Sulfated polysaccharides in marine sponges: extraction methods and anti-HIV activity

Fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus alleviate the intestinal barrier injury and oxidative stress damage in vitro and in vivo

This study aimed to investigate the alleviative effects of fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus (fCSSc) on the intestinal barrier injury and oxidative stress damage in vitro and in vivo. The results showed that fCS-Sc protected the intestinal barrier and improved the antioxidant function in H2O2 damaged Caco-2 cells via up-regulating the tight junction proteins and activating Keap1-Nrf2-ARE antioxidant pathway. Furthermore, administration fCS-Sc could ameliorate the weight loss and spleen index decrease in Cyclophosphamide (Cy) treated mice, improve the expressions of ZO-1, Claudin-1, Nrf2, SOD, and NQO-1 in Cy damaged colon tissue, showing significant protective effects against intestinal barrier damage and oxidative stress in vivo. fCS-Sc intervention also alleviated the gut microbiota disorder though increasing the richness and diversity of intestinal bacteria, regulating the structural composition of gut microbiota. fCS-Sc promoted the relative abundance of beneficial microbiota and inhibited the growth of harmful bacteria. This study provided a theoretical basis for the application of fCS-Sc as a prebiotic in chemotherapy.

Marine sulfated polysaccharides as potential antiviral drug candidates to treat Corona Virus disease (COVID-19)

The viral infection caused by SARS-CoV-2 has increased the mortality rate and engaged several adverse effects on the affected individuals. Currently available antiviral drugs have found to be unsuccessful in the treatment of COVID-19 patients. The demand for efficient antiviral drugs has created a huge burden on physicians and health workers. Plasma therapy seems to be less accomplishable due to insufficient donors to donate plasma and low recovery rate from viral infection. Repurposing of antivirals has been evolved as a suitable strategy in the current treatment and preventive measures. The concept of drug repurposing represents new experimental approaches for effective therapeutic benefits. Besides, SARS-CoV-2 exhibits several complications such as lung damage, blood clot formation, respiratory illness and organ failures in most of the patients. Based on the accumulation of data, sulfated marine polysaccharides have exerted successful inhibition of virus entry, attachment and replication with known or unknown possible mechanisms against deadly animal and human viruses so far. Since the virus entry into the host cells is the key process, the prevention of such entry mechanism makes any antiviral strategy effective. Enveloped viruses are more sensitive to polyanions than non-enveloped viruses. Besides, the viral infection caused by RNA virus types embarks severe oxidative stress in the human body that leads to malfunction of tissues and organs. In this context, polysaccharides play a very significant role in providing shielding effect against the virus due to their polyanionic rich features and a molecular weight that hinders their reactive surface glycoproteins. Significantly the functional groups especially sulfate, sulfate pattern and addition, uronic acids, monosaccharides, glycosidic linkage and high molecular weight have greater influence in the antiviral activity. Moreover, they are very good antioxidants that can reduce the free radical generation and provokes intracellular antioxidant enzymes. Additionally, polysaccharides enable a host-virus immune response, activate phagocytosis and stimulate interferon systems. Therefore, polysaccharides can be used as candidate drugs, adjuvants in vaccines or combination with other antivirals, antioxidants and immune-activating nutritional supplements and antiviral materials in healthcare products to prevent SARS-CoV-2 infection.

Current progress on identification of virus pathogens and the antiviral effectors in echinoderms

