Fucoidan Fractions Research Articles

Dietary fucoidan from a brown marine algae (Ecklonia cava) attenuates lipid accumulation in differentiated 3T3-L1 cells and alleviates high-fat diet-induced obesity in mice

Fucoidan from marine algae is used as a functional ingredient in the food. Here, we purified fucoidan fractions from a crude polysaccharide obtained after the crude polysaccharide of celluclast-assisted hydrolysate from Ecklonia cava (ECC). We evaluated the effect of ECC on lipid accumulation in differentiated 3T3-L1 adipocytes and investigated its anti-obesity effects in vivo in high-fat diet (HFD)-induced obese mice. In vitro Oil Red O staining revealed that treatment with ECC and its purified fucoidan fractions of celluclast assisted hydrolysate from Ecklonia cava (ECFs) remarkably reduced lipid accumulation in 3T3-L1 cells. ECF3 contained the highest contents of polysaccharides and sulfate compared with other fucoidan fractions. ECF3 treatment significantly reduced lipid accumulation in 3T3-L1 cells. Oral administration of ECC significantly reduced body weight, body weight gain, serum lipid content, and total white adipose tissue mass. Histological analysis revealed that ECC reduced lipid accumulation in EAT and liver tissues. Our findings suggest that the anti-obesity effects of ECC are associated with suppressing lipid accumulation in white adipose tissues and increased energy expenditure by upregulating the expression of thermogenic UCP1 and UCP3 in BAT. These results indicate that ECC and its ECFs possess anti-obesity properties and can be used in food and nutraceutical industries.

Low molecular weight fucoidan fraction LF2 improves metabolic syndrome via up-regulating PI3K-AKT-mTOR axis and increasing the abundance of Akkermansia muciniphila in the gut microbiota

Metabolic syndrome (MetS) is a pathological condition of a variety of metabolic abnormalities, which requires more urgent treatment and intervention. Fucoidan has been recommended as a supplement for health enhancement and disease management. Here, we first propose that the beneficial effect of low molecular weight fucoidan fraction LF2 in regulating metabolic syndrome induced by high-fat diet is similar to that of metformin, in terms of molecular mechanism and gut microbiota. The study found that LF2 significantly reduces fasting blood glucose, enhances insulin sensitivity and restores insulin homeostasis and lipid homeostasis. Moreover, LF2 reduced liver oxidative stress and inflammation, and improved hepatocyte steatosis. To decipher the mechanism behind this therapeutic effect, both the molecular mechanisms and gut microbiota were further analyzed. LF2 inhibited the activation of PI3K-Akt-mTOR axis and decreased the expression of SREBP-1c and PPARγ in liver. Interestingly, we found that LF2 and metformin have similar effects on gut microbiota, increasing the proportion of Verrucomicrobia and enriching the abundance of Akkermansia muciniphila, which is beneficial to host health. Collectively, our research clarifies the new application of fucoidan as a functional food for anti-MetS, and provides a new insight for fucoidan to exert systemic therapeutic effects from the perspective of molecular mechanism and gut microbiota.

In Vitro Anti-Orthohantavirus Activity of the High-and Low-Molecular-Weight Fractions of Fucoidan from the Brown Alga Fucus evanescens.

The Hantaan orthohantavirus (genovariant Amur–AMRV) is a rodent-borne zoonotic virus; it is the causative agent of haemorrhagic fever with renal syndrome in humans. The currently limited therapeutic options require the development of effective anti-orthohantavirus drugs. The ability of native fucoidan from Fucus evanescens (FeF) and its enzymatically prepared high-molecular-weight (FeHMP) and low-molecular-weight (FeLMP) fractions to inhibit different stages of AMRV infection in Vero cells was studied. The structures of derivatives obtained were determined using nuclear magnetic resonance (NMR) spectroscopy. We found that fucoidan and its derivatives exhibited significant antiviral activity by affecting the early stages of the AMRV lifecycle, notably virus attachment and penetration. The FeHMP and FeLMP fractions showed the highest anti-adsorption activity by inhibiting AMRV focus formation, with a selective index (SI) > 110; FeF had an SI of ~70. The FeLMP fraction showed a greater virucidal effect compared with FeF and the FeHMP fraction. It was shown by molecular docking that 2O-sulphated fucotetrasaccharide, a main component of the FeLMP fraction, is able to bind with the AMRV envelope glycoproteins Gn/Gc and with integrin β3 to prevent virus–cell interactions. The relatively small size of these sites of interactions explains the higher anti-AMRV activity of the FeLMP fraction.

