, TC, HDL, LDL) and liver enzymes (ALP, AST, and ALT) were decreased after fucoxanthin and fucoidan administration. According to the histopathological analysis, fucoxanthin and fucoidan attenuated lipid accumulation in the liver.

Otoprotective Effects of Fucoidan Reduce Cisplatin-Induced Ototoxicity in Mouse Cochlear UB/OC-2 Cells

Cisplatin is a widely used standard chemotherapy for various cancers. However, cisplatin treatment is associated with severe ototoxicity. Fucoidan is a complex sulfated polysaccharide mainly derived from brown seaweeds, and it shows multiple bioactivities such as antimicrobial, anti-inflammatory, anticancer, and antioxidant activities. Despite evidence of the antioxidant effects of fucoidan, research on its otoprotective effects remains limited. Therefore, the present study investigated the otoprotective effects of fucoidan in vitro using the mouse cochlear cell line UB/OC-2 to develop new strategies to attenuate cisplatin-induced ototoxicity. We quantified the cell membrane potential and analyzed regulators and cascade proteins in the apoptotic pathway. Mouse cochlear UB/OC-2 cells were pre-treated with fucoidan before cisplatin exposure. The effects on cochlear hair cell viability, mitochondrial function, and apoptosis-related proteins were determined via flow cytometry, Western blot analysis, and fluorescence staining. Fucoidan treatment reduced cisplatin-induced intracellular reactive oxygen species production, stabilized mitochondrial membrane potential, inhibited mitochondrial dysfunction, and successfully protected hair cells from apoptosis. Furthermore, fucoidan exerted antioxidant effects against oxidative stress by regulating the Nrf2 pathway. Therefore, we suggest that fucoidan may represent a potential therapeutic agent for developing a new otoprotective strategy.

Marine organisms as potential sources of natural products for the prevention and treatment of malaria

Vector-borne diseases (VBDs) are a worldwide critical concern accounting for 17% of the estimated global burden of all infectious diseases in 2020. Despite the various medicines available for the management, the deadliest VBD malaria, caused by Plasmodium sp., has resulted in hundreds of thousands of deaths in sub-Saharan Africa only. This finding may be explained by the progressive loss of antimalarial medication efficacy, inherent toxicity, the rise of drug resistance, or a lack of treatment adherence. As a result, new drug discoveries from uncommon sources are desperately needed, especially against multi-drug resistant strains. Marine organisms have been investigated, including sponges, soft corals, algae, and cyanobacteria. They have been shown to produce many bioactive compounds that potentially affect the causative organism at different stages of its life cycle, including the chloroquine (CQ)-resistant strains of P. falciparum. These compounds also showed diverse chemical structures belonging to various phytochemical classes, including alkaloids, terpenoids, polyketides, macrolides, and others. The current article presents a comprehensive review of marine-derived natural products with antimalarial activity as potential candidates for targeting different stages and species of Plasmodium in both in vitro and in vivo and in comparison with the commercially available and terrestrial plant-derived products, i.e., quinine and artemisinin.

Characterization and Cytotoxic Activity of Microwave-Assisted Extracted Crude Fucoidans from Different Brown Seaweeds

Microwave-assisted extraction (MAE) is recognized as a green method for extraction of natural products. The current research aimed to explore the MAE for fucoidans extraction from different brown seaweeds, including Fucus vesiculosus, F. spiralis, and Laminaria saccharina. Following several solvent-extraction pre-treatment steps and MAE optimization, the algal biomasses were extracted in a ratio of 1:25 in 0.1 M HCl containing 2 M CaCl2 for 1.0 min. The results showed that L. saccharina's extract was different from the others, regarding the highest sugar content reached 0.47 mg glucose equivalent/mg extract being confirmed by monosaccharide composition analysis and the lowest fucoidan content and sulfation degree at 0.09 mg/mg extract and 0.13, respectively. Moreover, these findings were confirmed by tentative structural elucidation based on Fourier-transform infrared spectrometry which also showed a different spectrum. However, the MAE enhanced melanoidins formation in products, which was confirmed by the intense band at 1420 cm-1. Interestingly, the results of monomeric composition showed that fucoidan extract by MAE from F. vesiculosus belonged to sulfated galactofucans which are known for their potential bioactivities. Furthermore, the cytotoxic activity of the four fucoidans in concentrations ranging from 4.9 µg/mL to 2500 µg/mL was investigated and correlated with the chemical characterization showing that F. vesiculosus_MAE fucoidan was the most potent and safest. The current research revealed the chemical heterogeneity of fucoidans regarding taxonomical class and used greener extraction method of fucoidans toward the achievement of the UN sustainability goals.

Structural Characterization and In Vivo Anti-Inflammatory Activity of Fucoidan from Cystoseira crinita (Desf.) Borry

The aim of this study was to evaluate the effects of fucoidan isolated from C. crinita on histamine-induced paw inflammation in rats, and on the serum levels of TNF-α, IL-1β, IL-6, and IL-10 in rats during systemic inflammation response. The levels of TNF-α in a model of acute peritonitis in rats were also investigated. The isolated crude fucoidan was identified as a sulfated xylogalactofucan with high, medium, and low molecular weight fractions and a content of fucose of 39.74%, xylose of 20.75%, and galactose of 15.51%. Fucoidan from C. crinita showed better anti-inflammatory effects in the rat paw edema model, and this effect was present during all stages of the experiment. When compared to controls, a commercial fucoidan from F. vesiculosus, the results also displayed anti-inflammatory activity on the 60th, 90th, and 120th minute of the experiment. A significant decrease in serum levels of IL-1β in rats treated with both doses of C. crinita fucoidan was observed in comparison to controls, whereas TNF-α concentrations were reduced only in the group treated with fucoidan from C. crinita at the dose of 25 mg/kg bw. In the model of carrageenan-induced peritonitis, we observed a tendency of decrease in the levels of the pro-inflammatory cytokine TNF-α in peritoneal fluid after a single dose of C. crinita fucoidan, but this did not reach the statistical significance margin. Single doses of C. crinita fucoidan did not alter serum levels of the anti-inflammatory cytokine IL-10 in animals with lipopolysaccharide-induced systemic inflammation.