Echinoderms are important marine organisms that live in a wide range from the intertidal zone to the abyssal zone. Members of this phylum are prone to dramatic population fluctuations that may trigger dramatic shifts in ecosystem structure. Despite the extremely complex nature of the marine environment, the immune systems of echinoderms induce a complex innate immune response to prokaryotic and eukaryotic pathogens. Previous studies showed that many echinoderm disease outbreaks were associated with specific bacteria, whereas recent scientific investigations using newly developed technologies revealed the amazing diversity of viruses in seawater. Viruses are potential pathogens of several infectious diseases of marine echinoderms. We reviewed the discovery of viruses in echinoderms and discussed the relationship between viruses and diseases for the first time. We further summarized the research progress of the potential immune-related genes and signal pathways induced by viruses and poly (I:C). Additionally, numbers of studies showed that active substances extracted from echinoderms, or the compounds synthesized from these substances, have significant antihuman virus ability. This result suggests that the active substances derived from echinoderms provide potential antiviral protection for the organism, which may provide future research directions for the antiviral immunity of echinoderms. Thus, this review also collected information on the antiviral activities of biologically active substances from echinoderms, which may pave the way for new trends in antiviral immunity for echinoderms and antiviral drugs in humans.

The Spirocyclic Imine from a Marine Benthic Dinoflagellate, Portimine, Is a Potent Anti-Human Immunodeficiency Virus Type 1 Therapeutic Lead Compound

In this study, we aimed to find chemicals from lower sea animals with defensive effects against human immunodeficiency virus type 1 (HIV-1). A library of marine natural products consisting of 80 compounds was screened for activity against HIV-1 infection using a luciferase-encoding HIV-1 vector. We identified five compounds that decreased luciferase activity in the vector-inoculated cells. In particular, portimine, isolated from the benthic dinoflagellate Vulcanodinium rugosum, exhibited significant anti-HIV-1 activity. Portimine inhibited viral infection with an 50% inhibitory concentration (IC₅₀) value of 4.1 nM and had no cytotoxic effect on the host cells at concentrations less than 200 nM. Portimine also inhibited vesicular stomatitis virus glycoprotein (VSV-G)-pseudotyped HIV-1 vector infection. This result suggested that portimine mainly targeted HIV-1 Gag or Pol protein. To analyse which replication steps portimine affects, luciferase sequences were amplified by semi-quantitative PCR in total DNA. This analysis revealed that portimine inhibits HIV-1 vector infection before or at the reverse transcription step. Portimine has also been shown to have a direct effect on reverse transcriptase using an in vitro reverse transcriptase assay. Portimine efficiently inhibited HIV-1 replication and is a potent lead compound for developing novel therapeutic drugs against HIV-1-induced diseases.

In vitro anti-HIV-1 activity of the bioactive compound extracted and purified from two different marine macroalgae (seaweeds) (Dictyota bartayesiana J.V.Lamouroux and Turbinaria decurrens Bory)

Highly active antiretroviral therapy (HAART) is the only available remedial measure to treat HIV infected patients, as recognized by the WHO. However, it is associated with toxicity (nephrotoxicity), high cost and most preferably drug resistance in the first-line treatment. Wherefore, potential and novel natural source is the only option for the modern world to challenge this global issue. In recent years, sulfated polysaccharide from marine macroalgae shown to be biologically active as anti-inflammatory, anticoagulant, antitumor, immunomodulatory and antiviral agents. As a direct inhibitor of HIV including other retroviruses, it is considered as a "new generation antiretroviral drug". In our present study, Fucoidan, a sulfated polysaccharide has been extracted from two different macroalgae Dictyota bartayesiana (DD) and Turbinaria decurrens (TD) based on hot water extraction method and further confirmed by FT-IR and RP-HPLC methods. Both the crude and purified fucoidan samples were evaluated for anti-HIV activity after ion exchange chromatography purification. The maximum inhibitory activity of crude and purified fucoidan samples are 90.5% and 89% in the fucoidan extracts of DD. Whereas, it was 89.7% and 92% in the fucoidan extracts of TD. Simultaneously, the IC50 values were determined and recorded as 1.56 µg/ml and 57.6 ng/ml in both the crude and purified fucoidan extracts of DD respectively. Similarly, for TD, it was 3 µg/ml and 131.7 ng/ml in the fucoidan extracts of TD. Therefore, further extensive research work is the most needful to fill the gaps to develop this sulfated polysaccharide as a potential drug for the treatment of HIV patients.