Antioxidant and Antisteatotic Activities of Fucoidan Fractions from Marine and Terrestrial Sources.

Fucoidan is a fucose-rich sulfated polysaccharide typically found in the cell wall of marine algae but also recently isolated from terrestrial sources. Due to a variety of biological activities, including antioxidant properties, fucoidan exhibits an attractive therapeutic potential against a wide array of metabolic diseases associated with oxidative stress. We used FTIR, 1H NMR and 13C NMR spectroscopy to investigate the structural features of a fucoidan fraction extracted from the brown alga Cystoseira compressa (CYS). The antioxidant potential of CYS was measured by DPPH, ABTS and FRAP assays, which revealed a radical scavenging capacity that was confirmed in in vitro cellular models of hepatic and endothelial cells. The same antioxidant effects were observed for another fucoidan fraction previously identified in the terrestrial tree Eucalyptus globulus (EUC). Moreover, in hepatic cells, CYS and EUC exhibited a significant antisteatotic action, being able to reduce intracellular triglyceride content through the regulation of key genes of hepatic lipid metabolism. EUC exerted stronger antioxidant and antisteatotic effects as compared to CYS, suggesting that both marine and terrestrial sources should be considered for fucoidan extraction and therapeutic applications.

Synthesis, process optimization and characterization of gold nanoparticles using crude fucoidan from the invasive brown seaweed Sargassum muticum

Crude fucoidans from Sargassum muticum obtained by hot water extraction at 40–80 °C were used for the synthesis of gold nanoparticles (AuNPs). The effect of operation temperature on the yield and properties of the extract was determined. The alginate fraction partially coextracted precipitated as calcium alginate and showed rheological properties slightly lower than those of commercial alginates reported elsewhere. The fraction of fucoidan with a larger amount of sulfate, obtained at 60 °C (45% saccharide, 22% fucose, 24% sulfate), also contained 8.5% phlorotannins and 3% protein, as well as showing 37% the 2,2-azinobis(3-ethyl-benzothiazoline-6-sulfonate) (ABTS) radical scavenging capacity of Trolox. This soluble product was used for optimization during the synthesis of AuNPs. Several reaction conditions were tested until the obtainment of homogeneous nanoparticles. The characterization of the synthesized nanoparticles was performed employing ultraviolet-visible spectroscopy, Z potential, transmission electron microscopy and Fourier transformed infrared spectroscopy.

Fucoidan Extracted From Sporophyll of Undaria pinnatifida Grown in Weihai, China - Chemical Composition and Comparison of Antioxidant Activity of Different Molecular Weight Fractions.

Fucoidan is a multifunctional marine carbohydrate polymer that differs in its chemical composition and bioactivity both between seaweed species and within species from different locations across the globe. In this study, fucoidan was extracted from the sporophyll of Undaria pinnatifida grown in Weihai, Shandong Province, China. Fucoidan fractions with molecular weight cutoffs (MWCO) of >300 kDa and <10 kDa were obtained via dialysis. The fucoidan standard from Sigma (Fstd, ≥95, CAS: 9072-19-9), fucoidan crude extract (WH), >300 kDa fraction (300k) and <10 kDa fraction (10k) were compared in terms of chemical composition and antioxidant capacity. Based on Fourier transform infrared spectroscopy (FT-IR) analysis, Fstd, WH, and 300k all showed strong bands around 830 cm−1, corresponding to the sulfate substituent in the molecule. The results showed that compared with WH and 300 k, the degree of sulfation at 10k was the lowest. From Nuclear magnetic resonance spectroscopy (NMR) result, the four fucoidan samples all contain α-L-fucose. The primary antioxidant ability of the 10k is significantly higher than that of the 300k, WH, and Fstd, but the secondary antioxidant capabilities of the 10k and 300k were similar, and both were higher than that of the butylated hydroxyanisole (BHA). The ferric reducing antioxidant ability was higher in the 300k and WH fractions. This demonstrates that fucoidan extracted from U. pinnatifida grown in Weihai, China should be a useful nutraceutical resource.

