Chemical Characterization and Immunomodulatory Activity of Fucoidan from Sargassum hemiphyllum

Antiviral activity of a polysaccharide from Sargassum fusiforme against respiratory syncytial virus

This experiment examined the antiviral activity of polysaccharides from Sargassum fusiforme against respiratory syncytial virus (RSV) in vitro, including their mechanism of action and preliminary structural analysis. Four polysaccharides (SFP1, SFP2, SFP3, and SFP4) were purified from Sargassum fusiforme using a DEAE-52 cellulose column and an NW Super 150 gel column. CCK-8 and western blot were utilized to study the antiviral activities and mechanisms of the polysaccharides. Preliminary structural analysis was conducted using HPLC and NMR techniques. The findings suggest that SFP4 (120 kD) is an acidic chemical compound composed of 88.8 % total sugars, 0.13 % proteins, 10.8 % glucuronidic acids, and 21.1 % sulfates. It contains at least ten monosaccharides, primarily mannuronic acid and fucose. Among the four polysaccharides, SFP4 had the highest anti-RSV activity, with a therapeutic index (TI) exceeding 139. SFP4 exhibited noteworthy antiviral efficacy in both upper and lower respiratory cells that were infected, especially when administered as a prophylactic treatment 2 h in advance. Furthermore, SFP4 showed a dose-dependent antiviral effect, with the highest therapeutic index (TI > 320) observed at a concentration of 7.81 μg·mL-1 during the prophylactic phase. It was speculated that SFP4's antiviral effect is due to its ability to inhibit the attachment of G-proteins to cells.

Fucoidan-based coatings extend the shelf-life of nectarines

This research investigated the efficacy of fucoidan-based coatings in preserving nectarine fruits at room temperature. The present study compared the preservation effects of different fucoidan concentrations (1%, 3%, 5%) with distilled water serving as a control (0%). The findings revealed that the addition of fucoidan dose-dependently improved the room temperature preservation quality of the nectarines. Notably, a 5% fucoidan concentration markedly delays the onset of the respiratory peak in nectarines. On day 14 of storage, the plants were subsequently cultured on a 5% fucoidan coating (F5), which exhibited a weight loss rate of 5.87%, a spoilage rate of 18.33%, a hardness of 3.87 kg/cm², a soluble solid content of 11.47%, a titratable acid content of 0.29% and an ascorbic acid content of 2.58%. The overall acceptability score was 7.83. These results demonstrated that coating with fucoidan is an effective method for the preservation of nectarines.

Fucoidan from the cell wall of Silvetia siliquosa with immunomodulatory effect on RAW 264.7 cells

Silvetia siliquosa, the only species of the family Fucaceae in China, is used as a medicine food homology. Fucoidan from S. siliquosa was extracted by hot water twice thoroughly (13 % of total yield), and a purified fucoidan SSF with a molecular weight of 93 kD was obtained. Chemical composition analysis demonstrated that SSF was primarily composed of sulfate (21.68 wt%) and fucose (84 % of all neutral monosaccharides). IR, methylation analysis, NMR and ESI-MS results indicated SSF had the backbone of mainly (1 → 3)-α-L-fucopyranose and minor (1 → 4)-α-L-fucopyranose, with little 1,3 and 1,4 branched β-D-Xylp and β-D-Galp. The in vitro immunomodulatory test on RAW 264.7 cells showed that SSF could up-regulate the expression of immune related factors and proteins in a concentration-dependent manner, but the immunomodulatory effect disappeared from desulfated SSF. This research indicated that highly sulfated fucan possessed immunomodulatory effect and the importance of sulfate groups in the activity of SSF.

