Enzyme-Assisted Fucoidan Extraction from Brown Macroalgae Fucus distichus subsp. evanescens and Saccharina latissima

Algal carbohydrates: Sources, biosynthetic pathway, production, and applications

Algae play a significant role in the global carbon cycle by utilizing photosynthesis to efficiently convert solar energy and atmospheric carbon dioxide into various chemical compounds, notably carbohydrates, pigments, lipids, and released oxygen, making them a unique sustainable cellular factory. Algae mostly consist of carbohydrates, which include a broad variety of structures that contribute to their distinct physical and chemical properties such as degree of polymerization, side chain, branching, degree of sulfation, hydrogen bond etc., these features play a crucial role in regulating many biological activity, nutritional and pharmaceutical properties. Algal carbohydrates have not received enough attention in spite of their distinctive structural traits linked to certain biological and physicochemical properties. Nevertheless, it is anticipated that there will be a significant increase in the near future due to increasing demand, sustainable source, biofuel generation and their bioactivity. This is facilitated by the abundance of easily accessible information on the structural data and distinctive characteristics of these biopolymers. This review delves into the different types of saccharides such as agar, alginate, fucoidan, carrageenan, ulvan, EPS and glucans synthesized by various macroalgal and microalgal systems, which include intracellular, extracellular and cell wall saccharides. Their structure, biosynthetic pathway, sources, production strategies and their applications in various field such as nutraceuticals, pharmaceuticals, biomedicine, food and feed, cosmetics, and bioenergy are also elaborately discussed. Algal polysaccharide has huge a scope for exploitation in future due to their application in food and pharmaceutical industry and it can become a huge source of capital and income.

Structural characterization and immunomodulating assessment of ultra-purified water extracted fucoidans from Saccharina latissima, Alaria esculenta and Laminaria hyperborea

Fucoidans, a group of high molecular weight polysaccharides derived mainly from brown algae, are characterized by their high fucose content, degree of sulfation (DS), and intra- and interspecific structural variation. Fucoidans are increasingly recognized due to various reported bioactivities, potentially beneficial for human health. To unlock their potential use within biomedical applications, a better understanding of their structure-functional relationship is needed. To achieve this, systematic bioactivity studies based on well-defined, pure fucoidans, and the establishment of standardized, satisfactory purification protocols are required. We performed a comprehensive compositional and structural characterization of crude and ultra-purified fucoidans from three kelps: Saccharina latissima (SL), Alaria esculenta (AE) and Laminaria hyperborea (LH). Further, the complement-inhibiting activity of the purified fucoidans was assessed in a human whole blood model. The purification process led to fucoidans with higher DS and fucose and lower concentrations of other monosaccharides. Fucoidans from SL and LH resembles homofucans, while AE is a heterofucan rich in galactose with comparably lower DS. Fucoidans from SL and LH showed complement-inhibiting activity in blood and blood plasma, while no inhibition was observed for AE under the same conditions. The results emphasize the importance of high DS and possibly fucose content for fucoidans' bioactive properties.

Marine-Derived Fucose-Containing Carbohydrates: Review of Sources, Structure, and Beneficial Effects on Gastrointestinal Health

Fucose, fucose-containing oligosaccharides, and fucose-containing polysaccharides have been widely applied in the fields of food and medicine, including applications in Helicobacter pylori eradication and renal function protection. Fucose-containing carbohydrates (FCCs) derived from marine organisms such as seaweed, invertebrates, microalgae, fungi, and bacteria have garnered growing attention due to their diverse bioactivities and potential therapeutic applications. Marine-derived FCCs characterized by high fucose residue content and extensive sulfate substitution, including fucoidan, fucosylated chondroitin sulfate, and fucose-rich microbial exopolysaccharides, have demonstrated significant potential in promoting gastrointestinal health. This review describes the unique structural features of FCCs and summarizes their health benefits, including regulation of gut microbiota, modulation of microbial metabolism, anti-adhesion activities against H. pylori and gut pathogens, protection against inflammatory injuries, and anti-tumor activities. Additionally, this review discusses the structural characteristics that influence the functional properties and the limitations related to the activity research and preparation processes of FCCs, providing a balanced perspective on the application potential and challenges of FCCs with specific structures for the regulation of gastrointestinal health and diseases.

Candidate genes involved in biosynthesis and degradation of the main extracellular matrix polysaccharides of brown algae and their probable evolutionary history

BACKGROUND

Brown algae belong to the Stramenopiles phylum and are phylogenetically distant from plants and other multicellular organisms. This independent evolutionary history has shaped brown algae with numerous metabolic characteristics specific to this group, including the synthesis of peculiar polysaccharides contained in their extracellular matrix (ECM). Alginates and fucose-containing sulphated polysaccharides (FCSPs), the latter including fucans, are the main components of ECMs. However, the metabolic pathways of these polysaccharides remain poorly described due to a lack of genomic data.

RESULTS

An extensive genomic dataset has been recently released for brown algae and their close sister species, for which we previously performed an expert annotation of key genes involved in ECM-carbohydrate metabolisms. Here we provide a deeper analysis of this set of genes using comparative genomics, phylogenetics analyses, and protein modelling. Two key gene families involved in both the synthesis and degradation of alginate were suggested to have been acquired by the common ancestor of brown algae and their closest sister species Schizocladia ischiensis. Our analysis indicates that this assumption can be extended to additional metabolic steps, and thus to the whole alginate metabolic pathway. The pathway for the biosynthesis of fucans still remains biochemically unresolved and we also investigate putative fucosyltransferase genes that may harbour a fucan synthase activity in brown algae.

CONCLUSIONS

Our analysis is the first extensive survey of carbohydrate-related enzymes in brown algae, and provides a valuable resource for future research into the glycome and ECM of brown algae. The expansion of specific families related to alginate metabolism may have represented an important prerequisite for the evolution of developmental complexity in brown algae. Our analysis questions the possible occurrence of FCSPs outside brown algae, notably within their closest sister taxon and in other Stramenopiles such as diatoms. Filling this knowledge gap in the future will help determine the origin and evolutionary history of fucan synthesis in eukaryotes.

Optimization and characterization of brown seaweed alginate for antioxidant, anticancer, antimicrobial, and antiviral properties

Alginate is a natural polysaccharide obtained from brown seaweeds and having advantageous health usefulness, was employed extensively in nutraceutical sectors and the pharmaceutical industry. This research was devoted for optimization of alginate extraction from different brown seaweeds. A Box-Behnken Design (BBD) was used for the optimization of alginate extraction from Padina pavonica by analyzing the influence of temperature (30, 40, and 50 °C), time (60, 120, and 180 min), and alkaline concentration (1 %, 2 %, and 3 %) on extraction yield and uronic acid content. The optimal conditions recorded to maximize the alginate yield and its uronic content were an alkali concentration of 2.5 % and a temperature of 39.95 °C for 102.5 min. The optimized parameters achieved from BBD were used to compare alginate extraction from P. pavonica, Sargassum cinereum, Turbinaria turbinata, and Dictyota dichotoma. FTIR, 1H NMR, and HPLC were used to characterize the extracted alginate. The bioactivity of alginate against free radicals, breast cancer cells (MCF-7), some pathogenic microbes, and SARS-CoV-2 viruses was tested. Under the optimized conditions, alginate was extracted from P. pavonica at a rate of 21.13 ± 2.47 % DW, S. cinereum at 24.08 ± 0.33 % DW g/L, T. turbinata at 17.47 ± 0.26 % DW, and D. dichotoma at a rate of 19.57 ± 3.60 % DW. The alginate extracted from D. dichotoma showed the highest antioxidant, anticancer, and antiviral activity.

