Polysaccharides from Padina tetrastromatica: Structural features, chemical modification and antiviral activity

Chemically modified seaweed polysaccharides: Improved functional and biological properties and prospective in food applications

Seaweed polysaccharides are natural biomacromolecules with unique physicochemical properties (e.g., good gelling, emulsifying, and film-forming properties) and diverse biological activities (e.g., anticoagulant, antioxidant, immunoregulatory, and antitumor effects). Furthermore, they are nontoxic, biocompatible and biodegradable, and abundant in resources. Therefore, they have been widely utilized in food, cosmetics, and pharmaceutical industries. However, their properties and bioactivities sometimes are not satisfactory for some purposes. Modification of polysaccharides can impart the amphiphilicity and new functions to the biopolymers and change the structure and conformation, thus effectively improving their functional properties and biological activities so as to meet the requirement for targeted applications. This review outlined the modification methods of representative red algae polysaccharides (carrageenan and agar), brown algae polysaccharides (fucoidan, alginate, and laminaran), and green algae polysaccharides (ulvan) that have potential food applications, including etherification, esterification, degradation, sulfation, phosphorylation, selenylation, and so on. The improved functional properties and bioactivities of the modified seaweed polysaccharides and their potential food applications are also summarized.

Padina Minor Extract Confers Resistance against Candida Albicans Infection: Evaluation in a Zebrafish Model

Padina minor is a seaweed rich in polysaccharides often used in food, feed, fertilizers, and antibacterial drugs. This study is the first to evaluate the effect of feeding zebrafish with Padina minor extract on preventing and treating C. albicans infections. This study evaluated the growth, survival, and disease resistance effects of P. minor extract on zebrafish. The fish were divided into four groups: three groups treated with 1%, 5%, or 10% P. minor extract and one untreated group (c, control). Subsequently, we analyzed how the extract affected the immune function of zebrafish infected with C. albicans. Based on the lethal concentration (LC50) calculated in the first stage, 1% was used as the effective therapeutic concentration. The results showed that the growth rate of the 1% feed group was the best, and no significant difference in survival rates between the four groups was observed. Feeding with 1% P. minor extract downregulated the expression of key inflammatory genes like tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and IL-10, effectively preventing and treating C. albicans infections in zebrafish. This study is a preliminary evaluation of the therapeutic efficacy of P. minor extracts against C. albicans.

Assessment of antimicrobial activity and GC-MS using culture filtrate of local marine Bacillus strains

Secondary metabolites produced by Bacillus species from marine sources encompass a variety of compounds such as lipopeptides, isocoumarins, polyketides, macrolactones, polypeptides and fatty acids. These bioactive substances exhibit various biological activities, including antibiotic, antifungal, antiviral, and antitumor properties. This study aimed to isolate and identify a particular species of Bacillus from marine water and organisms that can produce bioactive secondary metabolites. Among the 73 Bacillus isolates collected, only 5 exhibited antagonistic activity against various viral and bacterial pathogens. The active isolates were subjected to 16S rRNA sequencing to determine their taxonomical affiliation. Among them, Bacillus tequilensis CCASU-2024-66 strain no. 42, with the accession number ON 054302 in GenBank, exhibited the highest inhibitory potential. It displayed an inhibition zone of 21 mm against Bacillus cereus while showing a minimum zone of inhibition of 9 mm against Escherichia coli and gave different inhibition against pathogenic fungi, the highest inhibition zone 15 mm against Candida albicans but the lowest inhibition zone 10 mm was against Botrytis cinerea, Fusarium oxysporum. Furthermore, it demonstrated the highest percentage of virucidal effect against the Newcastle virus and influenza virus, with rates of 98.6% and 98.1%, respectively. Furthermore, GC-MS analysis was employed to examine the bioactive substance components, specifically focusing on volatile and polysaccharide compounds. Based on these results, Bacillus tequilensis strain 42 may have the potential to be employed as an antiviral agent in poultry cultures to combat Newcastle and influenza, two extremely destructive viruses, thus reducing economic losses in the poultry production sector. Bacteria can be harnessed for the purpose of preserving food and controlling pathogenic fungi in both human and plant environments. Molecular docking for the three highly active derivatives 2,3-Butanediol, 2TMS, D-Xylopyranose, 4TMS, and Glucofuranoside, methyl 2,3,5,6-tetrakis-O-(trimethylsilyl) was carried out against the active sites of Bacillus cereus, Listeria monocytogenes, Candida albicans, Newcastle virus and influenza virus. The data obtained from molecular docking is highly correlated with that obtained from biology. Moreover, these highly active compounds exhibited excellent proposed ADMET profile.