Low molecular weight fucoidan prepared by fucoidanase degradation – A promising browning inhibitor

Low molecular weight (MW) fucoidans have been proved with excellent tyrosinase inhibitory activity, which may proposed as a potential anti-browning ingredient for fruit and vegetable fresh-keeping agent. This study was conducted to obtain a low MW fucoidan fraction with high tyrosinase inhibitory capacity from Laminaria japonica crude fucoidan by fucoidanase degradation and to preliminary explore its type of tyrosinase inhibition and the application in browning inhibition of fresh-cut fruit. Firstly, the wild fucoidan-degrading strain, Flavobacteriaceae RC2-3, was mutated by UV irradiation and the fucoidanase production was improved by 40.5%. Fucoidan, which degraded by purified fucoidanase for 2 h, presented favourable tyrosinase inhibitory ability and were then separated by ultrafiltration. The fucoidan fraction with MW below 5 kDa (FF5) demonstrated the best tyrosinase inhibitory effect and shown obvious browning inhibition of fresh-cut apple slices. The inhibitory kinetics revealed that FF5 was a quite effectively competitive inhibitor of tyrosinase. The results of this study suggested that FF5 could be used as a promising browning inhibitor in the preservation of fruits and vegetables.

Fucoidan Fractionated from Sargassum coreanum via Step-Gradient Ethanol Precipitation Indicate Promising UVB-Protective Effects in Human Keratinocytes

Fucoidans exhibit a wide range of bioactivities and receive significant attention in functional food and cosmetic research. Industrial applications of fucoidan are limited partially due to high extraction and purification costs. The present study implements an enzyme-assisted extraction and step-gradient ethanol precipitation for fractionating fucoidan from Sargassum coreanum based on its charge and molecular weight and evaluation of ultraviolet B (UVB) protective effects in human keratinocytes (HaCaT). The fucoidan fraction SCOC4 indicated higher fucose and sulfate contents with Fourier-transform infrared and 1H NMR spectral patterns resembling fucoidans. SCOC4 dose-dependently abated UVB-induced keratinocyte damage via suppressing intracellular reactive oxygen species, apoptotic body formation, DNA damage via suppressing mitochondria-mediated apoptosis. UVB-protective effects of SCOC4 were further attributable to the augmentation of nuclear factor erythroid 2-related factor 2 mediated cellular antioxidant defense enzymes. Step-gradient ethanol precipitation was a convenient approach of fractionating fucoidans based on molecular weight and charge (depend on the degree of sulfation). Further evaluation of seasonal variations, biocompatibility parameters, efficacy, and shelf life may widen the use of S. coreanum fucoidans in developing UVB-protective cosmetics and functional foods.

Antioxidant and Antisteatotic Activities of a New Fucoidan Extracted from Ferula hermonis Roots Harvested on Lebanese Mountains.

Fucoidan is a fucose-rich sulfated polysaccharide with attractive therapeutic potential due to a variety of biological activities, including antioxidant action. Fucoidan is typically found in the cell wall of marine brown algae, but extra-algal sources have also been discovered. In the present work, for the first time we extracted a water soluble fucoidan fraction from the roots of the terrestrial shrub Ferula hermonis. This fucoidan fraction was termed FUFe, and contained fucose, glucose, sulfate, smaller amounts of monosaccharides such as galactose and mannose, and a minor quantity of proteins. FUFe structural features were investigated by FTIR, 1H NMR and 13C NMR spectroscopy. The antioxidant property of FUFe was measured by DPPH, ABTS and FRAP assays, which revealed a high radical scavenging capacity that was confirmed in in vitro cellular models. In hepatic and endothelial cells, 50 μg/mL FUFe could reduce ROS production induced by intracellular lipid accumulation. Moreover, in hepatic cells FUFe exhibited a significant antisteatotic action, being able to reduce intracellular triglyceride content and to regulate the expression of key genes of hepatic lipid metabolism. Altogether, our results candidate FUFe as a possible bioactive compound against fatty liver disease and related vascular damage.