A comprehensive review to assess the potential, health benefits and complications of fucoidan for developing as functional ingredient and nutraceutical

Polysaccharides from seaweeds or macroalgae are garnering significant interest from pharmaceutical and food industries due to their bioactivities and promising therapeutic effects. Among the diverse agal polysaccharides, fucoidan is a well-documented and stands out as a well-researched sulphated heteropolysaccharide found in brown seaweeds. It primarily consists of l-fucose and sulfate ester groups, along with other monosaccharides like xylose, mannose, uronic acid, rhamnose, arabinose, and galactose. Recent scientific investigations have unveiled the formidable inhibitory prowess of fucoidan against SARS-CoV-2, offering a promising avenue for therapeutic intervention in our current landscape. Moreover, fucoidan has demonstrated remarkable abilities in safeguarding the gastrointestinal tract, regulating angiogenesis, mitigating metabolic syndrome, and fortifying bone health. Despite the abundance of studies underscoring fucoidan's potential as a vital component sourced from nature, its exploitation remains constrained by inherent limitations. Thus, the primary objective of this article is to furnish a comprehensive discourse on the structural attributes, health-enhancing properties, safety parameters, and potential toxicity associated with fucoidan. Furthermore, the discourse extends to elucidating the practical applications and developmental prospects of fucoidan as a cornerstone in the realm of functional foods and nutraceuticals.

Application of MALDI-MS for characterization of fucoidan hydrolysates and screening of endo-fucoidanase activity

Brown macroalgae synthesize large amounts of fucoidans, sulfated fucose-containing polysaccharides, in the ocean. Fucoidans are of importance for their recently discovered contribution to marine carbon dioxide sequestration and due to their potential applications in biotechnology and biomedicine. However, fucoidans have high intra- and intermolecular diversity that challenges assignment of structure to biological function and the development of applications. Fucoidan-active enzymes may be used to simplify this diversity by producing defined oligosaccharides more applicable for structural refinement, characterization, and structure to function assignment for example via bioassays. In this study, we combined MALDI mass spectrometry with biocatalysis to show that the endo-fucoidanases P5AFcnA and Wv323 can produce defined oligosaccharide structures directly from unrefined macroalgal biomass. P5AFcnA released oligosaccharides from seven commercial fucoidan extracts in addition to unrefined biomass of three macroalgae species indicating a broadly applicable approach reproducible across 10 species. Both MALDI-TOF/TOF and AP-MALDI-Orbitrap systems were used, demonstrating that the approach is not instrument-specific and exploiting their combined high-throughput and high-resolution capabilities. Overall, the combination of MALDI-MS and endo-fucoidanase assays offers high-throughput evaluation of fucoidan samples and also enables extraction of defined oligosaccharides of known structure from unrefined seaweed biomass.

Advance in Hippophae rhamnoides polysaccharides: Extraction, structural characteristics, pharmacological activity, structure-activity relationship and application

Hippophae rhamnoides (Sea buckthorn) is an excellent medicinal and edible plant owing to its high nutritional and health-promoting properties. As an important bioactive component, H. rhamnoides polysaccharides (HRPs) have aroused wide attention due to their various pharmacological activities, including hepatoprotective, immuno-modulatory, anti-inflammatory, anti-oxidant, anti-tumor, hypoglycemic, anti-obesity, and so on. Nevertheless, the development and utilization of HRP-derived functional food and medicines are constrained to a lack of comprehensive understanding of the structure-activity relationship, application, and safety of HRPs. This review systematically summarizes the advancements on the extraction, purification, structural characteristics, pharmacological activities and mechanisms of HRPs. The structure-activity relationship, safety evaluation, application, as well as the shortcomings of current research and promising prospects are also highlighted. This article aims to offer a comprehensive understanding of HRPs and lay a groundwork for future research and utilization of HRPs as multifunctional biomaterials and therapeutic agents.

Sequential and enzyme-assisted extraction of algal bioproducts from Ecklonia maxima

Brown algae are gaining recognition as sources of bio-compounds with diverse properties and potential applications in the food, nutraceutical, and pharmaceutical industries. Compounds such as polyphenols, alginates and fucoidan possess multiple bioactivities, including antidiabetic, antioxidant, anticancer, anti-inflammatory, and antibacterial properties. Conventional extraction methods provide low yields, posing challenges for the industrial applications of biocompounds. However, innovations are rapidly emerging to address these challenges, and one such approach is enzyme-assisted extraction. Furthermore, extracting single compounds undervalues algal biomass as valuable compounds may remain in the waste. Therefore, the aim of our study was to develop a framework for the sequential and enzyme-assisted extraction of various bio-compounds using the same biomass in a biorefinery process. The Ecklonia maxima algal biomass was defatted, and polyphenols were extracted using solid-liquid extraction with aqueous ethanol. The remaining residue was treated with an enzyme combination (Cellic® Ctec 2 and Viscozyme L) to liberate carbohydrates into solution, where an alginate and fucoidan fraction were isolated. A second alginate fraction was harvested from the residue. The phenolic fraction yielded about 11% (dry weight of extract/dry weight of seaweed biomass), the alginate fraction 35% and the fucoidan fraction 18%. These were analysed using a variety of biochemical methods. Structural analyses, including FTIR, NMR and TGA, were performed to confirm the integrity of these compounds. This study demonstrated that a sequential extraction method for various algal bioproducts is possible, which can pave the way for a biorefinery approach. Furthermore, our study primarily employed environmentally and eco-friendly extraction technologies promoting an environmentally sustainable industrial approach. This approach enhances the feasibility and flexibility of biorefinery operations, contributing to the development of a circular bio-economy.

Understanding Macroalgae: A Comprehensive Exploration of Nutraceutical, Pharmaceutical, and Omics Dimensions

Driven by a surge in global interest in natural products, macroalgae or seaweed, has emerged as a prime source for nutraceuticals and pharmaceutical applications. Characterized by remarkable genetic diversity and a crucial role in marine ecosystems, these organisms offer not only substantial nutritional value in proteins, fibers, vitamins, and minerals, but also a diverse array of bioactive molecules with promising pharmaceutical properties. Furthermore, macroalgae produce approximately 80% of the oxygen in the atmosphere, highlighting their ecological significance. The unique combination of nutritional and bioactive attributes positions macroalgae as an ideal resource for food and medicine in various regions worldwide. This comprehensive review consolidates the latest advancements in the field, elucidating the potential applications of macroalgae in developing nutraceuticals and therapeutics. The review emphasizes the pivotal role of omics approaches in deepening our understanding of macroalgae's physiological and molecular characteristics. By highlighting the importance of omics, this review also advocates for continued exploration and utilization of these extraordinary marine organisms in diverse domains, including drug discovery, functional foods, and other industrial applications. The multifaceted potential of macroalgae warrants further research and development to unlock their full benefits and contribute to advancing global health and sustainable industries.

Polysaccharide extracted from cultivated Sanghuangporous vaninii spores using three-phase partitioning with enzyme/ultrasound pretreatment: Physicochemical characteristics and its biological activity in vitro

Sanghuangporous vaninii, as a valuable dietary supplement and medicinal ingredient, contains abundant bioactive polysaccharides that have health-promoting effects. In the present study, four polysaccharides (SVSPs-C, SVSPs-E, SVSPs-U, and SVSPs-E/U) were extracted for the first time from S. vaninii spores by three-phase partitioning (TPP), enzyme pretreatment before TPP (E-TPP), ultrasonic pretreatment before TPP (U-TPP), and enzyme pretreatment followed by ultrasonic before TPP (E/U-TPP) methods, respectively. Their physicochemical characteristics and in vitro pharmacological functions were determined and compared. Results showed that four TPP-based extraction methods had remarkable impacts on the extraction yield, chemical properties, monosaccharide compositions, and molecular weights (Mw) of SVSPs. Specifically, SVSPs-E/U obtained by E/U-TPP showed the highest extraction yield (25.40 %), carbohydrate content (88.50 %), and the lowest protein content (0.86 %). The four SVSPs had high-Mw (183.8-329.1 kDa) and low-Mw (23.0-156.4 kDa) fractions and mainly consisted of galactose, glucose, and mannose with different contents. In vitro bioactivities assays indicated that SVSPs-E/U possessed stronger antioxidant, hypoglycemic, hypouricemic, immunostimulatory, and antitumor activities than those of SVSPs-C, SVSPs-E, and SVSPs-U. Therefore, our results provide an efficient and promising extraction technique for bioactive polysaccharides from S. vaninii spores, as well as SVSPs had the potential to be applied in functional food, pharmaceutical, and cosmetics fields.

