Carrageenan nasal spray in virus confirmed common cold: individual patient data analysis of two randomized controlled trials

Inhibitory Activity of Hydroxypropyl Methylcellulose on Rhinovirus and Influenza A Virus Infection of Human Nasal Epithelial Cells

The nasal epithelium is the primary site for entry of respiratory viruses. In comparison to oral administration, nasal drug applications directed locally to the site of infection can serve as early interventional barriers against respiratory virus pathogenesis by limiting viral spread in the upper airway. Experiments on the diffusion of methylene blue and nanoparticles in both water and low pH conditions revealed that hydroxypropyl methylcellulose (HPMC) can act as an effective physical barrier. This study also evaluated the activity of HPMC as a barrier against common respiratory viruses, i.e., rhinovirus (RV) and influenza A virus (IAV) using the in vitro human nasal epithelial cell (hNEC) model. Utilizing the hNEC infection model, we assessed the protective effects of HPMC in pH 3.5 and pH 7 buffers against RV and IAV. Acidic and pH-neutral buffers and HPMC dissolved in acidic and pH-neutral buffers were administered for 4 h prior to virus infection and at 4 h post-infection (hpi). The apical supernatant was harvested at 24 hpi to determine the viral loads of RV and IAV (H1N1 and H3N2). HPMC was demonstrated to exert protective effects in the infected hNECs independent of acidic pH. Pre-treatment with HPMC in acidic buffer significantly diminished viral loads for both RV and IAV infections of hNECs. Similarly, direct treatment of HPMC in acidic buffer after infection (4 hpi) also effectively decreased viral loads of both RV and IAV. Moreover, treatment using HPMC in acidic buffer before or after infection did not affect the epithelial integrity and ciliary function of hNECs. This study demonstrates the protective effects of HPMC in acidic buffer against RV and IAV infections of the human nasal epithelium.

Debulking influenza and herpes simplex virus strains by a wide-spectrum anti-viral protein formulated in clinical grade chewing gum

Lack of Herpes Simplex Virus (HSV) vaccine, low vaccination rates of Influenza viruses, waning immunity and viral transmission after vaccination underscore the need to reduce viral loads at their transmission sites. Oral virus transmission is several orders of magnitude higher than nasal transmission. Therefore, in this study, we evaluated neutralization of viruses using a natural viral trap protein (FRIL) formulated in clinical-grade chewing gum. FRIL is highly stable in the lablab bean powder (683 days) and in chewing gum (790 days), and fully functional (794 days) when stored at ambient temperature. They passed the bioburden test with no aerobic bacteria, yeasts/molds, with minimal moisture content (1.28-5.9%). Bean gum extracts trapped HSV-1/HSV-2 75-94% in a dose-dependent manner through virus self-aggregation. Mastication simulator released >50% release of FRIL within 15 min of chewing the bean gum. In plaque reduction assays, >95% neutralization of H1N1 and H3N2 required ∼40 mg/mL, HSV-1 160 mg/mL, and HSV-2 74 mg/mL of bean gum for 1,000 copies/mL virus particles. Therefore, a 2000 mg bean gum tablet has more than adequate potency for clinical evaluation and is safe with no detectable levels of glycosides. These observations augur well for evaluating bean gum in human clinical studies to minimize virus infection/transmission.

Harnessing traditional Chinese medicine polysaccharides for combatting COVID-19

With the global spread of COVID-19 posing ongoing challenges to public health systems, there is an ever-increasing demand for effective therapeutics that can mitigate both viral transmission and disease severity. This review surveys the landscape of polysaccharides derived from traditional Chinese medicine, acclaimed for their medicinal properties and potential to contribute to the COVID-19 response. We specifically focus on the capability of these polysaccharides to thwart SARS-CoV-2 entry into host cells, a pivotal step in the viral life cycle that informs transmission and pathogenicity. Moreover, we delve into the concept of trained immunity, an innate immune system feature that polysaccharides may potentiate, offering an avenue for a more moderated yet efficacious immune response against various pathogens, including SARS-CoV-2. Our comprehensive overview aims to bolster understanding of the possible integration of these substances within anti-COVID-19 measures, emphasizing the need for rigorous investigation into their potential applications and underlying mechanisms. The insights provided here strongly support ongoing investigations into the adjunctive use of polysaccharides in the management of COVID-19, with the anticipation that such findings could lead to a deeper appreciation and clearer elucidation of the antiviral potentials inherent in complex Chinese herbal remedies.

Biodegradable Gelatin-Carrageenan Sponges: High-Potential Functional Nasal Packs for Efficient Secretome Delivery

Nasal packing is a critical procedure in postoperative care and trauma management aimed at controlling bleeding, providing structural support, and promoting tissue healing. However, conventional nasal packs often lead to discomfort, infection risks, and secondary tissue damage. To address these challenges, this study explores the potential use of biodegradable and biocompatible gelatin-carrageenan composite scaffolds as an alternative nasal packing material. Five compositions of gelatin-carrageenan scaffolds (ratios 10:0, 7:3, 5:5, 3:7, and 0:10) were fabricated and evaluated for physicochemical properties, hemocompatibility, and cytocompatibility. Results suggest that balanced ratios, such as 7:3 and 5:5, may provide a combination of structural integrity, improved biocompatibility, and controlled degradation, making them a potential candidate for nasal packing applications. The scaffolds exhibited low cytotoxicity and reasonable blood compatibility, which could reduce the risks associated with conventional materials. While these findings are promising, further in vivo studies are necessary to validate the efficacy and safety of these scaffolds in clinical settings. If proven effective, gelatin-carrageenan scaffolds may help address some of the limitations of conventional nasal packing materials and improve postoperative care outcomes.

Decongestant Effect of "Coldamaris Akut", a Carrageenan- and Sorbitol-Containing Nasal Spray in Seasonal Allergic Rhinitis

Purpose

This study aimed to develop a hyperosmolar, barrier-forming nasal spray based on carrageenan and sorbitol, and to demonstrate its decongestant effect in the context of allergic rhinitis (AR).

Methods

The efficacy of the nasal spray components was tested in vitro by barrier function, virus replication inhibition, and water absorption assays. The decongestant effectiveness was assessed in a randomized, controlled, crossover environmental chamber trial, where participants with a history of seasonal grass pollen AR were exposed to grass pollen allergens under controlled conditions. Forty-one adults were randomized to receive either carrageenan- and sorbitol-containing nasal spray (CS) or saline solution (SS). After 1 week, participants repeated the exposure with the treatment they had not received before. The primary efficacy endpoint was the mean change in nasal congestion symptom score (NCSS). Secondary efficacy endpoints were nasal airflow, nasal secretion, total nasal symptom score (TNSS), total ocular symptom score (TOSS) and total respiratory symptom score (TRSS).

