Morphogenetic (Mucin Expression) as Well as Potential Anti-Corona Viral Activity of the Marine Secondary Metabolite Polyphosphate on A549 Cells

A Comparative Experimental and Computational Study on the Nature of the Pangolin-CoV and COVID-19 Omicron

The relationship between pangolin-CoV and SARS-CoV-2 has been a subject of debate. Further evidence of a special relationship between the two viruses can be found by the fact that all known COVID-19 viruses have an abnormally hard outer shell (low M disorder, i.e., low content of intrinsically disordered residues in the membrane (M) protein) that so far has been found in CoVs associated with burrowing animals, such as rabbits and pangolins, in which transmission involves virus remaining in buried feces for a long time. While a hard outer shell is necessary for viral survival, a harder inner shell could also help. For this reason, the N disorder range of pangolin-CoVs, not bat-CoVs, more closely matches that of SARS-CoV-2, especially when Omicron is included. The low N disorder (i.e., low content of intrinsically disordered residues in the nucleocapsid (N) protein), first observed in pangolin-CoV-2017 and later in Omicron, is associated with attenuation according to the Shell-Disorder Model. Our experimental study revealed that pangolin-CoV-2017 and SARS-CoV-2 Omicron (XBB.1.16 subvariant) show similar attenuations with respect to viral growth and plaque formation. Subtle differences have been observed that are consistent with disorder-centric computational analysis.

Marine Sponge-Derived Secondary Metabolites Modulate SARS-CoV-2 Entry Mechanisms

The emergence of SARS-CoV 2 caused the COVID-19 pandemic, resulting in numerous global infections and deaths. In particular, people with metabolic diseases display an increased risk of severe COVID 19 and a fatal outcome. Treatment options for severe cases are limited, and the appearance of new virus variants complicates the development of novel therapies. To better manage viral infections like COVID 19, new therapeutic approaches are needed. Marine sponges offer a natural and renewable source of unique bioactive agents. These sponges produce secondary metabolites with various effects, including anti-viral, anti-inflammatory, and anti-tumorigenic properties. In the current study, we investigated the effect of five different marine sponge-derived secondary metabolites (four bromotyrosines and one sesquiterpenoid hydroquinone). Two of these, Avarol and Acetyl-dibromoverongiaquinol reduced the expression of ACE2, the main receptor for SARS-CoV 2, and the alternative receptor NRP1. Moreover, these substances derived from sponges demonstrated the ability to diminish the virus titer in SARS-CoV 2-infected cells, especially concerning the Omicron lineage. However, the reduction was not substantial enough to expect a significant impact on infected humans. Consequently, the investigated sponge-derived secondary metabolites are not likely to be effective to treat COVID 19 as a stand-alone therapy.

Marine natural products and human immunity: novel biomedical resources for anti-infection of SARS-CoV-2 and related cardiovascular disease

Marine natural products (MNPs) and marine organisms include sea urchin, sea squirts or ascidians, sea cucumbers, sea snake, sponge, soft coral, marine algae, and microalgae. As vital biomedical resources for the discovery of marine drugs, bioactive molecules, and agents, these MNPs have bioactive potentials of antioxidant, anti-infection, anti-inflammatory, anticoagulant, anti-diabetic effects, cancer treatment, and improvement of human immunity. This article reviews the role of MNPs on anti-infection of coronavirus, SARS-CoV-2 and its major variants (such as Delta and Omicron) as well as tuberculosis, H. Pylori, and HIV infection, and as promising biomedical resources for infection related cardiovascular disease (irCVD), diabetes, and cancer. The anti-inflammatory mechanisms of current MNPs against SARS-CoV-2 infection are also discussed. Since the use of other chemical agents for COVID-19 treatment are associated with some adverse effects in cardiovascular system, MNPs have more therapeutic advantages. Herein, it's time to protect this ecosystem for better sustainable development in the new era of ocean economy. As huge, novel and promising biomedical resources for anti-infection of SARS-CoV-2 and irCVD, the novel potential mechanisms of MNPs may be through multiple targets and pathways regulating human immunity and inhibiting inflammation. In conclusion, MNPs are worthy of translational research for further clinical application.

Polyphosphate coated nanoparticles: Enzyme-activated charge-reversal gene delivery systems

AIM

The current study aimed to develop enzyme-activated charge-reversal lipid nanoparticles (LNPs) as novel gene delivery systems.