Insight into Fucoidan-Based PEGylated PLGA Nanoparticles Encapsulating Methyl Anthranilic Acid: In Vitro Evaluation and In Vivo Anti-Inflammatory Study

A potential fucoidan-based PEGylated PLGA nanoparticles (NPs) offering a proper delivery of N-methyl anthranilic acid (MA, a model of hydrophobic anti-inflammatory drug) have been developed via the formation of fucoidan aqueous coating surrounding PEGylated PLGA NPs. The optimum formulation (FuP2) composed of fucoidan:m-PEG-PLGA (1:0.5 w/w) with particle size (365 ± 20.76 nm), zeta potential (-22.30 ± 2.56 mV), % entrapment efficiency (85.45 ± 7.41), drug loading (51.36 ± 4.75 µg/mg of NPs), % initial burst (47.91 ± 5.89), and % cumulative release (102.79 ± 6.89) has been further investigated for the anti-inflammatory in vivo study. This effect of FuP2 was assessed in rats' carrageenan-induced acute inflammation model. The average weight of the paw edema was significantly lowered (p ≤ 0.05) by treatment with FuP2. Moreover, cyclooxygenase-2 and tumor necrosis factor-alpha immunostaining were decreased in FuP2 treated group compared to the other groups. The levels of prostaglandin E2, nitric oxide, and malondialdehyde were significantly reduced (p ≤ 0.05) in the FuP2-treated group. A significant reduction (p ≤ 0.05) in the expression of interleukins (IL-1β and IL-6) with an improvement of the histological findings of the paw tissues was observed in the FuP2-treated group. Thus, fucoidan-based PEGylated PLGA-MA NPs are a promising anti-inflammatory delivery system that can be applied for other similar drugs potentiating their pharmacological and pharmacokinetic properties.

Preparation of Fucoxanthin Nanoemulsion Stabilized by Natural Emulsifiers: Fucoidan, Sodium Caseinate, and Gum Arabic

This study was proposed to investigate the possibility of O/W nanoemulsion stabilization via natural emulsifiers as a delivery system for fucoxanthin. Nanoemulsions were prepared using ultrasonic treatment (150 W, amplitude 80%, 10 min) with different levels (0.5%, 1%, and 2% wt) of fucoidan, gum Arabic, and sodium caseinate as natural emulsifires and they were compared with tween 80. Then, the creaming index, stability, encapsulation efficacy, Fourier-transform infrared (FT-IR) spectroscopy, and in vitro release were evaluated. The best stability and lowest creaming index were observed at 2% wt of emulsifiers. Nanoemulsions with droplet sizes (113.27−127.50 nm) and zeta potentials (−32.27 to −58.87 mV) were prepared. The droplet size of nanoemulsions was reduced by increasing the emulsifier concentration, and the best nanoemulsion stability after 15 days of storage was in the following order: tween 80 > sodium caseinate > fucoidan > gum Arabic. The encapsulation efficacy of nanoemulsions stabilized by sodium caseinate, fucoidan, and gum Arabic were 88.51 ± 0.11%, 79.32 ± 0.09%, and 60.34 ± 0.13%, respectively. The in vitro gastrointestinal fucoxanthin release of nanoemulsion stabilized with tween 80, sodium caseinate, fucoidan, and gum Arabic were 85.14 ± 0.16%, 76.91 ± 0.34%, 71.41 ± 0.14%, and 68.98 ± 0.36%, respectively. The release of fucoxanthin from nanoemulsions followed Fickian diffusion. The FTIR also confirmed the encapsulation of fucoxanthin.

Characterization and Bioactivity of Polysaccharides Separated through a (Sequential) Biorefinery Process from Fucus spiralis Brown Macroalgae

Marine macroalgae biomass is a valuable renewable resource that can be used for the development of bioeconomy through the valorisation of valuable compounds. The aim of the current study is separate macroalgal polysaccharides with bioactive properties from brown macroalgae Fucus spiralis based on a designed biocascading biorefinery approach. Thus, we applied an integrated processing method for the separation of fucoidan and alginate, in addition to characterization through IR spectroscopy and ¹H NMR. The bioactivity potential (antioxidant activity using superoxide anion and DPPH radical scavenging analysis) of the two polysaccharides was evaluated, together with DNA binding studies performed though voltametric techniques and electronic spectroscopy titration. In terms of results, functional groups S=O (1226 cm⁻¹), N=S=O (1136 cm⁻¹) and C-O-SO₃ (1024 cm⁻¹), which are characteristic of fucoidan, were identified in the first polysaccharidic extract, whereas guluronic units (G) (1017 cm⁻¹) and mannuronic units (M) (872 and 812 cm⁻¹) confirmed the separation of alginate. The DNA binding studies of the isolated polysaccharides revealed an electrostatic and an intercalation interaction of DNA with fucoidan and alginate, respectively. Both antioxidant activity assays revealed improved antioxidant activity for both fucoidan and alginate compared to the standard α-tocopherol.

Sulfated Galactofucans: An Outstanding Class of Fucoidans with Promising Bioactivities

Fucoidans encompass versatile and heterogeneous sulfated biopolysaccharides of marine origin, specifically brown algae and marine invertebrates. Their chemistry and bioactivities have been extensively investigated in the last few decades. The reported studies revealed diverse chemical skeletons in which l-fucose is the main sugar monomer. However, other sugars, i.e., galactose, mannose, etc., have been identified to be interspersed, forming several heteropolymers, including galactofucans/fucogalactans (G-fucoidans). Particularly, sulfated galactofucans are associated with rich chemistry contributing to more promising bioactivities than fucans and other marine polysaccharides. The previous reports in the last 20 years showed that G-fucoidans derived from Undaria pinnatifida were the most studied; 21 bioactivities were investigated, especially antitumor and antiviral activities, and unique biomedical applications compared to other marine polysaccharides were demonstrated. Hence, the current article specifically reviews the biogenic sources, chemistry, and outstanding bioactivities of G-fucoidans providing the opportunity to discover novel drug candidates.