Results

Preclinical assays demonstrated barrier-building, virus-blocking, and water-withdrawing properties of the CS components. In the clinical study, there was no significant difference in mean NCSS change from pre- to post-treatment between CS and SS. However, nasal airflow increased over time after treatment with CS, while it declined after SS, leading to a growing difference in airflow between CS and SS (p = 0.04 at 6:00 h). Mean nasal secretion over 2-6 h was reduced by ~25% after CS (p = 0.003) compared to pre-treatment, while it was reduced by only ~16% after SS (p = 0.137). No significant differences in TNSS, TOSS and TRSS were observed between CS and SS.

Conclusion

CS improves nasal airflow and reduces nasal secretion in adults with AR. We propose CS as a safe and effective adjuvant to baseline pharmacological treatments.

Trial Registration

NCT04532762.

Sulfated Polysaccharides from Seaweeds: A Promising Strategy for Combatting Viral Diseases-A Review

The limited availability of treatments for many infectious diseases highlights the need for new treatments, particularly for viral infections. Natural compounds from seaweed are attracting increasing attention for the treatment of various viral diseases, and thousands of novel compounds have been isolated for the development of pharmaceutical products. Seaweed is a rich source of natural bioactive compounds, including polysaccharides. The discovery of algal polysaccharides with antiviral activity has significantly increased in the past few decades. Furthermore, unique polysaccharides isolated from seaweeds, such as carrageenan, alginates, fucoidans, galactans, laminarians, and ulvans, have been shown to act against viral infections. The antiviral mechanisms of these agents are based on their inhibition of DNA or RNA synthesis, viral entry, and viral replication. In this article, we review and provide an inclusive description of the antiviral activities of algal polysaccharides. Additionally, we discuss the challenges and opportunities for developing polysaccharide-based antiviral therapies, including issues related to drug delivery and formulation. Finally, this review highlights the need for further research for fully understanding the potential of seaweed polysaccharides as a source of antiviral agents and for developing effective treatments for viral diseases.

Anti-SARS-CoV-2 Activity of Polysaccharides Extracted from Halymenia floresii and Solieria chordalis (Rhodophyta)

Even after hundreds of clinical trials, the search for new antivirals to treat COVID-19 is still relevant. Carrageenans are seaweed sulfated polysaccharides displaying antiviral activity against a wide range of respiratory viruses. The objective of this work was to study the antiviral properties of Halymenia floresii and Solieria chordalis carrageenans against SARS-CoV-2. Six polysaccharide fractions obtained from H. floresii and S. chordalis by Enzyme-Assisted Extraction (EAE) or Hot Water Extraction (HWE) were tested. The effect of carrageenan on viral replication was assessed during infection of human airway epithelial cells with a clinical strain of SARS-CoV-2. The addition of carrageenans at different times of the infection helped to determine their mechanism of antiviral action. The four polysaccharide fractions isolated from H. floresii displayed antiviral properties while the S. chordalis fractions did not. EAE-purified fractions caused a stronger reduction in viral RNA concentration. Their antiviral action is likely related to an inhibition of the virus attachment to the cell surface. This study confirms that carrageenans could be used as first-line treatment in the respiratory mucosa to inhibit the infection and transmission of SARS-CoV-2. Low production costs, low cytotoxicity, and a broad spectrum of antiviral properties constitute the main strengths of these natural molecules.

Utilization of Marine Seaweeds as a Promising Defense Against COVID-19: a Mini-review

COVID-19 is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which mainly affects the respiratory system. It has been declared as a "pandemic" in March 2020 by the World Health Organization due to the high spreading rate. SARS-CoV-2 binds with the angiotensin-converting enzyme 2 (ACE2) receptors on the cell surface which leads to the downregulation of ACE2 and upregulation of angiotensin-converting enzyme (ACE) receptors. The elevated level of cytokines and ACE receptors leads to the severity of SARS-CoV-2 infection. Due to the limited availability of vaccines and recurrent attacks of COVID-19 mainly in low-income countries, it is important to search for natural remedies to prevent or treat COVID-19 infection. Marine seaweeds are a rich source of bioactive compounds such as phlorotannins; fucoidan; carotenoids; omega-3 and omega-6 fatty acids; vitamins B₁₂, D, and C; and minerals including zinc and selenium that exhibit antioxidant, antiviral, and anti-inflammatory activities. Furthermore, bioactive compounds present in marine seaweeds have the ability to inhibit ACEs by inducing ACE2 which exhibits anti-inflammatory effects in COVID-19. Correspondingly, soluble dietary fibers present in seaweeds are served as prebiotics by generating short-chain fatty acids through fermentation. Hence, seaweeds can be utilized to reduce the gastrointestinal infections associated with SARS-CoV-2 infection.

A study protocol for a double-blind randomised placebo-controlled trial evaluating the efficacy of carrageenan nasal and throat spray for COVID-19 prophylaxis—ICE-COVID

Introduction

At present, vaccines form the only mode of prophylaxis against COVID-19. The time needed to achieve mass global vaccination and the emergence of new variants warrants continued research into other COVID-19 prevention strategies. The severity of COVID-19 infection is thought to be associated with the initial viral load, and for infection to occur, viruses including SARS-CoV-2 must first penetrate the respiratory mucus and attach to the host cell surface receptors. Carrageenan, a sulphated polysaccharide extracted from red edible seaweed, has shown efficacy against a wide range of viruses in clinical trials through the prevention of viral entry into respiratory host cells. Carrageenan has also demonstrated in vitro activity against SARS-CoV-2.

Methods and analysis

A single-centre, randomised, double-blinded, placebo-controlled phase III trial was designed. Participants randomised in a 1:1 allocation to either the treatment arm, verum Coldamaris plus (1.2 mg iota-carrageenan (Carragelose®), 0.4 mg kappa-carrageenan, 0.5% sodium chloride and purified water), or placebo arm, Coldamaris sine (0.5% sodium chloride) spray applied daily to their nose and throat for 8 weeks, while completing a daily symptom tracker questionnaire for a total of 10 weeks.

Primary outcome

Acquisition of COVID-19 infection as confirmed by a positive PCR swab taken at symptom onset or seroconversion during the study. Secondary outcomes include symptom type, severity and duration, subsequent familial/household COVID-19 infection and infection with non-COVID-19 upper respiratory tract infections. A within-trial economic evaluation will be undertaken, with effects expressed as quality-adjusted life years.

Discussion

This is a single-centre, phase III, double-blind, randomised placebo-controlled clinical trial to assess whether carrageenan nasal and throat spray reduces the risk of development and severity of COVID-19. If proven effective, the self-administered prophylactic spray would have wider utility for key workers and the general population.