Biopharmaceutical applications of microbial polysaccharides as materials: A review

Biological characteristics of natural polymers make microbial polysaccharides an excellent choice for biopharmaceuticals. Due to its easy purifying procedure and high production efficiency, it is capable of resolving the existing application issues associated with some plant and animal polysaccharides. Furthermore, microbial polysaccharides are recognized as prospective substitutes for these polysaccharides based on the search for eco-friendly chemicals. In this review, the microstructure and properties of microbial polysaccharides are utilized to highlight their characteristics and potential medical applications. From the standpoint of pathogenic processes, in-depth explanations are provided on the effects of microbial polysaccharides as active ingredients in the treatment of human diseases, anti-aging, and drug delivery. In addition, the scholarly developments and commercial applications of microbial polysaccharides as medical raw materials are also discussed. The conclusion is that understanding the use of microbial polysaccharides in biopharmaceuticals is essential for the future development of pharmacology and therapeutic medicine.

In vitro antiviral activities of fruit extract from Lycium barbarum and methylxanthines extracted from Pu-erh and Bancha tea leaves

INTRODUCTION

Based on traditional medicine, many countries use various plant products (fruits, leaves and other plant parts) as food supplements or in the form of tea. The use of these plant sources has been established through the years of use and the proven benefits of their ingredients to improve human health.

Antiviral Activities of Algal-Based Sulfated Polysaccharides

An antiviral agent is urgently needed based on the high probability of the emergence and re-emergence of future viral disease, highlighted by the recent global COVID-19 pandemic. The emergence may be seen in the discovery of the Alpha, Beta, Gamma, Delta, and recently discovered Omicron variants of SARS-CoV-2. The need for strategies besides testing and isolation, social distancing, and vaccine development is clear. One of the strategies includes searching for an antiviral agent that provides effective results without toxicity, which is well-presented by significant results for carrageenan nasal spray in providing efficacy against human coronavirus-infected patients. As the primary producer of sulfated polysaccharides, marine plants, including macro- and microalgae, offer versatility in culture, production, and post-isolation development in obtaining the needed antiviral agent. Therefore, this review will describe an attempt to highlight the search for practical and safe antiviral agents from algal-based sulfated polysaccharides and to unveil their features for future development.

Antiviral Strategies Using Natural Source-Derived Sulfated Polysaccharides in the Light of the COVID-19 Pandemic and Major Human Pathogenic Viruses

Only a mere fraction of the huge variety of human pathogenic viruses can be targeted by the currently available spectrum of antiviral drugs. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has highlighted the urgent need for molecules that can be deployed quickly to treat novel, developing or re-emerging viral infections. Sulfated polysaccharides are found on the surfaces of both the susceptible host cells and the majority of human viruses, and thus can play an important role during viral infection. Such polysaccharides widely occurring in natural sources, specifically those converted into sulfated varieties, have already proved to possess a high level and sometimes also broad-spectrum antiviral activity. This antiviral potency can be determined through multifold molecular pathways, which in many cases have low profiles of cytotoxicity. Consequently, several new polysaccharide-derived drugs are currently being investigated in clinical settings. We reviewed the present status of research on sulfated polysaccharide-based antiviral agents, their structural characteristics, structure-activity relationships, and the potential of clinical application. Furthermore, the molecular mechanisms of sulfated polysaccharides involved in viral infection or in antiviral activity, respectively, are discussed, together with a focus on the emerging methodology contributing to polysaccharide-based drug development.

