Metabolites of Seaweeds as Potential Agents for the Prevention and Therapy of Influenza Infection

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

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

Exploring carrageenan: From seaweed to biomedicine-A comprehensive review

Biomaterials are pivotal in the realms of tissue engineering, regenerative medicine, and drug delivery and serve as fundamental building blocks. Within this dynamic landscape, polymeric biomaterials emerge as the frontrunners, offering unparalleled versatility across physical, chemical, and biological domains. Natural polymers, in particular, captivate attention for their inherent bioactivity. Among these, carrageenan (CRG), extracted from red seaweeds, stands out as a naturally occurring polysaccharide with immense potential in various biomedical applications. CRG boasts a unique array of properties, encompassing antiviral, antibacterial, immunomodulatory, antihyperlipidemic, antioxidant, and antitumor attributes, positioning it as an attractive choice for cutting-edge research in drug delivery, wound healing, and tissue regeneration. This comprehensive review encapsulates the multifaceted properties of CRG, shedding light on the chemical modifications that it undergoes. Additionally, it spotlights pioneering research that harnesses the potential of CRG to craft scaffolds and drug delivery systems, offering high efficacy in the realms of tissue repair and disease intervention. In essence, this review celebrates the remarkable versatility of CRG and its transformative role in advancing biomedical solutions.

Algal Phycocolloids: Bioactivities and Pharmaceutical Applications

Seaweeds are abundant sources of diverse bioactive compounds with various properties and mechanisms of action. These compounds offer protective effects, high nutritional value, and numerous health benefits. Seaweeds are versatile natural sources of metabolites applicable in the production of healthy food, pharmaceuticals, cosmetics, and fertilizers. Their biological compounds make them promising sources for biotechnological applications. In nature, hydrocolloids are substances which form a gel in the presence of water. They are employed as gelling agents in food, coatings and dressings in pharmaceuticals, stabilizers in biotechnology, and ingredients in cosmetics. Seaweed hydrocolloids are identified in carrageenan, alginate, and agar. Carrageenan has gained significant attention in pharmaceutical formulations and exhibits diverse pharmaceutical properties. Incorporating carrageenan and natural polymers such as chitosan, starch, cellulose, chitin, and alginate. It holds promise for creating biodegradable materials with biomedical applications. Alginate, a natural polysaccharide, is highly valued for wound dressings due to its unique characteristics, including low toxicity, biodegradability, hydrogel formation, prevention of bacterial infections, and maintenance of a moist environment. Agar is widely used in the biomedical field. This review focuses on analysing the therapeutic applications of carrageenan, alginate, and agar based on research highlighting their potential in developing innovative drug delivery systems using seaweed phycocolloids.

Recent advances in cellulose, pectin, carrageenan and alginate-based oral drug delivery systems

Polymers-based drug delivery systems constitute one of the highly explored thrust areas in the field of the medicinal and pharmaceutical industries. In the past years, the properties of polymers have been modified in context to their solubility, release kinetics, targeted action site, absorption, and therapeutic efficacy. Despite the availability of diverse synthetic polymers for the bioavailability enhancement of drugs, the use of natural polymers is still highly recommended due to their easy availability, accessibility, and non-toxicity. The aim of the review is to provide the available literature of the last five years on oral drug delivery systems based on four natural polymers i.e., cellulose, pectin, carrageenan, and alginate in a concise and tabulated manner. In this review, most of the information is in tabulated form to provide easy accessibility to the reader. The data related to active pharmaceutical ingredients and supported components in different formulations of the mentioned polymers have been made available.