Trial registration

NCT04590365; ClinicalTrials.gov NCT04590365. Registered on 19 October 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06685-z.

A state-of-the-art review on fucoidan as an antiviral agent to combat viral infections

As a significant public health hazard with several drug side effects during medical treatment, searching for novel therapeutic natural medicines is promising. Sulfated polysaccharides from algae, such as fucoidan, have been discovered to have a variety of medical applications, including antibacterial and immunomodulatory properties. The review emphasized on the utilization of fucoidan as an antiviral agent against viral infections by inhibiting their attachment and replication. Moreover, it can also trigger immune response against viral infection in humans. This review suggested to be use the fucoidan for the potential protective remedy against COVID-19 and addressing the antiviral activities of sulfated polysaccharide, fucoidan derived from marine algae that could be used as an anti-COVID19 drug in near future.

Recommendation of the German Society of Hospital Hygiene (DGKH): Prevention of COVID-19 by virucidal gargling and virucidal nasal spray - updated version April 2022

The German Society of Hospital Hygiene develops guidelines, recommendations and standard operation procedures on a voluntary basis, published on the DGKH-website (https://www.krankenhaushygiene.de/). The original German version of this recommendation was published in April 2022 and has now been made available to the international professional public in English. Evaluating the current data on the efficacy of virucidal gargle/mouthwash solutions and nasal sprays against SARS-CoV-2 in vitro and in clinical trials, conducted with preventive or therapeutic objectives, recommendations are given for the prevention of COVID-19. The following areas are considered: Protection of the community when regional clusters or high incidences of infection become knownProtection of the community at low risk of infectionPre-exposure prophylaxis for the protection of healthcare workersPost-exposure prophylaxis.

Multifaceted role of natural sources for COVID-19 pandemic as marine drugs

COVID-19, which is caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has quickly spread over the world, posing a global health concern. The ongoing epidemic has necessitated the development of novel drugs and potential therapies for patients infected with SARS-CoV-2. Advances in vaccination and medication development, no preventative vaccinations, or viable therapeutics against SARS-CoV-2 infection have been developed to date. As a result, additional research is needed in order to find a long-term solution to this devastating condition. Clinical studies are being conducted to determine the efficacy of bioactive compounds retrieved or synthesized from marine species starting material. The present study focuses on the anti-SARS-CoV-2 potential of marine-derived phytochemicals, which has been investigated utilizing in in silico, in vitro, and in vivo models to determine their effectiveness. Marine-derived biologically active substances, such as flavonoids, tannins, alkaloids, terpenoids, peptides, lectins, polysaccharides, and lipids, can affect SARS-CoV-2 during the viral particle's penetration and entry into the cell, replication of the viral nucleic acid, and virion release from the cell; they can also act on the host's cellular targets. COVID-19 has been proven to be resistant to several contaminants produced from marine resources. This paper gives an overview and summary of the various marine resources as marine drugs and their potential for treating SARS-CoV-2. We discussed at numerous natural compounds as marine drugs generated from natural sources for treating COVID-19 and controlling the current pandemic scenario.

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.

Advances in the Prophylaxis of Respiratory Infections by the Nasal and the Oromucosal Route: Relevance to the Fight with the SARS-CoV-2 Pandemic

In this time of COVID-19 pandemic, the strategies for prevention of the infection are a primary concern. Looking more globally on the subject and acknowledging the high degree of misuse of protective face masks from the population, we focused this review on alternative pharmaceutical developments eligible for self-defense against respiratory infections. In particular, the attention herein is directed to the nasal and oromucosal formulations intended to boost the local immunity, neutralize or mechanically "trap" the pathogens at the site of entry (nose or mouth). The current work presents a critical review of the contemporary methods of immune- and chemoprophylaxis and their suitability and applicability in topical mucosal dosage forms for SARS-CoV-2 prophylaxis.

Algal Metabolites Can Be an Immune Booster against COVID-19 Pandemic

The world has faced the challenges of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) for the last two years, first diagnosed at the end of 2019 in Wuhan and widely distributed worldwide. As a result, the WHO has proclaimed the illness brought on by this virus to be a global pandemic. To combat COVID-19, researcher communities continuously develop and implement rapid diagnoses, safe and effective vaccinations and other alternative therapeutic procedures. However, synthetic drug-related side effects and high costs have piqued scientists’ interest in natural product-based therapies and medicines. In this regard, antiviral substances derived from natural resources and some medicines have seen a boom in popularity. For instance, algae are a rich source of compounds such as lectins and sulfated polysaccharides, which have potent antiviral and immunity-boosting properties. Moreover, Algae-derived compounds or metabolites can be used as antibodies and vaccine raw materials against COVID-19. Furthermore, some algal species can boost immunity, reduce viral activity in humans and be recommended for usage as a COVID-19 preventative measure. However, this field of study is still in its early stages of development. Therefore, this review addresses critical characteristics of algal metabolites, their antioxidant potential and therapeutic potential in COVID-19.

Cyanobacteria and Algae-Derived Bioactive Metabolites as Antiviral Agents: Evidence, Mode of Action, and Scope for Further Expansion; A Comprehensive Review in Light of the SARS-CoV-2 Outbreak

COVID-19—a severe acute respiratory syndrome disease caused by coronavirus 2 (SARS-CoV-2)—has recently attracted global attention, due to its devastating impact, to the point of being declared a pandemic. The search for new natural therapeutic drugs is mandatory, as the screening of already-known antiviral drugs so far has led to poor results. Several species of marine algae have been reported as sources of bioactive metabolites with potential antiviral and immunomodulatory activities, among others. Some of these bioactive metabolites might be able to act as antimicrobial drugs and also against viral infections by inhibiting their replication. Moreover, they could also trigger immunity against viral infection in humans and could be used as protective agents against COVID-In this context, this article reviews the main antiviral activities of bioactive metabolites from marine algae and their potential exploitation as anti-SARS-CoV-2 drugs.

Low Acyl Gellan as an Excipient to Improve the Sprayability and Mucoadhesion of Iota Carrageenan in a Nasal Spray to Prevent Infection With SARS-CoV-2

The COVID-19 global pandemic, as well as the widespread persistence of influenza and the common cold, create the need for new medical devices such as nasal sprays to prevent viral infection and transmission. Carrageenan, a sulfated polysaccharide, has a broad, non-pharmacological antiviral capacity, however it performs poorly in two key areas; spray coverage and mucoadhesion. Therefore gellan, another polysaccharide, was investigated as an excipient to improve these properties. It was found that viscoelastic relaxation time was the key predictor of spray coverage, and by reducing this value from 2.5 to 0.25 s, a mix of gellan and carrageenan gave more than four times the coverage of carrageenan alone (p < 0.0001). Gellan also demonstrated enhanced adhesion to a mucus analog that increased significantly with time (p < 0.0001), suggesting the development of specific gellan–mucin interactions. This property was conferred to carrageenan on mixing the two polymers. Together, this data suggests that gellan is a promising excipient to improve both sprayability and mucoadhesion of carrageenan for use in antiviral nasal sprays.

