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

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

Bioactive Polysaccharides from Microalgae: A Close Look at the Biomedical Applications

There is a current tendency towards bioactive natural products that can be used in different areas such as food, pharmaceutical, and biomedical. In the last decades, polysaccharides have attracted increasing interest because of their potent nontoxic effects, therapeutic properties, and diversified range of applications. Polysaccharides are complex and heterogeneous macromolecules constituted of different monosaccharides and, in some cases, of glucuronic acid and sulphate groups. Polysaccharides with biological activity can be derived from plants, animals and microorganisms, especially microalgae. Microalgae are considered one of the most promising sources of these compounds that have already proved to have several important biological properties. In this sense, our objective is to elucidate the use of bioactive polysaccharides from microalgae in biomedical applications, emphasizing the biological activity of these compounds. Furthermore, the microalgal biomass production systems and polysaccharides extraction methods were presented and discussed.

Improved Metal Cation Optosensing Membranes through the Incorporation of Sulphated Polysaccharides

Optosensing chitosan-based membranes have been applied for the detection of heavy metals, especially in drinking water. The novelty of this study is based on the use of sulphated polysaccharides, in such optosensing membranes, aiming at an improved analytical performance. The sulphated polysaccharides, such as ulvan, fucoidan and chondroitin sulfate, were extracted from by-products and wastes of marine-related activities. The membranes were developed for the analysis of aluminum. The variation in the visible absorbance of the sensor membranes after the contact between the chromophore and the aluminum cation was studied. The membranes containing sulphated polysaccharides showed improved signals when compared to the chitosan-only membrane. As for the detection limits for the membranes containing ulvan, fucoidan and chondroitin sulfate, 0.17 mg L⁻¹, 0.21 mg L⁻¹ and 0.36 mg L⁻¹ were obtained, respectively. The values were much lower than that obtained for the chitosan-only membrane, 0.52 mg L⁻¹, which shows the improvement obtained from the sulphated polysaccharides. The results were obtained with the presence of CTAB in analysis solution, which forms a ternary complex with the aluminum cation and the chromophore. This resulted in an hyperchromic and batochromic shift in the absorption band. When in the presence of this surfactant, the membranes showed lower detection limits and higher selectivity.

Bioprospection of Antiviral and Antitumor Compounds from Some Marine Algae from Egyptian Shoers

BACKGROUND

The marine algae are considered a diverse source of bioactive compounds. Many active compounds have been isolated from algae and show good biological activities.

Materials and Methods

The aim of this study is to detect the antiviral and anticancer activities in some extracts of marine algae. Extraction, purification and identification of some marine algae common in Egypt were conducted. Extraction of Ulva lactuca, Sargassum dentifolium, and Cystoseiara myrica was conducted. A sequence of extractions, including extraction by ethanol, boiling water, hydrochloric acid and sodium hydroxide were carried out. The obtained extracts were evaluated for their antitumour and antiviral activities against liver tumour cells, brain tumour cell lines, measles virus, mumps virus and hepatitis B virus (HBV). The extracts of the best activities were subjected for purification by size exclusion chromatography and anion exchange chromatography for ethanolic extracts or precipitation by cetylpyridinium chloride (CPC) then by size exclusion chromatography and anion exchange chromatography for aqueous extracts. Separation by GLS/MS was performed. The structures of the active compounds have been identified through different chemical analyses, including sugar analysis, configurational analysis, high-performance liquid chromatography (HPLC), infrared spectroscopy (IR), gas-liquid chromatography-mass spectroscopy (GLC-MS) and 1H,13C nuclear magnetic resonance (NMR) at ZV.

Results

The active compounds from the water extracts have been identified mainly as polysaccharides and sulphated polysaccharides. The antitumour and the antiviral activities of ethanolic extracts are attributable to compound identified as Ethyl Palmitate. These natural compounds did not show cytotoxic effect.

Conclusion

These outputs could be preliminary for further biological studies aiming to therapeutic application.

Metabolites of Seaweeds as Potential Agents for the Prevention and Therapy of Influenza Infection

CONTEXT

Seaweed metabolites (fucoidans, carrageenans, ulvans, lectins, and polyphenols) are biologically active compounds that target proteins or genes of the influenza virus and host components that are necessary for replication and reproduction of the virus.

OBJECTIVE

This review gathers the information available in the literature regarding to the useful properties of seaweeds metabolites as potential agents for the prevention and therapy of influenza infection.

MATERIALS AND METHODS

The sources of scientific literature were found in various electronic databases (i.e., PubMed, Web of Science, and ScienceDirect) and library search. The retrospective search depth is 25 years.

RESULTS

Influenza is a serious medical and social problem for humanity. Recently developed drugs are quite effective against currently circulating influenza virus strains, but their use can lead to the selection of resistant viral strains. In this regard, new therapeutic approaches and drugs with a broad spectrum of activity are needed. Metabolites of seaweeds fulfill these requirements. This review presents the results of in vitro and in vivo experimental and clinical studies about the effectiveness of these compounds in combating influenza infection and explains the necessity of their use as a potential basis for the creation of new drugs with a broad spectrum of activity.

Sulphated polysaccharides from Ulva clathrata and Cladosiphon okamuranus seaweeds both inhibit viral attachment/entry and cell-cell fusion, in NDV infection

Sulphated polysaccharides (SP) extracted from seaweeds have antiviral properties and are much less cytotoxic than conventional drugs, but little is known about their mode of action. Combination antiviral chemotherapy may offer advantages over single agent therapy, increasing efficiency, potency and delaying the emergence of resistant virus. The paramyxoviridae family includes pathogens causing morbidity and mortality worldwide in humans and animals, such as the Newcastle Disease Virus (NDV) in poultry. This study aims at determining the antiviral activity and mechanism of action in vitro of an ulvan (SP from the green seaweed Ulva clathrata), and of its mixture with a fucoidan (SP from Cladosiphon okamuranus), against La Sota NDV strain. The ulvan antiviral activity was tested using syncytia formation, exhibiting an IC50 of 0.1 μg/mL; ulvan had a better anti cell-cell spread effect than that previously shown for fucoidan, and inhibited cell-cell fusion via a direct effect on the F0 protein, but did not show any virucidal effect. The mixture of ulvan and fucoidan showed a greater anti-spread effect than SPs alone, but ulvan antagonizes the effect of fucoidan on the viral attachment/entry. Both SPs may be promising antivirals against paramyxovirus infection but their mixture has no clear synergistic advantage.

Surrogacy in antiviral drug development

The coming of age of molecular biology has resulted in an explosion in our understanding of the pathogenesis of virus related diseases. New pathogens have been identified and characterized as being responsible for old diseases. Empirical clinical evaluation of morbidity and mortality as outcome measures after a therapeutic intervention have started to give way to the use of an increasing number of surrogate markers. Using a combination of these markers, it is now possible to measure and monitor the pathogen as well as the host's response. Nowhere is this better exemplified in virology than in the field of AIDS. We have utilized the advances in pathogenesis and new antiretroviral drug development to: * develop a new class of drugs which block the entry of HIV-1 into cells. * develop a new approach for effectively delivering these drugs to those tissues in which most viral replication takes place. Over the last 10 years, our work has progressed from concept to clinical trial. Our laboratory based evaluation of the new molecules developed as well as our clinical evaluation of their safety and efficacy have had to respond and adapt to the rapid changes taking place in AIDS research. This paper discusses the problems encountered and the lessons learnt.