In vitro and in vivo immuno-enhancing effect of fucoidan isolated from non-edible brown seaweed Sargassum thunbergii

Fucoidan has been reported to have various biological activities, such as antioxidant, antitumor and anticoagulant, with various health benefits. However, few studies have been conducted to extract fucoidan from Sargassum thunbergii in terms of its immuno-enhancing activities. This aim of this study was to investigate the immuno-enhancing effect of fucoidan (S3) isolated from Sargassum thunbergii through water extraction and ethanol precipitation in RAW 264.7 macrophages and zebrafish. The results showed that S3 contained a relatively high content of fucose and sulfated polysaccharide. Fourier-transform infrared spectroscopy (FTIR) results show that the characteristic peaks at 845 cm-1 and 1220-1270 cm-1 indicate that S3 contains sulfate groups. In vitro, S3 effectively enhanced nitric oxide (NO) production and phagocytic activity. In addition, the results of the study demonstrated that the secretion of tumor necrosis factor-α, interleukin (IL)-6, IL-1β, and IL-10 was upregulated by nuclear factor kappa B (NF-κB) signaling pathway in a dose-dependent manner. In vivo, S3 activates zebrafish immune responses by promoting secretion of NO and activating the NF-κB pathway. Overall, these results suggest that S3 could be used as a functional ingredient added to nutritional supplements and functional foods.

Biocosmetics Made with Saccharina latissima Fractions from Sustainable Treatment: Physicochemical and Thermorheological Features

This work deals with the formulation of natural cosmetics enriched with antioxidant fractions from the ultrasound treatment (US) of the brown seaweed Saccharina latissima. The challenge was the development of a cosmetic matrix without jeopardizing the thermorheological features of the creams, adding microparticles containing the antioxidant fractions using two different carriers, mannitol and alginate. The fundamental chemical characteristics of seaweed and the extracts obtained via sonication, as well as the antioxidant properties of the latter, were analyzed. The highest TEAC (Trolox equivalent antioxidant capacity) value was identified for the extracts subjected to the longest processing time using ultrasound-assisted extraction (240 min). A similar yield of microparticle formulation (around 60%) and load capacity (about 85%) were identified with mannitol and alginate as carriers. Color testing of the creams exhibited small total color differences. The rheological results indicated that the testing temperature, from 5 to 45 °C, notably influenced the apparent viscosity of the matrices. All creams were adequately fitted with the two parameters of the Ostwald-de Waele model, with the flow consistency index following an Arrhenius dependency with the testing temperature. Neither hysteresis nor water syneresis was observed in the proposed cosmetics during 6 months of cold storage at 4-6 °C.

Structural and functional characterization of the novel endo-α(1,4)-fucoidanase Mef1 from the marine bacterium Muricauda eckloniae

Fucoidanases (EC 3.2.1.-) catalyze the hydrolysis of glycosidic bonds between fucose residues in fucoidans. Fucoidans are a compositionally and structurally diverse class of fucose-containing sulfated polysaccharides that are primarily found in brown seaweeds. Here, the structural characterization of a novel endo-α(1,4)-fucoidanase, Mef1, from the marine bacterium Muricauda eckloniae is presented, showing sequence similarity to members of glycoside hydrolase family 107. Using carbohydrate polyacrylamide gel electrophoresis and nuclear magnetic resonance analyses, it is shown that the fucoidanase Mef1 catalyzes the cleavage of α(1,4)-linkages between fucose residues sulfated on C2 in the structure [-3)-α-L-Fucp2S-(1,4)-α-L-Fucp2S-(1-]n in fucoidan from Fucus evanescens. Kinetic analysis of Mef1 activity by Fourier transform infrared spectroscopy revealed that the specific Mef1 fucoidanase activity (Uf) on F. evanescens fucoidan was 0.1 × 10-3 Uf µM-1. By crystal structure determination of Mef1 at 1.8 Å resolution, a single-domain organization comprising a (β/α)8-barrel domain was determined. The active site was in an extended, positively charged groove that is likely to be designed to accommodate the binding of the negatively charged, sulfated fucoidan substrate. The active site of Mef1 comprises the amino acids His270 and Asp187, providing acid/base and nucleophile groups, respectively, for the hydrolysis of glycosidic bonds in the fucoidan backbone. Electron densities were identified for two possible Ca2+ ions in the enzyme, one of which is partially exposed to the active-site groove, while the other is very tightly coordinated. A water wire was discovered leading from the exterior of the Mef1 enzyme into the active site, passing the tightly coordinated Ca2+ site.

Structural Characterization and Cytotoxic Activity Evaluation of Ulvan Polysaccharides Extracted from the Green Algae Ulva papenfussii

Ulvan, a sulfated heteropolysaccharide with structural and functional properties of interest for various uses, was extracted from the green seaweed Ulva papenfussii. U. papenfussii is an unexplored Ulva species found in the South China Sea along the central coast of Vietnam. Based on dry weight, the ulvan yield was ~15% (w/w) and the ulvan had a sulfate content of 13.4 wt%. The compositional constitution encompassed L-Rhamnose (Rhap), D-Xylose (Xylp), D-Glucuronic acid (GlcAp), L-Iduronic acid (IdoAp), D-Galactose (Galp), and D-Glucose (Glcp) with a molar ratio of 1:0.19:0.35:0.52:0.05:0.11, respectively. The structure of ulvan was determined using High-Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FT-IR), and Nuclear Magnetic Resonance spectroscopy (NMR) methods. The results showed that the extracted ulvan comprised a mixture of two different structural forms, namely ("A3s") with the repeating disaccharide [→4)-β-D-GlcAp-(1→4)-α-L-Rhap 3S-(1→]n, and ("B3s") with the repeating disaccharide [→4)-α-L-IdoAp-(1→4)-α-L-Rhap 3S(1→]n. The relative abundance of A3s, and B3s was 1:1.5, respectively. The potential anticarcinogenic attributes of ulvan were evaluated against a trilogy of human cancer cell lineages. Concomitantly, Quantitative Structure-Activity Relationship (QSAR) modeling was also conducted to predict potential adverse reactions stemming from pharmacological interactions. The ulvan showed significant antitumor growth activity against hepatocellular carcinoma (IC50 ≈ 90 µg/mL), human breast cancer cells (IC50 ≈ 85 µg/mL), and cervical cancer cells (IC50 ≈ 67 µg/mL). The QSAR models demonstrated acceptable predictive power, and seven toxicity indications confirmed the safety of ulvan, warranting its candidacy for further in vivo testing and applications as a biologically active pharmaceutical source for human disease treatment.

Chemical Composition, Antioxidant, and Antitumor Activity of Fucoidan from the Brown Alga Dictyota dichotoma

Brown macroalgae are a rich source of fucoidans with many pharmacological uses. This research aimed to isolate and characterize fucoidan from Dictyota dichotoma var. dichotoma (Hudson) J.V. Lamouroux and evaluate in vitro its antioxidant and antitumor potential. The fucoidan yield was 0.057 g/g algal dry wt with a molecular weight of about 48.6 kDa. In terms of fucoidan composition, the sulfate, uronic acid, and protein contents were 83.3 ± 5.20 mg/g fucoidan, 22.5 ± 0.80 mg/g fucoidan, and 26.1 ± 1.70 mg/g fucoidan, respectively. Fucose was the primary sugar component, as were glucose, galactose, mannose, xylose, and glucuronic acid. Fucoidan exhibited strong antioxidant potential that increased by more than 3 times with the increase in concentration from 0.1 to 5.0 mg/mL. Moreover, different concentrations of fucoidan (0.05-1 mg/mL) showed their ability to decrease the viability of Ehrlich ascites carcinoma cells in a time-dependent manner. These findings provided a fast method to obtain an appreciable amount of natural fucoidan with established structural characteristics as a promising compound with pronounced antioxidant and anticancer activity.