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.

Iota-carrageenan extracted from red algae is a potent inhibitor of SARS-CoV-2 infection in reconstituted human airway epithelia

Iota-carrageenan (IC) nasal spray, a medical device approved for treating respiratory viral infections, has previously been shown to inhibit the ability of a variety of respiratory viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), to enter and replicate in the cell by interfering with the virus binding to the cell surface. The aim of this study was to further investigate the efficacy and safety of IC in SARS-CoV-2 infection in advanced in vitro models of the human respiratory epithelium, the primary target and entry port for SARS-CoV-2. We extended the in vitro safety assessment of nebulized IC in a 3-dimensional model of reconstituted human bronchial epithelium, and we demonstrated the efficacy of IC in protecting reconstituted nasal epithelium against viral infection and replication of a patient-derived SARS-CoV-2 strain. The results obtained from these two advanced models of human respiratory tract epithelia confirm previous findings from in vitro SARS-CoV-2 infection assays and demonstrate that topically applied IC can effectively prevent SARS-CoV-2 infection and replication. Moreover, the absence of toxicity and functional and structural impairment of the mucociliary epithelium demonstrates that the nebulized IC is well tolerated.

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IC had a potent antiviral effect in SARS-CoV-2 infected organotypic nasal epithelial cultures.

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Topical application (nasal drops) was non-toxic at anti-virally efficient doses.

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Aerosolized IC had no adverse effects on reconstituted human bronchial epithelium.

The direct and indirect effects of bioactive compounds against coronavirus

Emerging viruses are known to pose a threat to humans in the world. COVID‐19, a newly emerging viral respiratory disease, can spread quickly from people to people via respiratory droplets, cough, sneeze, or exhale. Up to now, there are no specific therapies found for the treatment of COVID‐19. In this sense, the rising demand for effective antiviral drugs is stressed. The main goal of the present study is to cover the current literature about bioactive compounds (e.g., polyphenols, glucosinolates, carotenoids, minerals, vitamins, oligosaccharides, bioactive peptides, essential oils, and probiotics) with potential efficiency against COVID‐19, showing antiviral activities via the inhibition of coronavirus entry into the host cell, coronavirus enzymes, as well as the virus replication in human cells. In turn, these compounds can boost the immune system, helping fight against COVID‐19. Overall, it can be concluded that bioactives and the functional foods containing these compounds can be natural alternatives for boosting the immune system and defeating coronavirus.

Iota-Carrageenan Inhibits Replication of SARS-CoV-2 and the Respective Variants of Concern Alpha, Beta, Gamma and Delta

The COVID-19 pandemic continues to spread around the world and remains a major public health threat. Vaccine inefficiency, vaccination breakthroughs and lack of supply, especially in developing countries, as well as the fact that a non-negligible part of the population either refuse vaccination or cannot be vaccinated due to age, pre-existing illness or non-response to existing vaccines intensify this issue. This might also contribute to the emergence of new variants, being more efficiently transmitted, more virulent and more capable of escaping naturally acquired and vaccine-induced immunity. Hence, the need of effective and viable prevention options to reduce viral transmission is of outmost importance. In this study, we investigated the antiviral effect of iota-, lambda- and kappa-carrageenan, sulfated polysaccharides extracted from red seaweed, on SARS-CoV-2 Wuhan type and the spreading variants of concern (VOCs) Alpha, Beta, Gamma and Delta. Carrageenans as part of broadly used nasal and mouth sprays as well as lozenges have the potential of first line defense to inhibit the infection and transmission of SARS-CoV-2. Here, we demonstrate by using a SARS-CoV-2 spike pseudotyped lentivirus particles (SSPL) system and patient-isolated SARS-CoV-2 VOCs to infect transgenic A549ACE2/TMPRSS2 and Calu-3 human lung cells that all three carrageenan types exert antiviral activity. Iota-carrageenan exhibits antiviral activity with comparable IC₅₀ values against the SARS-CoV-2 Wuhan type and the VOCs. Altogether, these results indicate that iota-carrageenan might be effective for prophylaxis and treatment of SARS-CoV-2 infections independent of the present and potentially future variants.

Carbohydrates-based diagnosis, prophylaxis and treatment of infectious diseases: Special emphasis on COVID-19

COVID-19 pandemic is taking a dangerous turn due to unavailability of approved and effective vaccines and therapy. Currently available diagnostic techniques are time-consuming, expensive, and maybe impacted by the mutations produced in the virus. Therefore, investigation of novel, rapid, and economic diagnosis techniques, prophylactic vaccines and targeted efficacious drug delivery systems as treatment strategy is imperative. Carbohydrates are essential biomolecules which also act as markers in the realization of immune systems. Moreover, they exhibit antiviral, antimicrobial, and antifungal properties. Carbohydrate-based vaccines and therapeutics including stimuli sensitive systems can be developed successfully and used effectively to fight COVID-19. Thus, carbohydrate-based diagnostic, prophylactic and therapeutic alternatives could be promising to defeat COVID-19 propitiously. Morphology of SARS-CoV-2 and its relevance in devising combat strategies has been discussed. Carbohydrate-based approaches for tackling infectious diseases and their importance in the design of various diagnostic and treatment modalities have been reviewed.

Iota-carrageenan and xylitol inhibit SARS-CoV-2 in Vero cell culture

Last year observed a global pandemic caused by SARS-CoV-2 (severe acute respiratory syndrome-coronavirus 2) infection affecting millions of individuals worldwide. There is an urgent unmet need to provide an easily producible and affordable medicine to prevent transmission and provide early treatment for this disease. Since the nasal cavity and the rhinopharynx are the sites of initial replication of SARS-CoV-2, a nasal spray may be an effective option to target SARS-CoV-2 infection. In this study, we tested the antiviral action of three candidate nasal spray formulations against SARS-CoV-2 in vitro. We determined that iota-carrageenan in concentrations as low as 6 μg/mL inhibits SARS-CoV-2 in vitro. The concentrations of iota-carrageenan with activity against SARS-CoV-2 in vitro may be easily achieved through the application of nasal sprays as commonly used in several countries. Recently a double-blind, placebo-controlled study showed that iota-carrageenan in isotonic sodium chloride reduces ca. five times the risk of infection by SARS-CoV-2 in health care personnel. Further, xylitol at a concentration of 50 mg/mL (ca. 329 mM) was found to exert some antiviral action, though this preliminary finding needs further confirmation.