METHODS

Palmitic acid was covalently bound to protamine being utilised as transfection promoter to anchor it on the surfaces of LNPs. Green fluorescent protein (GFP) encoding plasmid DNA (pDNA) was ion paired with various cationic counter ions to achieve high encapsulation in LNPs. Protamine-decorated LNPs were prepared by solvent injection method followed by coating with sodium tripolyphosphate (TPP) to generate a bio-inert anionic outer surface. Resulting LNPs were characterised regarding size, polydispersity, zeta potential and encapsulation efficiency. Enzyme-triggered charge-reversal of LNPs was investigated using isolated alkaline phosphatase (ALP) monitoring changes in zeta potential as well as monophosphate release. Furthermore, monophosphate release, cell viability and transfection efficiency were evaluated on a human alveolar epithelial (A549) cell line.

RESULTS

Protamine-decorated and TPP-coated (Prot-pDNA/DcChol-TPP) LNPs displayed a mean size of 298.8 ± 17.4 nm and a zeta potential of -13.70 ± 0.61 mV. High pDNA encapsulation was achieved with hydrophobic ion pairs of pDNA with 3ß-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol hydrochloride (DcChol). Zeta potential of Prot-pDNA/DcChol-TPP LNPs reversed to positive values with a total Δ26.8 mV shift upon incubation with ALP. Conformably, a notable amount of monophosphate was released upon incubation of Prot-pDNA/DcChol-TPP LNPs with isolated as well as cell-associated ALP. A549 cells well tolerated LNPs displaying more than 95 % viability. Compared with naked pDNA, unmodified LNPs and control LNPs, Prot-pDNA/DcChol-TPP LNPs showed a significantly increased transfection efficiency.

CONCLUSION

Prot-pDNA/DcChol-TPP LNPs can be regarded as promising gene delivery systems.

Phosphatase-degradable nanoparticles: A game-changing approach for the delivery of antifungal proteins

HYPOTHESIS

Polyphosphate nanoparticles as phosphatase-degradable carriers for Penicillium chrysogenum antifungal protein (PAF) can enhance the antifungal activity of the protein against Candida albicans biofilm.

EXPERIMENTS

PAF-polyphosphate (PP) nanoparticles (PAF-PP NPs) were obtained through ionic gelation. The resulting NPs were characterized in terms of their particle size, size distribution and zeta potential. Cell viability and hemolysis studies were carried out in vitro on human foreskin fibroblasts (Hs 68 cells) and human erythrocytes, respectively. Enzymatic degradation of NPs was investigated by monitoring release of free monophosphates in the presence of isolated as well as C. albicans-derived phosphatases. In parallel, shift in zeta potential of PAF-PP NPs as a response to phosphatase stimuli was determined. Diffusion of PAF and PAF-PP NPs through C. albicans biofilm matrix was analysed by fluorescence correlation spectroscopy (FCS). Antifungal synergy was evaluated on C. albicans biofilm by determining the colony forming units (CFU).

FINDINGS

PAF-PP NPs were obtained with a mean size of 300.9 ± 4.6 nm and a zeta potential of -11.2 ± 2.8 mV. In vitro toxicity assessments revealed that PAF-PP NPs were highly tolerable by Hs 68 cells and human erythrocytes similar to PAF. Within 24 h, 21.9 ± 0.4 μM of monophosphate was released upon incubation of PAF-PP NPs having final PAF concentration of 156 μg/ml with isolated phosphatase (2 U/ml) leading to a shift in zeta potential up to -0.7 ± 0.3 mV. This monophosphate release from PAF-PP NPs was also observed in the presence of C. albicans-derived extracellular phosphatases. The diffusivity of PAF-PP NPs within 48 h old C. albicans biofilm matrix was similar to that of PAF. PAF-PP NPs enhanced antifungal activity of PAF against C. albicans biofilm decreasing the survival of the pathogen up to 7-fold in comparison to naked PAF. In conclusion, phosphatase-degradable PAF-PP NPs hold promise as nanocarriers to augment the antifungal activity of PAF and enable its efficient delivery to C. albicans cells for the potential treatment of Candida infections.