Evaluation of MxOy/fucoidan hybrid system and their application in lipase immobilization process

In this work, new M_xO_y/fucoidan hybrid systems were fabricated and applied in lipase immobilization. Magnesium (MgO) and zirconium (ZrO₂) oxides were used as M_xO_y inorganic matrices. In the first step, the proposed oxides were functionalized with fucoidan from Fucus vesiculosus (Fuc). The obtained MgO/Fuc and ZrO₂/Fuc hybrids were characterized by means of spectroscopic analyses, including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance. Additionally, thermogravimetric analysis was performed to determine the thermal stability of the hybrids. Based on the results, the mechanism of interaction between the oxide supports and fucoidan was also determined. Furthermore, the fabricated M_xO_y/fucoidan hybrid materials were used as supports for the immobilization of lipase from Aspergillus niger, and a model reaction (transformation of p-nitrophenyl palmitate to p-nitrophenol) was performed to determine the catalytic activity of the proposed biocatalytic system. In that reaction, the immobilized lipase exhibited high apparent and specific activity (145.5 U/g_catalyst and 1.58 U/mg_enzyme for lipase immobilized on MgO/Fuc; 144.0 U/g_catalyst and 2.03 U/mg_enzyme for lipase immobilized on ZrO₂/Fuc). The immobilization efficiency was also confirmed using spectroscopic analyses (FTIR and XPS) and confocal microscopy.

Considerable Production of Ulvan from Ulva lactuca with Special Emphasis on Its Antimicrobial and Anti-fouling Properties

In the current study, a significant amount of ulvan was extracted from Ulva lactuca collected from Alexandria coastline, Egypt, using a simple extraction method. According to the chemical analysis, the obtained polysaccharide content is estimated to be 36.50 g/100 g with a high sulfate content of 19.72%. Physio-chemically, the FTIR analysis confirmed the presence of sulfated groups attached to the carbohydrate backbone. The GC–MS results revealed the presence of various monosaccharides with relative abundances in the order: fucopyranose (22.09%) > L-rhamnose (18.17%) > L-fucose (17.46%) > rhamnopyranose (14.29%) > mannopyranose (8.59%) > α-D-glactopyranose (7.64%) > galactopyranose (6.14%) > β-arabinopyranose (5.62%). In addition, the SEM–EDX depicted an amorphous architecture with a majority wt% for the elements of C, O, and S. The partially purified ulvan demonstrated potent antimicrobial activity against some fish and human pathogenic microbes. The inhibition zone diameter ranged from 11 to 18 mm. On the other hand, the prepared ulvan-chitosan hydrogel significantly improved the antimicrobial activity as the inhibition zone diameter ranged from 12 to 20. Moreover, when compared to the controls, the extracted ulvan demonstrated anti-fouling properties and successfully disrupted the biofilm formed on a glass slide submerged in seawater.

The Biochemical Composition and Antioxidant Properties of Fucus vesiculosus from the Arctic Region

Fucus vesiculosus is one of the most prominent brown algae in the shallow waters of the seas of the Arctic region (Barents (BS), White (WS), Norwegian (NS), and Irminger (IS)). The aim of this study was to determine the biochemical composition of F. vesiculosus from the Arctic at different reproductive phases, and to evaluate the antioxidant properties of F. vesiculosus extracts. The amounts of monosaccharides, phlorotannins, flavonoids, and ash and the mineral composition significantly varied in the algae. A strong correlation was established between monosaccharide, phlorotannin, and flavonoid accumulation and water salinity (Pearson’s correlation coefficients r = −0.58, 0.83, and 0.44, respectively; p < 0.05). We noted a negative correlation between the antioxidant activity and the amount of the structural monosaccharides of fucoidan (r = −0.64). A positive correlation of phlorotannins and flavonoids with antioxidant power was confirmed for all samples. The ash accumulation was relatively lower in the sterile phase for the algae from the BS and WS. The correlation between the Metal Pollution Index (MPI) and the reproductive phases was medium with high fluctuation. Meanwhile, the MPI strongly correlated with the salinity and sampling site. The gradient of the MPI values across the sea was in the following ranking order: BS < WS < NS < IS. Taken together, and based on our data on the elemental contents of F. vesiculosus, we believe that this alga does not accumulate toxic doses of elements. Therefore, the Arctic F. vesiculosus could be safely used in food and drug development as a source of active biochemical compounds and as a source of dietary elements to cover the daily nutritional requirements of humans.

Marine Health-Promoting Compounds: Recent Trends for Their Characterization and Human Applications

Seaweeds represent a rich source of biologically active compounds with several applications, especially in the food, cosmetics, and medical fields. The beneficial effects of marine compounds on health have been increasingly explored, making them an excellent choice for the design of functional foods. When studying marine compounds, several aspects must be considered: extraction, identification and quantification methods, purification steps, and processes to increase their stability. Advanced green techniques have been used to extract these valuable compounds, and chromatographic methods have been developed to identify and quantify them. However, apart from the beneficial effects of seaweeds for human health, these natural sources of bioactive compounds can also accumulate undesirable toxic elements with potential health risks. Applying purification techniques of extracts from seaweeds may mitigate the amount of excessive toxic components, ensuring healthy and safer products for commercialization. Furthermore, limitations such as stability and bioavailability problems, chemical degradation reactions during storage, and sensitivity to oxidation and photo-oxidation, need to be overcome using, for example, nanoencapsulation techniques. Here we summarize recent advances in all steps of marine products identification and purification and highlight selected human applications, including food and feed applications, cosmetic, human health, and fertilizers, among others.