The Antiviral Activity of Bacterial, Fungal, and Algal Polysaccharides as Bioactive Ingredients: Potential Uses for Enhancing Immune Systems and Preventing Viruses

Viral infections may cause serious human diseases. For instance, the recent appearance of the novel virus, SARS-CoV-2, causing COVID-19, has spread globally and is a serious public health concern. The consumption of healthy, proper, functional, and nutrient-rich foods has an important role in enhancing an individual's immune system and preventing viral infections. Several polysaccharides from natural sources such as algae, bacteria, and fungi have been considered as generally recognized as safe (GRAS) by the US Food and Drug Administration. They are safe, low-toxicity, biodegradable, and have biological activities. In this review, the bioactive polysaccharides derived from various microorganisms, including bacteria, fungi, and algae were evaluated. Antiviral mechanisms of these polysaccharides were discussed. Finally, the potential use of microbial and algal polysaccharides as an antiviral and immune boosting strategy was addressed. The microbial polysaccharides exhibited several bioactivities, including antioxidant, anti-inflammatory, antimicrobial, antitumor, and immunomodulatory activities. Some microbes are able to produce sulfated polysaccharides, which are well-known to exert a board spectrum of biological activities, especially antiviral properties. Microbial polysaccharide can inhibit various viruses using different mechanisms. Furthermore, these microbial polysaccharides are also able to modulate immune responses to prevent and/or inhibit virus infections. There are many molecular factors influencing their bioactivities, e.g., functional groups, conformations, compositions, and molecular weight. At this stage of development, microbial polysaccharides will be used as adjuvants, nutrient supplements, and for drug delivery to prevent several virus infections, especially SARS-CoV-2 infection.

Design of a New Fermented Beverage from Medicinal Plants and Organic Sugarcane Molasses via Lactic Fermentation

Functional beverages obtained using medicinal plants and fermented with lactic acid bacteria are gaining much interest from the scientific community, driven by the growing demand for food and beverages with beneficial properties. In this work, three different batches of medicinal plants and organic sugarcane molasses, named FB-lc, FB-sp and FB-lcsp, were prepared and fermented by using Lactobacillus acidophilus ATCC 43121, Bifidobacterium breve B632 and a mix of both strains’ culture, respectively. The three fermented beverages revealed a high level of polyphenols (expressed as gallic acid equivalent), ranging from 182.50 to 315.62 µg/mL. The highest content of flavonoids (152.13 µg quercetin equivalent/mL) and tannins (93.602 µg catechin equivalent/mL) was detected in FB-lcsp trial. The IR spectroscopy analysis showed a decrease in sugar (pyranose forms, D-glucopyranose and rhamnosides). In addition, the aromatic compounds of the fermented beverages, detected by GC-MS headspace analysis, showed twenty-four interesting volatile compounds, which could give positive aroma attributes to the flavor of the beverages. The highest antioxidant activity was observed in the beverage obtained by the mix culture strains. Accordingly, the production of these beverages can be further investigated for considering their well-being effects on human health.

Medicinal Plants, Phytochemicals, and Herbs to Combat Viral Pathogens Including SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome corona virus-2 (SARS-CoV-2), is the most important health issue, internationally. With no specific and effective antiviral therapy for COVID-19, new or repurposed antiviral are urgently needed. Phytochemicals pose a ray of hope for human health during this pandemic, and a great deal of research is concentrated on it. Phytochemicals have been used as antiviral agents against several viruses since they could inhibit several viruses via different mechanisms of direct inhibition either at the viral entry point or the replication stages and via immunomodulation potentials. Recent evidence also suggests that some plants and its components have shown promising antiviral properties against SARS-CoV-2. This review summarizes certain phytochemical agents along with their mode of actions and potential antiviral activities against important viral pathogens. A special focus has been given on medicinal plants and their extracts as well as herbs which have shown promising results to combat SARS-CoV-2 infection and can be useful in treating patients with COVID-19 as alternatives for treatment under phytotherapy approaches during this devastating pandemic situation.

Exploiting the Amazing Diversity of Natural Source-Derived Polysaccharides: Modern Procedures of Isolation, Engineering, and Optimization of Antiviral Activities

Naturally occurring polysaccharide sulfates are highly diverse, owning variations in the backbone structure, linkage pattern and stereochemistry, branching diversity, sulfate content and positions of sulfate group(s). These structural characteristics bring about diverse sulfated polymers with dissimilar negative charge densities and structure-activity relationships. Herein, we start with a short discussion of techniques needed for extraction, purification, chemical sulfation, and structural characterization of polysaccharides. Processes of isolation and sulfation of plant-derived polysaccharides are challenging and usually involve two steps. In this context, we describe an integrated extraction-sulfation procedure that produces polysaccharide sulfates from natural products in one step, thereby generating additional pharmacological activities. Finally, we provide examples of the spectrum of natural source-derived polysaccharides possessing specific features of bioactivity, in particular focusing on current aspects of antiviral drug development and drug-target interaction. Thus, the review presents a detailed view on chemically engineered polysaccharides, especially sulfated derivatives, and underlines their promising biomedical perspectives.