Functional importance of coacervation to convert calcium polyphosphate nanoparticles into the physiologically active state

Inorganic polyphosphates (polyP) are of increasing medical interest due to their unprecedented ability to exhibit both morphogenetic and ATP-delivering properties. However, these polymers are only physiologically active in the coacervate state, but not as amorphous nanoparticles (NP), the storage form of the polymer. Little is known about the mechanism of formation and interconversion of these two distinct polyP phases in the presence of metal ions. Based on in silico simulation studies, showing a differential clustering of polyP and calcium ions, the pH-dependent NP and coacervate formation of polyP was examined experimentally. Turbidimetric studies showed that Ca-polyP coacervate formation at pH 7 is a slow process compared to NP formation at pH 10. In FTIR spectra, the asymmetric stretching vibration signal of the internal (PO₂)⁻ units, which is present in the Ca-polyP coacervate formed at pH 7, disappears in the NP formed at pH 10 using the conventional method (dropping of a CaCl₂ solution into a Na-polyP solution). Surprisingly, when reversing the procedure, adding Na-polyP to CaCl₂, a coacervate is obtained at both pH 7 and pH 10, as confirmed by SEM and FTIR analyses. The (PO₂)⁻ signal also disappears when Ca-polyP-NP are exposed to peptides, leading to the transformation of the NP into the coacervate phase. From these results, a mechanistic model of pH-dependent coacervate and NP formation is proposed that considers not only electrostatic ion-ion but also ion-dipole interactions. Functional studies revealed a delayed polyP release kinetics for Ca-polyP-NP embedded in a hydrogel due to NP/coacervate conversion. Human A549 epithelial cells grown on the coacervate show increased proliferation and ATP production compared to cells cultured on particulate polyP. Ca-polyP NP taken up by endocytosis undergo intracellular coacervate transformation. Understanding the differential expression of the two polyP phases is of functional importance for the potential therapeutic application of this physiological, regeneratively active polymer.

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Polyphosphate (polyP) is a polymer that is abundantly formed in blood platelets.

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This polyanionic polymer exists both in the form of soluble polyP chains and as nanoparticles.

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PolyP polymers must undergo coacervation before reaching functional activity.

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Coacervation is based on a redistribution of the Ca²⁺ and polyP ions, distinct from nanoparticle formation.

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In the coacervate state, polyP causes cell proliferation and ATP generation.

Focus on Marine Animal Safety and Marine Bioresources in Response to the SARS-CoV-2 Crisis

SARS-CoV-2 as a zoonotic virus has significantly affected daily life and social behavior since its outbreak in late 2019. The concerns over its transmission through different media directly or indirectly have evoked great attention about the survival of SARS-CoV-2 virions in the environment and its potential infection of other animals. To evaluate the risk of infection by SARS-CoV-2 and to counteract the COVID-19 disease, extensive studies have been performed to understand SARS-CoV-2 biogenesis and its pathogenesis. This review mainly focuses on the molecular architecture of SARS-CoV-2, its potential for infecting marine animals, and the prospect of drug discovery using marine natural products to combat SARS-CoV-2. The main purposes of this review are to piece together progress in SARS-CoV-2 functional genomic studies and antiviral drug development, and to raise our awareness of marine animal safety on exposure to SARS-CoV-2.

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.

The Impact of COVID-19 Pandemic on Seafood Safety and Human Health

The coronavirus disease (COVID-19) pandemic caused several negative impacts on global human health and the world’s economy. Food and seafood safety and security were among the principal challenges and causes of concern for the food industry and consumers during the spread of this global pandemic. This article focused on the effects of COVID-19 pandemic on potential safety issues with seafood products and their processing methods. Moreover, the potential impacts of coronavirus transmission through seafood on human health were evaluated. The role of authenticity, traceability, and antimicrobials from natural sources to preserve seafood and the possible interaction of functional foods on the human immune system are also discussed. Although seafood is not considered a principal vector of SARS-CoV-2 transmission, the possible infections through contaminated surfaces of such food products cannot be neglected. The positive effects of seafood consumption on possible immunity built up, and COVID-19 are also summarized.

Recent methods for discovering novel bioactive metabolites, specifically antimicrobial agents, from marine-associated microorganisms

Marine microorganisms are a promising source for novel natural compounds with many medical and biotechnological applications. Here we demonstrate limitations and recent strategies for investigating the marine microbial community for novel bioactive metabolites, specifically those of antimicrobial potential. These strategies include culture-dependent methods such as modifying the standard culture media, including changing the gelling agent, dissolving vehicle, media supplementation, and preparation to access a broader range of bacterial diversity from marine samples. Furthermore, we discuss strategies like in situ cultivation, dilution-to-extinction cultivation, and long-term incubation. We are presenting recent applications of culture-independent methods such as genome mining, proteomics profiling, and the application of metagenomics as a novel strategy for structure confirmation in the discovery of the marine microorganism for novel antimicrobial metabolites. We present this review as a simple guide and a helpful resource for those who seek to enter the challenging field of applied marine microbiology.