Biological activity of algal derived carrageenan: A comprehensive review in light of human health and disease

Carrageenans are a family of natural linear sulfated polysaccharides derived from red seaweeds and used as a common food additive. Carrageenan's properties, impact on health, and aesthetic benefits have all been studied for a long time; however, the mechanisms are still unclear. In pharmaceutical aspects, carrageenan displayed potential antioxidant and immunomodulatory properties in both in vivo and in vitro action. It also contributes to potential disease-preventive activities through dynamic modulation of important intracellular signaling pathways, regulation of ROS buildup, and preservation of major cell survival and death processes which leads to potential drug development. Furthermore, the chemical synthesis of the current bioactive medicine with confirmational rearrangement may increase availability and bioactivity needs diligent examination. In this review, we give an up-to-date overview of recent research on Carrageenan with reference to health and therapeutic advantages. In addition, we have focused on structural conformation and its primary strategic deployment in disease prevention, as well as the mechanistic investigation of how it functions to combat various disease-preventive employed for future therapeutic interventions. This review may get new insights into the possible novel role of carrageenan and open up a novel disease-preventive mechanism and enhance human health.

A review on the immunomodulatory properties of functional nutraceuticals as dietary interventions for children to combat COVID-19 related infections

COVID-19 is a significant threat to humanity in the present day due to the rapid increase in the number of infections worldwide. While most children may be spared of the direct mortality effects of the disease, those with weak immune systems are prone to adverse effects. Child mortality increases due to the stress caused to the health care system that disrupts essential health care needs such as immunisation and antenatal care. The use of functional foods (FF) aids in disease-prevention as they are known to have protective effects against COVID-19 by boosting children’s cellular and humoral immunity. Plant components such as glycyrrhizin, epigallocatechin gallate, allicin, and fucoidan exhibit antiviral properties against various viruses, including SARS-CoV 2. Microbial foods that are made of probiotics, can enhance immunity against various respiratory viruses. Food enriched with additives such as lactoferrin, piperine, and zinc can boost immunity against COVID-19. With proper definitive drug therapy not available for treating COVID-19 and most of the disease management tools rely on symptoms and non-specific supportive care, developing a functional paediatric formulation will prevent further deterioration in infant health. It is wise to investigate the toxicological aspects of Functional Foods components especially when formulating for children. The safe limits of ingredients should be strictly followed during FFs formulation. Stronger regulations with advanced analytical techniques can help to formulate functional foods into the mainstream in child nutraceuticals. The purpose of this review is to compile collective information on the functional nutraceuticals specifically for infants and children up to the age of 10 years that could confer immunity against COVID-19 and other related viruses.

Use of Nanomaterials for Diagnosis and Treatment: The Advancement of Next-Generation Antiviral Therapy

Globally, viral illness propagation is the leading cause of morbidity and death, causing wreaking havoc on socioeconomic development and health care systems. The rise of infected individuals has outpaced the existing critical care facilities. Early and sophisticated methods are desperately required in this respect to halt the spread of the infection. Therefore, early detection of infectious agents and an early treatment approach may help minimize viral outbreaks. Conventional point-of-care diagnostic techniques such as computed tomography scan, quantitative real time polymerase chain reaction (qRT-PCR), X-ray, and immunoassay are still deemed valuable. However, the labor demanding, low sensitivity, and complex infrastructure needed for these methods preclude their use in distant areas. Nanotechnology has emerged as a potentially transformative technology due to its promise as an effective theranostic platform for diagnosing and treating viral infection, circumventing the limits of traditional techniques. Their unique physical and chemical characteristics make nanoparticles (NPs) advantageous for drug delivery platforms due to their size, encapsulation efficiency, improved bioavailability, effectiveness, immunogenicity, and antiviral response. This study discusses the recent research on nanotechnology-based treatments designed to combat new viruses.

Carrageenan of Red Algae Eucheuma gelatinae: Extraction, Antioxidant Activity, Rheology Characteristics, and Physicochemistry Characterization