A Comprehensive and Comparative Analysis of the Fucoidan Compositional Data Across the Phaeophyceae

In the current review, compositional data on fucoidans extracted from more than hundred different species were surveyed through the available literature. The analysis of crude extracts, purified extracts or carefully isolated fractions is included in tabular form, discriminating the seaweed source by its taxonomical order (and sometimes the family). This survey was able to encounter some similarities between the different species, as well as some differences. Fractions which were obtained through anion-exchange chromatography or cationic detergent precipitation showed the best separation patterns: the fractions with low charge correspond mostly to highly heterogeneous fucoidans, containing (besides fucose) other monosaccharides like xylose, galactose, mannose, rhamnose, and glucuronic acid, and contain low-sulfate/high uronic acid proportions, whereas those with higher total charge usually contain mainly fucose, accompanied with variable proportions of galactose, are highly sulfated and show almost no uronic acids. The latter fractions are usually the most biologically active. Fractions containing intermediate proportions of both polysaccharides appear at middle ionic strengths. This pattern is common for all the orders of brown seaweeds, and most differences appear from the seaweed source (habitat, season), and from the diverse extraction, purification, and analytitcal methods. The Dictyotales appear to be the most atypical order, as usually large proportions of mannose and uronic acids appear, and thus they obscure the differences between the fractions with different charge. Within the family Alariaceae (order Laminariales), the presence of sulfated galactofucans with high galactose content (almost equal to that of fucose) is especially noteworthy.

Therapeutic effects of an orally administered edible seaweed-derived polysaccharide preparation, ascophyllan HS, on a Streptococcus pneumoniae infection mouse model

Ascophyllan HS is a commercially available preparation of the edible brown alga Ascophyllum nodosum containing ascophyllan, a sulfated polysaccharide with diverse beneficial biological activities. In this study, the effects of ascophyllan HS were evaluated in a severe intranasal Streptococcus pneumoniae infection mouse model. The control untreated mice started to die on day 7 and 80% had died by day 14 post-infection. Continuous oral administration of ascophyllan HS before and after bacterial infection resulted in a remarkable increase in survival rate, with 90% of the low (167 mg/kg body weight/day) and 100% of the high (500 mg/kg body weight/day) dose ascophyllan HS-treated mice surviving at day 14 post-infection. Histopathological observation of the lungs of the infected mice revealed the induction of typical pneumonia features in the alveolar spaces of the untreated control mice, such as extensive infiltration of inflammatory cells, edema, and fibrin deposition. In contrast, notable levels of lung injuries or alterations were not observed in the ascophyllan HS-treated mice, and only a minor lesion was observed in one mouse. Furthermore, bacterial burdens in the lungs were significantly reduced in the ascophyllan HS-treated mice as compared to the control mice at day 4 post-infection. Significantly higher levels of IL-12 were detected in the serum of ascophyllan HS-treated mice than that of control mice measured at the end of the infection experiment (day 14). These results suggest that orally administered ascophyllan HS exerts a therapeutic effect on S. pneumoniae infection by activating the host defense systems. This is the first report of the therapeutic effect of an orally administered seaweed polysaccharide preparation on S. pneumoniae infection. Our findings suggest that ascophyllan HS has the potential to be developed as nutraceuticals and pharmaceuticals applicable for humans as well as a safe and promising therapeutic agent against S. pneumoniae infection.