Enzyme-Assisted Extraction of Ulvan from the Green Macroalgae Ulva fenestrata

Ulvan is a sulfated polysaccharide extracted from green macroalgae with unique structural and compositional properties. Due to its biocompatibility, biodegradability, and film-forming properties, as well as high stability, ulvan has shown promising potential as an ingredient of biopolymer films such as sustainable and readily biodegradable biomaterials that could replace petroleum-based plastics in diverse applications such as packaging. This work investigates the potential of Ulva fenestrata as a source of ulvan. Enzyme-assisted extraction with commercial cellulases (Viscozyme L and Cellulysin) and proteases (Neutrase 0.8L and Flavourzyme) was used for cell wall disruption, and the effect of the extraction time (3, 6, 17, and 20 h) on the ulvan yield and its main characteristics (molecular weight, functional groups, purity, and antioxidant capacity) were investigated. Furthermore, a combined process based on enzymatic and ultrasound extraction was performed. Results showed that higher extraction times led to higher ulvan yields, reaching a maximum of 14.1% dw with Cellulysin after 20 h. The combination of enzymatic and ultrasound-assisted extraction resulted in the highest ulvan extraction (17.9% dw). The relatively high protein content in U. fenestrata (19.8% dw) makes the residual biomass, after ulvan extraction, a potential protein source in food and feed applications.

Determining the potent immunostimulation potential arising from the heteropolysaccharide structure of a novel fucoidan, derived from Sargassum Zhangii

A preliminary study was conducted of the chemical, structural properties and immunomodulatory activities of fucoidan isolated from Sargassum Zhangii (SZ). Sargassum Zhangii fucoidan (SZF) was determined to have a sulfate content of 19.74 ± 0.01% (w/w) and an average molecular weight of 111.28 kDa. SZF possessed a backbone structure of (1,4)-α-d-linked-galactose, (3,4)-α-l-fucose, (1,3)-α-d-linked-xylose, β-d-linked-mannose and a terminal (1,4)-α-d-linked-glucose. The main monosaccharide composition was determined as (w/w) 36.10% galactose, 20.13% fucose, 8.86% xylose, 7.36% glucose, 5.62% mannose, and 18.07% uronic acids, respectively. An immunostimulatory assay showed that SZF, compared to commercial fucoidans (Undaria pitnnaifida and Fucus vesiculosus sources), significantly elevated nitric oxide production via up-regulation of cyclooxygenase-2 and inducible nitric oxide synthase at both gene and protein levels. These results suggest that SZ has the potential to be a source of fucoidan with enhanced properties that may act as a useful ingredient for functional foods, nutritional supplements, and immune enhancers.

Arctic Edible Brown Alga Fucus distichus L.: Biochemical Composition, Antiradical Potential and Human Health Risk

Fucus distichus L. is the dominant canopy-forming macroalga in the rocky intertidal areas of the Arctic and Subarctic. In the present study, the impact of the geographic location of F. distichus collected in the Baffin Sea (BfS), Norwegian Sea (NS), White Sea (WS), and Barents Sea (BS) on the variations in biochemical composition, antiradical properties, and health risk was evaluated. The accumulation of main carbohydrates (fucoidan, mannitol, and alginic acid) varied from 335 mg/g dry weight (DW) in NS to 445 mg/g DW in BS. The highest level of the sum of polyphenols and flavonoids was found in samples of F. distichus from WS and was located in the following ranking order: BS < BfS < NS < WS. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of seaweed is correlated with its phenolic content. It is notable that in most Arctic F. distichus samples, Cd, Cr, Pb, and Ni were not detected or their concentrations were below the limit of quantification. According to calculated targeted hazard quotient and hazard index values, all studied samples of Arctic F. distichus are safe for daily consumption as they do not pose a carcinogenic risk to the health of adults or children. The results of this study support the rationale for using Arctic F. distichus as a rich source of polysaccharides, polyphenols, and flavonoids with important antiradical activity. We believe that our data will help to effectively use the potential of F. distichus and expand the use of this algae as a promising and safe raw material for the food and pharmaceutical industries.

Impact of Enzymatically Extracted High Molecular Weight Fucoidan on Lipopolysaccharide-Induced Endothelial Activation and Leukocyte Adhesion

The endothelial cell lining creates an interface between circulating blood and adjoining tissue and forms one of the most critical barriers and targets for therapeutical intervention. Recent studies suggest that fucoidans, sulfated and fucose-rich polysaccharides from brown seaweed, show multiple promising biological effects, including anti-inflammatory properties. However, their biological activity is determined by chemical characteristics such as molecular weight, sulfation degree, and molecular structure, which vary depending on the source, species, and harvesting and isolation method. In this study, we investigated the impact of high molecular weight (HMW) fucoidan extract on endothelial cell activation and interaction with primary monocytes (MNCs) in lipopolysaccharide (LPS)-induced inflammation. Gentle enzyme-assisted extraction combined with fractionation by ion exchange chromatography resulted in well-defined and pure fucoidan fractions. FE_F3, with a molecular weight ranging from 110 to 800 kDa and a sulfate content of 39%, was chosen for further investigation of its anti-inflammatory potential. We observed that along with higher purity of fucoidan fractions, the inflammatory response in endothelial mono- and co-cultures with MNCs was reduced in a dose-dependent manner when testing two different concentrations. This was demonstrated by a decrease in IL-6 and ICAM-1 on gene and protein levels and a reduced gene expression of TLR-4, GSK3β and NF-kB. Expression of selectins and, consequently, the adhesion of monocytes to the endothelial monolayer was reduced after fucoidan treatment. These data indicate that the anti-inflammatory effect of fucoidans increases with their purity and suggest that fucoidans might be useful in limiting the inflammatory response of endothelial cells in cases of LPS-induced bacterial infection.

Purification and Molecular Characterization of Fucoidan Isolated from Ascophyllum nodosum Brown Seaweed Grown in Ireland

The present study investigates the molecular characteristics of fucoidan obtained from the brown Irish seaweed Ascophyllum nodosum, employing hydrothermal-assisted extraction (HAE) followed by a three-step purification protocol. The dried seaweed biomass contained 100.9 mg/g of fucoidan, whereas optimised HAE conditions (solvent, 0.1N HCl; time, 62 min; temperature, 120 °C; and solid to liquid ratio, 1:30 (w/v)) yielded 417.6 mg/g of fucoidan in the crude extract. A three-step purification of the crude extract, involving solvents (ethanol, water, and calcium chloride), molecular weight cut-off filter (MWCO; 10 kDa), and solid-phase extraction (SPE), resulted in 517.1 mg/g, 562.3 mg/g, and 633.2 mg/g of fucoidan (p < 0.05), respectively. In vitro antioxidant activity, as determined by 1,1-diphenyl-2-picryl-hydrazyl radical scavenging and ferric reducing antioxidant power assays, revealed that the crude extract exhibited the highest antioxidant activity compared to the purified fractions, commercial fucoidan, and ascorbic acid standard (p < 0.05). The molecular attributes of biologically active fucoidan-rich MWCO fraction was characterised by quadruple time of flight mass spectrometry and Fourier-transform infrared (FTIR) spectroscopy. The electrospray ionisation mass spectra of purified fucoidan revealed quadruply ([M+4H]4+) and triply ([M+3H]3+) charged fucoidan moieties at m/z 1376 and m/z 1824, respectively, and confirmed the molecular mass 5444 Da (~5.4 kDa) from multiply charged species. The FTIR analysis of both purified fucoidan and commercial fucoidan standard exhibited O-H, C-H, and S=O stretching which are represented by bands at 3400 cm-1, 2920 cm-1, and 1220-1230 cm-1, respectively. In conclusion, the fucoidan recovered from HAE followed by a three-step purification process was highly purified; however, purification reduced the antioxidant activity compared to the crude extract.