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

Simple SummaryThe continuous emergence of new pathogenic strains of bacteria resistant to antibiotics highlights the importance of search for the new natural sources of antimicrobial compounds. Fucoidans, sulfated polysaccharides from the cell walls of brown algae, attract the attention of many researchers due to their wide range of biological activities. Being natural and practically non-toxic, they are considered as a promising antimicrobial component that could, where possible, replace the use of strong chemical antiseptics and modern antibiotics. Natural fucoidans are polydisperse polysaccharides whose composition can vary greatly depending on the species, habitat, as well as on the way of purification. In this work, we investigate the structure and antibacterial properties of fucoidans from the brown algae Fucus vesiculosus gathered in the littoral of the Barents Sea. These fucoidans appear to have a significant bacteriostatic effect on the growth of four tested bacterial strains. Such an effect was more pronounced for crude fucoidan samples that did not undergo additional steps of purification.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.

Low molecular weight fucoidan fraction ameliorates inflammation and deterioration of skin barrier in fine-dust stimulated keratinocytes

Recently evidence linking the effects of fine-dust (FD) on skin inflammation is exaggerating. Fucoidan derived from brown algae has great potential for ameliorating oxidative stress and inflammation. Herein, a fucoidan fraction (SHC4-6) was purified from an enzymatic (Celluclast) extract of an invasive seaweed, Sargassum horneri following gradient ethanol precipitation and anion exchange chromatography. Effectiveness of SHC4-6 in ameliorating FD (from Beijing, China)-induced inflammatory responses in HaCaT keratinocytes and recovery of skin barrier dysfunction was evaluated. SHC4-6 was comprising of sulfated mannofucans with their molecular weights distributed around 45 kDa. SHC4-6 dose-dependently lowered ROS levels in FD-induced HaCaT keratinocytes, ameliorating viability at 50 μg mL−1. SHC4–6 downregulated inflammatory cytokines, tumor necrosis factor-α, interleukin (IL)-1β, -5, -6, -8, -13, interferon-γ, and chemokines, macrophage-derived chemokine, eotaxin, and thymus and activation regulated chemokine by inhibiting mitogen-activated protein kinase and nuclear factor-κB pathways. SHC4–6 treatment ameliorated key tight junction proteins and skin hydration factors, depicting the effects of fucoidan in reducing FD-induced inflammation and skin barrier deterioration. With further studies in place, SHC4-6 could be used as an ingredient for developing cosmetics to relieve FD-induced skin inflammation.

Structural elucidation of fucoidans from Sargassum pallidum

The brown alga Sargassum pallidum has been used as a traditional Chinese medicine to treat a variety of diseases. Fucoidan is an important bioactive component in S. pallidum; however, its chemical structure has not been thoroughly investigated. In the present study, two fucoidan fractions (SPF-1 and SPF-2) from S. pallidum were obtained by extraction with hot-water, ethanol precipitation, anion-exchange, and size-exclusion chromatography. The structural characterizations of SPF-1 and SPF-2 were investigated using the high-performance gel permeation chromatography (HPGPC) and gas chromatography (GC), followed by periodate oxidation, Smith degradation, and methylation analysis. The results revealed the monosaccharide composition of SPF-1 and SPF-2 to be fucose, mannose, and galactose with small amounts of glucose, xylose, and rhamnose. The molecular weight of SPF-1 and SPF-2 was estimated to be 61.5 kDa and 167.6 kDa, respectively. The backbone of SPF-1 was mainly constituted by (1→3) linked Fuc, (1→3) linked Man, and (1→3,4) linked Man whereas the branches were composed of (1→3) linked Fuc. SPF-2 was a branched polysaccharide with a backbone consisted of (1→3) linked Fuc, (1→3) linked Gal, and (1→3,4) linked Gal and branches composed of (1→3) linked Fuc or Gal. In vitro bioassay revealed that SPF-2 showed higher cytotoxic activity than SPF-1 against P388 and A549 cells. These results provided an insight into the utilization and development of seaweed resources.