The activation of NF-κB and MAPKs signaling pathways of RAW264.7 murine macrophages and natural killer cells by fucoidan from Nizamuddinia zanardinii

Polysaccharides from Nizamuddinia zanardinii were extracted using water at elevated temperature and fractionated by a DEAE Sepharose FF column yielding four fractions (F1-F4). Crude and fractions were composed of neutral sugars (50.8-57.4%), proteins (10.8-18.1%), sulfates (7.5-17.3%) and uronic acids (3.5-7.7%). Various levels of galactose (13.4-44.4%), fucose (34.1-40.1%), mannose (14.1-33.2%) and xylose (7.4-15.2%) formed the building blocks of the polysaccharide structures. The weight average molecular weights (Mw) of polysaccharides varied between 40.3 and 1254.4 × 103 g/mol. F3 polysaccharide was the most active fraction stimulating RAW264.7 murine macrophage cells to secrete NO, TNF-α, IL-1β and IL-6, and activating NK cells to release TNF-α, INF-γ, granzyme-B, perforin, NKG2D and FasL through NF-κB and MAPKs signaling pathways. Highly-branched F3 polysaccharide mainly consisted of (1 → 2)-Fucp, (1 → 2,3)-Manp, (1 → 3)-Galp, (1 → 2)-Manp, (1 → 3)-Manp, (1 → 2,3,4)-Manp and (1 → 2,3,6)-Manp residues with great amount of (→1)-Fucp and (→1)-Xylp. Sulfates substituted at C-2 of fucose and galactose residues. Overall, fucoidan from N. zanardinii showed immense potency in boosting immune system through macrophages and NK cells activations and therefore suitable for further exploration in immune-mediated biomedical applications.

Fructan from Polygonatum cyrtonema Hua as an eco-friendly corrosion inhibitor for mild steel in HCl media

An effective and biodegradable polygonatum fructan (PF) from Polygonatum cyrtonema Hua was studied as an eco-friendly corrosion inhibitor for mild steel protection in 1 M HCl, whose inhibition performance was studied by weight loss tests, electrochemical techniques, and surface analysis techniques (SECM, FTIR). The experimental results showed that PF has outstanding inhibition performance for mild steel in hydrochloric acid, and the inhibition efficiency increased with the increase of its concentration and temperature. Polarization studies indicated that PF is a mixed-type corrosion inhibitor, and its adsorption mode conforms to Langmuir isotherm, mainly chemisorption. An adsorption-related protective inhibitor film formed on the surface of mild steel was verified and investigated based on its surface analysis and characterization. Quantum chemical analysis showed that the adsorption of PF on the surface of mild steel has obvious chemical properties.

Natural Products-Derived Chemicals: Breaking Barriers to Novel Anti-HSV Drug Development

Recently, the problem of viral infection, particularly the infection with herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), has dramatically increased and caused a significant challenge to public health due to the rising problem of drug resistance. The antiherpetic drug resistance crisis has been attributed to the overuse of these medications, as well as the lack of new drug development by the pharmaceutical industry due to reduced economic inducements and challenging regulatory requirements. Therefore, the development of novel antiviral drugs against HSV infections would be a step forward in improving global combat against these infections. The incorporation of biologically active natural products into anti-HSV drug development at the clinical level has gained limited attention to date. Thus, the search for new drugs from natural products that could enter clinical practice with lessened resistance, less undesirable effects, and various mechanisms of action is greatly needed to break the barriers to novel antiherpetic drug development, which, in turn, will pave the road towards the efficient and safe treatment of HSV infections. In this review, we aim to provide an up-to-date overview of the recent advances in natural antiherpetic agents. Additionally, this paper covers a large scale of phenolic compounds, alkaloids, terpenoids, polysaccharides, peptides, and other miscellaneous compounds derived from various sources of natural origin (plants, marine organisms, microbial sources, lichen species, insects, and mushrooms) with promising activities against HSV infections; these are in vitro and in vivo studies. This work also highlights bioactive natural products that could be used as templates for the further development of anti-HSV drugs at both animal and clinical levels, along with the potential mechanisms by which these compounds induce anti-HSV properties. Future insights into the development of these molecules as safe and effective natural anti-HSV drugs are also debated.