Polysaccharides-Naturally Occurring Immune Modulators

The prevention of disease and infection requires immune systems that operate effectively. This is accomplished by the elimination of infections and abnormal cells. Immune or biological therapy treats disease by either stimulating or inhibiting the immune system, dependent upon the circumstances. In plants, animals, and microbes, polysaccharides are abundant biomacromolecules. Due to the intricacy of their structure, polysaccharides may interact with and impact the immune response; hence, they play a crucial role in the treatment of several human illnesses. There is an urgent need for the identification of natural biomolecules that may prevent infection and treat chronic disease. This article addresses some of the naturally occurring polysaccharides of known therapeutic potential that have already been identified. This article also discusses extraction methods and immunological modulatory capabilities.

Establishment of specific age-related macular degeneration relevant gene expression panels using porcine retinal pigment epithelium for assessing fucoidan bioactivity

PURPOSE

Age-related macular degeneration (AMD) is the leading cause of severe vision loss in industrialized nations. Important factors in pathogenesis are oxidative stress, inflammation, and, in the wet form of AMD, angiogenesis. Fucoidans, sulfated polysaccharides from brown algae, may have antioxidant, anti-inflammatory, and antiangiogenic effects. In this study, we established specific gene expression panels for inflammation, oxidative stress and angiogenesis in porcine retinal pigment epithelium (RPE), and investigated the effect of fucoidans on gene expression under different noxious agents.

METHODS

Primary porcine RPE cells cultured for at least 14 days were used. Using viability assays with tetrazolium bromide and real-time polymerase chain reaction of marker genes, positive controls were established for appropriate concentrations and exposure times of selected noxious agents (lipopolysaccharide (LPS), H₂O₂, CoCl₂). Three different AMD relevant gene panels specific for porcine RPE for inflammation, oxidative stress, and angiogenesis were established, and the influence of fucoidans (mainly Fucus vesiculosus; FV) on gene expression was investigated.

RESULTS

The following was shown by gene expression analyses: (1) Inflammation panel: Expression of 18 genes was affected under LPS (three days). Among them, LPS increased genes for interleukin 1 receptor 2, interleukin 8, cyclooxygenase-2 and vascular cell adhesion protein 1 expression which were diminished when FV was present. (2) Oxidative stress panel: Under stimulation of H₂O₂ (one day) and LPS (one day), expression of a total of 15 genes was affected. LPS induced increase in genes for superoxide dismutase-1, C-X-C motif chemokine 10, and CC chemokine ligand-5 expression was not detected when FV was present. (3) Angiogenesis panel: Under stimulation with CoCl₂ (three days) expression of six genes was affected, with the increase of genes for angiopoietin 2, vascular endothelial growth factor receptor-1, and follistatin being diminished when FV was present.

CONCLUSION

Three specific gene expression panels for porcine RPE that map genes for three of the major pathological factors of AMD, inflammation, oxidative stress, and angiogenesis, were established. Further, we demonstrated that fucoidans can reduce stress related gene activation in all of these three major pathogenic pathways. This study is another indication that fucoidans can act on different pathomechanisms of AMD simultaneously, which provides further evidence for fucoidans as a possible drug for treatment and prevention of AMD.

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

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

Water-Soluble Saccharina latissima Polysaccharides and Relation of Their Structural Characteristics with In Vitro Immunostimulatory and Hypocholesterolemic Activities

Brown macroalgae are an important source of polysaccharides, mainly fucose-containing sulphated polysaccharides (FCSPs), associated with several biological activities. However, the structural diversity and structure-function relationships for their bioactivities are still undisclosed. Thus, the aim of this work was to characterize the chemical structure of water-soluble Saccharina latissima polysaccharides and evaluate their immunostimulatory and hypocholesterolemic activities, helping to pinpoint a structure-activity relationship. Alginate, laminarans (F1, neutral glucose-rich polysaccharides), and two fractions (F2 and F3) of FCSPs (negatively charged) were studied. Whereas F2 is rich in uronic acids (45 mol%) and fucose (29 mol%), F3 is rich in fucose (59 mol%) and galactose (21 mol%). These two fractions of FCSPs showed immunostimulatory activity on B lymphocytes, which could be associated with the presence of sulphate groups. Only F2 exhibited a significant effect in reductions in in vitro cholesterol's bioaccessibility attributed to the sequestration of bile salts. Therefore, S. latissima FCSPs were shown to have potential as immunostimulatory and hypocholesterolemic functional ingredients, where their content in uronic acids and sulphation seem to be relevant for the bioactive and healthy properties.

Fucoidan in Pharmaceutical Formulations: A Comprehensive Review for Smart Drug Delivery Systems

Fucoidan is a heterogeneous group of polysaccharides isolated from marine organisms, including brown algae and marine invertebrates. The physicochemical characteristics and potential bioactivities of fucoidan have attracted substantial interest in pharmaceutical industries in the past few decades. These polysaccharides are characterized by possessing sulfate ester groups that impart negatively charged surfaces, low/high molecular weight, and water solubility. In addition, various promising bioactivities have been reported, such as antitumor, immunomodulatory, and antiviral effects. Hence, the formulation of fucoidan has been investigated in the past few years in diverse pharmaceutical dosage forms to be able to reach their site of action effectively. Moreover, they can act as carriers for various drugs in value-added drug delivery systems. The current work highlights the attractive biopharmaceutical properties of fucoidan being formulated in oral, inhalable, topical, injectable, and other advanced formulations treating life-quality-affecting diseases. Therefore, the present work points out the current status of fucoidan pharmaceutical formulations for future research transferring their application from in vitro and in vivo studies to clinical application and market availability.

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.

Production and Characterization of Durvillaea antarctica Enzyme Extract for Antioxidant and Anti-Metabolic Syndrome Effects

In this study, three enzyme hydrolysate termed Dur-A, Dur-B, and Dur-C, were produced from Durvillaea antarctica biomass using viscozyme, cellulase, and α-amylase, respectively. Dur-A, Dur-B, and Dur-C, exhibited fucose-containing sulfated polysaccharide from chemical composition determination and characterization by FTIR analyses. In addition, Dur-A, Dur-B, and Dur-C, had high extraction yields and low molecular weights. All extracts determined to have antioxidant activities by DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,20-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt), and ferrous ion-chelating methods. All extracts were also able to positively suppress the activities of key enzymes involved in metabolic syndrome: angiotensin I-converting enzyme (ACE), α-amylase, α-glucosidase, and pancreatic lipase. In general, Dur-B exhibited higher antioxidant and higher anti-metabolic syndrome effects as compared to the other two extracts. Based on the above health promoting properties, these extracts (especially Dur-B) can be used as potential natural antioxidants and natural anti-metabolic syndrome agents in a variety of food, cosmetic, and nutraceutical products for health applications.

Global seaweed farming and processing in the past 20 years

Seaweed has emerged as one of the most promising resources due to its remarkable adaptability, short development period, and resource sustainability. It is an effective breakthrough to alleviate future resource crises. Algal resources have reached a high stage of growth in the past years due to the increased output and demand for seaweed worldwide. Several aspects global seaweed farming production and processing over the last 20 years are reviewed, such as the latest situation and approaches of seaweed farming. Research progress and production trend of various seaweed application are discussed. Besides, the challenges faced by seaweed farming and processing are also analyzed, and the related countermeasures are proposed, which can provide advice for seaweed farming and processing. The primary products, extraction and application, or waste utilization of seaweed would bring greater benefits with the continuous development and improvement of applications in various fields.