CA 15-3 prognostic biomarker in SARS-CoV-2 pneumonia

The severity of lung involvement is the main prognostic factor in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Carbohydrate antigen 15-3 (CA 15-3), a marker of lung damage and fibrosis, could help predict the prognosis of SARS-CoV-2 pneumonia. This was a retrospective and observational study. CA 15-3 was analyzed in the blood samples of patients consecutively admitted for SARS-CoV-2 pneumonia and whose blood samples were available in the biobank. Other prognostic markers were also measured (interleukin 6 [IL6], C-reactive protein [CRP], D-dimer, troponin T, and NT-ProBNP). The occurrence of in-hospital complications was registered, including death, the need for medical intensive care, and oxygen therapy at discharge. In this study, 539 patients were recruited (54.9% men, mean age: 59.6 ± 16.4 years). At admission, the mean concentrations of CA 15-3 was 20.5 ± 15.8 U/mL, and the concentration was correlated with male sex, older age, and other severity markers of coronavirus disease of 2019 (COVID-19) (IL6, CRP, D-dimer, troponine T, and NT-ProBNP). CA 15-3 levels were higher in patients who died (n = 56, 10.4%) (35.33 ± 30.45 vs. 18.8 ± 12.11, p < 0.001), who required intensive medical support (n = 78, 14.4%; 31.17 ± 27.83 vs. 18.68 ± 11.83; p < 0.001), and who were discharged with supplemental oxygen (n = 64, 13.3%; 22.65 ± 14.41 vs. 18.2 ± 11.7; p = 0.011). Elevated CA 15-3 levels (above 34.5 U/mL) were a strong predictor of a complicated in-hospital course, in terms of a higher risk of death (adjusted odds ratio [OR] 3.74, 95% confidence interval [CI]: 1.22–11.9, p = 0.022) and need for intensive care (adjusted OR 4.56, 95% CI: 1.37–15.8) after adjusting for all other risk factors. The degree of lung damage and fibrosis evaluated in terms of CA 15-3 concentrations may allow early identification of the increased risk of complications in patients with SARS-CoV-2 pneumonia.

Pathophysiological Response to SARS-CoV-2 Infection Detected by Infrared Spectroscopy Enables Rapid and Robust Saliva Screening for COVID-19

Fourier transform infrared (FTIR) spectroscopy provides a (bio)chemical snapshot of the sample, and was recently used in proof-of-concept cohort studies for COVID-19 saliva screening. However, the biological basis of the proposed technology has not been established. To investigate underlying pathophysiology, we conducted controlled infection experiments on Vero E6 cells in vitro and K18-hACE2 mice in vivo. Potentially infectious culture supernatant or mouse oral lavage samples were treated with ethanol or 75% (v/v) Trizol for attenuated total reflectance (ATR)-FTIR spectroscopy and proteomics, or RT-PCR, respectively. Controlled infection with UV-inactivated SARS-CoV-2 elicited strong biochemical changes in culture supernatant/oral lavage despite a lack of viral replication, determined by RT-PCR or a cell culture infectious dose 50% assay. Nevertheless, SARS-CoV-2 infection induced additional FTIR signals over UV-inactivated SARS-CoV-2 infection in both cell and mouse models, which correspond to aggregated proteins and RNA. Proteomics of mouse oral lavage revealed increased secretion of kallikreins and immune modulatory proteins. Next, we collected saliva from a cohort of human participants (n = 104) and developed a predictive model for COVID-19 using partial least squares discriminant analysis. While high sensitivity of 93.48% was achieved through leave-one-out cross-validation, COVID-19 patients testing negative on follow-up on the day of saliva sampling using RT-PCR was poorly predicted in this model. Importantly, COVID-19 vaccination did not lead to the misclassification of COVID-19 negatives. Finally, meta-analysis revealed that SARS-CoV-2 induced increases in the amide II band in all arms of this study and in recently published cohort studies, indicative of altered β-sheet structures in secreted proteins. In conclusion, this study reveals a consistent secretory pathophysiological response to SARS-CoV-2, as well as a simple, robust method for COVID-19 saliva screening using ATR-FTIR.

