Fucoidan from Ascophyllum nodosum and Undaria pinnatifida attenuate SARS-CoV-2 infection in vitro and in vivo by suppressing ACE2 and alleviating inflammation.

The global healthcare challenge posed by COVID-19 necessitates the continuous exploration for novel antiviral agents. Fucoidans have demonstrated antiviral activity. However, the underlying structure-activity mechanism responsible for the inhibitory activity of fucoidans from Ascophyllum nodosum (FUCA) and Undaria pinnatifida (FUCU) against SARS-CoV-2 remains unclear. FUCA was characterized as a homopolymer with a backbone structure of repeating (1 â†’ 3) and (1 â†’ 4) linked α-l-fucopyranose residues, whereas FUCU was a heteropolysaccharide composed of Fuc1-3Gal1-6 repeats. Furthermore, FUCA demonstrated significantly higher anti-SARS-CoV-2 activity than FUCU (EC50: 48.66 vs 69.52 µg/mL), suggesting the degree of branching rather than sulfate content affected the antiviral activity. Additionally, FUCA exhibited a dose-dependent inhibitory effect on ACE2, surpassing the inhibitory activity of FUCU. In vitro, both FUCA and FUCU treatments downregulated the expression of pro-inflammatory cytokines (IL-6, IFN-α, IFN-γ, and TNF-α) and anti-inflammatory cytokines (IL-10 and IFN-ß) induced by viral infection. In hamsters, FUCA demonstrated greater effectiveness in attenuating lung and gastrointestinal injury and reducing ACE2 expression, compared to FUCU. Analysis of the 16S rRNA gene sequencing revealed that only FUCU partially alleviated the gut microbiota dysbiosis caused by SARS-CoV-2. Consequently, our study provides a scientific basis for considering fucoidans as poteintial prophylactic food components against SARS-CoV-2.

Anti-Hyperlipidemic Effect of Fucoidan Fractions Prepared from Iceland Brown Algae Ascophyllum nodosum in an Hyperlipidemic Mice Model.

Ascophyllum nodosum, a brown algae abundantly found along the North Atlantic coast, is recognized for its high polysaccharide content. In this study, we investigated the anti-hyperlipidemic effect of fucoidans derived from A. nodosum, aiming to provide information for their potential application in anti-hyperlipidemic therapies and to explore comprehensive utilization of this Iceland brown seaweed. The crude fucoidan prepared from A. nodosum was separated using a diethylethanolamine column, resulting in two fucoidan fractions, AFC-1 and AFC-2. Both fractions were predominantly composed of fucose and xylose. AFC-1 exhibited a higher sulfate content of 27.8% compared to AFC-2 with 17.0%. AFC-2 was primarily sulfated at the hydroxy group of C2, whereas AFC-1 was sulfated at both the hydroxy groups of C2 and C4. To evaluate the anti-hyperlipidemic effect, a hyperlipidemia mouse model was established by feeding mice a high-fat diet. The effects of AFC-1, AFC-2, and the crude extract were investigated, with the drug atorvastatin used as a positive comparison. Among the different fucoidan fractions and doses, the high dose of AFC-2 administration demonstrated the most significant anti-hyperlipidemic effect across various aspects, including physiological parameters, blood glucose levels, lipid profile, histological analysis, and the activities of oxidative stress-related enzymes and lipoprotein-metabolism-related enzymes (p < 0.05 for the final body weight and p < 0.01 for the rest indicators, compared with the model group), and its effect is comparable to the atorvastatin administration. Furthermore, fucoidan administration resulted in a lower degree of loss in gut flora diversity compared to atorvastatin administration. These findings highlight the significant biomedical potential of fucoidans derived from A. nodosum as a promising therapeutic solution for hypolipidemia.

Fecal microbiota transplantation from sodium alginate-dosed mice and normal mice mitigates intestinal barrier injury and gut dysbiosis induced by antibiotics and cyclophosphamide.