Composition of polysaccharides and radiosensitizing activity of native and sulfated laminarans from the Tаuуа basicrassa Kloczc. et Krupn

Polysaccharide fractions of alginate, laminarans and fucoidans were obtained from the brown alga Tauya basicrassa. Yields of alginate and laminarans were large (19.7 % and 5.62 %, respectively), whereas the content of fucoidans (0.52 %) was not significant. Alginate and laminarans had typical structures for those substances. Fucoidans were low- and medium-sulfated heterogeneous polysaccharides. The fucoidan fraction 1TbF1 was sulfated fucogalactan containing a backbone from 1,6-linked residues of β-d-galactopyranose with branches at C3 and C4, terminal fucose and galactose residues and fragments from 1,3-; 1,4-; and 1,2-fucose residues. Sulfate groups were found at positions 2 and 4 of fucose, and positions 2, 3 and 4 of galactose residues. Laminaran 2TbL was subjected to a sulfation to obtain the derivative 2TbLS with partial sulfation (46 %) at C2, C4 and C6. It was shown that 2TbL and 2TbLS inhibited colony formation of sensitize-tested colon cancer cells HT-29 and HCT-116 to X-ray radiation.

Fucoidan refined by Sargassum confusum indicate protective effects suppressing photo-oxidative stress and skin barrier perturbation in UVB-induced human keratinocytes

Damage from ultraviolet (UV)B exposure is cumulative and proceeds via augmenting cellular oxidative stress. The present study investigates UVB-protective effects of Sargassum confusum derived fucoidans in human keratinocytes. Algae was extracted using Celluclast, and fucoidan fractions were recovered by step gradient ethanol precipitation. Refined fucoidan fractions were treated to human HaCaT keratinocytes and exposed to UVB (50 mJ cm−2). Among fucoidan fractions, SCFC4, the lowest molecular weight (MW) fraction indicated better UVB-protective effects with dose-dependent reduction of intracellular ROS levels, while recovering the cell viability. SCFC4 suppressed UVB-induced apoptotic body formation, sub-G1 cell content, and DNA damage by hindering the mitochondria-mediated apoptotic pathway. Also, SCFC4 repressed upstream mediators of UVB-induced inflammatory responses, which would impair stratum corneum hydration. The above therapeutic effects of SCFC4 could be attributed to suppression of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) pathways while activating nuclear factor erythroid 2-related factor 2 (Nrf2) mediated production of antioxidant enzymes. SCFC4 was identified as a fucoidan (MW ≈ 20 kDa) with a 64.64% fucose and 23.62% sulfate contents. Further analysis of shelf life, safety, and efficacy could promote SCFC4's use as a cosmetic ingredient.

Structural Characterization and α-Glucosidase Inhibitory and Antioxidant Activities of Fucoidans Extracted from Saccharina japonica.