Carrageenan is an anionic sulfated polysaccharide that accounts for a high content of red seaweed Eucheuma gelatinae. This paper focused on the extraction, optimization, and evaluation of antioxidant activity, rheology characteristics, and physic-chemistry characterization of β-carrageenan from Eucheuma gelatinae. The extraction and the optimization of β-carrageenan were by the maceration-stirred method and the experimental model of Box-Behken. Antioxidant activity was evaluated to be the total antioxidant activity and reducing power activity. The rheology characteristics of carrageenan were measured to be gel strength and viscosity. Physic-chemistry characterization was determined, including the molecular weight, sugar composition, function groups, and crystal structure, through GCP, GC-FID, FTIR, and XRD. The results showed that carrageenan possessed antioxidant activity, had intrinsic viscosity and gel strength, corresponding to 263.02 cps and 487.5 g/cm², respectively. Antioxidant carrageenan is composed of rhamnose, mannose, glucose, fucose, and xylose, with two molecular weight fractions of 2.635 × 10⁶ and 2.58 × 10⁶ g/mol, respectively. Antioxidant carrageenan did not exist in the crystal. The optimization condition of antioxidant carrageenan extraction was done at 82.35 °C for 115.35 min with a solvent-to-algae ratio of 36.42 (v/w). At the optimization condition, the extraction efficiency of carrageenan was predicted to be 87.56 ± 5.61 (%), the total antioxidant activity and reducing power activity were predicted to 71.95 ± 5.32 (mg ascorbic acid equivalent/g DW) and 89.84 ± 5.84 (mg FeSO₄ equivalent/g DW), respectively. Purity carrageenan content got the highest value at 42.68 ± 2.37 (%, DW). Antioxidant carrageenan from Eucheuma gelatinae is of potential use in food and pharmaceuticals.

Marine Health-Promoting Compounds: Recent Trends for Their Characterization and Human Applications

Seaweeds represent a rich source of biologically active compounds with several applications, especially in the food, cosmetics, and medical fields. The beneficial effects of marine compounds on health have been increasingly explored, making them an excellent choice for the design of functional foods. When studying marine compounds, several aspects must be considered: extraction, identification and quantification methods, purification steps, and processes to increase their stability. Advanced green techniques have been used to extract these valuable compounds, and chromatographic methods have been developed to identify and quantify them. However, apart from the beneficial effects of seaweeds for human health, these natural sources of bioactive compounds can also accumulate undesirable toxic elements with potential health risks. Applying purification techniques of extracts from seaweeds may mitigate the amount of excessive toxic components, ensuring healthy and safer products for commercialization. Furthermore, limitations such as stability and bioavailability problems, chemical degradation reactions during storage, and sensitivity to oxidation and photo-oxidation, need to be overcome using, for example, nanoencapsulation techniques. Here we summarize recent advances in all steps of marine products identification and purification and highlight selected human applications, including food and feed applications, cosmetic, human health, and fertilizers, among others.

Experimental Evaluation of Food-Grade Semi-Refined Carrageenan Toxicity

The safety of food additives E407 and E407a has raised concerns in the scientific community. Thus, this study aims to assess the local and systemic toxic effects of the common food additive E407a in rats orally exposed to it for two weeks. Complex evaluations of the effects of semi-refined carrageenan (E407a) on rats upon oral exposure were performed. Local effects of E407a on the intestine were analyzed using routine histological stains and CD68 immunostaining. Furthermore, circulating levels of inflammatory markers were assessed. A fluorescent probe O1O (2- (2'-OH-phenyl)-5-phenyl-1,3-oxazole) was used for evaluating the state of leukocyte cell membranes. Cell death modes of leukocytes were analyzed by flow cytometry using Annexin V and 7-aminoactinomycin D staining. Oral administration of the common food additive E407a was found to be associated with altered small and large intestinal morphology, infiltration of the lamina propria in the small intestine with macrophages (CD68+ cells), high systemic levels of inflammation markers, and changes in the lipid order of the phospholipid bilayer in the cell membranes of leukocytes, alongside the activation of their apoptosis. Our findings suggest that oral exposure to E407a through rats results in the development of intestinal inflammation.

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.