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.

Polyphosphate in Antiviral Protection: A Polyanionic Inorganic Polymer in the Fight Against Coronavirus SARS-CoV-2 Infection

Polyanions as polymers carrying multiple negative charges have been extensively studied with regard to their potential antiviral activity. Most studies to date focused on organic polyanionic polymers, both natural and synthetic. The inorganic polymer, polyphosphate (polyP), despite the ubiquitous presence of this molecule from bacteria to man, has attracted much less attention. More recently, and accelerated by the search for potential antiviral agents in the fight against the pandemic caused by the coronavirus SARS-CoV-2, it turned out that polyP disrupts the first step of the viral replication cycle, the interaction of the proteins in the virus envelope and in the cell membrane that are involved in the docking process of the virus with the target host cell. Experiments on a molecular level using the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and the cellular angiotensin converting enzyme 2 (ACE2) receptor revealed that polyP strongly inhibits the binding reaction through an electrostatic interaction between the negatively charged centers of the polyP molecule and a cationic groove, which is formed by positively charged amino acids on the RBD surface. In addition, it was found that polyP, due to its morphogenetic and energy delivering activities, enhances the antiviral host innate immunity defense of the respiratory epithelium. The underlying mechanisms and envisaged application of polyP in the therapy and prevention of COVID-19 are discussed.

Biological Models of the Lower Human Airways-Challenges and Special Requirements of Human 3D Barrier Models for Biomedical Research

In our review, we want to summarize the current status of the development of airway models and their application in biomedical research. We start with the very well characterized models composed of cell lines and end with the use of organoids. An important aspect is the function of the mucus as a component of the barrier, especially for infection research. Finally, we will explain the need for a nondestructive characterization of the barrier models using TEER measurements and live cell imaging. Here, organ-on-a-chip technology offers a great opportunity for the culture of complex airway models.

An unexpected biomaterial against SARS-CoV-2: Bio-polyphosphate blocks binding of the viral spike to the cell receptor

No other virus after the outbreak of the influenza pandemic of 1918 affected the world's population as hard as the coronavirus SARS-CoV-2. The identification of effective agents/materials to prevent or treat COVID-19 caused by SARS-CoV-2 is an urgent global need. This review aims to survey novel strategies based on inorganic polyphosphate (polyP), a biologically formed but also synthetically available polyanionic polymeric material, which has the potential of being a potent inhibitor of the SARS-CoV-2 virus-cell-docking machinery. This virus attaches to the host cell surface receptor ACE2 with its receptor binding domain (RBD), which is present at the tips of the viral envelope spike proteins. On the surface of the RBD an unusually conserved cationic groove is exposed, which is composed of basic amino acids (Arg, Lys, and His). This pattern of cationic amino acids, the cationic groove, matches spatially with the anionic polymeric material, with polyP, allowing an electrostatic interaction. In consequence, the interaction between the RBD and ACE2 is potently blocked. PolyP is a physiological inorganic polymer, synthesized by cells and especially enriched in the blood platelets, which releases metabolically useful energy through enzymatic degradation and coupled ADP/ATP formation. In addition, this material upregulates the steady-state-expression of the mucin genes in the epithelial cells. We propose that polyP, with its two antiviral properties (blocking the binding of the virus to the cells and reinforcing the defense barrier against infiltration of the virus) has the potential to be a novel protective/therapeutic anti-COVID-19 agent.

Triple-target stimuli-responsive anti-COVID-19 face mask with physiological virus-inactivating agents