Self-Assembling Sulfated Lactobacillus Exopolysaccharide Nanoparticles as Adjuvants for SARS-CoV-2 Subunit Vaccine Elicit Potent Humoral and Cellular Immune Responses

Coronavirus disease 2019 (COVID-19) has caused a global pandemic since its onset in 2019, and the development of effective vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to induce potent and long-lasting immunity remains a priority. Herein, we prepared two Lactobacillus exopolysaccharide (EPS) nanoparticle adjuvants (NPs 7-4 and NPs 8-2) that were constructed by using sulfation-modified EPS and quaternization-modified chitosan. These two NPs displayed a spherical morphology with sizes of 39 and 47 nm. Furthermore, the zeta potentials of NPs 7-4 and NPs 8-2 were 50.40 and 44.40 mV, respectively. In vitro assays demonstrated that NPs could effectively adsorb antigenic proteins and exhibited a sustained release effect. Mouse immunization tests showed that the NPs induced the expression of cytokines and chemokines at the injection site and promoted the uptake of antigenic proteins by macrophages. Mechanically, the NPs upregulated the expression of pattern recognition receptors (toll-like receptors and nod-like receptors) and activated the immune response of T cells and the production of neutralizing antibodies. In addition, the NP adjuvants had favorable immune-enhancing effects in cats, which are of great significance for controlling the trans-host transmission and re-endemicity of SARS-CoV-2. Overall, we demonstrated that NP-adjuvanted SARS-CoV-2 receptor binding domain proteins could induce robust specific humoral and cellular immunity.

The physiological activities of fucoidan and its application in animal breeding

Fucoidan, a water-soluble heteropolysaccharide predominantly found in brown algae, comprises active components such as fucose and sulfate groups. This polysaccharide exhibits a range of physiological activities, including antioxidant, antiviral, anticancer, and immunomodulatory activities. In light of the global prohibition of antibiotics in animal feed, there is increasing interest in identifying safe, natural antibiotic alternatives that lack toxic side effects. This study focuses on analysing the impact of fucoidan in animal husbandry and provides a comprehensive review of the methods for preparing fucoidan, along with its physical and chemical characteristics. Its applications in the breeding of aquatic species, livestock, and poultry have also been summarized. The aim of this study was to establish a theoretical framework for the use of fucoidan in animal husbandry and to contribute to the theoretical underpinnings of the animal breeding and feed industries.

Biomimetic triumvirate nanogel complexes via peptide-polysaccharide-polyphenol self-assembly

Self-assembled peptide and polysaccharide nanogels are excellent candidates for bioactive delivery vectors. However, there are still significant challenges in the application of nanogels as delivery tools for bioactive elements. This study aims to deliver, and control the release of a hydrophobic bioactive flavonoid hesperidin. Using the self-assembling peptide (SAP) Fmoc-FRGDF, extracellular matrix mimicking nanofibrils were fabricated, which were decorated and bolstered with immunomodulatory polysaccharide strands of fucoidan and infused with hesperidin. The mechanical properties, secondary structure, and microscopic morphologies of the composite hydrogels were characterized using rheometer, FTIR, XRD, and TEM, etc. The encapsulation efficiency (EE) and release behavior of hesperidin were determined. Coassembly of the SAP with fucoidan improved the mechanical properties (from 9.54 Pa of Fmoc-FRGDF hydrogel to 7735 Pa of coassembly hydrogel at 6 mg/mL fucoidan concentration), formed thicker nanofibril bundles at 4 and 6 mg/mL fucoidan concentration, improved the EE of hesperidin from 72.86 % of Fmoc-FRGDF hydrogel to over 90 % of coassembly hydrogels, and showed effectively controlled release of hesperidin in vitro. Intriguingly, the first order kinetic model predicted an enhanced hydrogel retention and release of hesperidin. This study revealed a new approach for bioengineered nanogels that could be used to stabilize and release hydrophobic payloads.

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.

Isolation, Characterization, and Anti-Idiopathic Pulmonary Fibrosis Activity of a Fucoidan from Costaria costata

Pulmonary fibrosis is a chronic, progressive, and fatal disease of the interstitial lung. There is currently a lack of efficient therapy to reverse the prognosis of patients. In this study, a fucoidan from Costaria costata was isolated, and its anti-idiopathic fibrosis activity was investigated both in vitro and in vivo. The chemical composition analysis showed that C. costata polysaccharide (CCP) consists of galactose and fucose as the main monosaccharides with a sulfate group content of 18.54%. Further study found that CCP could resist TGF-β1-induced epithelial-mesenchymal transition (EMT) in A549 cells by inhibiting the TGF-β/Smad and PI3K/AKT/mTOR signaling pathways. Moreover, in vivo study found that CCP treatment alleviated bleomycin (BLM)-stimulated fibrosis and inflammation in mice lung tissue. In conclusion, the present study suggests that CCP could protect the lung from fibrosis by relieving the EMT process and inflammation in lung cells.

