Seaweed Sulfated Polysaccharides against Respiratory Viral Infections

Heparin-azithromycin microparticles show anti-inflammatory effects and inhibit SARS-CoV-2 and bacterial pathogens associated to lung infections

Pulmonary infections are a leading cause of morbidity and mortality worldwide, a situation exacerbated by the COVID-19. Azithromycin (AZM) is used orally to treat pulmonary infections due to its ability to accumulate in lung tissues and immune cells after oral administration. Sulfated polysaccharides, such as heparin, are known to inhibit SARS-CoV-2 entry. This study presents a novel approach focused on developing a dry powder inhaler of AZM-loaded microparticles composed of either heparin or its derivatives. The microparticle formulations exhibited potent antiviral activity against SARS-CoV-2 (IC50 ≤ 95 nM) while retaining superior antibacterial efficacy against Streptococcus pneumoniae and Pseudomonas aeruginosa compared to free AZM (MIC ≤15 μg/mL). Importantly, at bactericidal concentrations, no cytotoxic effects were observed on mammalian cells, including Calu-3 cells and red blood cells. The formulations demonstrated effective alveolar aerodynamic deposition (MMAD ranging from 1 μm to 3 μm) with a Fine Particle Fraction below 5 μm close to 50 %. Adopting a conservative estimate of 20 mL for the pulmonary epithelial lining fluid volume in healthy adults, efficacious local concentrations of sulfated polysaccharides and AZM would be delivered to the lung using this multifaceted strategy which holds promise for the treatment of bacterial pulmonary infections associated with COVID-19.

In vitro antiviral effect of sulfated pectin from Mangifera indica against the infection of the viral agent of childhood bronchiolitis (Respiratory Syncytial Virus - RSV)

The Human Respiratory Syncytial Virus (RSV) is the leading cause of acute respiratory infections in children. Currently, no safe, effective, or feasible option for pharmacological management of RSV exists. Hence, plant-derived natural compounds have been explored as promising antiviral agents. Mangifera indica is a globally distributed plant with reported anti-inflammatory, cardioprotective, and antiviral activities. Our study investigated the antiviral potential of a novel pectin from M. indica peels (PMi) and its chemically sulfated derivative (PSMi) against RSV in HEp-2 cells. The compounds were characterized using Fourier-transform infrared spectroscopy and nuclear magnetic resonance (NMR). NMR analysis revealed the presence of ester and carboxylic acid groups in PMi, and sulfation resulted in a sulfation degree of 0.5. PMi and PSMi showed no cytotoxic effects even at concentrations as high as 2000 μg/mL. PSMi completely inhibited RSV infectivity (100-1.56 μg/mL, 50 % inhibitory concentration of viral infectivity = 0.77 ± 0.11 μg/mL). The mechanism of action was investigated using the 50 % tissue culture infectious dose assay. PSMi displayed virucidal activity at concentrations from 100 to 6.25 μg/mL, and a significant reduction in viral infection was observed at all treatment times. Overall, PSMi is antiviral, cell-safe, and exhibits promising potential as an RSV treatment.

Anti-respiratory syncytial virus and anti-herpes simplex virus activity of chemically engineered sulfated fucans from Cystoseira indica

Seaweed polysaccharides, particularly sulfated ones, exhibited potent antiviral activity against a wide variety of enveloped viruses, such as herpes simplex virus and respiratory viruses. Different mechanisms of action were suggested, which may range from preventing infection to intracellular antiviral activity, at different stages of the viral cycle. Herein, we generated two chemically engineered sulfated fucans (C303 and C304) from Cystoseira indica by an amalgamated extraction-sulfation procedure using chlorosulfonic acid-pyridine/N,N-dimethylformamide and sulfur trioxide-pyridine/N,N-dimethylformamide reagents, respectively. These compounds exhibited activity against HSV-1 and RSV with 50 % inhibitory concentration values in the range of 0.75-2.5 μg/mL and low cytotoxicity at concentrations up to 500 μg/mL. The antiviral activities of chemically sulfated fucans (C303 and C304) were higher than the water (C301) and CaCl2 extracted (C302) polysaccharides. Compound C303 had a (1,3)-linked fucan backbone and was branched. Sulfates were present at positions C-2, C-4, and C-2,4 of Fucp, and C-6 of Galp residues of this polymer. Compound C304 had a comparable structure but with more sulfates at C-4 of Fucp residue. Both C303 and C304 were potent antiviral candidates, acting in a dose-dependent manner on the adsorption and other intracellular stages of HSV-1 and RSV replication, in vitro.