Graphical Abstract

A new FTIR assay for quantitative measurement of endo-fucoidanase activity

Endo-fucoidanases, including EC 3.2.1.211 endo-α-1,3-L-fucanase and EC 3.2.1.212 endo-α-1,4-L-fucanase activities, catalyze depolymerization of fucoidans - a group of bioactive, sulfated fucosyl-polysaccharides found primarily in brown macroalgae (brown seaweeds). Quantitative assessment of endo-fucoidanase activity is critical for characterizing endo-fucoidanase kinetics and for comparing the action of different endo-fucoidanases on different types of fucoidans. However, the current state-of-the-art endo-fucoidanase assay consists of a qualitative assessment based on Carbohydrate-Polyacrylamide Gel Electrophoresis. Here, we report a new quantitative endo-fucoidanase assay based on real time spectral evolution profiling of changes in substrate and product during endo-fucoidanase action using Fourier Transform InfraRed spectroscopy (FTIR) combined with Parallel Factor Analysis (PARAFAC). The FTIR-PARAFAC assay was validated by monitoring the reaction progress of three different microbial endo-fucoidanase enzymes, FcnAΔ229, FFA2 and Fhf1Δ470, on two different fucoidan substrates. The substrates were purified from the brown macroalgae Fucus evanescens and Fucus vesiculosus, respectively. The evolution profiling showed that the strongest spectral change of the fucoidans during enzymatic depolymerization occurred in the spectral range 1220-1260 cm-1, but the profiles differed depending on the substrate and the enzyme used. Spectral changes within 1220-1260 cm-1 are in agreement with the enzymatic depolymerization inducing signature changes in the mid-infrared absorption of sulfated fucosyls as sulfate ester bonds and C-O stretching vibrations absorb in this spectral region. Based on the data obtained, we also introduce an activity unit for endo-fucoidanases: One endo-fucoidanase Unit, Uf, is the amount of enzyme able to catalyze a change in the FTIR-PARAFAC score by 0.01 during 498 s of reaction (8.3 min) on 20 g/L pure fucoidan from F. evanescens at 42 °C, pH 7.4, 100 mM NaCl and 10 mM CaCl2. This new quantitative endo-fucoidanase assay can pave the way for better kinetic characterizations as well as novel explorations of endo-fucoidanases.

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.

Depolymerization of fucoidan with endo-fucoidanase changes bioactivity in processes relevant for bone regeneration

Fucoidans are polysaccharides from brown macroalgae, showing multiple bioactivities important for bone regeneration and bone health. However, the use of fucoidans in medical applications remains sparse due to the heterogeneity in their chemical properties and unclear structure-function relationships. Innovations in extraction techniques and post processing steps are needed to produce homogeneous fucoidan molecules with tailorable bioactivities. Here, we applied enzyme-assisted extraction coupled with enzymatic hydrolysis by Fhf1 fucoidanase to generate low (LMW) and medium molecular weight (MMW) fucoidans from Fucus evanescens. In contrast to the anti-angiogenic properties of the high molecular weight fucoidan, LMW and MMW no longer suppressed the production of pro-angiogenic molecules by bone stem cells, nor impaired the formation of prevascular structures in vitro. In contrast to LMW, a pro-inflammatory response of OEC was observed after treatment with high concentrations of MMW. Thus, fucoidanase hydrolysis could be a useful tool to tailor the bioactivity of fucoidans.

Characteristics of Marine Biomaterials and Their Applications in Biomedicine

Oceans have vast potential to develop high-value bioactive substances and biomaterials. In the past decades, many biomaterials have come from marine organisms, but due to the wide variety of organisms living in the oceans, the great diversity of marine-derived materials remains explored. The marine biomaterials that have been found and studied have excellent biological activity, unique chemical structure, good biocompatibility, low toxicity, and suitable degradation, and can be used as attractive tissue material engineering and regenerative medicine applications. In this review, we give an overview of the extraction and processing methods and chemical and biological characteristics of common marine polysaccharides and proteins. This review also briefly explains their important applications in anticancer, antiviral, drug delivery, tissue engineering, and other fields.

A critical look at challenges and future scopes of bioactive compounds and their incorporations in the food, energy, and pharmaceutical sector

Bioactive compounds refer to secondary metabolites extracted from plants, fungi, microbes, or animals. Besides having pharmacological or toxicological effects on organisms leading to utilization in food and pharmaceutical industries, the discovery of novel properties of such compounds has led to the diversification of their applications, ranging from cosmetics and functionalized biomaterials to bioremediation and alternate fuels. Conventional time-consuming and solvent-intensive methods of extraction are increasingly being replaced by green solvents such as ionic liquids, supercritical fluids, and deep eutectic solvents, as well as non-conventional methods of extraction assisted by microwaves, pulse electric fields, enzymes, ultrasound, or pressure. These methods, along with advances in characterization and optimization strategies, have boosted the commercial viability of extraction especially from agrowastes and organic residues, promoting a sustainable circular economy. Further development of microfluidics, optimization models, nanoencapsulation, and metabolic engineering are expected to overcome certain limitations that restrict the growth of this field, in the context of improving screening, extraction, and economy of processes, as well as retaining biodiversity and enhancing the stability and functionality of such compounds. This review is a compilation of the various extraction and characterization methods employed for bioactive compounds and covers major applications in food, pharmacy, chemicals, energy, and bioremediation. Major limitations and scope of improvement are also discussed.

The Endo-α(1,3)-Fucoidanase Mef2 Releases Uniquely Branched Oligosaccharides from Saccharina latissima Fucoidans

Fucoidans are complex bioactive sulfated fucosyl-polysaccharides primarily found in brown macroalgae. Endo-fucoidanases catalyze the specific hydrolysis of α-L-fucosyl linkages in fucoidans and can be utilized to tailor-make fucoidan oligosaccharides and elucidate new structural details of fucoidans. In this study, an endo-α(1,3)-fucoidanase encoding gene, Mef2, from the marine bacterium Muricauda eckloniae, was cloned, and the Mef2 protein was functionally characterized. Based on the primary sequence, Mef2 was suggested to belong to the glycosyl hydrolase family 107 (GH107) in the Carbohydrate Active enZyme database (CAZy). The Mef2 fucoidanase showed maximal activity at pH 8 and 35 °C, although it could tolerate temperatures up to 50 °C. Ca2+ was shown to increase the melting temperature from 38 to 44 °C and was furthermore required for optimal activity of Mef2. The substrate specificity of Mef2 was investigated, and Fourier transform infrared spectroscopy (FTIR) was used to determine the enzymatic activity (Units per μM enzyme: Uf/μM) of Mef2 on two structurally different fucoidans, showing an activity of 1.2 × 10-3 Uf/μM and 3.6 × 10-3 Uf/μM on fucoidans from Fucus evanescens and Saccharina latissima, respectively. Interestingly, Mef2 was identified as the first described fucoidanase active on fucoidans from S. latissima. The fucoidan oligosaccharides released by Mef2 consisted of a backbone of α(1,3)-linked fucosyl residues with unique and novel α(1,4)-linked fucosyl branches, not previously identified in fucoidans from S. latissima.