SARS-CoV-2 inhibition using a mucoadhesive, amphiphilic chitosan that may serve as an anti-viral nasal spray

There are currently no cures for coronavirus infections, making the prevention of infections the only course open at the present time. The COVID-19 pandemic has been difficult to prevent, as the infection is spread by respiratory droplets and thus effective, scalable and safe preventive interventions are urgently needed. We hypothesise that preventing viral entry into mammalian nasal epithelial cells may be one way to limit the spread of COVID-19. Here we show that N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ), a positively charged polymer that has been through an extensive Good Laboratory Practice toxicology screen, is able to reduce the infectivity of SARS-COV-2 in A549ACE2+ and Vero E6 cells with a log removal value of - 3 to - 4 at a concentration of 10-100 μg/ mL (p < 0.05 compared to untreated controls) and to limit infectivity in human airway epithelial cells at a concentration of 500 μg/ mL (p < 0.05 compared to untreated controls). In vivo studies using transgenic mice expressing the ACE-2 receptor, dosed nasally with SARS-COV-2 (426,000 TCID50/mL) showed a trend for nasal GCPQ (20 mg/kg) to inhibit viral load in the respiratory tract and brain, although the study was not powered to detect statistical significance. GCPQ's electrostatic binding to the virus, preventing viral entry into the host cells, is the most likely mechanism of viral inhibition. Radiolabelled GCPQ studies in mice show that at a dose of 10 mg/kg, GCPQ has a long residence time in mouse nares, with 13.1% of the injected dose identified from SPECT/CT in the nares, 24 h after nasal dosing. With a no observed adverse effect level of 18 mg/kg in rats, following a 28-day repeat dose study, clinical testing of this polymer, as a COVID-19 prophylactic is warranted.

Exploring the therapeutic potential of marine-derived bioactive compounds against COVID-19

The ocean is the most biodiverse habitat of various organisms. The organisms surviving in the harsh conditions of the ocean consist of several spectacular properties and produce bioactive compounds of pharmacological importance. These compounds are effective even in small quantities with various immunomodulatory qualities such as antioxidant and anti-inflammatory properties. Though the vaccines for COVID-19 are developed, and drug development is also in progress, but till now no effective drug is available for this deadly virus. Researchers are mining the huge data of bioactive compounds to develop the specific drug for COVID-19. The use of the repurposed drugs is challenging against the rapidly mutating virus with variable symptoms and mode of transmission. This review is an attempt to compile all the spattered data of marine-derived bioactive compounds with antiviral properties and to explore their therapeutic potential against COVID-19.

The Saliva of Probands Sucking an Iota-Carrageenan Containing Lozenge Inhibits Viral Binding and Replication of the Most Predominant Common Cold Viruses and SARS-CoV-2

PURPOSE

The aim of this study was to investigate whether sucking of an iota-carrageenan containing lozenge releases sufficient iota-carrageenan into the saliva of healthy subjects to neutralize representatives of the most common respiratory virus families causing common cold and SARS-CoV-2.

PATIENTS AND METHODS

In this monocentric, open label, prospective clinical trial, 31 healthy subjects were included to suck a commercially available iota-carrageenan containing lozenge. Saliva samples from 27 subjects were used for ex vivo efficacy analysis. The study's primary objective was to assess if the mean iota-carrageenan concentration of the saliva samples exceeded 5 µg/mL, which is the concentration known to reduce replication of human rhinovirus (hRV) 1a and 8 by 90%. The iota-carrageenan concentration of the saliva samples was analyzed by UV-Vis spectroscopy. The antiviral effectiveness of the individual saliva samples was determined in vitro against a panel of respiratory viruses including hRV1a, hRV8, human coronavirus OC43, influenza virus A H1N1pdm09, coxsackievirus A10, parainfluenza virus 3 and SARS-CoV-2 using standard virological assays.

RESULTS

The mean iota-carrageenan concentration detected in the saliva exceeds the concentration needed to inhibit 90% of hRV1a and hRV8 replication by 134-fold (95% CI 116.3-160.8-fold; p < 0.001). Thus, the study met the primary endpoint. Furthermore, the iota-carrageenan saliva concentration was 60 to 30,351-fold higher than needed to reduce viral replication/binding of all tested viruses by at least 90% (p < 0.001). The effect was most pronounced in hCoV OC43; in case of SARS-CoV-2, the IC90 was exceeded by 121-fold (p < 0.001).

CONCLUSION

Sucking an iota-carrageenan containing lozenge releases sufficient iota-carrageenan to neutralize and inactivate the most abundant respiratory viruses as well as pandemic SARS-CoV-2. The lozenges are therefore an appropriate measure to reduce the viral load at the site of infection, hereby presumably limiting transmission within a population as well as translocation to the lower respiratory tract.

TRIAL REGISTRATION

NCT04533906.

Carrageenan nasal spray may double the rate of recovery from coronavirus and influenza virus infections: Re-analysis of randomized trial data

In this individual patient data meta-analysis we examined datasets of two randomized placebo-controlled trials which investigated the effect of nasal carrageenan separately on children and adults. In both trials, iota-carrageenan was administered nasally three times per day for 7 days for patients with the common cold and follow-up lasted for 21 days. We used Cox regression to estimate the effect of carrageenan on recovery rate. We also used quantile regression to calculate the effect of carrageenan on colds of differing lengths. Nasal carrageenan increased the recovery rate from all colds by 54% (95% CI 15%-105%; p = .003). The increase in recovery rate was 139% for coronavirus infections, 119% for influenza A infections, and 70% for rhinovirus infections. The mean duration of all colds in the placebo groups of the first four quintiles were 4.0, 6.8, 8.8, and 13.7 days, respectively. The fifth quintile contained patients with censored data. The 13.7-day colds were shortened by 3.8 days (28% reduction), and 8.8-day colds by 1.3 days (15% reduction). Carrageenan had no meaningful effect on shorter colds. In the placebo group, 21 patients had colds lasting over 20 days, compared with six patients in the carrageenan group, which corresponds to a 71% (p = .003) reduction in the risk of longer colds. Given that carrageenan has an effect on diverse virus groups, and effects at the clinical level on two old coronaviruses, it seems plausible that carrageenan may have an effect on COVID-19. Further research on nasal iota-carrageenan is warranted.

Antiviral Activity of Carrageenans and Processing Implications

Carrageenan and carrageenan oligosaccharides are red seaweed sulfated carbohydrates with well-known antiviral properties, mainly through the blocking of the viral attachment stage. They also exhibit other interesting biological properties and can be used to prepare different drug delivery systems for controlled administration. The most active forms are λ-, ι-, and κ-carrageenans, the degree and sulfation position being determined in their properties. They can be obtained from sustainable worldwide available resources and the influence of manufacturing on composition, structure, and antiviral properties should be considered. This review presents a survey of the antiviral properties of carrageenan in relation to the processing conditions, particularly those assisted by intensification technologies during the extraction stage, and discusses the possibility of further chemical modifications.