From Ocean to Medicine: Harnessing Seaweed's Potential for Drug Development

Seaweed, a miscellaneous group of marine algae, has long been recognized for its rich nutritional composition and bioactive compounds, being considered nutraceutical ingredient. This revision delves into the promising role of seaweed-derived nutrients as a beneficial resource for drug discovery and innovative product development. Seaweeds are abundant sources of essential vitamins, minerals, polysaccharides, polyphenols, and unique secondary metabolites, which reveal a wide range of biological activities. These bioactive compounds possess potential therapeutic properties, making them intriguing candidates for drug leads in various medical applications and pharmaceutical drug development. It explores their pharmacological properties, including antioxidant, anti-inflammatory, antimicrobial, and anticancer activities, shedding light on their potential as therapeutic agents. Moreover, the manuscript provides insights into the development of formulation strategies and delivery systems to enhance the bioavailability and stability of seaweed-derived compounds. The manuscript also discusses the challenges and opportunities associated with the integration of seaweed-based nutrients into the pharmaceutical and nutraceutical industries. Regulatory considerations, sustainability, and scalability of sustainable seaweed sourcing and cultivation methods are addressed, emphasizing the need for a holistic approach in harnessing seaweed's potential. This revision underscores the immense potential of seaweed-derived compounds as a valuable reservoir for drug leads and product development. By bridging the gap between marine biology, pharmacology, and product formulation, this research contributes to the critical advancement of sustainable and innovative solutions in the pharmaceutical and nutraceutical sectors.

Seaweed for climate mitigation, wastewater treatment, bioenergy, bioplastic, biochar, food, pharmaceuticals, and cosmetics: a review

The development and recycling of biomass production can partly solve issues of energy, climate change, population growth, food and feed shortages, and environmental pollution. For instance, the use of seaweeds as feedstocks can reduce our reliance on fossil fuel resources, ensure the synthesis of cost-effective and eco-friendly products and biofuels, and develop sustainable biorefinery processes. Nonetheless, seaweeds use in several biorefineries is still in the infancy stage compared to terrestrial plants-based lignocellulosic biomass. Therefore, here we review seaweed biorefineries with focus on seaweed production, economical benefits, and seaweed use as feedstock for anaerobic digestion, biochar, bioplastics, crop health, food, livestock feed, pharmaceuticals and cosmetics. Globally, seaweeds could sequester between 61 and 268 megatonnes of carbon per year, with an average of 173 megatonnes. Nearly 90% of carbon is sequestered by exporting biomass to deep water, while the remaining 10% is buried in coastal sediments. 500 gigatonnes of seaweeds could replace nearly 40% of the current soy protein production. Seaweeds contain valuable bioactive molecules that could be applied as antimicrobial, antioxidant, antiviral, antifungal, anticancer, contraceptive, anti-inflammatory, anti-coagulants, and in other cosmetics and skincare products.

Synthesis and Anti-influenza Activity of Vinylphosphonic Acid (Co)polymers

New copolymers of vinylphosphonic acid (VPA) with 2-deoxy-2-methacrylamido-D-glucose, 4-acryloylmorpholine (4-AM), and acrylamide have been synthesized, and their antiviral activity against influenza virus has been studied in in vitro and in vivo experiments. Optimal antiviral characteristics and low cytotoxicity were exhibited by the copolymer of VPA with 4-AM, composition 56 : 44 mol %, molecular weight 33 000. The polymer exhibited virus-inhibiting properties with an IC50 = 1 µg/mL and a selectivity index of 302. Prophylactic intranasal administration of the polymer in a murine model of influenza pneumonia completely prevented the virus-induced death of animals, whereas the level of mortality in the placebo group was 90%. The results of this study indicate a high antiviral potential of polymeric compounds based on VPA.

Antiviral Activity and Mechanisms of Seaweeds Bioactive Compounds on Enveloped Viruses-A Review

In the last decades, the interest in seaweed has significantly increased. Bioactive compounds from seaweed’s currently receive major attention from pharmaceutical companies as they express several interesting biological activities which are beneficial for humans. The structural diversity of seaweed metabolites provides diverse biological activities which are expressed through diverse mechanisms of actions. This review mainly focuses on the antiviral activity of seaweed’s extracts, highlighting the mechanisms of actions of some seaweed molecules against infection caused by different types of enveloped viruses: influenza, Lentivirus (HIV-1), Herpes viruses, and coronaviruses. Seaweed metabolites with antiviral properties can act trough different pathways by increasing the host’s defense system or through targeting and blocking virus replication before it enters host cells. Several studies have already established the large antiviral spectrum of seaweed’s bioactive compounds. Throughout this review, antiviral mechanisms and medical applications of seaweed’s bioactive compounds are analyzed, suggesting seaweed’s potential source of antiviral compounds for the formulation of novel and natural antiviral drugs.