Pelagic Sargassum events in Jamaica: Provenance, morphotype abundance, and influence of sample processing on biochemical composition of the biomass

Pelagic Sargassum species have been known for centuries in the Sargasso Sea of the North Atlantic Ocean. In 2011, a new area concentrating high biomass of these brown algae started developing in the Tropical Atlantic Ocean. Since then, massive and recurrent Sargassum influxes have been reported in the Caribbean and off the coast of Western Africa. These Sargassum events have a major negative impact on coastal ecosystems and nearshore marine life, and affect socio-economic sectors, including public health, coastal living, tourism, fisheries, and maritime transport. Despite recent advances in the forecasting of Sargassum events, and elucidation of the seaweed composition, many knowledge gaps remain, including morphotype abundance during Sargassum events, drift of the seaweeds in the months prior to stranding, and influence of sample processing methods on biomass biochemical composition. Using seaweeds harvested on the coasts of Jamaica in summer of 2020, we observed that S. fluitans III was the most abundant morphotype at different times and sampling locations. No clear difference in the geographical origin, or provenance, of the Sargassum mats was observed. The majority of Sargassum backtracked from both north and south of Jamaica experienced ambient temperatures of around 27 °C and salinity in the range of 34-36 psu before stranding. We also showed that cheap (sun) compared to expensive (freeze) drying techniques influence the biochemical composition of biomass. Sun-drying increased the proportion of phenolic compounds, but had a deleterious impact on fucoxanthin content and on the quantities of monosaccharides, except for mannitol. Effects on the content of fucose containing sulfated polysaccharides depended on the method used for their extraction, and limited variation was observed in ash, protein, and fatty acid content within most of the sample locations investigated. These observations are important for the storage and transport of the biomass in the context of its valorisation.

Beneficial effects of seaweed-derived dietary fiber: Highlights of the sulfated polysaccharides

Seaweeds and their derivatives are important bioresources of natural bioactive compounds. Nutritional studies indicate that dietary fibers derived from seaweeds have great beneficial potentials in human health and can be developed as functional food. Moreover, sulfated polysaccharides are more likely to be the main bioactive components which are widely distributed in various species of seaweeds including Phaeophyceae, Rhodophyceae and Chlorophyceae. The catabolism by gut microbiota of the seaweeds-derived dietary fibers (DFs) may be one of the pivotal pathways of their physiological functions. Therefore, in this review, we summarized the latest results of the physiological characteristics of seaweed-derived dietary fiber and highlighted the roles of sulfated polysaccharides in the potential regulatory mechanisms against disorders. Meanwhile, the effects of different types of seaweed-derived dietary fiber on gut microbiota were discussed. The analysis of the structure-function correlations and gut microbiota related mechanisms and will contribute to further better applications in food and biotherapeutics.

Current application of algae derivatives for bioplastic production: A review

Improper use of conventional plastics poses challenges for sustainable energy and environmental protection. Algal derivatives have been considered as a potential renewable biomass source for bioplastic production. Algae derivatives include a multitude of valuable substances, especially starch from microalgae, short-chain length polyhydroxyalkanoates (PHAs) from cyanobacteria, polysaccharides from marine and freshwater macroalgae. The algae derivatives have the potential to be used as key ingredients for bioplastic production, such as starch and PHAs or only as an additive such as sulfated polysaccharides. The presence of distinctive functional groups in algae, such as carboxyl, hydroxyl, and sulfate, can be manipulated or tailored to provide desirable bioplastic quality, especially for food, pharmaceutical, and medical packaging. Standardizing strains, growing conditions, harvesting and extracting algae in an environmentally friendly manner would be a promising strategy for pollution control and bioplastic production.

The Endo-α(1,4) Specific Fucoidanase Fhf2 From Formosa haliotis Releases Highly Sulfated Fucoidan Oligosaccharides

Fucoidanases are endo-fucoidanases (also known as endo-fucanases) that catalyze hydrolysis of α-glycosidic linkages in fucoidans, a family of sulfated fucose-rich polysaccharides primarily found in the cell walls of brown seaweeds. Fucoidanases are promising tools for producing bioactive fucoidan oligosaccharides for a range of biomedical applications. High sulfation degree has been linked to high bioactivity of fucoidans. In this study, a novel fucoidanase, Fhf2, was identified in the genome of the aerobic, Gram-negative marine bacterium Formosa haliotis. Fhf2 was found to share sequence similarity to known endo-α(1,4)-fucoidanases (EC 3.2.1.212) from glycoside hydrolase family 107. A C-terminal deletion mutant Fhf2∆484, devoid of 484 amino acids at the C-terminus, with a molecular weight of approximately 46 kDa, was constructed and found to be more stable than the full-length Fhf2 protein. Fhf2∆484 showed endo-fucoidanase activity on fucoidans from different seaweed species including Fucus evanescens, Fucus vesiculosus, Sargassum mcclurei, and Sargassum polycystum. The highest activity was observed on fucoidan from F. evanescens. The Fhf2∆484 enzyme was active at 20-45°C and at pH 6-9 and had optimal activity at 37°C and pH 8. Additionally, Fhf2∆484 was found to be calcium-dependent. NMR analysis showed that Fhf2∆484 catalyzed hydrolysis of α(1,4) linkages between L-fucosyl moieties sulfated on C2 (similar to Fhf1 from Formosa haliotis), but Fhf2∆484 in addition released oligosaccharides containing a substantial amount of 2,4-disulfated fucose residues. The data thus suggest that the Fhf2∆484 enzyme could be a valuable candidate for producing highly sulfated oligosaccharides applicable for fucoidan bioactivity investigations.

Sulfated Polysaccharides from Seaweed Strandings as Renewable Source for Potential Antivirals against Herpes simplex Virus 1

Herpes simplex virus 1 (HSV-1) remains a prominent health concern widespread all over the world. The increasing genital infections by HSV-1 that might facilitate acquisition and transmission of HIV-1, the cumulative evidence that HSV-1 promotes neurodegenerative disorders, and the emergence of drug resistance signify the need for new antiviral agents. In this study, the in vitro anti-herpetic activity of sulfated polysaccharides (SPs) extracted by enzyme or hot water from seaweeds collected in France and Mexico from stranding events, were evaluated. The anti-herpetic activity evaluation of the semi-refined-polysaccharides (sr-SPs) and different ion exchange purified fractions showed a wide range of antiviral activity. Among them, the sr-SPs from the Rhodophyta Halymenia floresii showed stronger activity EC₅₀ 0.68 μg/mL with SI 1470, without cytotoxicity. Further, the antiviral activity of the sr-SPs evaluated at different treatment schemes showed a high EC₅₀ of 0.38 μg/mL during the viral adsorption assays when the polysaccharide and the virus were added simultaneously, whilst the protection on Vero cell during the post-infection assay was effective up to 1 h. The chemical composition, FTIR and ¹H NMR spectroscopic, and molecular weights of the sr-SPs from H. floresii were determined and discussed based on the anti-herpetic activity. The potential utilization of seaweed stranding as a source of antiviral compounds is addressed.

A Combination Approach in Inhibiting Type 2 Diabetes-Related Enzymes Using Ecklonia radiata Fucoidan and Acarbose

Although there are chemotherapeutic efforts in place for Type 2 diabetes mellitus (T2DM), there is a need for novel strategies (including natural products) to manage T2DM. Fucoidan, a sulphated polysaccharide was extracted from Ecklonia radiata. The integrity of the fucoidan was confirmed by structural analysis techniques such as FT-IR, NMR and TGA. In addition, the fucoidan was chemically characterised and tested for cell toxicity. The fucoidan was investigated with regards to its potential to inhibit α-amylase and α-glucosidase. The fucoidan was not cytotoxic and inhibited α-glucosidase (IC50 19 µg/mL) more strongly than the standard commercial drug acarbose (IC50 332 µg/mL). However, the fucoidan lacked potency against α-amylase. On the other hand, acarbose was a more potent inhibitor of α-amylase (IC50 of 109 µg/mL) than α-glucosidase. Due to side effects associated with the use of acarbose, a combination approach using acarbose and fucoidan was investigated. The combination showed synergistic inhibition (>70%) of α-glucosidase compared to when the drugs were used alone. The medicinal implication of this synergism is that a regimen with a reduced acarbose dose may be used, thus minimising side effects to the patient, while achieving the desired therapeutic effect for managing T2DM.