Antiviral Potential of Algal Metabolites-A Comprehensive Review

Historically, algae have stimulated significant economic interest particularly as a source of fertilizers, feeds, foods and pharmaceutical precursors. However, there is increasing interest in exploiting algal diversity for their antiviral potential. Here, we present an overview of 50-years of scientific and technological developments in the field of algae antivirals. After bibliometric analysis of 999 scientific references, a survey of 16 clinical trials and analysis of 84 patents, it was possible to identify the dominant algae, molecules and viruses that have been shaping and driving this promising field of research. A description of the most promising discoveries is presented according to molecule class. We observed a diverse range of algae and respective molecules displaying significant antiviral effects against an equally diverse range of viruses. Some natural algae molecules, like carrageenan, cyanovirin or griffithsin, are now considered prime reference molecules for their outstanding antiviral capacity. Crucially, while many algae antiviral applications have already reached successful commercialization, the large spectrum of algae antiviral capacities already identified suggests a strong potential for future expansion of this field.

Fucoidan and Lung Function: Value in Viral Infection

Compromised lung function is a feature of both infection driven and non-infective pathologies. Viral infections-including the current pandemic strain SARS-CoV-2-that affect lung function can cause both acute and long-term chronic damage. SARS-CoV-2 infection suppresses innate immunity and promotes an inflammatory response. Targeting these aspects of SARS-CoV-2 is important as the pandemic affects greater proportions of the population. In clinical and animal studies, fucoidans have been shown to increase innate immunity and decrease inflammation. In addition, dietary fucoidan has been shown to attenuate pulmonary damage in a model of acute viral infection. Direct inhibition of SARS-CoV-2 in vitro has been described, but is not universal. This short review summarizes the current research on fucoidan with regard to viral lung infections and lung damage.

Dietary supplementation of Ascophylum nodosum improved kidney function of mink challenged with Aleutian mink disease virus

BACKGROUND

Feed additives which can ease the negative effects of infection by the Aleutian mink disease virus (AMDV) are of interest to mink farmers. The effects of kelp meal (Ascophylum nodosum) supplementation on immune response, virus replication and blood parameters of mink inoculated with AMDV were assessed. AMDV-free black mink (n = 75) were intranasally inoculated with a local strain of AMDV and fed a commercial pellet supplemented with kelp meal at the rates of 1.5% or 0.75% of the feed or were kept as controls (no kelp) for 451 days. Blood was collected on days 0 (pre-inoculation), 31, 56, 99, 155, 366 and 451 post-inoculation (dpi).

RESULTS

No significant difference was observed among the treatments for the proportion of animals positive for antibodies against the virus measured by the counter-immunoelectrophoresis (CIEP), viremia measured by PCR, antibody titer measured by quantitative ELISA, total serum protein measured by a refractometer or elevated levels of gamma globulin measured by iodine agglutination test at the sampling occasions. At the termination of the experiment on 451 dpi, there were no differences among treatments for antibody titer measured by CIEP, total serum protein, albumin, globulins, albumin:globulin ratio, alkaline phosphatase, gamma-glutamyl transferase, and proportions of PCR positive spleen, lymph node or bone marrow samples, but blood urea nitrogen and creatine levels were significantly lower in the 1.5% kelp supplemented group than in the controls.

CONCLUSION

Kelp supplementation improved kidney function of mink infected with AMDV with no effect on liver function, immune response to infection by AMDV or virus replication.

Carrageenan: Drug Delivery Systems and Other Biomedical Applications

Marine resources are today a renewable source of various compounds, such as polysaccharides, that are used in the pharmaceutical, medical, cosmetic, and food fields. In recent years, considerable attention has been focused on carrageenan-based biomaterials due to their multifunctional qualities, including biodegradability, biocompatibility, and non-toxicity, in addition to bioactive attributes, such as their antiviral, antibacterial, antihyperlipidemic, anticoagulant, antioxidant, antitumor, and immunomodulating properties. They have been applied in pharmaceutical formulations as both their bioactive and physicochemical properties make them suitable biomaterials for drug delivery, and recently for the development of tissue engineering. This article provides a review of recent research on the various types of carrageenan-based biomedical and pharmaceutical applications.

