Carrageenans as Broad-Spectrum Microbicides: Current Status and Challenges

Safety of carrageenan-based gels as preventive microbicides: a narrative review

BACKGROUND

Carrageenan-containing gels researched for the prevention of sexually transmitted infections (STIs) have shown promising results for human papillomavirus prevention in women, but not in men. We conducted a narrative review to assess the safety of these gels for genital use.

METHODS

We searched PubMed using MeSH terms and keywords on 5 November 2023. Title/abstract of articles were screened to identify relevant ones. Full-text screening determined eligibility: empirical study evaluating safety of carrageenan-containing gel(s) for genital use.

RESULTS

Of the 125 identified records, 15 were eligible, comprising 14 (10 randomised controlled trials and 4 cohorts) unique study populations. Studies included women only (n=11), men only (n=1) or both (n=3); number of participants ranged from 4 to 6202. Safety was assessed for vaginal (n=13), penile (n=3) and anal use (n=2). Most studies assessed safety of Carraguard (53%), followed by Divine9 (14%), and one each of iota-carrageenan gel, lambda-carrageenan gel, Carvir, PC-6500 (griffithsin and carrageenan) and PC-1005 (MIV-150/zinc acetate/carrageenan). Safety assessment relied on self-report (80.0%), testing for STIs (53.3%), investigator-identified genital findings (93.3%) and/or testing for changes in genital flora (60.0%). Adverse events (AEs) were described by investigators as mostly mild, (mostly) comparable between groups, not observed and/or not significant for vaginal and penile use. Only one study, assessing anal use of carrageenan, reported a significantly higher proportion of AEs in the carrageenan compared with placebo group.

CONCLUSIONS

Carrageenan-based gels are generally well tolerated for vaginal and penile, but not anal use. Studies on carrageenan gel's safety for anal use are scarce.

Piezoelectric Behaviour in Biodegradable Carrageenan and Iron (III) Oxide Based Sensor

This paper is dedicated to the research of phenomena noticed during tests of biodegradable carrageenan-based force and pressure sensors. Peculiar voltage characteristics were noticed during the impact tests. Therefore, the sensors' responses to impact were researched more thoroughly, defining time-dependent sensor output signals from calibrated energy impact. The research was performed using experimental methods when a free-falling steel ball impacted the sensor material to create relatively definable impact energy. The sensor's output signal, which is analogue voltage, was registered using an oscilloscope and transmitted to the PC for further analysis. The obtained results showed a very interesting outcome, where the sensor, which was intended to be piezoresistive, demonstrated a combination of behaviour typical for galvanic cells and piezoelectric material. It provides a stable DC output that is sensitive to the applied statical pressure, and in case of a sudden impact, like a hit, it demonstrates piezoelectric behaviour with some particular effects, which are described in the paper as proton transfer in the sensor-sensitive material. Such phenomena and sensor design are a matter of further development and research.

Comparative study of HIV-1 inhibition efficiency by carrageenans from red seaweeds family gigartinaceae, Tichocarpaceae and Phyllophoraceae

The efficiency of human immunodeficiency virus-1 (HIV-1) inhibition by sulfated polysaccharides isolated from the various families of red algae of the Far East Pacific coast were studied. The anti-HIV-1 activity of kappa and lambda-carrageenans from Chondrus armatus, original highly sulfated X-carrageenan with low content of 3,6-anhydrogalactose from Tichocarpus crinitus and i/κ-carrageenan with hybrid structure isolated from Ahnfeltiopsis flabelliformis was found. The antiviral action of these polysaccharides and its low-weight oligosaccharide was compared with commercial κ-carrageenan. Here we used the HIV-1-based lentiviral particles and evaluated that these carrageenans in non-toxic concentrations significantly suppress the transduction potential of lentiviral particles pseudotyped with different envelope proteins, targeting cells of neuronal or T-cell origin. The antiviral action of these carrageenans was confirmed using the chimeric replication competent Mo-MuLV (Moloney murine leukemia retrovirus) encoding marker eGFP protein. We found that X-carrageenans from T. crinitus and its low weight derivative and λ-carrageenan from C. armatus effectively suppress the infection caused by retrovirus. The obtained data suggest that the differences in the suppressive effect of carrageenans on the transduction efficiency of HIV-1 based lentiviral particles may be related to the structural features of the studied polysaccharides.