Conventional face masks to prevent SARS-CoV-2 transmission are mostly based on a passive filtration principle. Ideally, anti-COVID-19 masks should protect the carrier not only by size exclusion of virus aerosol particles, but also be able to capture and destroy or inactivate the virus. Here we present the proof-of-concept of a filter mat for such a mask, which actively attracts aerosol droplets and kills the virus. The electrospun mats are made of polycaprolactone (PCL) a hydrophilic, functionalizable and biodegradable polyester, into which inorganic polyphosphate (polyP) a physiological biocompatible, biodegradable and antivirally active polymer (chain length, ∼40 Pi units) has been integrated. A soluble Na-polyP as well as amorphous calcium polyP nanoparticles (Ca-polyP-NP) have been used. In this composition, the polyP component of the polyP-PCL mats is stable in aqueous protein-free environment, but capable of transforming into a gel-like coacervate upon contact with divalent cations and protein like mucin present in (virus containing) aerosol droplets. In addition, the Ca-polyP-NP are used as a carrier of tretinoin (all-trans retinoic acid) which blocks the function of the SARS-CoV-2 envelope (E) protein, an ion channel forming viroporin. The properties of this novel mask filter mats are as follows: First, to attract and to trap virus-like particles during the polyP coacervate formation induced in situ by aerosol droplets on the spun PCL fibers, as shown here by using SARS-CoV-2 mimicking fluorescent nanoparticles. Second, after disintegration the NP by the aerosol-mucus constituents, to release polyP that binds to and abolishes the function of the receptor binding domain of the viral spike protein. Third, to destroy the virus by releasing tretinoin, as shown by the disruption of virus-mimicking liposomes with the integrated recombinant viral viroporin. It is proposed that these properties, which are inducible (stimuli responsive), will allow the design of antiviral masks that are smart.

The Anti-Viral Applications of Marine Resources for COVID-19 Treatment: An Overview

The ongoing pandemic has led to an urgent need for novel drug discovery and potential therapeutics for Sars-CoV-2 infected patients. Although Remdesivir and the anti-inflammatory agent dexamethasone are currently on the market for treatment, Remdesivir lacks full efficacy and thus, more drugs are needed. This review was conducted through literature search of PubMed, MDPI, Google Scholar and Scopus. Upon review of existing literature, it is evident that marine organisms harbor numerous active metabolites with anti-viral properties that serve as potential leads for COVID-19 therapy. Inorganic polyphosphates (polyP) naturally found in marine bacteria and sponges have been shown to prevent viral entry, induce the innate immune response, and downregulate human ACE-2. Furthermore, several marine metabolites isolated from diverse sponges and algae have been shown to inhibit main protease (Mpro), a crucial protein required for the viral life cycle. Sulfated polysaccharides have also been shown to have potent anti-viral effects due to their anionic properties and high molecular weight. Likewise, select marine sponges produce bromotyrosines which have been shown to prevent viral entry, replication and protein synthesis. The numerous compounds isolated from marine resources demonstrate significant potential against COVID-19. The present review for the first time highlights marine bioactive compounds, their sources, and their anti-viral mechanisms of action, with a focus on potential COVID-19 treatment.

Recent Advances on Nanomaterials to COVID-19 Management: A Systematic Review on Antiviral/Virucidal Agents and Mechanisms of SARS-CoV-2 Inhibition/Inactivation

The current pandemic of coronavirus disease 2019 (COVID-19) is recognized as a public health emergency of worldwide concern. Nanomaterials can be effectively used to detect, capture/inactivate or inhibit coronavirus cell entry/replication in the human host cell, preventing infection. Their potential for nanovaccines, immunoengineering, diagnosis, repurposing medication, and disinfectant surfaces targeting the novel coronavirus (SARS-CoV-2) is highlighted. In this systematic review the aim is to present an unbiased view of which and how nanomaterials can reduce the spread of COVID-19. Herein, the focus is on SARS-CoV-2, analyzing 46 articles retrieved before December 31, 2020. The interface between nanomaterials is described, and the main mechanisms to inhibit SARS-CoV-2 pathogenesis and viral inactivation are also discussed. Nanocarbons, biopolymeric, copper, and silver nanoparticles are potential antiviral and virucidal agents toward self-cleaning and reusable filter media and surfaces (e.g., facial masks), drug administration, vaccines, and immunodiagnostic assays. Trends in toxicology research and safety tests can help fill the main gaps in the literature and overcome health surveillance's challenges. Phytochemicals delivery by nanocarriers also stand out as candidates to target and bio-friendly therapy. Nanocellulose might fill in the gaps. Future research using nanomaterials targeting novel therapies/prophylaxis measures to COVID-19 and future outbreaks is discussed.