Griffithsin and Carrageenan Combination Results in Antiviral Synergy against SARS-CoV-1 and 2 in a Pseudoviral Model

Over 182 million confirmed cases of COVID-19 and more than 4 million deaths have been reported to date around the world. It is essential to identify broad-spectrum antiviral agents that may prevent or treat infections by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) but also by other coronaviruses that may jump the species barrier in the future. We evaluated the antiviral selectivity of griffithsin and sulfated and non-sulfated polysaccharides against SARS-CoV-1 and SARS-CoV-2 using a cytotoxicity assay and a cell-based pseudoviral model. The half-maximal cytotoxic concentration (CC₅₀) and half-maximal effective concentration (EC₅₀) were determined for each compound, using a dose-response-inhibition analysis on GraphPad Prism v9.0.2 software (San Diego, CA, USA). The therapeutic index (TI = CC₅₀/EC₅₀) was calculated for each compound. The potential synergistic, additive, or antagonistic effect of different compound combinations was determined by CalcuSyn v1 software (Biosoft, Cambridge, UK), which estimated the combination index (CI) values. Iota and lambda carrageenan showed the most potent antiviral activity (EC₅₀ between 3.2 and 7.5 µg/mL). Carrageenan and griffithsin combinations exhibited synergistic activity (EC₅₀ between 0.2 and 3.8 µg/mL; combination index <1), including against recent SARS-CoV-2 mutations. The griffithsin and carrageenan combination is a promising candidate to prevent or treat infections by SARS-CoV-1 and SARS-CoV-2.

Marine Sulfated Polysaccharides as Promising Antiviral Agents: A Comprehensive Report and Modeling Study Focusing on SARS CoV-2

SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) is a novel coronavirus strain that emerged at the end of 2019, causing millions of deaths so far. Despite enormous efforts being made through various drug discovery campaigns, there is still a desperate need for treatments with high efficacy and selectivity. Recently, marine sulfated polysaccharides (MSPs) have earned significant attention and are widely examined against many viral infections. This article attempted to produce a comprehensive report about MSPs from different marine sources alongside their antiviral effects against various viral species covering the last 25 years of research articles. Additionally, these reported MSPs were subjected to molecular docking and dynamic simulation experiments to ascertain potential interactions with both the receptor-binding domain (RBD) of SARS CoV-2's spike protein (S-protein) and human angiotensin-converting enzyme-2 (ACE2). The possible binding sites on both S-protein's RBD and ACE2 were determined based on how they bind to heparin, which has been reported to exhibit significant antiviral activity against SARS CoV-2 through binding to RBD, preventing the virus from affecting ACE2. Moreover, our modeling results illustrate that heparin can also bind to and block ACE2, acting as a competitor and protective agent against SARS CoV-2 infection. Nine of the investigated MSPs candidates exhibited promising results, taking into consideration the newly emerged SARS CoV-2 variants, of which five were not previously reported to exert antiviral activity against SARS CoV-2, including sulfated galactofucan (1), sulfated polymannuroguluronate (SPMG) (2), sulfated mannan (3), sulfated heterorhamnan (8), and chondroitin sulfate E (CS-E) (9). These results shed light on the importance of sulfated polysaccharides as potential SARS-CoV-2 inhibitors.

Effect of the Anchoring Layer and Transport Type on the Adsorption Kinetics of Lambda Carrageenan

The kinetics of lambda carrageenan (λ-car) adsorption/desorption on/from anchoring layers under diffusion- and convection-controlled transport conditions were investigated. The eighth generation of poly(amidoamine) dendrimers and branched polyethyleneimine possessing different shapes and polydispersity indexes were used for anchoring layer formation. Dynamic light scattering, electrophoresis, streaming potential measurements, optical waveguide lightmode spectroscopy, and quartz crystal microbalance were applied to characterize the formation of mono- and bilayers. The unique combination of the employed techniques enabled detailed insights into the mechanism of the λ-car adsorption mainly controlled by electrostatic interactions. The results show that the macroion adsorption efficiency is strictly correlated with the value of the final zeta potentials of the anchoring layers, the transport type, and the initial bulk concentration of the macroions. The type of the macroion forming the anchoring layer had a minor impact on the kinetics of λ-car adsorption. Besides significance to basic science, the results presented in this paper can be used for the development of biocompatible and stable macroion multilayers of well-defined electrokinetic properties and structure.

Viral inhibitors derived from macroalgae, microalgae, and cyanobacteria: A review of antiviral potential throughout pathogenesis

Viruses are abiotic obligate parasites utilizing complex mechanisms to hijack cellular machinery and reproduce, causing multiple harmful effects in the process. Viruses represent a growing global health concern; at the time of writing, COVID-19 has killed at least two million people around the world and devastated global economies. Lingering concern regarding the virus' prevalence yet hampers return to normalcy. While catastrophic in and of itself, COVID-19 further heralds in a new era of human-disease interaction characterized by the emergence of novel viruses from natural sources with heretofore unseen frequency. Due to deforestation, population growth, and climate change, we are encountering more viruses that can infect larger groups of people with greater ease and increasingly severe outcomes. The devastation of COVID-19 and forecasts of future human/disease interactions call for a creative reconsideration of global response to infectious disease. There is an urgent need for accessible, cost-effective antiviral (AV) drugs that can be mass-produced and widely distributed to large populations. Development of AV drugs should be informed by a thorough understanding of viral structure and function as well as human biology. To maximize efficacy, minimize cost, and reduce development of drug-resistance, these drugs would ideally operate through a varied set of mechanisms at multiple stages throughout the course of infection. Due to their abundance and diversity, natural compounds are ideal for such comprehensive therapeutic interventions. Promising sources of such drugs are found throughout nature; especially remarkable are the algae, a polyphyletic grouping of phototrophs that produce diverse bioactive compounds. While not much literature has been published on the subject, studies have shown that these compounds exert antiviral effects at different stages of viral pathogenesis. In this review, we follow the course of viral infection in the human body and evaluate the AV effects of algae-derived compounds at each stage. Specifically, we examine the AV activities of algae-derived compounds at the entry of viruses into the body, transport through the body via the lymph and blood, infection of target cells, and immune response. We discuss what is known about algae-derived compounds that may interfere with the infection pathways of SARS-CoV-2; and review which algae are promising sources for AV agents or AV precursors that, with further investigation, may yield life-saving drugs due to their diversity of mechanisms and exceptional pharmaceutical potential.