Two sulfated fucoidan fractions (Lj3 and Lj5) were extracted from Saccharina japonica and then subjected to acid hydrolysis to obtain Lj3h and Lj5h. Lj3h and Lj5h were characterized using IR, methylation analysis, and mass spectrometry. It was found that Lj3h and Lj5h were homogeneous low molecular weight fucoidans. Specifically, Lj3h was composed of the main chain of 1,3-linked α-L-fucopyranose residues with sulfate at C-2 and/or C-4 and three different monosaccharides (galactose, glucose, mannose) branched at C-2 and/or C-4 of fucose residue. Lj5h contained backbones of alternating galactopyranose residues and fucopyranose residues attached via a 1→3 linkage (galactofucan) and 1→6 linked galactan. The sulfation pattern was mainly located at C2/C4 fucose or galactose residues and more branches occupied at C-4 of fucose residue and C-2, C-3 or/and C-6 of galactose residue. In vitro assay indicated that, among the four fucoidans tested, only Lj5 showed potent α-glucosidase inhibitory activity with IC50 of 153.27±22.89 μg/mL, and the two parent fucoidans, Lj3 and Lj5, showed better antioxidant activity than their derivatives. These findings highlight the structure and bioactivity diversity of Saccharina japonica-derived fucoidans.

Step gradient alcohol precipitation for the purification of low molecular weight fucoidan from Sargassum siliquastrum and its UVB protective effects

Ultraviolet B (UVB) can induce oxidative damage to outermost layers of skin causing suntans, sunburns, and, in severe cases, blisters leading to photoaging. Low molecular weight (MW) fucoidan is renowned for possessing enhanced antioxidant activities. The present study discloses the use of step gradient ethanol precipitation in refining fucoidan fractions (SSQC1-SSQC4) from Sargassum siliquastrum and evaluation of their UVB-protective effects in human HaCaT keratinocytes. Among the fractions, SSQC4 indicated the best bioactive effects. 1H NMR, FTIR, monosaccharide composition by HPAEC-PAD analysis, MW estimation by agarose gel electrophoresis were used to characterize the fractions. SSQC4 was comprising of fucoidan, with an estimated MW distribution of 8–25 kDa. Exposure of UVB increased intracellular ROS, DNA damage, loss of mitochondrial membrane potential, apoptotic body formation causing cell death through the mitochondria-mediated apoptosis pathway. SSQC4 treatment could dose-dependently attenuate the ROS levels and suppress mitochondria-mediated apoptosis in UVB exposed keratinocytes. SSQC4 treatment enhanced cellular antioxidant defense by increasing Nrf2 mediated HO-1 generation, which was identified as the cause of observed bioactivities. The safety and stability of SSQC4 could be further evaluated to promote its use as a bioactive natural ingredient in UV-protective cosmetics.

Protective Effect of Fucoidan against MPP+-Induced SH-SY5Y Cells Apoptosis by Affecting the PI3K/Akt Pathway.

The main pathologic changes of the Parkinson’s disease (PD) is dopaminergic (DA) neurons lost. Apoptosis was one of the important reasons involved in the DA lost. Our previous study found a fucoidan fraction sulfated heterosaccharide (UF) had neuroprotective activity. The aim of this study was to clarify the mechanism of UF on DA neurons using human dopaminergic neuroblastoma (SH-SY5Y) cells a typical as a PD cellular model. Results showed that UF prevented MPP+-induced SH-SY5Y cells apoptosis and cell death. Additionally, UF pretreated cells increased phosphorylation of Akt, PI3K and NGF, which means UF-treated active PI3K–Akt pathway. Moreover, UF treated cells decreased the expression of apoptosis-associated protein, such as the ratio of Bax/Bcl-2, GSK3β, caspase-3 and p53 nuclear induced by MPP+. This effect was partially blocked by PI3K inhibitor LY294002. Our data suggested that protective effect of UF against MPP+-induced SH-SY5Y cells death by affecting the PI3K–Akt pathway. These findings contribute to a better understanding of the critical roles of UF in treating PD and may elucidate the molecular mechanisms of UF effects in PD.