Characteristics of Neutrophil Migration and Function in Acute Inflammation Induced by Zymosan and Carrageenan in the Mice Air Pouch Model

Deciphering the complex and redundant process of acute inflammation remains challenging. The failure of numerous clinical trials assessing anti-inflammation agents which had promising preclinical effects inevitably questions the validity of current animal models of inflammation. This study aimed to better understand the process of immune inflammatory response and to select more suitable models to evaluate the effect of potential anti-inflammatory drugs. Zymosan and λ-carrageenan are the most used representatives of particulate and soluble irritants that trigger acute inflammation in the air pouch inflammation model. When zymosan was used, the number of exudate cells first increased at 4 h-8 h, followed by a drop at 12 h-24 h. While, the changes in number of leukocytes in peripheral blood and proportion of neutrophils in bone marrow have the opposite trend. Meanwhile, neutrophils released neutrophil extracellular traps (NETs) to clean zymosan particles. In contrast, the cell migration response to carrageenan increased during 4 h to 24 h, no obvious NETs were observed, and the number of leukocytes in peripheral blood increased and the proportion of neutrophils in bone marrow decreased slightly. This study indicated that although both zymosan and carrageenan are sterile irritants, the characteristics of the inflammatory response induced by each other were different. In the acute phase of inflammation, zymosan-stimulated neutrophils were mobilized, recruited, and engulfed, and then died by NETs. Carrageenan stimulated the production of cytokines/chemokines by neutrophils or macrophages, but did not lead to an obvious death by releasing NETs.

Benzene with Alkyl Chains Is a Universal Scaffold for Multivalent Virucidal Antivirals

Most viruses start their invasion by binding to glycoproteins' moieties on the cell surface (heparan sulfate proteoglycans [HSPG] or sialic acid [SA]). Antivirals mimicking these moieties multivalently are known as broad-spectrum multivalent entry inhibitors (MEI). Due to their reversible mechanism, efficacy is lost when concentrations fall below an inhibitory threshold. To overcome this limitation, we modify MEIs with hydrophobic arms rendering the inhibitory mechanism irreversible, i.e., preventing the efficacy loss upon dilution. However, all our HSPG-mimicking MEIs only showed reversible inhibition against HSPG-binding SARS-CoV-2. Here, we present a systematic investigation of a series of small molecules, all containing a core and multiple hydrophobic arms terminated with HSPG-mimicking moieties. We identify the ones that have irreversible inhibition against all viruses including SARS-CoV-2 and discuss their design principles. We show efficacy in vivo against SARS-CoV-2 in a Syrian hamster model through both intranasal instillation and aerosol inhalation in a therapeutic setting (12 h postinfection). We also show the utility of the presented design rules in producing SA-mimicking MEIs with irreversible inhibition against SA-binding influenza viruses.

Carrageenan films as promising mucoadhesive ocular drug delivery systems

Polymer mucoadhesive films being developed for use in ophthalmology represent a new tool for drug delivery and are considered an alternative to traditional dosage forms. Due to their mucoadhesive properties, carrageenans (CRGs) are widely used in various forms for drug delivery. In this study, films based on CRGs of various structural types (κ/β, κ, x, and λ) for use in ophthalmology were studied. The films were loaded with the active substance echinochrome (ECH), a sea urchin pigment used in ophthalmology. Spectral data showed that ECH remained stable after its incorporation into the CRG films and did not oxidize for at least six months. Hydrophilic CRG films with a thickness of 10-12 µm were characterized in terms of their swelling and mucoadhesive properties. The rheological properties of solutions formed after film dissolution in artificial tears were also assessed. κ- and κ/β-CRG films with ECH exhibited pseudoplastic behavior after rehydrating films with an artificial tear solution. The CRG-loaded films had different swelling characteristics depending on the structure of the CRG used. The films based on highly sulfated CRGs dissolved in artificial tears, while the films of low-sulfated κ/β-CRG exhibited limited swelling. All studied ECH-loaded films exhibited mucoadhesive properties, which were evaluated by a texture analyzer using mucous tissue of the small intestine of the pig as a model. There was a slight prolongation of ECH release from CRG films in artificial tears. The effect of CRG/ECH on the epithelial cell lines of the outer shell of the human eye was investigated. At low concentrations, ECH in the composition of the CRG/ECH complex had no cytotoxic effect on corneal epithelial and conjunctival human cells. The use of ECH-containing films can prevent the drug from being immediately washed away by tears and help to retain it by increasing viscosity and having mucoadhesive properties.