Seaweed Sulfated Polysaccharides against Respiratory Viral Infections

Respiratory viral infections have been a leading cause of morbidity and mortality worldwide. Despite massive advancements in the virology field, no specific treatment exists for most respiratory viral infections. Approved therapies against respiratory viruses rely almost exclusively on synthetic drugs that have potential side effects, restricting their use. This review aims to present natural marine sulfated polysaccharides possessing promising antiviral activity against respiratory viruses that could be a safe alternative to synthetic broad-spectrum antiviral drugs. The antiviral properties of marine sulfated polysaccharides are presented according to their mechanism of action on different types and strains of respiratory viruses, and the potential limits of their use are discussed.

Carrageenan-containing over-the-counter nasal and oral sprays inhibit SARS-CoV-2 infection of airway epithelial cultures

Pharmaceutical interventions are urgently needed to prevent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and transmission. As SARS-CoV-2 infects and spreads via the nasopharyngeal airways, we analyzed the antiviral effect of selected nasal and oral sprays on virus infection in vitro. Two nose sprays showed virucidal activity but were cytotoxic precluding further analysis in cell culture. One nasal and one mouth spray suppressed SARS-CoV-2 infection of TMPRSS2-expressing Vero E6 cells and primary differentiated human airway epithelial cultures. The antiviral activity in both sprays could be attributed to polyanionic ι- and κ-carrageenans. Thus, application of carrageenan-containing nasal and mouth sprays may reduce the risk of acquiring SARS-CoV-2 infection and may limit viral spread, warranting further clinical evaluation.

On the Health Benefits vs. Risks of Seaweeds and Their Constituents: The Curious Case of the Polymer Paradigm

To exploit the nutraceutical and biomedical potential of selected seaweed-derived polymers in an economically viable way, it is necessary to analyze and understand their quality and yield fluctuations throughout the seasons. In this study, the seasonal polysaccharide yield and respective quality were evaluated in three selected seaweeds, namely the agarophyte Gracilaria gracilis, the carrageenophyte Calliblepharis jubata (both red seaweeds) and the alginophyte Sargassum muticum (brown seaweed). It was found that the agar synthesis of G. gracilis did not significantly differ with the seasons (27.04% seaweed dry weight (DW)). In contrast, the carrageenan content in C. jubata varied seasonally, being synthesized in higher concentrations during the summer (18.73% DW). Meanwhile, the alginate synthesis of S. muticum exhibited a higher concentration (36.88% DW) during the winter. Therefore, there is a need to assess the threshold at which seaweed-derived polymers may have positive effects or negative impacts on human nutrition. Furthermore, this study highlights the three polymers, along with their known thresholds, at which they can have positive and/or negative health impacts. Such knowledge is key to recognizing the paradigm governing their successful deployment and related beneficial applications in humans.

Iota-carrageenan neutralizes SARS-CoV-2 and inhibits viral replication in vitro

In the absence of a vaccine and other effective prophylactic or therapeutic countermeasures the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) remains a significant public health threat. Attachment and entry of coronaviruses including SARS-CoV-2 is mainly mediated by the spike glycoprotein. Here, we show that iota-carrageenan can inhibit the cell entry of the SARS-CoV-2 spike pseudotyped lentivirus in a dose dependent manner. SARS-CoV-2 spike pseudotyped lentivirus particles were efficiently neutralized with an IC₅₀ value of 2.6 μg/ml iota-carrageenan. Experiments with patient isolated wild type SARS-CoV-2 virus showed an inhibition of replication in a similar range. In vitro data on iota-carrageenan against various Rhino- and endemic Coronaviruses showed similar IC₅₀ values and translated readily into clinical effectiveness when a nasal spray containing iota-carrageenan demonstrated a reduction of severity and duration of symptoms of common cold caused by various respiratory viruses. Accordingly, our in vitro data on SARS-CoV-2 spike pseudotyped lentivirus and replication competent SARS-CoV-2 suggest that administration of iota-carrageenan may be an effective and safe prophylaxis or treatment for SARS-CoV-2 infections.

Review of the use of nasal and oral antiseptics during a global pandemic

A review of nasal sprays and gargles with antiviral properties suggests that a number of commonly used antiseptics including povidone-iodine, Listerine®, iota-carrageenan and chlorhexidine should be studied in clinical trials to mitigate both the progression and transmission of SARS-CoV-2. Several of these antiseptics have demonstrated the ability to cut the viral load of SARS-CoV-2 by 3-4 log10 in 15-30 s in vitro. In addition, hypertonic saline targets viral replication by increasing hypochlorous acid inside the cell. A number of clinical trials are in process to study these interventions both for prevention of transmission, prophylaxis after exposure, and to diminish progression by reduction of viral load in the early stages of infection.

Elucidating Molecular Interactions of Ten Natural Compounds Targeting E6 HPV High Risk Oncoproteins Using Microsecond Molecular Dynamics Simulations

BACKGROUND

Cervical cancer is a major public health issue worldwide, occurring in the vast majority of cases (85%) in low-income countries. Human papillomavirus (HPV) mainly infects the mucosal epithelium, and a small portion causes over 600,000 cases every year worldwide at various anatomical spots, mainly leading to anogenital and head and neck.

INTRODUCTION

The E6 oncoprotein encoded by cancer-associated alpha HPV can transform epithelial cells into tumorigenic tissue. Therapy for this infection and blocking of the HPV E6 oncoprotein could be provided with cost-effective and abundant natural products which are an exponentially growing topic in the literature. Finding an active natural compound that readily blocks HPV E6 oncoprotein which could be available for developing countries without expensive extraction processes or costly synthetic pathways is of major interest.

METHODS

Molecular dynamics simulation was performed using the most up-to-date AMBER protein force field ff14SB and a GPU enabled high performance computing cluster.

RESULTS

In this research, we present a study of the binding properties between 10 selected natural compounds that are readily available with two variants of the E6 oncoprotein types (HPV-16 and HPV-18) using 10+ microsecond molecular dynamics simulations.

CONCLUSION

Our results suggest that crocetin, ergosterol peroxide and κ-carrageenan natural products bind strongly to both HPV-16 and HPV-18 and could potentially serve as a scaffolding for further drug development.

Topical Oral and Intranasal Antiviral Agents for Coronavirus Disease 2019 (COVID-19)

With the largest viral loads in both symptomatic and asymptomatic patients with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) present in the oral and nasal cavities, agents that act on these two areas have the potential for large therapeutic and prophylactic benefit. A literature review was conducted to elucidate the possible agents useful in treatment of SARS-CoV-2. These agents were evaluated for their current applications, adverse reactions, their current state of study, and any future considerations in their management of coronavirus disease 2019 (COVID-2019). Our review has found that, while there are many promising agents with proven efficacy in their in-vitro efficacy against SARS-CoV-2, more clinical trials and in-vivo studies, as well as safety trials, must be conducted before these agents can be effectively implemented.