Immune stimulatory and anti-HIV-1 potential of extracts derived from marine brown algae Padina tetrastromatica

Background Marine brown algae are biologically diverse and their medicinal value has been explored limited. We assessed whether Padina tetrastromatica Hauck will possess the immune stimulatory and human immunodeficiency virus (HIV-1) inhibitory activity. Materials and Methods Aqueous and methanolic extracts were tested for the Th1/Th2 cytokines using PBMC. Subsequently, leukotriene B4 (LTB4), nitric oxide (NO) and anti-oxidant effect were analyzed using RAW264.7 cells. In addition, Padina extracts were tested for the HIV-1 clade C & A by measuring the levels of viral p24 antigen in infected peripheral blood mononuclear cells (PBMCs) and against reverse transcriptase (RT). Results At 100 μg/mL, aqueous and methanolic extracts produced a significant amount of IL-10 and IFN-γ at 24 h and 72 h post-stimulation by PBMCs. It also produced a significant amount of LTB4, NO and had an antioxidant effect on RAW264.7 cell, suggesting the immune stimulating potential of P. tetrastromatica. Upon infection of PBMCs with 100 TCID50, aqueous and methanolic extracts of P. tetrastromatica inhibited HIV-1 C (>90%) and HIV-1 A (>50%) showed a significant reduction in HIV-1 p24 levels and HIV-1 RT inhibition (>50%). GC-MS study revealed a relative abundance of tetradecanoic and oleic acid in the methanolic extract of P. tetrastromatica, which might be responsible for immune stimulation and anti-HIV-1 activity. Conclusion At lower concentrations (100 mg/mL), the aqueous and methanolic extracts of P. tetrastromatica showed the strong immune stimulation and greatest anti-HIV-1 potential in vitro. This study demonstrates the therapeutic potential of these brown algae P. tetrastromatica for the benefit of mankind.

Antiherpetic Effect of Topical Formulations Containing Sulfated Polysaccharide from Adenanthera pavonina

Adenanthera pavonina is a native tree of Africa and Asia, introduced in Brazil for reforestation and wood industry. Several pharmacological activities have described scientifically, including antiviral activity. This study evaluated the antiviral effect of sulfated polysaccharide of Adenanthera pavonina (SPAp) against acyclovir (ACV)-resistant (AR-29) and sensitive (KOS) herpes simplex virus strains. The 50% cytotoxic concentration (CC50) was determined by MTT method and the 50% inhibitory concentration (IC50) was evaluated by plaque reduction assay. The in vivo SPAp antiviral activity was performed in Balb/c mice infected by skin scarification and treated with topical 0.5% (w/w) SPAp formulations. SPAp showed a CC50 of 47.81 μg/mL and the IC50 were 0.49 μg/mL (SI = 97.5) and 0.54 μg/mL (SI = 88.5) for the strains KOS and AR-29, respectively. Our results demonstrated that mice treated with SPAp presented a delay in the development and progression of skin lesions compared with the control group.

Attenuation of oxidative stress induced mitochondrial dysfunction and cytotoxicity in fibroblast cells by sulfated polysaccharide from Padina gymnospora

In this present study, isolation, characterization and protective effect of sulfated polysaccharide (SP) isolated from the brown algae Padina gymnospora was investigated. SP was isolated and characterized through FT-IR, 1H NMR, TGA, GC-MS and CHN analysis. The molecular weight of SP was found to be 16 kDa. The isolated SP contains 29.4 ± 0.35% of sulfate, 27 ± 0.11% of fucose, 0.05 ± 0.12% of protein, respectively. Furthermore, SP exhibits its excellent radical scavenging effects were evaluated by DPPH, ABTS radical scavenging and reducing power assays. Moreover, pretreatment with SP significantly mitigates H2O2 induced cytotoxicity in L-929 cells in a dose dependent manner. Furthermore, SP pretreatment ameliorates oxidative stress induced apoptosis and DNA damage, alleviates the generation of intracellular reactive oxygen species (ROS) and restores mitochondrial membrane potential (MMP) in L-929 cells through its antioxidant potential. Together, these results suggest that SP can be exploited as a natural antioxidant in the food and pharmaceutical industries.

Structural elucidation of fucoidan from Cladosiphon okamuranus (Okinawa mozuku)

Fucoidan is a sulphated polysaccharide, made up mainly of l-fucose, which is found in brown seaweeds. Its chemical structure is diverse and depends on maturity, species and geographical location. The objective of this study was to elucidate the chemical structure of fucoidan from Cladosiphon okamuranus harvested in Japan. The fucoidan was subject to purification prior to monosaccharide profiling, sulphate content determination, and linkage analysis. Our results showed that Japanese Cladosiphon okamuranus fucoidan contained 70.13 ± 0.22 wt% fucose and 15.16 ± 1.17 wt% sulphate. Other minor monosaccharides found were d-xylose, d-galactose, d-mannose, d-glucose, d-arabinose, d-rhamnose and d-glucuronic acid. Linkage analysis revealed that fucopyranoside units along the backbone are linked, through α-1,3-glycosidic bonds, with fucose branching at C-2, and one sulphate group at C-4 per every three fucose units, i.e. the structure of fucoidan from Japanese Cladosiphon okamuranus is [→3)-α-fuc(1→]0.52[→3)-α-fuc-4-OSO3-(1→]0.33[→2)-α-fuc]0.14.