Nanobiosensors for the Detection of Novel Coronavirus 2019-nCoV and Other Pandemic/Epidemic Respiratory Viruses: A Review

The coronavirus disease 2019 (COVID-19) pandemic is considered a public health emergency of international concern. The 2019 novel coronavirus (2019-nCoV) or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that caused this pandemic has spread rapidly to over 200 countries, and has drastically affected public health and the economies of states at unprecedented levels. In this context, efforts around the world are focusing on solving this problem in several directions of research, by: (i) exploring the origin and evolution of the phylogeny of the SARS-CoV-2 viral genome; (ii) developing nanobiosensors that could be highly effective in detecting the new coronavirus; (iii) finding effective treatments for COVID-19; and (iv) working on vaccine development. In this paper, an overview of the progress made in the development of nanobiosensors for the detection of human coronaviruses (SARS-CoV, SARS-CoV-2, and Middle East respiratory syndrome coronavirus (MERS-CoV) is presented, along with specific techniques for modifying the surface of nanobiosensors. The newest detection methods of the influenza virus responsible for acute respiratory syndrome were compared with conventional methods, highlighting the newest trends in diagnostics, applications, and challenges of SARS-CoV-2 (COVID-19 causative virus) nanobiosensors.

Semi-refined carrageenan promotes generation of reactive oxygen species in leukocytes of rats upon oral exposure but not in vitro

AIM

To assess the ability of the common food additive E407a (semi-refined carrageenan) to enter leukocytes in vitro and generate reactive oxygen species (ROS) in leukocytes as a whole and granulocytes in particular, both during incubation and in experimental animals.

METHODS

ROS production was assessed in leukocytes incubated with E407a for 2 h at the final concentrations of 5 and 10 g/L using the dye 2',7'-dichlorodihydrofluorescein diacetate (H₂DCFDA), as well as in cells isolated from rats orally exposed to E407a (140 mg/kg of weight) during 2 weeks (n = 8) and control rats (n = 8), by flow cytometry. Carrageenan uptake by leukocytes was estimated by confocal microscopy using incubation of rhodamine B isothiocyanate-labelled carrageenan with leukocyte suspensions.

RESULTS

Uptake of carrageenan by viable neutrophils, monocytes, and lymphocytes was confirmed. Oral administration of the food additive E407a was associated with excessive ROS formation by viable leukocytes (CD45⁺, 7‑aminoactinomycin D^- cells) and especially in granulocytes. Unexpectedly, a direct impact of semi-refined carrageenan during incubation for 2 h did not affect ROS production in leukocytes, evidenced by statistically insignificant differences in mean fluorescence intensity values of 2',7'-dichlorofluorescein, which is a ROS-sensitive product of intracellular H₂DCFDA conversion. Oral intake of E407a and direct exposure of leukocyte suspensions to it decreased the viability of leukocytes.

CONCLUSION

Food-grade carrageenan can enter leukocytes without affecting ROS generation as a result of incubation for 2 h with leukocyte suspensions. On the contrary, oral exposure to E407a is accompanied by ROS overproduction by white blood cells, suggesting an indirect mechanism for the stimulation of ROS synthesis in vivo. E407a promotes cell death of leukocytes both in vivo and in vitro.

Nutraceutical characteristics of the brown seaweed carotenoid fucoxanthin

Fucoxanthin (Fx), a major carotenoid found in brown seaweed, is known to show a unique and wide variety of biological activities. Upon absorption, Fx is metabolized to fucoxanthinol and amarouciaxanthin, and these metabolites mainly accumulate in visceral white adipose tissue (WAT). As seen in other carotenoids, Fx can quench singlet oxygen and scavenge a wide range of free radicals. The antioxidant activity is related to the neuroprotective, photoprotective, and hepatoprotective effects of Fx. Fx is also reported to show anti-cancer activity through the regulation of several biomolecules and signaling pathways that are involved in either cell cycle arrest, apoptosis, or metastasis suppression. Among the biological activities of Fx, anti-obesity is the most well-studied and most promising effect. This effect is primarily based on the upregulation of thermogenesis by uncoupling protein 1 expression and the increase in the metabolic rate induced by mitochondrial activation. In addition, Fx shows anti-diabetic effects by improving insulin resistance and promoting glucose utilization in skeletal muscle.