A new biomimetic nanozyme of hemin/graphdiyne oxide with superior peroxidase-like activity for colorimetric bioassays

Graphdiyne oxide (GDYO) is a novel type of two-dimensional carbon allotrope nanomaterial consisting of a large conjugated system and excellent chemical stability. To date, application of GDYO as a nanozyme in biosensing has been rarely reported. In this study, a novel ultrasensitive colorimetric bioassay was constructed using a hemin/GDYO nanocomposite (H/GDYO) as a new nanozyme with superior peroxidase-like activity for the detection of H₂O₂ and glucose. It was discovered that H/GDYO exhibited 6-fold higher peroxidase-like activity than pure hemin. Catalytic kinetic analysis showed that H/GDYO had a much higher affinity for H₂O₂ and glucose than that of hemin. The designed colorimetric bioassay displayed excellent sensitivity for H₂O₂ and glucose detection with a wide linear range of 0.015-0.5 mM and 0.1-10 mM, respectively, while the limit of detection (LOD) was as low as 4.39 μM and 38 μM, respectively. Moreover, it was successfully applied for the analysis of H₂O₂ in milk and glucose in real human serum samples with acceptable recoveries. Importantly, the developed colorimetric bioassay shows good agreement with the results obtained from a commercial blood glucose meter. We believe that the proposed method could provide a promising prospect for medical diagnosis and biotechnology.

Efficacy of marine bioactive compound fucoidan for bone regeneration and implant fixation in sheep

The need for a substitute for allograft and autograft is rising as bone graft surgeries exceed available supplies. We investigated the efficacy of the low-molecular weight marine bioactive compound fucoidan (FUC) on bone regeneration and implant fixation in seven female sheep, as FUC has shown great promise as a bone substitute. Titanium implants were inserted bilaterally in the distal femurs to test three hydroxyapatite/fucoidan (HA/FUC) groups and compared to allograft. The HA was coated with either 500 or 1500 μg of FUC, obtained by microwave-assisted chemical extraction, or 500 μg of FUC obtained by an enzyme-assisted extraction method. The concentric 2-mm gap around the implant was filled with either one of the HA/FUCs or allograft from the donor sheep. After 12 weeks, implant-bone blocks were harvested and divided into three parts for mechanical push-out testing, immunohistochemistry, and micro-CT and histomorphometry. Pronounced bone formations were observed by micro-CT and histomorphometry in all groups, but higher bone volume fractions were seen in the allograft group compared to the three HA/FUC groups. The trabecular thickness, trabecular separation, and architectural anisotropy were all significantly higher in the allograft group compared to the three HA/FUC groups. In conclusion, adequate bone formation was observed in all groups, although the bone formation was significantly greater in the allograft group. Also, no significant differences existed in the shear mechanical properties between groups, suggesting that the combination of HA and FUC can achieve a similar fixation strength to allograft in this model.

A novel thermostable prokaryotic fucoidan active sulfatase PsFucS1 with an unusual quaternary hexameric structure

Fucoidans are sulfated, fucose-rich marine polysaccharides primarily found in cell walls of brown seaweeds (macroalgae). Fucoidans are known to possess beneficial bioactivities depending on their structure and sulfation degree. Here, we report the first functional characterization and the first crystal structure of a prokaryotic sulfatase, PsFucS1, belonging to sulfatase subfamily S1_13, able to release sulfate from fucoidan oligosaccharides. PsFucS1 was identified in the genome of a Pseudoalteromonas sp. isolated from sea cucumber gut. PsFucS1 (57 kDa) is Ca²⁺ dependent and has an unusually high optimal temperature (68 °C) and thermostability. Further, the PsFucS1 displays a unique quaternary hexameric structure comprising a tight trimeric dimer complex. The structural data imply that this hexamer formation results from an uncommon interaction of each PsFucS1 monomer that is oriented perpendicular to the common dimer interface (~ 1500 Ų) that can be found in analogous sulfatases. The uncommon interaction involves interfacing (1246 Ų) through a bundle of α-helices in the N-terminal domain to form a trimeric ring structure. The high thermostability may be related to this unusual quaternary hexameric structure formation that is suggested to represent a novel protein thermostabilization mechanism.

Seaweed polysaccharides: Emerging extraction technologies, chemical modifications and bioactive properties

Nowadays, consumers are increasingly aware of the relationship between diet and health, showing a greater preference of products from natural origin. In the last decade, seaweeds have outlined as one of the natural sources with more potential to obtain bioactive carbohydrates. Numerous seaweed polysaccharides have aroused the interest of the scientific community, due to their biological activities and their high potential on biomedical, functional food and technological applications. To obtain polysaccharides from seaweeds, it is necessary to find methodologies that improve both yield and quality and that they are profitable. Nowadays, environmentally friendly extraction technologies are a viable alternative to conventional methods for obtaining these products, providing several advantages like reduced number of solvents, energy and time. On the other hand, chemical modification of their structure is a useful approach to improve their solubility and biological properties, and thus enhance the extent of their potential applications since some uses of polysaccharides are still limited. The present review aimed to compile current information about the most relevant seaweed polysaccharides, available extraction and modification methods, as well as a summary of their biological activities, to evaluate knowledge gaps and future trends for the industrial applications of these compounds.Key teaching pointsStructure and biological functions of main seaweed polysaccharides.Emerging extraction methods for sulfate polysaccharides.Chemical modification of seaweeds polysaccharides.Potential industrial applications of seaweed polysaccharides.Biological activities, knowledge gaps and future trends of seaweed polysaccharides.

Perspective on the Therapeutic Applications of Algal Polysaccharides

Abstract

Algae are an enormous source of polysaccharides and have gained much interest in human flourishing as organic drugs. Algal polysaccharides have aroused interest in the health sector owing to the various bioactivities namely anticancer, antiviral, immunoregulation, antidiabetic and antioxidant effects. The research community has comprehensively described the importance of algal polysaccharides regarding their extraction, purification, and potential use in various sectors. However, regardless of all the intriguing properties and potency in the health sector, these algal polysaccharides deserve detailed investigation. Hence, the present review emphasizes extensively on the previous and latest developments in the extraction, purification, structural properties and therapeutic bioactivities of algal polysaccharides to upgrade the knowledge for further advancement in this area of research. Moreover, the review also addresses the challenges, prospective research gaps and future perspective. We believe this review can provide a boost to upgrade the traditional methods of algal polysaccharide production for the development of efficacious drugs that will promote human welfare.

Graphic Abstract

Current Status of Mining, Modification, and Application of Cellulases in Bioactive Substance Extraction

Cellulases have been used to extract bioactive ingredients from medical plants; however, the poor enzymatic properties of current cellulases significantly limit their application. Two strategies are expected to address this concern: (1) new cellulase gene mining strategies have been promoted, optimized, and integrated, thanks to the improvement of gene sequencing, genomic data, and algorithm optimization, and (2) known cellulases are being modified, thanks to the development of protein engineering, crystal structure data, and computing power. Here, we focus on mining strategies and provide a systemic overview of two approaches based on sequencing and function. Strategies based on protein structure modification, such as introducing disulfide bonds, proline, salt bridges, N-glycosylation modification, and truncation of loop structures, have already been summarized. This review discusses four aspects of cellulase-assisted extraction. Initially, cellulase alone was used to extract bioactive substances, and later, mixed enzyme systems were developed. Physical methods such as ultrasound, microwave, and high hydrostatic pressure have assisted in improving extraction efficiency. Cellulase changes the structure of biomolecules during the extraction process to convert them into effective ingredients with better activity and bioavailability. The combination of cellulase with other enzymes and physical technologies is a promising strategy for future extraction applications.