Structural Features of Sulfated Glucuronomannan Oligosaccharides and Their Antioxidant Activity

Glucuronomannan oligosaccharides (Gs) were derived from fucoidan, which was extracted from the brown alga Sargassum thunbergii. Sulfated glucuronomannan oligosaccharides (SGs) were obtained by the sulfation of Gs. NMR techniques were used to reveal that the order of sulfation was Man-C6 > Man-C4 > Man-C1R > GlcA-C3 > Man-C3 > GlcA-C2. Finally, the antioxidant activities (hydroxyl radical scavenging activity, superoxide radical scavenging activity, reducing power and DPPH radical scavenging activity) of Gs and SGs were determined. The findings showed that the higher the degree of polymerization, the better the activity, except for the hydroxyl radical scavenging activity. In addition, the higher the sulfate content, the lower the activities for the reducing power and DPPH radical scavenging activity. Opposite results were found for the superoxide radical scavenging activity. Finally, compared with fucoidan, most Gs and SGs had higher antioxidant activity, suggesting that they might be good candidates for antioxidants.

Structural characteristics and anticancer activity in vitro of fucoidan from brown alga Padina boryana

The sulfated and acetylated fucoidan fraction, containing fucose, galactose, mannose, glucose and uronic acid residues, was isolated from the brown alga Padina boryana. The structure of galactofucan part was studied after different modifications by NMR spectroscopy and mass spectrometry. It was shown that galactofucan contained the main chain of alternating 1,4-linked α-l-fucopyranose and 1,3-linked β-d-Galactopyranose. Single fucose residues were found as branches at C4 of galactose residues. Also, fucoidan contained 1,3- or 1,4-linked Fuc-Fuc and Gal-Gal fragments. The sulfate groups occupied positions C2, C3 and C4 of both fucose and galactose residues, which was shown by tandem mass spectrometry of fragments, labeled with heavy-oxygen. The anticancer effect of native and modified fucoidan fractions was studied in vitro on the colorectal carcinoma cells DLD-1 and HCT-116. All fucoidans had no cytotoxicity under 400 μg/mL and inhibited colony formation of cancer cells at concentration of 200 μg/mL.

The structure-activity relationship between polysaccharides from Sargassum thunbergii and anti-tumor activity

Polysaccharides derived from Sargassum thunbergii were prepared to investigate the structure-activity relationship between polysaccharides and anti-tumor activity in vitro. Many factors were examined. Overall, STW (polysaccharide extracted by hot water) had the best activity, followed by STJ (polysaccharide extracted by dilute alkali), and then STA (polysaccharide extracted by dilute acid). Location of algae had no effect at 500μg/mL and 1000μg/mL, while STW-QD (algae collected from Qingdao, China) had the best activity, followed by STW-WZ (algae collected from Wenzhou, China) and STW-LJ (algae collected from Lianjiang, China) and then STW-DL (algae collected from Dalian, China) and STW-RC (algae collected from Rongcheng, China) at 250μg/mL. Moreover, molecular weight had no effect at 1000μg/mL, while higher molecular weights were associated with better activities at 250μg/mL and 500μg/mL. Sulfate content had no effect at 1000μg/mL, while anti-tumor activities decreased accompanying with the changes of sulfate content. Uronic acid content was an important factor influencing activity. The fractions of STW showed little anti-tumor activity; however, the mixture of the fractions of STW showed approximately 60% inhibition. Overall, these findings suggested that the anti-tumor activity of polysaccharides required multilateral cooperation and that some of the effective components were lost.