Studying the Relationship between the Antiviral Activity and the Structure of ἰ-Carrageenan Using Ultrasonication

ἰ-carrageenan is a linear macroalgal polysaccharide that is well known for its antiviral bioactivity. Although it is considered a candidate for antiviral therapeutics, its application is highly limited due to its low solubility and high viscosity, which lower its adsorption efficiency. With the aim of deriving an active ἰ-carrageenan fragment with an improved adsorption capacity, we studied the effects of ultrasonication on structural changes in ἰ-carrageenan with respect to changes in its bioactivity against herpesviruses. An FTIR analysis revealed that ultrasonication increased the hydrophilicity of ἰ-carrageenan without changing its functional groups, and a rheological analysis demonstrated that it gradually decreased the strength of the polysaccharide gel, which completely lost its gel structure and formed small nanoparticles after 30 min of ultrasonication. Concomitantly with these physicochemical changes, a plaque assay revealed that longer ultrasonication increased the antiviral activity of ἰ-carrageenan against two herpesviruses, namely, HSV-1 and VZV. Finally, we separated the 30-min ultrasonicated ἰ-carrageenan into four fractions and found that fractions with a lower molecular weight were significantly less active against both herpesviruses than those with a higher molecular weight. Our findings show that ultrasonication induces physicochemical changes in ἰ-carrageenan that increase its antiviral bioactivity.

Contemporary Aspects of Designing Marine Polysaccharide Microparticles as Drug Carriers for Biomedical Application

The main goal of modern pharmaceutical technology is to create new drug formulations that are safer and more effective. These formulations should allow targeted drug delivery, improved drug stability and bioavailability, fewer side effects, and reduced drug toxicity. One successful approach for achieving these objectives is using polymer microcarriers for drug delivery. They are effective for treating various diseases through different administration routes. When creating pharmaceutical systems, choosing the right drug carrier is crucial. Biomaterials have become increasingly popular over the past few decades due to their lack of toxicity, renewable sources, and affordability. Marine polysaccharides, in particular, have been widely used as substitutes for synthetic polymers in drug carrier applications. Their inherent properties, such as biodegradability and biocompatibility, make marine polysaccharide-based microcarriers a prospective platform for developing drug delivery systems. This review paper explores the principles of microparticle design using marine polysaccharides as drug carriers. By reviewing the current literature, the paper highlights the challenges of formulating polymer microparticles, and proposes various technological solutions. It also outlines future perspectives for developing marine polysaccharides as drug microcarriers.

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.

Physicochemical Properties and Antiherpetic Activity of κ-Carrageenan Complex with Chitosan

Nanoparticles formation is one of the ways to modulate the physicochemical properties and enhance the activity of original polysaccharides. For this purpose, based on the polysaccharide of red algae, κ-carrageenan (κ-CRG), it polyelectrolyte complex (PEC), with chitosan, were obtained. The complex formation was confirmed by ultracentrifugation in a Percoll gradient, with dynamic light scattering. According to electron microscopy and DLS, PEC is dense spherical particles with sizes in the range of 150-250 nm. A decrease in the polydispersity of the initial CRG was detected after the PEC formation. Simultaneous exposure of Vero cells with the studied compounds and herpes simplex virus type 1 (HSV-1) showed that the PEC exhibited significant antiviral activity, effectively inhibiting the early stages of virus-cell interaction. A two-fold increase in the antiherpetic activity (selective index) of PEC compared to κ-CRG was shown, which may be due to a change in the physicochemical characteristics of κ-CRG in PEC.

Recent advances in exploiting carrageenans as a versatile functional material for promising biomedical applications

Carrageenans are a group of biopolymers widely found in red seaweeds. Commercial carrageenans have been traditionally used as emulsifiers, stabilizers, and thickening and gelling agents in food products. Carrageenans are regarded as bioactive polysaccharides with disease-modifying and microbiota-modulating activities. Novel biomedical applications of carrageenans as biocompatible functional materials for fabricating hydrogels and nanostructures, including carbon dots, nanoparticles, and nanofibers, have been increasingly exploited. In this review, we describe the unique structural characteristics of carrageenans and their functional relevance. We summarize salient physicochemical features, including thixotropic and shear-thinning properties, of carrageenans. Recent results from clinical trials in which carrageenans were applied as both antiviral and antitumor agents and functional materials are discussed. We also highlight the most recent advances in the development of carrageenan-based targeted drug delivery systems with various pharmaceutical formulations. Promising applications of carrageenans as a bioink material for 3D printing in tissue engineering and regenerative medicine are systematically evaluated. We envisage some key hurdles and challenges in the commercialization of carrageenans as a versatile material for clinical practice. This comprehensive review of the intimate relationships among the structural features, unique rheological properties, and biofunctionality of carrageenans will provide novel insights into their biomedicine application potential.