Development of a Green Downstream Process for the Valorization of Porphyridium cruentum Biomass

As the interest in biorefinery approaches is continuously increasing, new alternatives for the downstream valorization of biomasses are sought. Porphyridium cruentum microalga is a good natural source for a variety of interesting bioactive compounds, including carotenoids, phycoerythrin, and sulfated polysaccharides. In the present contribution, the use of compressed fluids-based techniques is explored towards the efficient and green extraction of bioactive compounds to valorize microalgal biomass. The extraction of carotenoids was first optimized using pressurized ethanol. The best extraction conditions involved the use of 125 °C for 20 min at 10.5 MPa. Subsequently, a sequential valorization process was devised based on the application of different steps directed towards the extraction of phycoerythrin, sulfated polysaccharides, and carotenoids, respectively. The applied pressurized conditions allowed the attainment of a good recovery of polar components without compromising the stability and extraction of carotenoids. Therefore, the proposed approach could be employed to obtain different bioactives from P. cruentum microalgal biomass employing green extraction processes.

Bioactive potential and structural characterization of sulfated polysaccharides from Bullet tuna (Auxis Rochei) by-products

The present study deals with the isolation of sulfated polysaccharides (Ps) from the Bullet tuna by-products (head, skin and bones). Results of chemical characterization revealed that Ps-bones showed the highest total sugar, uronic acid and sulfate group contents. Tuna extracted-Ps contained a mixture of neutral sugars, with high amounts of glucuronic and galacturonic acids and presented different molecular weights. The presence of sulfate groups in different Ps was confirmed by FTIR analysis. Interestingly, Ps-bones showed the highest antioxidant activity among all the extracted Ps. Moreover, results revealed that all polysaccharides displayed varying degrees of antibacterial activity. Ps-bones exhibited high and wide spectrum of activities, inhibiting the growth of all bacteria tested. Ps-bones incorporated during fillet cooking offered an excellent protection of fish fillet by avoiding pH change, color loss, lipid oxidation and spoilage. Overall, the results demonstrated that Ps could be potentially used as natural antioxidant and antibacterial agents.

Sample Processing Impacts the Viability and Cultivability of the Sponge Microbiome

Sponges host complex microbial communities of recognized ecological and biotechnological importance. Extensive cultivation efforts have been made to isolate sponge bacteria, but most still elude cultivation. To identify the bottlenecks of sponge bacterial cultivation, we combined high-throughput 16S rRNA gene sequencing with a variety of cultivation media and incubation conditions. We aimed to determine the extent to which sample processing and cultivation conditions can impact bacterial viability and recovery in culture. We isolated 325 sponge bacteria from six specimens of Cymbastela concentrica and three specimens of Scopalina sp. These isolates were distributed over 37 different genera and 47 operational taxonomic units (defined at 97% 16S rRNA gene sequence identity). The cultivable bacterial community was highly specific to its sponge host and different media compositions yielded distinct microbial isolates. Around 97% of the isolates could be detected in the original sponge and represented a large but highly variable proportion (0.5–92% total abundance, depending on sponge species) of viable bacteria obtained after sample processing, as determined by propidium monoazide selective DNA modification of compromised cells. Our results show that the most abundant viable bacteria are also the most predominant groups found in cultivation, reflecting, to some extent, the relative abundances of the viable bacterial community, rather than the overall community estimated by direct molecular approaches. Cultivation is therefore shaped not only by the growth conditions provided, but also by the different cell viabilities of the bacteria that constitute the cultivation inoculum. These observations highlight the need to perform experiments to assess each method of sample processing for its accurate representation of the actual in situ bacterial community and its yield of viable cells.