Extraction of Fucoidan from Turbinaria decurrens and the Synthesis of Fucoidan-Coated AgNPs for Anticoagulant Application

Brown seaweeds usually contain alginate as a major polymer. The second major sulfated polymer in brown seaweeds is fucoidan, which has huge potential in medicinal applications. In this study, the photosynthetic pigments from Turbinaria decurrens were first extracted using chloroform/methanol in the ratio of 1:1 (v/v), followed by fucoidan extraction with yields of 5.58% (crude) and 1.28% (purified fucoidan) from the dry weight of seaweed, whereas alginate was extracted with a yield of 14.7% DW of seaweed. The isolated fucoidan possessing anticoagulation property was identified and characterized as (1-3)-α-l-fucopyranosyl residues with sulfate groups primarily at the C4 position and to a lesser extent at the C2 position, whereas in the case of galactose, at the C3 and C6 positions. The AgNPs synthesized using isolated fucoidan exhibit strong anticoagulant activity and possess a good antibacterial property against Gram-negative clinical bacteria. Functional groups such as O-H, C-H, and S=O associated with sugar residues in sulfated fucoidan are involved in the synthesis of the nanoparticles with a spherical shape, size ranging from 10 to 60 nm, and showing polydispersity. From this study, we conclude that fucoidan-coated anionic AgNPs synthesized from T. decurrens have tremendous potential in drug development.

Antibacterial activities of physiologically stable, self-assembled peptide nanoparticles

In this study, we report that host defense protein-derived ten amino acid long disulfide-linked peptides self-assemble in the form of β-sheets and β-turns, and exhibit concentration-dependent self-assembly in the form of nanospheres, termed as disulfide linked nanospheres (DSNs). As expected, bare DSNs are prone to aggregation in ionic solutions and in the presence of serum proteins. To yield physiologically stable self-assembled peptide-based materials, DSNs are stabilized in the form of supramolecular assemblies using β-cyclodextrins (β-CD) and fucoidan, as delivery carriers. The inclusion complexes of DSNs with β-CD (β-CD-DSN) and electrostatic complexation of fucoidan with DSNs (FC-DSN) stabilizes the secondary structure of DSNs. Comparison of β-CD-DSNs with FC-DSNs reveals that inclusion complexes of DSNs formed in the presence of β-CD are highly stable under physiological conditions, show high cellular uptake, exhibit bacterial flocculation, and enhance antibacterial efficacies of DSNs in a range of Gram-positive and Gram-negative bacteria.

Coating of Magnetite Nanoparticles with Fucoidan to Enhance Magnetic Hyperthermia Efficiency

Magnetic nanoparticles (NP), such as magnetite, have been the subject of research for application in the biomedical field, especially in Magnetic Hyperthermia Therapy (MHT), a promising technique for cancer therapy. NP are often coated with different compounds such as natural or synthetic polymers to protect them from oxidation and enhance their colloidal electrostatic stability while maintaining their thermal efficiency. In this work, the synthesis and characterization of magnetite nanoparticles coated with fucoidan, a biopolymer with recognized biocompatibility and antitumoral activity, is reported. The potential application of NP in MHT was evaluated through the assessment of Specific Loss Power (SLP) under an electromagnetic field amplitude of 14.7 kA m⁻¹ and at 276 kHz. For fucoidan-coated NP, it was obtained SLP values of 100 and 156 W/g, corresponding to an Intrinsic Loss Power (ILP) of 1.7 and 2.6 nHm²kg⁻¹, respectively. These values are, in general, higher than the ones reported in the literature for non-coated magnetite NP or coated with other polymers. Furthermore, in vitro assays showed that fucoidan and fucoidan-coated NP are biocompatible. The particle size (between ca. 6 to 12 nm), heating efficiency, and biocompatibility of fucoidan-coated magnetite NP meet the required criteria for MHT application.

Chemical Structure and Anticoagulant Property of a Novel Sulfated Polysaccharide from the Green Alga Cladophora oligoclada

Marine macroalgae are efficient producers of sulfated polysaccharides. The algal sulfated polysaccharides possess diverse bioactivities and peculiar chemical structures, and represent a great potential source to be explored. In the present study, a heparinoid-active sulfated polysaccharide was isolated from the green alga Cladophora oligoclada. Results of chemical and spectroscopic analyses indicated that the sulfated polysaccharide was composed of →6)-β-d-Galp-(1→, β-d-Galp-(1→, →6)-α-d-Glcp-(1→ and →3)-β-d-Galp-(1→ units with sulfate esters at C-2/C-4 of →6)-β-d-Galp-(1→, C-6 of →3)-β-d-Galp-(1→ and C-3 of →6)-α-d-Glcp-(1→ units. The branches consisting of β-d-Galp-(1→ and →6)-β-d-Galp-(1→ units were located in C-3 of →6)-β-d-Galp-(1→ units. The sulfated polysaccharide exhibited potent anticoagulant activity in vitro and in vivo as evaluated by activated partial thromboplastin time (APTT), thrombin time, and the fibrinogen level. For the APTT, the signal for clotting time was more than 200 s at 100 μg/mL in vitro and at 15 mg/kg in vivo. The obvious thrombolytic activity of the sulfated polysaccharide in vitro was also found. The mechanism analysis of anticoagulant action demonstrated that the sulfated polysaccharide significantly inhibited the activities of all intrinsic coagulation factors, which were less than 1.0% at 50 μg/mL, but selectively inhibited common coagulation factors. Furthermore, the sulfated polysaccharide strongly stimulated the inhibition of thrombin by potentiating antithrombin-III (AT-III) or heparin cofactor-II, and it also largely promoted the inhibition of factor Xa mediated by AT-III. These results revealed that the sulfated polysaccharide from C. oligoclada had potential to become an anticoagulant agent for prevention and therapy of thrombotic diseases.

Ion-exchange purification and structural characterization of five sulfated fucoidans from brown algae

Fucoidans are a diverse class of sulfated polysaccharides integral to the cell wall of brown algae, and due to their various bioactivities, they are potential drugs. Standardized work with fucoidans is required for structure-function studies, but remains challenging since available fucoidan preparations are often contaminated with other algal compounds. Additionally, fucoidans are structurally diverse depending on species and season, urging the need for standardized purification protocols. Here, we use ion-exchange chromatography to purify different fucoidans and found a high structural diversity between fucoidans. Ion-exchange chromatography efficiently removes the polysaccharides alginate and laminarin and other contaminants such as proteins and phlorotannins across a broad range of fucoidans from major brown algal orders including Ectocarpales, Laminariales and Fucales. By monomer composition, linkage analysis and NMR characterization, we identified galacturonic acid, glucuronic acid and O-acetylation as new structural features of certain fucoidans and provided a novel structure of fucoidan from Durvillaea potatorum with α-1,3-linked fucose backbone and β-1,6 and β-1,3 galactose branches. This study emphasizes the use of standardized ion-exchange chromatography to obtain defined fucoidans for subsequent molecular studies.