This study investigated the protective properties of fecal microbiota derived from mice treated with sodium alginate (SA) and normal mice with both types immunosuppressed by exposure to antibiotics and cyclophosphamide. A dietary intervention using SA obviously increased the diversity and improved the composition of gut microbiota in normal mice. Fecal microbiota transfer (FMT) from both mice treated with sodium alginate and normal mice alleviated spleen tissue damage and improved immune function. FMT alleviated intestinal mucosal injury and reduced intestinal permeability via increasing mucin and tight junction protein expression. In addition, FMT reduced gut inflammation via down-regulating the expression of toll-like receptor 4 protein. Furthermore, FMT treatment improved the disordered gut microbiota via increasing the abundance of Lactobacillus and Lachnospiraceae NK4A136 group whilst decreasing the abundance of Bacteroides. PICRUSt2 function prediction analysis showed that, compared with the model group, FMT treatment significantly down-regulated lipopolysaccharide biosynthesis and the mitogen-activated protein kinase signaling pathway-fly. Collectively, we found that SA can regulate the gut microbiota structure of normal mice and confirms the effectiveness of FMT in alleviating intestinal barrier damage and gut dysbiosis in antibiotic-cyclophosphamide-induced immunosuppressed mice. This work also reveals that SA can potentially alleviate the immunosuppression caused by cyclophosphamide in mice by modulating the intestinal microbiota and exploiting their functional properties.

A Novel Sodium Alginate-Carnauba Wax Film Containing Calcium Ascorbate: Structural Properties and Preservative Effect on Fresh-Cut Apples.

In order to improve the mechanical properties, nutritional value and fresh-keeping ability of conventional sodium alginate edible composite membranes, a new type of edible composite film was prepared by adding water-blocking agent carnauba wax, plasticizer glycerin, antioxidant and nutritional enhancer sodium ascorbate on a basis of traditional sodium alginate composite film. In this study, the physical, mechanical and structural properties of different film components were investigated. The results showed the components did not simply combine, but produced interaction forces which improved the stability and mechanical properties of composite film. When the amount of calcium ascorbate was 0.4%, the water vapor transmittance of the composite film reached a minimum of 0.65 g·mm/(cm2·d·kPa), and the tensile strength and elongation at break reached the maximum, which were 398.64 MPa and 17.93%, respectively. Additionally, the sodium alginate-carnauba wax film exhibited better performance on the preservation of fresh-cut apples. Compared with other composite films, the color and hardness of fresh-cut apples coated with this composite film were better maintained, and the losses of titration acid content and soluble solid content were reduced. Moreover, the weight loss rate, increase in polyphenol oxidase activity and total colony count were inhibited. All results determined that the edible film has good application value in the field of fresh-cut fruit preservation, which provides a theoretical basis for further research on edible film.

High-efficiency chromosomal integrative amplification strategy for overexpressing α-amylase in Bacillus licheniformis.

Bacillus licheniformis is a well-known platform strain for production of industrial enzymes. However, the development of genetically stable recombinant B. licheniformis for high-yield enzyme production is still laborious. Here, a pair of plasmids, pUB-MazF and pUB'-EX1, were firstly constructed. pUB-MazF is a thermosensitive, self-replicable plasmid. It was able to efficiently cure from the host cell through induced expression of an endoribonuclease MazF, which is lethal to the host cell. pUB'-EX1 is a nonreplicative and integrative plasmid. Its replication was dependent on the thermosensitive replicase produced by pUB-MazF. Transformation of pUB'-EX1 into the B. licheniformis BL-UBM harboring pUB-MazF resulted in both plasmids coexisting in the host cell. At an elevated temperature, and in the presence of isopropyl-1-thio-ß-d-galactopyranoside and kanamycin, curing of the pUB-MazF and multiple-copy integration of pUB'-EX1 occurred, simultaneously. Through this procedure, genetically stable recombinants integrated multiple copies of amyS, from Geobacillus stearothermophilus ATCC 31195 were facilely obtained. The genetic stability of the recombinants was verified by repeated subculturing and shaking flask fermentations. The production of α-amylase by recombinant BLiS-002, harboring five copies of amyS, in a 50-l bioreactor reached 50 753 U/ml after 72 hr fermentation. This strategy therefore has potential for production of other enzymes in B. licheniformis and for genetic modification of other Bacillus species.

Preparation of Fucoidan-Based Electrospun Nanofibers and Their Interaction With Endothelial Cells.

Sulfated polysaccharide fucoidan (FD) is widely applied in biomedical applications owing to its outstanding bioactivities. In addition to the biochemical features, the architecture of biomaterials plays a critical role in tissue repair and regeneration. Particularly, nanofibers have elicited great interest due to their extracellular matrix-like structure, high specific surface area, and favorable biological properties. Herein, chitosan-modified FD/ultra-high molecular weight polyethylene oxide (UHMWPEO) nanofibers are developed via green electrospinning and electrostatic interaction for studying their interaction with endothelial cells. The appropriate solvent is screened to dissolve FD. The electrospinnability of FD/UHMWPEO aqueous solutions is greatly dependent on the weight ratios of FD/UHMWPEO. The incorporation of UHMWPEO significantly improves the electrospinnability of solution and thermo-stability of nanofibers. Also, it is found that there is good miscibility or no phase separation in FD/UHMWPEO solutions. In vitro biological experiments show that the chitosan-modified FD/UHMWPEO nanofibers greatly facilitate the adhesion of endothelial cells and inhibit the attachment of monocytes. Thus, the designed FD-based nanofibers are promising bio-scaffolds in building tissue-engineered blood vessels.