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

Fucoidans from brown macroalgae (brown seaweeds) have different structures and many interesting bioactivities. Fucoidans are classically extracted from brown seaweeds by hot acidic extraction. Here, we report a new targeted enzyme-assisted methodology for fucoidan extraction from brown seaweeds. This enzyme-assisted extraction protocol involves a one-step combined use of a commercial cellulase preparation (Cellic®CTec2) and an alginate lyase from Sphingomonas sp. (SALy), reaction at pH 6.0, 40 °C, removal of non-fucoidan polysaccharides by Ca2+ precipitation, and ethanol-precipitation of crude fucoidan. The workability of this method is demonstrated for fucoidan extraction from Fucus distichus subsp. evanescens (basionym Fucus evanescens) and Saccharina latissima as compared with mild acidic extraction. The crude fucoidans resulting directly from the enzyme-assisted method contained considerable amounts of low molecular weight alginate, but this residual alginate was effectively removed by an additional ion-exchange chromatographic step to yield pure fucoidans (as confirmed by 1H NMR). The fucoidan yields that were obtained by the enzymatic method were comparable to the chemically extracted yields for both F. evanescens and S. latissima, but the molecular sizes of the fucoidans were significantly larger with enzyme-assisted extraction. The molecular weight distribution of the fucoidan fractions was 400 to 800 kDa for F. evanescens and 300 to 800 kDa for S. latissima, whereas the molecular weights of the corresponding chemically extracted fucoidans from these seaweeds were 10–100 kDa and 50–100 kDa, respectively. Enzyme-assisted extraction represents a new gentle strategy for fucoidan extraction and it provides new opportunities for obtaining high yields of native fucoidan structures from brown macroalgae.

Integrated valorization of Sargassum muticum in biorefineries

Marine macroalgae represent an excellent raw material for the production of bioactives, adsorbents, plant biostimulants, soil fertilizers and biogas. The success in the exploitation of seaweeds depends on their characteristics, and the approach used to separate their specific active components. In the context of circular economy, invasive species are a good candidate for exploitation, and biorefinery a key valorization technique. Here we investigate a novel biorefinery scheme for an integral valorization of Sargassum muticum. An initial pressing stage allowed the production of a Sap fraction, which showed potential as a plant biostimulant, increasing both root development and shoot/root ratio, especially when used at a dose of 0.1 g/L lyophilized Sap. The solids after pressing were processed by non isothermal autohydrolysis, using pressurized hot water (up to 120-210 °C), a process previously optimized to solubilize the fucoidan and phlorotannin fractions. The residual solids remaining after pressing and autohydrolysis stages were evaluated for the production of biogas. The obtained value (150 mL CH4/g residual solids at 150 °C) was significantly higher than that found for the raw seaweed. The optimal autohydrolysis temperature (150 °C) is compatible with the production of the fucoidan fraction, although the phenolic content is favoured under more severe operation conditions. We also discuss the possibility of preparing adsorbents for pollutant removal and mineral amendments from the autohydrolysis waste solids.

Human Keratinocyte UVB-Protective Effects of a Low Molecular Weight Fucoidan from Sargassum horneri Purified by Step Gradient Ethanol Precipitation.

Ultraviolet B (UVB) radiation-induced oxidative skin cell damage is a major cause of photoaging. In the present study, a low molecular weight fucoidan fraction (SHC4) was obtained from Sargassum horneri by Celluclast-assisted extraction, followed by step gradient ethanol precipitation. The protective effect of SHC4 was investigated in human keratinocytes against UVB-induced oxidative stress. The purified fucoidan was characterized by Fourier-transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (NMR), agarose gel-based molecular weight analysis and monosaccharide composition analysis. SHC4 had a mean molecular weight of 60 kDa, with 37.43% fucose and 28.01 ± 0.50% sulfate content. The structure was mainly composed of α-L-Fucp-(1→4) linked fucose units. SHC4 treatment dose-dependently reduced intracellular reactive oxygen species (ROS) levels and increased the cell viability of UVB exposed HaCaT keratinocytes. Moreover, SHC4 dose-dependently inhibited UVB-induced apoptotic body formation, sub-G1 accumulation of cells and DNA damage. Inhibition of apoptosis was mediated via the mitochondria-mediated pathway, re-establishing the loss of mitochondrial membrane potential. The UVB protective effect of SHC4 was facilitated by enhancing intracellular antioxidant defense via nuclear factor erythroid 2–related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling. Further studies may promote the use of SHC4 as an active ingredient in cosmetics and nutricosmetics.