The therapeutic potential of inorganic polyphosphate: A versatile physiological polymer to control coronavirus disease (COVID-19)

Rationale: The pandemic caused by the novel coronavirus SARS-CoV-2 is advancing rapidly. In particular, the number of severe courses of the disease is still dramatically high. An efficient drug therapy that helps to improve significantly the fatal combination of damages in the airway epithelia, in the extensive pulmonary microvascularization and finally multiorgan failure, is missing. The physiological, inorganic polymer, polyphosphate (polyP) is a molecule which could prevent the initial phase of the virus life cycle, the attachment of the virus to the target cells, and improve the epithelial integrity as well as the mucus barrier. Results: Surprisingly, polyP matches perfectly with the cationic groove on the RBD. Subsequent binding studies disclosed that polyP, with a physiological chain length of 40 phosphate residues, abolishes the binding propensity of the RBD to the ACE2 receptor. In addition to this first mode of action of polyP, this polymer causes in epithelial cells an increased gene expression of the major mucins in the airways, of MUC5AC and MUC1, as well as a subsequent glycoprotein production. MUC5AC forms a gel-like mucus layer trapping inhaled particles which are then transported out of the airways, while MUC1 constitutes the periciliary liquid layer and supports ciliary beating. As a third mode of action, polyP undergoes enzymatic hydrolysis of the anhydride bonds in the airway system by alkaline phosphatase, releasing metabolic energy. Conclusions: This review summarizes the state of the art of the biotherapeutic potential of the polymer polyP and the findings from basic research and outlines future biomedical applications.

Polyphosphate Reverses the Toxicity of the Quasi-Enzyme Bleomycin on Alveolar Endothelial Lung Cells In Vitro

The anti-cancer antitumor antibiotic bleomycin(s) (BLM) induces athyminic sites in DNA after its activation, a process that results in strand splitting. Here, using A549 human lung cells or BEAS-2B cells lunc cells, we show that the cell toxicity of BLM can be suppressed by addition of inorganic polyphosphate (polyP), a physiological polymer that accumulates and is released from platelets. BLM at a concentration of 20 µg ml^-1 causes a decrease in cell viability (by ~70%), accompanied by an increased DNA damage and chromatin expansion (by amazingly 6-fold). Importantly, the BLM-caused effects on cell growth and DNA integrity are substantially suppressed by polyP. In parallel, the enlargement of the nuclei/chromatin in BLM-treated cells (diameter, 20-25 µm) is normalized to ~12 µm after co-incubation of the cells with BLM and polyP. A sequential application of the drugs (BLM for 3 days, followed by an exposure to polyP) does not cause this normalization. During co-incubation of BLM with polyP the gene for the BLM hydrolase is upregulated. It is concluded that by upregulating this enzyme polyP prevents the toxic side effects of BLM. These data might also contribute to an application of BLM in COVID-19 patients, since polyP inhibits binding of SARS-CoV-2 to cellular ACE2.

New Hopes for Drugs against COVID-19 Come from the Sea

The latest chapter of the historic battle of humans against pathogenic microbes is the severe acute respiratory syndrome (SARS)-like coronavirus-2 (SARS-CoV-2), responsible for COVID-19, a respiratory disease declared a global pandemic by the WHO on March 11, 2020 [...].

Caged Dexamethasone/Quercetin Nanoparticles, Formed of the Morphogenetic Active Inorganic Polyphosphate, are Strong Inducers of MUC5AC

Inorganic polyphosphate (polyP) is a widely distributed polymer found from bacteria to animals, including marine species. This polymer exhibits morphogenetic as well as antiviral activity and releases metabolic energy after enzymatic hydrolysis also in human cells. In the pathogenesis of the coronavirus disease 2019 (COVID-19), the platelets are at the frontline of this syndrome. Platelets release a set of molecules, among them polyP. In addition, the production of airway mucus, the first line of body defense, is impaired in those patients. Therefore, in this study, amorphous nanoparticles of the magnesium salt of polyP (Mg-polyP-NP), matching the size of the coronavirus SARS-CoV-2, were prepared and loaded with the secondary plant metabolite quercetin or with dexamethasone to study their effects on the respiratory epithelium using human alveolar basal epithelial A549 cells as a model. The results revealed that both compounds embedded into the polyP nanoparticles significantly increased the steady-state-expression of the MUC5AC gene. This mucin species is the major mucus glycoprotein present in the secreted gel-forming mucus. The level of gene expression caused by quercetin or with dexamethasone, if caged into polyP NP, is significantly higher compared to the individual drugs alone. Both quercetin and dexamethasone did not impair the growth-supporting effect of polyP on A549 cells even at concentrations of quercetin which are cytotoxic for the cells. A possible mechanism of the effects of the two drugs together with polyP on mucin expression is proposed based on the scavenging of free oxygen species and the generation of ADP/ATP from the polyP, which is needed for the organization of the protective mucin-based mucus layer.