How does carrageenan cause colitis? A review

Carrageenan is a common additive, but mounting studies have reported that it may cause or aggravate inflammation in the intestines. The safety of carrageenan remains controversial and its inflammatory mechanisms are unclear. In this review, the pathogenesis of colitis by carrageenans was discussed. We analyzed the pathogenesis of inflammatory bowel disease, followed that line of thought, the existing evidence of carrageenans causing colitis in cellular and animal models was summarized to draw its colitis pathogenesis. Two pathways were described including: 1) carrageenan changed the composition of intestinal microbiota, especially Akkermansia muciniphila, which destroyed the mucosal barrier and triggered the inflammatory immune response; and 2) carrageenan directly contacted with receptors on epithelial cells and activated the NF-κB inflammatory pathway. This review aim to provide guidance for exploring the treatment of colitis caused by carrageenan, and safe processing and utilization of carrageenan in food industry, which is worthy of study in the future.

Assessment of the Resource Potential of Baltic Sea Macroalgae

The excess biomass of drifting algae and their casting to the Baltic Sea coast imposes a significant environmental burden. The analysis of beach-cast algae showed that the dominant species are macroalgae Ulva sp., Furcellaria lumbricalis, Cladophora sp., and Polysiphonia fucoides. The biomass of Furcellaria and Polysiphonia algae, containing 25.6% and 19.98% sugars, respectively, has the greatest resource potential in terms of obtaining carbohydrates. Fucose, glucose, and galactose were found to be the most common carbohydrates. The lipid content did not exceed 4.3% (2.3–4.3%), while the fatty acid composition was represented by saturated fatty acids (palmitic, stearic, methyloleic, behenic, etc.). The highest content of crude protein was found in samples of macroalgae of the genus Polysiphonia and amounted to 28.2%. A study of the elemental composition of drifting algae revealed that they have a high carbon content (31.3–37.5%) and a low hydrogen (4.96–5.82%), and sulfur (1.75–3.00%) content. Red algal biomass has the most resource potential in terms of biofuel generation, as it has a high number of lipids and proteins that can produce melanoidins during hydrothermal liquefaction, enhancing the fuel yield. The study noted the feasibility of using the biomass of the studied algae taxa to produce polysaccharides and biofuels. The analyses of antioxidant properties, fat content, and fat composition do not provide convincing evidence of the viability of using the aforementioned macroalgae for their production.

BIBLIOMETRIC ANALYSIS: NANOTECHNOLOGY AND COVID-19

BACKGROUND

COVID-19 pandemic information is critical in order to study it further, but the virus has still not been confined. In addition, even if there is no longer any threat, more knowledge may be gathered from these resources.

METHODS

The data used in this study was gathered from several scientific areas and the links between them. Due to the fact that the COVID-19 pandemic has not been fully contained and additional information can be gleaned from these references, bibliometric analysis of it is important.

RESULTS

In total 155 publications on the topic of "COVID-19" and the keyword "nanotechnology" were identified in the Scopus database between 2020 and 2021 in a network visualization map.

CONCLUSION

As a result, our analysis was conducted at the appropriate time to provide a comprehensive understanding of COVID-19 and nanotechnology and prospective research directions for medicinal chemistry.

NMR spectroscopy for structural elucidation of sulfated polysaccharides from red seaweeds

Some sulfated polysaccharides from red seaweeds are used as hydrocolloids. In addition, it is well known that there are sulfated galactans (carrageenans and agarans) and sulfated mannans, with remarkable biological properties, as antiviral, antitumoral, immunomodulating, antiangiogenic, antioxidant, anticoagulant, and antithrombotic activities, and so on. Knowledge of the detailed structure of the active compound is essential and difficult to acquire. The substitution patterns of the polymer chain, as degree of sulfation and position of sulfate groups, as well as other substituents of the backbone, determine their biological behavior. NMR spectroscopy is a powerful and versatile tool for structural determination. It can be used for elucidation of structures of polysaccharides from new algal sources with novel substitutions or to detect the already known structures from different algal sources, and it could even help to monitor the quality of the active compound on a productive scale. In this review, the available information about NMR spectroscopy of sulfated polysaccharides from red seaweeds is revised and rationalized, to help other researchers working in different fields to study their structures. In addition, considerations about the effects of different structural features, as well as some recording conditions on the chemical shifts of the signals are analyzed.