Fucoidan induces ROS-dependent epigenetic modulation in cervical cancer HeLa cell

Fucoidan is a sulfated polysaccharide obtained from marine algae and known for various pharmacological activities. In this study, we investigated the effect of Fucoidan on cell viability, redox balance, cytoskeletal component F-actin, HDAC inhibition, autophagy, and senescence phenomenon in human cervical cancer HeLa cell line in comparison to positive control suberoylanilide hydroxamic acid by flow cytometry, fluorescence microscopy, and western blotting. Our observations revealed that Fucoidan exposure induces cytotoxicity in HeLa cells via ROS and mitochondrial superoxide generation and loss of ATP. Colorimetrical studies suggested that Fucoidan impairs the function of HDAC expression. Fucoidan treatment also contributes to the change in the granularity of cells, senescence-associated heterochromatin foci formation that leads to senescence in HeLa cells. Moreover, we visualize that Fucoidan exhibits autophagosomes formation with monodansylcadaverine, and flow cytometry analysis by acridine orange further substantiates that Fucoidan triggers autophagy in HeLa cells. Additionally, the changes in the expression of proteins p21, p16, BECN1, and HDAC1 were seen as markers of senescence, autophagy, and HDAC inhibition by FACS and immunoblotting. Molecular docking study validates Fucoidan-HDAC1 association in corroboration with the experimental data. Collectively, these mechanistic studies demonstrated that Fucoidan could be a therapeutic molecule for targeting HDACs in cervical cancer.

Antibacterial Properties of Fucoidans from the Brown Algae Fucus vesiculosus L. of the Barents Sea

Fucoidans, sulfated polysaccharides found in cell walls of brown algae, are considered as a promising antimicrobial component for various applications in medicine and the food industry. In this study, we compare the antibacterial properties of two fractions of fucoidan from the brown algae Fucus vesiculosus gathered in the littoral of the Barents Sea and sampled at different stages of purification. The crude fraction of fucoidan was isolated from algae by extraction with aqueous ethanol and sonication. The purified fraction was obtained by additional treatment of the crude fraction with a solution of calcium chloride. The structural features of both fractions were characterized in detail and their antibacterial effects against several Gram-positive and Gram-negative bacteria were compared by photometry, acridine orange staining assay, and atomic force microscopy. Fucoidan inhibited growth in all of the above microorganisms, showing a bacteriostatic effect with minimum inhibitory concentrations (MIC) in the range between 4 and 6 mg/mL, with E. coli being the most sensitive to both fractions. Changes in the chemical composition after treatment of the crude fraction with a solution of calcium chloride led to a decrease in the content of sulfates and uronic acids and diminished antibacterial activity.

Fucoidan Structure and Its Impact on Glucose Metabolism: Implications for Diabetes and Cancer Therapy

Fucoidans are complex polysaccharides derived from brown seaweeds which consist of considerable proportions of L-fucose and other monosaccharides, and sulphated ester residues. The search for novel and natural bioproduct drugs (due to toxicity issues associated with chemotherapeutics) has led to the extensive study of fucoidan due to reports of it having several bioactive characteristics. Among other fucoidan bioactivities, antidiabetic and anticancer properties have received the most research attention in the past decade. However, the elucidation of the fucoidan structure and its biological activity is still vague. In addition, research has suggested that there is a link between diabetes and cancer; however, limited data exist where dual chemotherapeutic efforts are elucidated. This review provides an overview of glucose metabolism, which is the central process involved in the progression of both diseases. We also highlight potential therapeutic targets and show the relevance of fucoidan and its derivatives as a candidate for both cancer and diabetes therapy.

Progress in Modern Marine Biomaterials Research

The growing demand for new, sophisticated, multifunctional materials has brought natural structural composites into focus, since they underwent a substantial optimization during long evolutionary selection pressure and adaptation processes. Marine biological materials are the most important sources of both inspiration for biomimetics and of raw materials for practical applications in technology and biomedicine. The use of marine natural products as multifunctional biomaterials is currently undergoing a renaissance in the modern materials science. The diversity of marine biomaterials, their forms and fields of application are highlighted in this review. We will discuss the challenges, solutions, and future directions of modern marine biomaterialogy using a thorough analysis of scientific sources over the past ten years.

Fucoidan Characterization: Determination of Purity and Physicochemical and Chemical Properties

Fucoidans are marine sulfated biopolysaccharides that have heterogenous and complicated chemical structures. Various sugar monomers, glycosidic linkages, molecular masses, branching sites, and sulfate ester pattern and content are involved within their backbones. Additionally, sources, downstream processes, and geographical and seasonal factors show potential effects on fucoidan structural characteristics. These characteristics are documented to be highly related to fucoidan potential activities. Therefore, numerous chemical qualitative and quantitative determinations and structural elucidation methods are conducted to characterize fucoidans regarding their physicochemical and chemical features. Characterization of fucoidan polymers is considered a bottleneck for further biological and industrial applications. Consequently, the obtained results may be related to different activities, which could be improved afterward by further functional modifications. The current article highlights the different spectrometric and nonspectrometric methods applied for the characterization of native fucoidans, including degree of purity, sugar monomeric composition, sulfation pattern and content, molecular mass, and glycosidic linkages.

Affinity chromatography: A review of trends and developments over the past 50 years

The field of affinity chromatography, which employs a biologically-related agent as the stationary phase, has seen significant growth since the modern era of this method began in 1968. This review examines the major developments and trends that have occurred in this technique over the past five decades. The basic principles and history of this area are first discussed. This is followed by an overview of the various supports, immobilization strategies, and types of binding agents that have been used in this field. The general types of applications and fields of use that have appeared for affinity chromatography are also considered. A survey of the literature is used to identify major trends in these topics and important areas of use for affinity chromatography in the separation, analysis, or characterization of chemicals and biochemicals.