Preparation of triamcinolone acetonide-loaded chitosan/fucoidan hydrogel and its potential application as an oral mucosa patch.

Oral inflammatory diseases (OIDs) are among the most common lesions in the oral cavity, affecting the quality of human life and even causing oral cancer. However, most of the current oral mucosa patches still have some limitations, particularly instant, poor mechanical strength and conformability, low adhesion to tissue, and foreign body sensation. Herein, triamcinolone acetonide (TA)-loaded chitosan/fucoidan (CF) composite hydrogels were prepared via chemical crosslinking. The macro/microscopic morphologies and (bio)physicochemical properties of composite hydrogels were investigated. Incorporating fucoidan in chitosan hydrogels greatly enhanced their swelling behavior, mechanical strength, and adhesion properties. Further, the addition of TA in CF hydrogels improved their elastic feature, inhibited inflammatory response, and promoted the formation of mature and well-organized collagen fibers. The developed composite hydrogels displayed not only good antibacterial properties but also good cytocompatibility and histocompatibility. Thus, the designed hydrogels allow the development of oral mucosa patches as a potential treatment for OIDs.

Marine polysaccharide-based composite hydrogels containing fucoidan: Preparation, physicochemical characterization, and biocompatible evaluation.

Marine polysaccharide-based hydrogels have drawn much attention for diversified biomedical applications owing to their excellent (bio)physicochemical properties. In the present work, a series of marine polysaccharide-based hydrogels composed of chitosan, alginate, or fucoidan are prepared via a facile chemical cross-linking approach in an alkali/urea aqueous system. The prepared hydrogels possess tunable microporous architecture, swelling, and biodegradable properties by changing the components and proportions of marine polysaccharides. Importantly, the developed hydrogels are mechanically robust and the maximum compressive stress is up to 28.37 ± 4.63 kPa. Furthermore, the composite hydrogels exhibit excellent cytocompatibility, blood compatibility, and histocompatibility. When implanted subcutaneously in rats, the hydrogels containing fucoidan inhibit the inflammatory response of surrounding tissue. Thus, the designed composite hydrogels are promising bio-scaffolds in biomedical applications.

Exploitation of ammonia-inducible promoters for enzyme overexpression in Bacillus licheniformis.

Ammonium hydroxide is conventionally used as an alkaline reagent and cost-effective nitrogen source in enzyme manufacturing processes. However, few ammonia-inducible enzyme expression systems have been described thus far. In this study, genomic-wide transcriptional changes in Bacillus licheniformis CBBD302 cultivated in media supplemented with ammonia were analyzed, resulting in identification of 1443 differently expressed genes, of which 859 genes were upregulated and 584 downregulated. Subsequently, the nucleotide sequences of ammonia-inducible promoters were analyzed and their functionally-mediated expression of amyL, encoding an α-amylase, was shown. TRNA_RS39005 (copA), TRNA_RS41250 (sacA), TRNA_RS23130 (pdpX), TRNA_RS42535 (ald), TRNA_RS31535 (plp), and TRNA_RS23240 (dfp) were selected out of the 859 upregulated genes and each showed higher transcription levels (FPKM values) in the presence of ammonia and glucose than that of the control. The promoters, PcopA from copA, PsacA from sacA, PpdpX from pdpX, Pald from ald, and Pplp from plp, except Pdfp from dfp, were able to mediate amyL expression and were significantly induced by ammonia. The highest enzyme expression level was mediated by Pplp and represented 23% more α-amylase activity after induction by ammonia in a 5-L fermenter. In conclusion, B. licheniformis possesses glucose-independent ammonia-inducible promoters, which can be used to mediate enzyme expression and therefore enhance the enzyme yield in fermentations conventionally fed with ammonia for pH adjustment and nitrogen supply.

Fucoidan as a marine-origin prebiotic modulates the growth and antibacterial ability of Lactobacillus rhamnosus.