Sulfated Polysaccharides from Seaweed Strandings as Renewable Source for Potential Antivirals against Herpes simplex Virus 1

Herpes simplex virus 1 (HSV-1) remains a prominent health concern widespread all over the world. The increasing genital infections by HSV-1 that might facilitate acquisition and transmission of HIV-1, the cumulative evidence that HSV-1 promotes neurodegenerative disorders, and the emergence of drug resistance signify the need for new antiviral agents. In this study, the in vitro anti-herpetic activity of sulfated polysaccharides (SPs) extracted by enzyme or hot water from seaweeds collected in France and Mexico from stranding events, were evaluated. The anti-herpetic activity evaluation of the semi-refined-polysaccharides (sr-SPs) and different ion exchange purified fractions showed a wide range of antiviral activity. Among them, the sr-SPs from the Rhodophyta Halymenia floresii showed stronger activity EC₅₀ 0.68 μg/mL with SI 1470, without cytotoxicity. Further, the antiviral activity of the sr-SPs evaluated at different treatment schemes showed a high EC₅₀ of 0.38 μg/mL during the viral adsorption assays when the polysaccharide and the virus were added simultaneously, whilst the protection on Vero cell during the post-infection assay was effective up to 1 h. The chemical composition, FTIR and ¹H NMR spectroscopic, and molecular weights of the sr-SPs from H. floresii were determined and discussed based on the anti-herpetic activity. The potential utilization of seaweed stranding as a source of antiviral compounds is addressed.

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

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

Bioactive Carbohydrate Polymers-Between Myth and Reality

Polysaccharides are complex macromolecules long regarded as energetic storage resources or as components of plant and fungal cell walls. They have also been described as plant mucilages or microbial exopolysaccharides. The development of glycosciences has led to a partial and difficult deciphering of their other biological functions in living organisms. The objectives of glycobiochemistry and glycobiology are currently to correlate some structural features of polysaccharides with some biological responses in the producing organisms or in another one. In this context, the literature focusing on bioactive polysaccharides has increased exponentially during the last two decades, being sometimes very optimistic for some new applications of bioactive polysaccharides, notably in the medical field. Therefore, this review aims to examine bioactive polysaccharide, taking a critical look of the different biological activities reported by authors and the reality of the market. It focuses also on the chemical, biochemical, enzymatic, and physical modifications of these biopolymers to optimize their potential as bioactive agents.

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.

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.

Food-grade carrageenans and their implications in health and disease

Food additives, often used to guarantee the texture, shelf-life, taste, and appearance of processed foods, have gained widespread attention due to their increased link to the growing incidence of chronic diseases. As one of the most common additives, carrageenans have been used in human diets for hundreds of years. While classified as generally recognized as safe (GRAS) for human consumption, numerous studies since the 1980s have suggested that carrageenans, particularly those with random coil conformations, may have adverse effects on gastrointestinal health, including aggravating intestinal inflammation. While these studies have provided some evidence of adverse effects, the topic is still controversial. Some have suggested that the negative consequence of the consumption of carrageenans may be structure dependent. Furthermore, pre-existing conditions may predispose individuals to varied outcomes of carrageenan intake. In this review, structure-function relationships of various carrageenans in the context of food safety are discussed. We reviewed the molecular mechanisms by which carrageenans exert their biological effects. We summarized the findings associated with carrageenan intake in animal models and clinical trials. Moreover, we examined the interactions between carrageenans and the gut microbiome in the pathogenesis of gastrointestinal disorders. This review argues for personalized guidance on carrageenan intake based on individuals' health status. Future research efforts that aim to close the knowledge gap on the effect of low-dose and chronic carrageenan intake as well as interactions among food additives should be conducive to the improved safety profile of carrageenans in processed food products.

Pine Needle Extract Applicable to Topical Treatment for the Prevention of Human Papillomavirus Infection

Most cervical cancers are associated with high-risk human papillomavirus (HPV) infection. Currently, cervical cancer treatment entails surgical removal of the lesion, but treatment of infection and preventing tissue damage are issues that still remain to be addressed. Herbal medicine and biological studies have focused on developing antiviral drugs from natural sources. In this study, we analyzed the potential antiviral effects of Pinus densiflora Sieb. et Zucc. leaf extracts against HPV. The pine needle extracts from each organic solvent were analyzed for antiviral activity. The methylene chloride fraction (PN-MC) showed the highest activity against HPV pseudovirus (PV). The PN-MC extract was more effective before, rather than after treatment, and therefore represents a prophylactic intervention. Mice were pre-treated with PN-MC via genital application or oral administration, followed by a genital or subcutaneous challenge with HPV PV, respectively. The HPV challenge results showed that mice treated via genital application exhibited complete protection against HPV. In conclusion, PN-MC represents a potential topical virucide for HPV infection.