Mechanisms of Bioactivities of Fucoidan from the Brown Seaweed Fucus vesiculosus L. of the Barents Sea

The aim of this study was to elucidate some mechanisms of radical scavenging and the anti-inflammatory, anti-hyperglycemic, and anti-coagulant bioactivities of high molecular weight fucoidan from Fucus vesiculosus in several in vitro models. Fucoidan has displayed potent 1, 1-diphenyl-2-picryl hydrazil radical scavenging and reduction power activities. It significantly inhibits the cyclooxygenase-2 (COX-2) enzyme (IC₅₀ 4.3 μg mL⁻¹) with a greater selectivity index (lg(IC₈₀ COX-2/IC₈₀COX-1), −1.55) than the synthetic non-steroidal anti-inflammatory drug indomethacin (lg(IC₈₀ COX-2/IC₈₀COX-1), −0.09). A concentration-dependent inhibition of hyaluronidase enzyme with an IC₅₀ of 2.9 μg mL⁻¹ was observed. Fucoidan attenuated the lipopolysaccharide-induced expression of mitogen-activated protein kinase p38. Our findings suggest that the inhibition of dipeptidyl peptidase-IV (DPP-IV) (IC₅₀ 1.11 μg mL⁻¹) is one of the possible mechanisms involved in the anti-hyperglycemic activity of fucoidan. At a concentration of 3.2 μg mL⁻¹, fucoidan prolongs the activated partial thromboplastin time and thrombin time by 1.5-fold and 2.5-fold compared with a control, respectively. A significant increase of prothrombin time was observed after the concentration of fucoidan was increased above 80 μg mL⁻¹. This evidenced that fucoidan may have an effect on intrinsic/common pathways and little effect on the extrinsic mechanism. This study sheds light on the multiple pathways of the bioactivities of fucoidan. As far as we know, the inhibition of hyaluronidase and DPP-IV by high molecular fucoidan was studied for the first time in this work. Our results and literature data suggest that molecular weight, sulfate content, fucose content, and polyphenols may contribute to these activities. It seems that high molecular weight fucoidan has promising therapeutic applications in different pharmacological settings. Anti-oxidant, anti-inflammatory and anti-coagulant drugs have been used for the management of complications of COVID19. Taken as a whole, fucoidan could be considered as a prospective candidate for the treatment of patients with COVID19; however, additional research in this field is required.

Study of antioxidant and antibacterial activities of depolymerized fucoidans extracted from Sargassum tenerrimum

This work was performed to compare the effect of two water-extraction methods of fucoidan from Sargassum tenerrimum on their chemical composition, antioxidant capacity and antimicrobial activity after hydrothermal depolymerization. The number of extraction steps and ethanol concentration used for extraction were different between the two methods. Extraction yield of fucoidan obtained from the first method (DFM1) and the second method (DFM2) were 3.68 and 1.09%, respectively (P < 0.05). The IC50 value of DPPH radical scavenging activity for DFM1 was 1.93 times more than DFM2. The Fe+2 ions chelating activity were 78.3% for DFM1 and 89.4% for DFM2 at 10 mg/mL concentration. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration of DFM2 were lower compared to DFM1 for Enterococcus faecalis and Escherichia coli The DFM2 was more effective to decrease the MIC value of chloramphenicol on the gram negative strains than DFM1. Both of the fucoidans showed a synergistic effect in combination with chloramphenicol to inhibit the growth of Escherichia coli Based on the results of this study, depolymerized fucoidans can also be more considered as effective antibacterial agent with synergistic potential in combination with antibiotics to decrease the prescribed doses of antibiotic drugs in humans and animals.

Fucoidans: Downstream Processes and Recent Applications

Fucoidans are multifunctional marine macromolecules that are subjected to numerous and various downstream processes during their production. These processes were considered the most important abiotic factors affecting fucoidan chemical skeletons, quality, physicochemical properties, biological properties and industrial applications. Since a universal protocol for fucoidans production has not been established yet, all the currently used processes were presented and justified. The current article complements our previous articles in the fucoidans field, provides an updated overview regarding the different downstream processes, including pre-treatment, extraction, purification and enzymatic modification processes, and shows the recent non-traditional applications of fucoidans in relation to their characters.

Size distribution and chain conformation of six different fucoidans using size-exclusion chromatography with multiple detection

Fucoidans represent an intriguing class of fucose-containing sulfated polysaccharides. The biological activities of these polysaccharides are related to their compositional and structural parameters, whereby their degree of sulfation, as well as molecular weight (MW) distribution and chain conformation play important roles. Modern NMR and mass spectrometry techniques allow elucidating details of the glycan structure, but not the structure of the whole molecules in their native state. Accordingly, the knowledge about the latter of the fucoidans is currently still limited. Contrary to traditional MW determination by SEC with column calibration, SEC with triple detection provides not only the absolute Mw, but can also give information on additional molecule characteristics. In the present study, we used this method to compare six fucoidans extracted from Fucus vesiculosus (FV), F. serratus (FS), F. evanescens (FE), Dictyosiphon foeniculaceus (DF), Laminaria digitata (LD), and Saccharina latissima (SL) concerning their molar mass (Mw, Mn, Mp, dispersity) and size (rms radius, Rh) characteristics and distribution as well as their chain conformation in solution. The tested fucoidans displayed considerable structural diversity including large differences in their MW profiles and showed to be heterogeneously composed. Fuc-FV and Fuc-SL showed the broadest MW distributions, those from Fuc-FE and Fuc-DF the narrowest ones. Most of the fucoidan fractions (except for Fuc-DF) turned out to exist as expanded flexible chains in PBS solution. The conformation data suggest branched structures with partly long side chains. The knowledge obtained by this study is useful for further fractionation and structural characterization as well as the interpretation of the bioactivity differences between the various fucoidans.