Fucoidan has received much attention in healthy food and biomedicine owing to their unique (bio)physicochemical properties, particularly antibacterial and antiviral. Pathogenic microorganisms and probiotics are coexisting in many tissues (e.g., gut, oral, and vagina). However, the effect of fucoidan on probiotics has not been examined. Herein, fucoidan sterilized by different methods (i.e., 0.22 µm filter and high-temperature autoclave) is applied to explore its effect on the responses of Lactobacillus rhamnosus. It is found that high-temperature autoclave treatment causes the depolymerization of fucoidan. Further, the proliferation, morphology, and metabolism of probiotics are greatly dependent on the concentrations of fucoidan. The formation of probiotic biofilm is reduced with an increased concentration of fucoidan. Moreover, the antibacterial ability of probiotics initially increases and then decreases with an increased concentration of fucoidan. Thus, fucoidan could serve as a new marine-origin prebiotic, offering new insight into probiotic modulation and its application in inhibiting bacterial infections.

Galactofucan from Laminaria japonica is not degraded by the human digestive system but inhibits pancreatic lipase and modifies the intestinal microbiota.

The effects of galactofucan from Laminaria japonica on the digestion and intestinal microbiota of human were investigated in the present study. Crude fraction of the sulfated polysaccharide from L. japonica (CF) and its molecular-weight homogeneous fraction (CGF-3) were prepared and characterized. In the simulated digestion model for the human saliva and gastrointestinal tract, no obvious changes in the molecular weight or the reducing sugar content of CGF-3 were observed, indicating CGF-3 is resistant to the human digestive system. Then CGF-3 did not affect the α-amylase activity while it dose-dependently inhibited the activity of pancreatic lipase partly depending on its sulfate groups. In the in vitro fermentation with the human fecal microbiota, CF did not change the total carbohydrate, reducing sugar and short chain fatty acids contents, which indicated CF was not utilized by the microbiota. However, the microbiota composition was modulated greatly by CF intervention. These findings shed a light on the better understanding of the impacts of dietary galactofucan on the digestion and intestinal microbiota.

Structures, properties and application of alginic acid: A review.

Alginic acid is a natural polysaccharide, which has been widely concerned and applied due to its excellent water solubility, film formation, biodegradability and biocompatibility. This paper briefly describes the source, properties, structure and application of sodium alginate by summarizing and analyzing the current literature. This paper reviews the application of sodium alginate in the fields of food industry, catalyst, health, water treatment, packaging, immobilized cells, and looks forward to its application prospects.

A Novel Pectic Polysaccharide of Jujube Pomace: Structural Analysis and Intracellular Antioxidant Activities.

After extraction from jujube pomace and purification by two columns (DEAE-Sepharose Fast Flow and Sepharcyl S-300), the structure of SAZMP4 was investigated by HPGPC, GC, FI-IR, GC-MS, NMR, SEM, and AFM. Analysis determined that SAZMP4 (Mw = 28.94 kDa) was a pectic polysaccharide mainly containing 1,4-linked GalA (93.48%) with side chains of 1,2,4-linked Rha and 1,3,5-linked Ara and terminals of 1-linked Rha and 1-linked Ara, which might be the homogalacturonan (HG) type with side chains of the RG-I type, corresponding to the results of NMR. In AFM and SEM images, self-assembly and aggregation of SAZMP4 were respectively observed indicating its structural features. The antioxidant activity of SAZMP4 against H2O2-induced oxidative stress in Caco-2 cells was determined by activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) as well as malondialdehyde (MDA) and reactive oxygen species (ROS) levels, indicating SAZMP4 can be a natural antioxidant. Also, a better water retention capacity and thermal stability of SAZMP4 was observed based on DSC analysis, which could be applied in food industry as an additive.

Alginate Oligosaccharide (AOS) induced resistance to Pst DC3000 via salicylic acid-mediated signaling pathway in Arabidopsis thaliana.

Alginate Oligosaccharide (AOS) is a natural biological carbohydrate extracted from seaweed. In our study, Arabidopsis thaliana was used to evaluate the AOS-induced resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). Resistance was vitally enhanced at 25 mg/L in wild type (WT), showing the decreased disease index and bacteria colonies, burst of ROS and NO, high transcription expression of resistance genes PR1 and increased content of salicylic acid (SA). In SA deficient mutant (sid2), AOS-induced disease resistance dropped obviously compared to WT. The disease index was significantly higher than WT and the expression of recA and avrPtoB are two and four times lower than WT, implying that AOS induces disease resistance injecting Pst DC3000 after three days treatment by arousing the SA pathway. Our results provide a reference for the profound research and application of AOS in agriculture.

Microwave assisted extraction of phenolic compounds from four economic brown macroalgae species and evaluation of their antioxidant activities and inhibitory effects on α-amylase, α-glucosidase, pancreatic lipase and tyrosinase.