Natural Plant Alkaloid (Emetine) Inhibits HIV-1 Replication by Interfering with Reverse Transcriptase Activity

Ipecac alkaloids are secondary metabolites produced in the medicinal plant Psychotria ipecacuanha. Emetine is the main alkaloid of ipecac and one of the active compounds in syrup of Ipecac with emetic property. Here we evaluated emetine’s potential as an antiviral agent against Human Immunodeficiency Virus. We performed in vitro Reverse Transcriptase (RT) Assay and Natural Endogenous Reverse Transcriptase Activity Assay (NERT) to evaluate HIV RT inhibition. Emetine molecular docking on HIV-1 RT was also analyzed. Phenotypic assays were performed in non-lymphocytic and in Peripheral Blood Mononuclear Cells (PBMC) with HIV-1 wild-type and HIV-harboring RT-resistant mutation to Nucleoside Reverse Transcriptase Inhibitors (M184V). Our results showed that HIV-1 RT was blocked in the presence of emetine in both models: in vitro reactions with isolated HIV-1 RT and intravirion, measured by NERT. Emetine revealed a strong potential of inhibiting HIV-1 replication in both cellular models, reaching 80% of reduction in HIV-1 infection, with low cytotoxic effect. Emetine also blocked HIV-1 infection of RT M184V mutant. These results suggest that emetine is able to penetrate in intact HIV particles, and bind and block reverse transcription reaction, suggesting that it can be used as anti-HIV microbicide. Taken together, our findings provide additional pharmacological information on the potential therapeutic effects of emetine.

Characterization and antitumor activity of a polysaccharide from Sarcodia ceylonensis

A water-soluble polysaccharide from Sarcodia ceylonensis was obtained by using the method of water-extraction and ethanol-precipitation. The polysaccharide was further purified by chromatography on AB-8 and ADS-7 columns, yielding a pure polysaccharide termed SCP-60. The molecular weight (Mw) of SCP-60 was calculated to be 50.0 kDa, based on the calibration curve obtained with a series of Dextran T standards. The results of FT-IR indicated that the polysaccharide contains the α-configuration of sugar units. GC-MS analysis revealed that SCP-60 was mainly composed of galactose and glucose. NMR spectroscopy revealed SCP-60 had the backbone consisting of → 6)-α-Manp-(1 →, α-D-Glcp-(1 →, → 6)-α-D-Glcp-(1 → and → 6)-α-Galp-(1 →. In order to evaluate the antitumor activity in vivo of the polysaccharide, a sarcoma 180 model was used. The results showed SCP-60 had strong antitumor ability, meanwhile, SCP-60 at a high dose (100 mg/kg) could significantly increase the thymic and splenic indices of S180 mice, and strongly promote the secretion of IL-2, TNF-α and IFN-γ, increase the SOD activities and reduce the concentrations of MDA in blood. Therefore the polysaccharide SCP-60 should be explored as a novel potential antitumor drug.

Anticancer and cancer preventive properties of marine polysaccharides: some results and prospects

Many marine-derived polysaccharides and their analogues have been reported as showing anticancer and cancer preventive properties. These compounds demonstrate interesting activities and special modes of action, differing from each other in both structure and toxicity profile. Herein, literature data concerning anticancer and cancer preventive marine polysaccharides are reviewed. The structural diversity, the biological activities, and the molecular mechanisms of their action are discussed.

Brominated compounds from marine sponges of the genus Aplysina and a compilation of their 13C NMR spectral data

Aplysina is the best representative genus of the family Aplysinidae. Halogenated substances are its main class of metabolites. These substances contribute greatly to the chemotaxonomy and characterization of the sponges belonging to this genus. Due to their pharmacological activities, these alkaloids are of special interest. The chemistry of halogenated substances and of the alkaloids has long been extensively studied in terrestrial organisms, while the number of marine organisms studied has just started to increase in the last decades. This review describes 101 halogenated substances from 14 species of Aplysina from different parts of the world. These substances can be divided into the following classes: bromotyramines (A), cavernicolins (B), hydroverongiaquinols (C), bromotyrosineketals (D), bromotyrosine lactone derivatives (E), oxazolidones (F), spiroisoxazolines (G), verongiabenzenoids (H), verongiaquinols (I), and dibromocyclohexadienes (J). A compilation of their (13)C NMR data is also part of the review. For this purpose 138 references were consulted.