Chitosan-toluidine blue beads for purification of fucoidans

A simple and green method was developed to purify fucoidans from their crude extracts. The new method utilizes a genipin-crosslinked chitosan beads as a support matrix for toluidine blue (TB). The modification of the mostly composed of d-glucosamine polymer was performed in one-step reaction to improve its mechanical stability and affinity to fucoidans. The adsorption kinetics and isotherm were investigated, which showed a maximum loading capacity (q_max) of 137.8 mg fucoidans/g wet beads. Moreover, the modified chitosan-TB beads were applied for purification of fucoidans from Fucus vesiculosus crude extract at different pH values, pH 1.0 and pH 6.0, producing two fractions: FC_1 and FC_6, respectively. The fractions were then characterized in comparison with crude and Sigma-Aldrich® purified product by FTIR and elemental analysis. The new method produced beads with higher loading capacity and used a natural crosslinker compared to the previously-reported methods.

Therapies from Fucoidan: New Developments

Since our last review in 2015, the study and use of fucoidan has extended in several research areas. Clinical use of fucoidan for the treatment of renal disease has become available and human safety studies have been undertaken on radiolabeled fucoidan for the purpose of imaging thrombi. Fucoidan has been incorporated into an increasing number of commercially available supplements and topical treatments. In addition, new measuring techniques are now available to assess the biologically relevant uptake of fucoidans and to assist in production. Microbiome modulation and anti-pathogenic effects are increasingly promising applications for fucoidans, due to the need for alternative approaches to antibiotic use in the food chain. This review outlines promising new developments in fucoidan research, including potential future therapeutic use.

Isolation and structural characterization of sulfated polysaccharide from Spirulina platensis and its bioactive potential: In vitro antioxidant, antibacterial activity and Zebrafish growth and reproductive performance

In this study, the sulfated polysaccharide (SPs) was isolated from Spirulina platensis. The isolated SPs contains carbohydrate, sulfate, protein and uronic acid at 38.7 ± 0.30%, 21.3 ± 0.87%, 7.1 ± 0.15% and 7.9 ± 0.4% respectively. The elemental analysis confirmed the presence of carbon (18.01 ± 0.10%), hydrogen (1.83 ± 0.02%) and nitrogen (3.43 ± 0.01%). The monosaccharide composition and molecular weight of SPs were analyzed by high-performance liquid chromatography and size exclusion chromatography respectively. The monosaccharide composition analysis showed the existence of glucose, rhamnose, xylose, fucose, mannose, galactose and the molecular weight of SPs was 1016 kDa. Further, the characterization of SPs was done by UV-visible spectroscopy, X-ray diffraction, FT-IR, ¹H NMR and ¹³C NMR analysis. The obtained SPs exhibited potent antioxidant activity in DPPH (76.45 ± 0.49%), reducing power (absorbance: 1.3 ± 0.02), hydrogen peroxide scavenging (66.3 ± 1.16%), hydroxyl scavenging (68.6 ± 3.2%), nitric oxide (81.36 ± 1.85%) and total antioxidant (absorbance:1.66 ± 0.02) activities at 5 mg/ml. In addition, SPs revealed the highest antibacterial efficacy against the pathogenic bacteria Vibrio vulnificus in disc diffusion, agar bioassay and protein leakage assays at 100 μg/ml. Furthermore, the supplementation of 2% SPs through a feed to the Danio rerio fish enhances the growth and reproductive performances. This finding confirmed that the isolated SPs from S. platensis possess pharmaceutical as well as nutritional properties.

The fucoidan A3 from the seaweed Ascophyllum nodosum enhances RCT-related genes expression in hyperlipidemic C57BL/6J mice

Reverse cholesterol transport (RCT) has been demonstrated to reduce hyperlipidemia, and fucoidans are found to possess hypolipidemic effect. This study was designed to investigate the lipid-lowering effect of the fucoidan from the brown seaweed A. nodosum and whether it improves RCT-related genes expression in C57 BL/6J mice. Our results indicated that fucoidan A3 (100 mg/kg/day) intervention significantly reduced plasma total cholesterol (~23.2%), triglyceride (~48.7%) and fat pad index. This fucoidan significantly increased the mRNA expression of low-density lipoprotein receptor (LDLR), scavenger receptor B type 1 (SR-B1), cholesterol 7 alpha-hydroxylase A1 (CYP7A1), liver X receptor (LXR) β, ATP-binding cassette transporter (ABC) A1 and sterol regulatory element-binding protein (SREBP) 1c, and decreased the expression of peroxisome proliferator-activated receptor (PPAR) γ, however, it had no effect on the expression of proprotein convertase subtilisin/kexin type 9, PPARα, LXRα, SREBP-2, ABCG1, ABCG8 and Niemann-Pick C1-like 1. These results demonstrated that this fucoidan improved lipid transfer from plasma to the liver by activating SR-B1 and LDLR, and up-regulated lipid metabolism by activating LXRβ, ABCA1 and CYP7A1. In conclusion, this fucoidan lowers lipid by enhancing RCT-related genes expression, and it can be explored as a potential candidate for prevention or treatment of lipid disorders.

Phycochemical Constituents and Biological Activities of Fucus spp

Seaweeds are known to be a good supply of key nutrients including carbohydrates, protein, minerals, polyunsaturated lipids, as well as several other health-promoting compounds capable of acting on a wide spectrum of disorders and/or diseases. While these marine macroalgae are deeply rooted in the East Asian culture and dietary habits, their major application in Western countries has been in the phycocolloid industry. This scenario has however been gradually changing, since seaweed consumption is becoming more common worldwide. Among the numerous edible seaweeds, members of the genus Fucus have a high nutritional value and are considered good sources of dietary fibers and minerals, especially iodine. Additionally, their wealth of bioactive compounds such as fucoidan, phlorotannins, fucoxanthin and others make them strong candidates for multiple therapeutic applications (e.g., antioxidant, anti-inflammatory, anti-tumor, anti-obesity, anti-coagulant, anti-diabetes and others). This review presents an overview of the nutritional and phytochemical composition of Fucus spp., and their claimed biological activities, as well as the beneficial effects associated to their consumption. Furthermore, the use of Fucus seaweeds and/or their components as functional ingredients for formulation of novel and enhanced foods is also discussed.