Four economically important brown algae species (Ascophyllum nodosum, Laminaria japonica, Lessonia trabeculate and Lessonia nigrecens) were investigated for phenolic compound extraction and evaluated for their antioxidant, anti-hyperglycemic, and pancreatic lipase and tyrosinase inhibition activities. Microwave assisted extraction (MAE) at 110 °C for 15 min resulted in both higher crude yield and higher total phenolic content (TPC) for all algae species compared with those obtained by conventional extraction at room temperature for 4 h, and Ascophyllum nodosum yielded the highest TPC. Antioxidant tests indicated that extracts acquired by MAE from four species all exhibited higher DPPH, ABTS free radical scavenging ability and reducing power than the conventional method. The extract of Lessonia trabeculate exhibited good α-amylase, α-glucosidase, pancreatic lipase, and tyrosinase inhibition activities, and the MAE extract showed even better α-glucosidase inhibitory activity than acarbose.

An Extended Approach to Quantify Triacylglycerol in Microalgae by Characteristic Fatty Acids.

Microalgae represent a third generation biofuel feedstock due to their high triacylglycerol (TAG) content under adverse environmental conditions. Microalgal TAG resides in a single cell and serves as a lipid class mixed with complicated compositions. We previously showed that TAG possessed characteristic fatty acids (CFAs) for quantification and was linearly correlated with the relative abundance of CFA within certain limits in microalgae. Here, we defined the application range of the linear correlation between TAG and CFA in the oleaginous microalgae Chlamydomonas reinhardtii and Phaeodactylum tricornutum. In addition, TAG quantification was further expanded to a wide range of levels and the absolute amounts of saturated or monounsaturated CFAs, 16:0 and 18:1n9 of C. reinhardtii and 16:0 and 16:1n7 of P. tricornutum, instead of polyunsaturated CFAs, were verified to be linearly correlated to TAG levels throughout the entire period of nitrogen stress. This approach utilizes a single fatty acid to quantify TAG mixtures, and is rapid, simple and precise, which provides a useful tool for monitoring TAG accumulation of distinct microalgal species and facilitating high-throughput mutant screening for microalgae.

Identification of Characteristic Fatty Acids to Quantify Triacylglycerols in Microalgae.

The fatty acid profiles of lipids from microalgae are unique. Polyunsaturated fatty acids are generally enriched in polar lipids, whereas saturated and monounsaturated fatty acids constitute the majority of fatty acids in triacylglycerols (TAG). Each species has characteristic fatty acids, and their content is positively or negatively correlated with TAGs. The marine oleaginous diatom Phaeodactylum tricornutum was used as the paradigm to determine the quantitative relationship between TAG and characteristic fatty acid content. Fatty acid profiles and TAG content of Phaeodactylum tricornutum were determined in a time course. C16:0/C16:1 and eicosapentaenoic acid (EPA, C20:5n3) were identified as characteristic fatty acids in TAGs and polar lipids, respectively. The percentage of those characteristic fatty acids in total fatty acids had a significant linear relationship with TAG content, and thus, the correlation coefficient presenting r (2) were 0.96, 0.94, and 0.97, respectively. The fatty acid-based method for TAG quantification could also be applied to other microalgae such as Nannochloropsis oceanica in which the r (2) of C16:0 and EPA were 0.94 and 0.97, respectively, and in Chlorella pyrenoidosa r (2)-values for C18:1 and C18:3 with TAG content were 0.91 and 0.99, repectively. This characteristic fatty acid-based method provided a distinct way to quantify TAGs in microalgae, by which TAGs could be measured precisely by immediate transesterification from wet biomass rather than using conventional methods. This procedure simplified the operation and required smaller samples than conventional methods.

The utilization of natural soda resource of Ordos in the cultivation of Nannochloropsis oceanica.

Nannochloropsis oceanica is famous for its strong environmental adaptability and oil-richness, especially high eicosapentaenoic acid (EPA) content. In this report, the possibility and cultivation parameters for N. oceanica using natural crude soda were testified and compared with seawater culture. To keep a suitable salinity range, different ratio of sea salt addition into soda lake water were used and the growth, lipid content, Fv/Fm and fatty acids profiling were inspected with nitrogen repletion or depletion. The results showed the best performance were achieved while 18g/L (salinity 25‰) sea salt was added into crude soda solution. The µmax and EPA content in fatty acids were 0.72/0.42 and 36%/23% in 500mL/100L bioreactor cultivations respectively, which maintained a relative high productivity to other reports. By comparing the growth and operations with Spirulina production, the feasibility of N. Oceanica in Ordos was proved on both technical and economical point of view.