[Antiviral action and pathogenetic targets for seaweed sulfated polysaccharides in herpesvirus infections]

The review summarizes results of studies of effects of sulfated polysaccharides from seaweed on herpesviruses and the course of herpesvirus infections. Importance of this problem is determined by the prevalence of herpesviruses that can persist in the human body and demonstrate a high degree of immune mimicry and resistance to antiviral agents. A wide range of physiological action of sulfated polysaccharides, receptor agonists of innate and adaptive immune cells, which possess potent antiviral, antioxidant and anti-inflammatory activities, open the possibility of their use for creation of new generation pharmacological substances and agents with associated activity for the treatment of herpesvirus infections.

Review on cell models to evaluate the potential antioxidant activity of polysaccharides

Owing to various health functions, natural polysaccharides are becoming a kind of popular dietary nutritional supplement.

Antioxidant activities of the polysaccharides of Chuanminshen violaceum

The water-soluble polysaccharides were extracted and purified from the root of Chuanminshen violaceum (CVPS). The antioxidant activities of the CVPS were evaluated both with in vitro and in vivo experiments. The results of the in vitro antioxidant assay suggested that the CVPS scavenged DPPH, hydroxyl, and superoxide anion radicals. The oral administration of three different doses of CVPS administered over a period of 6 weeks to D-galactose induced aging mice models, enhanced the activities of T-SOD, Mn-SOD, Cu, Zn-SOD, and CAT, and markedly decreased the content of MDA. Therefore, significant up-regulation of mRNA expression levels of Cu, Zn-SOD, Mn-SOD, CAT, glutathione peroxidase 1 (GPx), thioredoxin 1 (Trx1), and thioredoxin 2 (Trx1) occurred. Finally, the results demonstrated that the CVPS are a novel potential resource for natural antioxidants and anti-aging drugs.

The Structure-Activity Relationship between Marine Algae Polysaccharides and Anti-Complement Activity

In this study, 33 different polysaccharides were prepared to investigate the structure-activity relationships between the polysaccharides, mainly from marine algae, and anti-complement activity in the classical pathway. Factors considered included extraction methods, fractionations, molecular weight, molar ratio of galactose to fucose, sulfate, uronic acid (UA) content, linkage, branching, and the type of monosaccharide. It was shown that the larger the molecular weights, the better the activities. The molar ratio of galactose (Gal) to fucose (Fuc) was a positive factor at a concentration lower than 10 µg/mL, while it had no effect at a concentration more than 10 µg/mL. In addition, sulfate was necessary; however, the sulfate content, the sulfate pattern, linkage and branching had no effect at a concentration of more than 10 µg/mL. Moreover, the type of monosaccharide had no effect. Laminaran and UA fractions had no activity; however, they could reduce the activity by decreasing the effective concentration of the active composition when they were mixed with the active compositions. The effect of the extraction methods could not be determined. Finally, it was observed that sulfated galactofucan showed good anti-complement activity after separation.

Chuanminshen violaceum polysaccharides improve the immune responses of foot-and-mouth disease vaccine in mice

Water-soluble polysaccharides from Chuanminshen violaceum (CVPS) were evaluated for their physicochemical properties, monosaccharide composition, and adjuvant potential to specific cellular and humoral immune responses in a mouse model of foot-and-mouth disease virus (FMDV) vaccination. The average molecular weight (Mw) of the CVPS was 968.31 kDa. The monosaccharide components of the CVPS was rhamnose, arabinose, fucose, mannose, glucose, and galactose with a relative mass of 6.29%, 21.87%, 16.59%, 12.54%, 13.07%, and 28.05%, respectively. Administering CVPS as an adjuvant significantly enhanced the phagocytic capacity of peritoneal macrophages, splenocyte proliferation, and the activity of NK cells and CTL as well as increased FMDV-specific IgG and IgG subclass antibody titers. Moreover, CVPS increased the expression of IL-2, IFN-γ, and IL-4 in CD4(+) T cells and IFN-γ expression in CD8(+) T cells. Additionally, CVPS enhanced CD40(+), CD80(+), and CD86(+) expression on DCs. Moreover, CVPS upregulated MHC-I/II, TLR-2/4 mRNA levels. In contrast, CVPS downregulated TGF-β mRNA expression and the frequency of CD4(+)CD25(+)Foxp3(+) Treg cells. Taken together, these results indicate that administering CVPS as an adjuvant enhances both cellular and humoral immune responses via the TLR-2 and TLR-4 signalling pathways, thereby promoting DC maturation and suppressing TGF-β expression and Treg frequency.