Physicochemical Characterization and Antitumor Activity of Fucoidan and Its Degraded Products from Sargassum hemiphyllum (Turner) C. Agardh

Fucoidan has many biological functions, including anti-tumor activity. Additionally, it has been suggested that low-molecular-weight fucoidans have greater bioactivities. This study aimed to examine the degradation, purification, physicochemical characterization and in vitro antitumor activity of fucoidan from Sargassum hemiphyllum (Turner) C. Agardh. Fucoidan was isolated using DEAE-cellulose-52 (F1, F2), Vc-H2O2 degration, and Sepharose CL-6B gel (DF1, DF2) from crude Sargassum fucoidans. Physicochemical characteristics of four isolated fucoidans were examined using chemical and monosaccharide composition, average molecular weight (Mw), and FTIR. Furthermore, the anti-proliferative effects of purified fucoidans on human hepatocellular carcinoma cells (HepG2), human Burkitt Lymphoma cells (MCF-7), human uterine carcinoma cells (Hela) and human lung cancer cells (A549) were analyzed by MTT method. The apoptosis of HepG2 cells was detected by flow cytometry. Our data suggest that the contents of polysaccharide, L-fucose and sulfate of DF2 were the highest, which were 73.93%, 23.02% and 29.88%, respectively. DF1 has the smallest molecular weight (14,893 Da) followed by DF2 (21,292 Da). The four fractions are mainly composed of fucose, mannose and rhamnose, and the infrared spectra are similar, all of which contain polysaccharide and sulfate characteristic absorption peaks. The results of MTT assay showed that the four fractions had inhibitory effects on HepG2 and A549 in the range of 0.5-8 mg/mL, and the four fractions had strong cytotoxic effects on HepG2 cells. DF2 had the best inhibitory effect on HepG2 (IC50 = 2.2 mg/mL). In general, the antitumor activity of Sargassum fucoidans is related to the content of L-fucose, sulfate and molecular weight, and Sargassum fucoidan has the best inhibitory effect on HepG2 hepatocellular carcinoma cells. Furthermore, when compared to MCF-7, Hela, and A549 cells, Sargassum fucoidans had the best capacity to reduce the viability of human hepatocellular carcinoma cells (HepG2) and to induce cell apoptosis, proving itself to have a good potential in anti-liver cancer therapy.

Antioxidative and Protective Effect of Morchella esculenta against Dextran Sulfate Sodium-Induced Alterations in Liver

Morchella esculenta is an edible mushroom with special flavor and high nutritional value for humans, primarily owing to its polysaccharide constituents. M. esculenta polysaccharides (MEPs) possess remarkable pharmaceutical properties, including antioxidant, anti-inflammatory, immunomodulatory, and anti-atherogenic activities. The aim of this study was to evaluate the in vitro and in vivo antioxidant potential of MEPs. In vitro activity was determined using free radical scavenging assays, whereas in vivo activity was evaluated through dextran sodium sulfate (DSS)-induced liver injury in mice with acute colitis. MEPs effectively scavenged 1,1-diphenyl-2-picrylhydrazyl and 2,2-azinobis-6-(3-ethylbenzothiazoline sulfonic acid) free radicals in a dose-dependent manner. Additionally, DSS-induced mice showed severe liver damage, cellular infiltration, tissue necrosis, and decreased antioxidant capacity. In contrast, intragastric administration of MEPs showed hepatoprotective effects against DSS-induced liver injury. MEPs remarkably elevated the expression levels of superoxide dismutase, glutathione peroxidase, and catalase. Additionally, it decreased malondialdehyde and myeloperoxidase levels in the liver. These results indicate that the protective effects of MEP against DSS-induced hepatic injury could rely on its ability to reduce oxidative stress, suppress inflammatory responses, and improve antioxidant enzyme activity in the liver. Therefore, MEPs could be explored as potential natural antioxidant agents in medicine or as functional foods to prevent liver injury.