Microalgal drugs: A promising therapeutic reserve for the future

Over the decades, a variety of chemically synthesized drugs are being used to cure existing diseases but often these drugs could not be effectively employed for the treatment of serious and newly emerging diseases. Fortunately, in nature there occurs immense treasure of plants and microorganisms which are living jewels with respect to their richness of medically important metabolites of high value. Hence, amongst the existing microorganism(s), the marine world offers a plethora of biological entities that can contribute to alleviate numerous human ailments. Algae are one such photosynthetic microorganism found in both marine as well as fresh water which are rich source of metabolites known for their nutrient content and health benefits. Various algal species like Haematococcus, Diatoms, Griffithsia, Chlorella, Spirulina, Ulva, etc. have been identified and isolated to produce biologically active and pharmaceutically important high value compounds like astaxanthin, fucoxanthin, sulphur polysaccharides mainly galactose, rhamnose, xylose, fucose etc., which show antimicrobial, antifungal, anti-cancer, and antiviral activities. However, the production of either of these bio compounds is favored under conditions of stress. This review gives detailed information on various nutraceutical metabolites extracted from algae. Additionally focus has been made on the role of these bio compounds extracted from algae especially sulphur polysaccharides to treat several diseases with prospective treatment for SARS-CoV-2. Lastly it covers the knowledge gaps and future perspectives in this area of research.

Polysaccharides and Their Derivatives as Potential Antiviral Molecules

In the current context of the COVID-19 pandemic, it appears that our scientific resources and the medical community are not sufficiently developed to combat rapid viral spread all over the world. A number of viruses causing epidemics have already disseminated across the world in the last few years, such as the dengue or chinkungunya virus, the Ebola virus, and other coronavirus families such as Middle East respiratory syndrome (MERS-CoV) and severe acute respiratory syndrome (SARS-CoV). The outbreaks of these infectious diseases have demonstrated the difficulty of treating an epidemic before the creation of vaccine. Different antiviral drugs already exist. However, several of them cause side effects or have lost their efficiency because of virus mutations. It is essential to develop new antiviral strategies, but ones that rely on more natural compounds to decrease the secondary effects. Polysaccharides, which have come to be known in recent years for their medicinal properties, including antiviral activities, are an excellent alternative. They are essential for the metabolism of plants, microorganisms, and animals, and are directly extractible. Polysaccharides have attracted more and more attention due to their therapeutic properties, low toxicity, and availability, and seem to be attractive candidates as antiviral drugs of tomorrow.

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.

Influence of the Structural Features of Carrageenans from Red Algae of the Far Eastern Seas on Their Antiviral Properties

The structural diversity and unique physicochemical properties of sulphated polysaccharides of red algae carrageenans (CRGs), to a great extent, determine the wide range of their antiviral properties. This work aimed to compare the antiviral activities of different structural types of CRGs: against herpes simplex virus type 1 (HSV-1) and enterovirus (ECHO-1). We found that CRGs significantly increased the resistance of Vero cells to virus infection (preventive effect), directly affected virus particles (virucidal effect), inhibited the attachment and penetration of virus to cells, and were more effective against HSV-1. CRG1 showed the highest virucidal effect on HSV-1 particles with a selective index (SI) of 100. CRG2 exhibited the highest antiviral activity by inhibiting HSV-1 and ECHO-1 plaque formation, with a SI of 110 and 59, respectively, when it was added before virus infection. CRG2 also significantly reduced the attachment of HSV-1 and ECHO-1 to cells compared to other CRGs. It was shown by molecular docking that tetrasaccharides—CRGs are able to bind with the HSV-1 surface glycoprotein, gD, to prevent virus–cell interactions. The revealed differences in the effect of CRGs on different stages of the lifecycle of the viruses are apparently related to the structural features of the investigated compounds.

Luminescent polyelectrolytes with antiviral activity

Radical polymerization was used to synthesize and characterize (co)polymers with sodium styrenesulfonate (NaSS), 4-methacryloylamidosalicylic acid (MASA), and N-vinylpyrrolidone, which have a low cytotoxicity and a high antiviral activity against the human respiratory syncytial virus. The interaction of copolymers with Tb³⁺ ions was studied. The complexes formed in dilute aqueous solutions at a concentration of MASA units c ⩽ 1 · 10^-4 mol L^-1 demonstrate a strong luminescence. The luminescence intensity is independent of copolymer composition, but increases when the NaSS units are substituted with uncharged N-vinylpyrrolidone units. The obtained Tb³⁺ polymer complexes are promising luminescent sensors for the visualization of biological objects interacting with copolymers.