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.

Antiviral activity of sulfated polysaccharides from marine algae and its application in combating COVID-19: Mini review

Marine-derived sulfated polysaccharides possess various antiviral activities against a broad range of enveloped and non-enveloped viruses. It has become the potential source of antiviral drugs for pharmaceutical development. In this review, we will discuss the different types of sulfated polysaccharides and their structural classification. Some of the major sulfated polysaccharides with potent antiviral activity, including carrageenan, agar, ulvan, fucoidan, and alginates, are considered in this review. The mechanism of these sulfated polysaccharides in inhibiting the different stages of the viral infection process inside the host cell is also demonstrated. It involves blocking the initial entry of the virus or inhibiting its transcription and translation by modulating the immune response of the host cell. In addition, we explore the potential of sulfated polysaccharides as antiviral agents in preventing recent Corona Virus Disease-2019 (COVID-19).

Application prospect of polysaccharides in the development of anti-novel coronavirus drugs and vaccines

Since the outbreak of the novel coronavirus disease COVID-19, caused by the SARS-CoV-2 virus, it has spread rapidly worldwide and poses a great threat to public health. This is the third serious coronavirus outbreak in <20 years, following SARS in 2002-2003 and MERS in 2012. So far, there are almost no specific clinically effective drugs and vaccines available for COVID-19. Polysaccharides with good safety, immune regulation and antiviral activity have broad application prospects in anti-virus, especially in anti-coronavirus applications. Here, we reviewed the antiviral mechanisms of some polysaccharides, such as glycosaminoglycans, marine polysaccharides, traditional Chinese medicine polysaccharides, and their application progress in anti-coronavirus. In particular, the application prospects of polysaccharide-based vaccine adjuvants, nanomaterials and drug delivery systems in the fight against novel coronavirus were also analyzed and summarized. Additionally, we speculate the possible mechanisms of polysaccharides anti-SARS-CoV-2, and propose the strategy of loading S or N protein from coronavirus onto polysaccharide capped gold nanoparticles vaccine for COVID-19 treatment. This review may provide a new approach for the development of COVID-19 therapeutic agents and vaccines.

The Potential of Algal Biotechnology to Produce Antiviral Compounds and Biopharmaceuticals

The emergence of the Coronavirus Disease 2019 (COVID-19) caused by the SARS-CoV-2 virus has led to an unprecedented pandemic, which demands urgent development of antiviral drugs and antibodies; as well as prophylactic approaches, namely vaccines. Algae biotechnology has much to offer in this scenario given the diversity of such organisms, which are a valuable source of antiviral and anti-inflammatory compounds that can also be used to produce vaccines and antibodies. Antivirals with possible activity against SARS-CoV-2 are summarized, based on previously reported activity against Coronaviruses or other enveloped or respiratory viruses. Moreover, the potential of algae-derived anti-inflammatory compounds to treat severe cases of COVID-19 is contemplated. The scenario of producing biopharmaceuticals in recombinant algae is presented and the cases of algae-made vaccines targeting viral diseases is highlighted as valuable references for the development of anti-SARS-CoV-2 vaccines. Successful cases in the production of functional antibodies are described. Perspectives on how specific algae species and genetic engineering techniques can be applied for the production of anti-viral compounds antibodies and vaccines against SARS-CoV-2 are provided.

Carrageenans as Broad-Spectrum Microbicides: Current Status and Challenges

Different kinds of red algae are enriched with chemically diverse carbohydrates. In particular, a group of sulfated polysaccharides, which were isolated from the cell walls of red algae, gained a large amount of attention due to their broad-spectrum antimicrobial activities. Within that group, carrageenans (CGs) were expected to be the first clinically applicable microbicides that could prevent various viral infections due to their superior antiviral potency and desirable safety profiles in subclinical studies. However, their anticipated beneficial effects could not be validated in human studies. To assess the value of a second attempt at pharmacologically developing CGs as a new class of preventive microbicides, all preclinical and clinical development processes of CG-based microbicides need to be thoroughly re-evaluated. In this review, the in vitro toxicities; in vivo safety profiles; and in vitro, ex vivo, and in vivo antiviral activities of CGs are summarized according to the study volume of their target viruses, which include human immunodeficiency virus, herpesviruses, respiratory viruses, human papillomavirus, dengue virus, and other viruses along with a description of their antiviral modes of action and development of antiviral resistance. This evaluation of the strengths and weaknesses of CGs will help provide future research directions that may lead to the successful development of CG-based antimicrobial prophylactics.

Biocides and Novel Antimicrobial Agents for the Mitigation of Coronaviruses

In December, 2019, a highly infectious and rapidly spreading new pneumonia of unknown cause was reported to the Chinese WHO Country Office. A cluster of these cases had appeared in Wuhan, a city in the Hubei Province of China. These infections were found to be caused by a new coronavirus which was given the name "2019 novel coronavirus" (2019-nCoV). It was later renamed "severe acute respiratory syndrome coronavirus 2," or SARS-CoV-2 by the International Committee on Taxonomy of Viruses on February 11, 2020. It was named SARS-CoV-2 due to its close genetic similarity to the coronavirus which caused the SARS outbreak in 2002 (SARS-CoV-1). The aim of this review is to provide information, primarily to the food industry, regarding a range of biocides effective in eliminating or reducing the presence of coronaviruses from fomites, skin, oral/nasal mucosa, air, and food contact surfaces. As several EPA approved sanitizers against SARS-CoV-2 are commonly used by food processors, these compounds are primarily discussed as much of the industry already has them on site and is familiar with their application and use. Specifically, we focused on the effects of alcohols, povidone iodine, quaternary ammonium compounds, hydrogen peroxide, sodium hypochlorite (NaOCl), peroxyacetic acid (PAA), chlorine dioxide, ozone, ultraviolet light, metals, and plant-based antimicrobials. This review highlights the differences in the resistance or susceptibility of different strains of coronaviruses, or similar viruses, to these antimicrobial agents.

Oral Fucoidan Attenuates Lung Pathology and Clinical Signs in a Severe Influenza a Mouse Model

Fucoidans are known to be effective inhibitors of inflammation, and of virus binding and cellular entry. Undaria pinnatifida-derived fucoidan (UPF) was assessed in a severe influenza A (H1N1, PR8) infection model in mice. Initially, UPF was gavaged at 3.52 mg daily in a treatment model. Gross lung pathology (consolidation) was significantly reduced as compared to controls. UPF was then presented as a feed supplement at a rate of either nil, 3.52 mg/day or 7.04 mg/day in a prophylactic model, dosed three days before infection. A significant improvement was observed in the clinical signs of ill-health, as well as a reduction in gross lung pathology in animals treated with the higher dose, although there was no significant reduction in lung viral titres.