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

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

Doxorubicin-fucoidan-gold nanoparticles composite for dual-chemo-photothermal treatment on eye tumors

The current research demonstrates the feasible biomedical application of AuNPs coated with doxorubicin (Dox)-loaded fucoidan (Fu) for dual-chemotherapy and photothermal treatment (PTT) on eye tumors in vitro and in vivo. Marine-derived Fu was used as a capping agent to achieve high photostability for AuNPs, and Dox as a FDA-approved anti-cancer drug was added to induce chemotherapy. The synthesized Dox-Fu@AuNPs exhibited high cytotoxicity on the tumor cells and strong light absorption for temperature increase in vitro. After intratumoral injection of Dox-Fu@AuNPs in the rabbit eye tumors, PTT-assisted Dox-Fu@AuNPs entailed the complete removal of the eye tumors without recurrence for 14 days after the treatment. Photoacoustic image contrast from the tumor regions was enhanced due to selective light absorption by the administered Dox-Fu@AuNPs. Therefore, the proposed Dox-Fu@AuNPs can be a potential nano-theranostic material for treating and diagnosing the eye tumors.

Application of phototrophic biofilms: from fundamentals to processes

Biotechnological production of valuables by microorganisms is commonly achieved by cultivating the cells as suspended solids in an appropriate liquid medium. However, the main portion of these organisms features a surface-attached growth in their native habitats. The utilization of such biofilms shows significant challenges, e.g. concerning control of pH, nutrient supply, and heat/mass transfer. But the use of biofilms might also enable novel and innovative production processes addressing robustness and strength of the applied biocatalyst, for example if variable conditions might occur in the process or a feedstock (substrate) is changed in its composition. Besides the robustness of a biofilm, the high density of the immobilized biocatalyst facilitates a simple separation of the catalyst and the extracellular product, whereas intracellular target compounds occur in a concentrated form; thus, expenses for downstream processing can be drastically reduced. While phototrophic organisms feature a fabulous spectrum of metabolites ranging from biofuels to biologically active compounds, the low cell density of phototrophic suspension cultures is still limiting their application for production processes. The review is focusing on pro- and eukaryotic microalgae featuring the production of valuable compounds and highlights requirements for their cultivation as phototrophic biofilms, i.e. setup as well as operation of biofilm reactors, and modeling of phototrophic growth.

A review about brown algal cell walls and fucose-containing sulfated polysaccharides: Cell wall context, biomedical properties and key research challenges

Studies on brown algal cell walls have entered a new phase with the concomitant discovery of novel polysaccharides present in cell walls and the establishment of a comprehensive generic model for cell wall architecture. Brown algal cell walls are composites of structurally complex polysaccharides. In this review we discuss the most recent progress in the structural composition of brown algal cell walls, emphasizing the significance of extraction and screening techniques, and the biological activities of the corresponding polysaccharides, with a specific focus on the fucose-containing sulfated polysaccharides. They include valuable marine molecules that exert a broad range of pharmacological properties such as antioxidant and anti-inflammatory activities, functions in the regulation of immune responses and of haemostasis, anti-infectious and anticancer actions. We identify the key remaining challenges in this research field.

Fucoidan from Fucus vesiculosus suppresses hepatitis B virus replication by enhancing extracellular signal-regulated Kinase activation

BACKGROUND

Hepatitis B virus (HBV) infection is a serious public health problem leading to cirrhosis and hepatocellular carcinoma. As the clinical utility of current therapies is limited, the development of new therapeutic approaches for the prevention and treatment of HBV infection is imperative. Fucoidan is a natural sulfated polysaccharide that extracted from different species of brown seaweed, which was reported to exhibit various bioactivities. However, it remains unclear whether fucoidan influences HBV replication or not.

METHODS

The HBV-infected mouse model was established by hydrodynamic injection of HBV replicative plasmid, and the mice were treated with saline or fucoidan respectively. Besides, we also tested the inhibitory effect of fucoidan against HBV infection in HBV-transfected cell lines.

RESULTS

The result showed that fucoidan from Fucus vesiculosus decreased serum HBV DNA, HBsAg and HBeAg levels and hepatic HBcAg expression in HBV-infected mice. Moreover, fucoidan treatment also suppressed intracellular HBcAg expression and the secretion of the HBV DNA as well as HBsAg and HBeAg in HBV-expressing cells. Furthermore, we proved that the inhibitory activity by fucoidan was due to the activation of the extracellular signal-regulated kinase (ERK) pathway and the subsequent production of type I interferon. Using specific inhibitor of ERK pathway abrogated the fucoidan-mediated inhibition of HBV replication.

CONCLUSION

This study highlights that fucoidan might be served as an alternative therapeutic approach for the treatment of HBV infection.

The Sea as a Rich Source of Structurally Unique Glycosaminoglycans and Mimetics

Glycosaminoglycans (GAGs) are sulfated glycans capable of regulating various biological and medical functions. Heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate and hyaluronan are the principal classes of GAGs found in animals. Although GAGs are all composed of disaccharide repeating building blocks, the sulfation patterns and the composing alternating monosaccharides vary among classes. Interestingly, GAGs from marine organisms can present structures clearly distinct from terrestrial animals even considering the same class of GAG. The holothurian fucosylated chondroitin sulfate, the dermatan sulfates with distinct sulfation patterns extracted from ascidian species, the sulfated glucuronic acid-containing heparan sulfate isolated from the gastropode Nodipecten nodosum, and the hybrid heparin/heparan sulfate molecule obtained from the shrimp Litopenaeus vannamei are some typical examples. Besides being a rich source of structurally unique GAGs, the sea is also a wealthy environment of GAG-resembling sulfated glycans. Examples of these mimetics are the sulfated fucans and sulfated galactans found in brown, red and green algae, sea urchins and sea cucumbers. For adequate visualization, representations of all discussed molecules are given in both Haworth projections and 3D models.