Types Of Carrageenan Research Articles

Study of the effect of Adding Green Tea (Camellia sinensis) Extract on the Propoerties of Biodegradable Film from κ-Carrageenan

Carrageenan is a polysaccharide widely used as a material in the packaging industry in search of plastic replacement. κ-Carrageenan contains the lowest amount of sulfat group among other types of carrageenan which makes it the most hydrophobic one. Hence, the most suitable kind for this particular purpose. This research combined commercially available of both κ-Carrageenan and green tea extract (gte) to create a biodegradable film and then to study its characteristics. The concentration of gte was made as 0 µg/mL, 5 µg/mL, and 1 µg/mL while the concentration of κ-Carrageenan and glycerol remained constant. Incorporation of gte produces in darker, colorless film. While there is no effect of gte addition in water content observed, the higher concentration of gte will create a thinner film and lower level of water vapor permeability (WVP). An additional study of the mechanical properties of κ-Carrageenan/gte film indicated a direct proportion between the concentration of gte and tensile strength of the film. Meanwhile, there is no sign of correlation between gte concentration and elongation at break. SEM study displayed a more compact surface with smaller pores when the concentration of gte is increased

Co-stabilization effects of gluten/carrageenan to the over-heated myofibrillar protein: Inhibit the undesirable gel weakening and protein over-aggregations

High-temperature (120 °C) sterilization is an indispensable process for manufacturing ready-to-eat surimi products, yet risking the denaturation of their myofibrillar proteins (MP), thus significantly reducing the gelling properties. To resolve this problem, herein, a synergistic co-strengthening strategy was designed. The negatively charged polysaccharide carrageenan (CG) was introduced into MP simultaneously with wheat gluten, followed by 120 °C thermal treatment for 30 min. A substantial enhancement in mechanical strength, up to four times greater (from 9.86 to 42.38 g·cm), was observed for MP gels, which even surpassed that subjected to conventional gelation processes at 90 °C (36.53 g·cm). Gels that were concurrently added with gluten and CG exhibited porous networks, uniform water distribution, and improved water holding capacity. Accordingly, over-aggregation behaviors of MP were restricted, as evidenced by their reduced particle sizes and polymer dispersity index. Other heat-induced protein deteriorations at 120 °C, i.e., changes of secondary structures and disulfide bonding conformations, were also alleviated. By varying the CG types, it was shown that the κ-CG/gluten-added MP achieved highest gel strength, while the ι-CG/gluten combination may better stabilize the moisture in gel networks. This study introduces a co-reinforcement paradigm and scientific insights to the quality improvement of ready-to-eat meat products.

Chemometric insights into milk-carrageenan breaking and gel strength

The relationship between the molecular structure and composition of carrageenan and its milk gelation properties has been studied using chemometric and machine learning tools. Carrageenan types—κ-carrageenan and κ/ι-hybrid— were analyzed for their gel and breaking strengths, crucial for their industrial application as food gelling and thickening agents. Four analytical platforms, Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, size-exclusion chromatography with multi-angle light scattering detection (SEC-MALS), and inductively coupled plasma mass spectrometry (ICP-MS), were employed to characterize the molecular structure and composition aiming to predict milk-carrageenan breaking strength.Both single and multi-block predictive modeling were applied to predict functionality, challenging the conventional approach that relies only on single analytical platforms for prediction.Support Vector Machine (SVM) trained on FT-IR spectra, achieved the most accurate predictions, indicating its potential as an efficient alternative to traditional characterization methods by requiring only measurements directly on the carrageenan powder rather than the laborious functionality testing.In examining multi-block modeling, particularly through Sequential and Orthogonalized PLS (SO-PLS), the study evaluated the added value of incorporating further analytical blocks. While adding SEC-MALS and ICP-MS data did not significantly improve prediction models, their inclusion enriched the causal understanding of carrageenan's structure-function relationship.

Characteristics of carrageenan from seaweed hydrolysis using marine fungi as hard-shell capsule material

Carrageenan is a polysaccharide extracted from red algae and can be used as a raw material for hard-shell capsules. Carrageenan can be produced by biological hydrolysis of marine fungi. The viscosity of carrageenan resulting from hydrolysis using marine fungi is lower than that of commercial carrageenan. Gelatine can be used to modify the characteristics of polysaccharide-based materials. The characteristics and types of carrageenan and plasticizers influence the interactions between carrageenan and gelatin. This study aimed to determine the characteristics of carrageenan produced by seaweed hydrolysis of a hard-shell capsule material. The physical characteristics of the carrageenan produced by hydrolysis were determined, including yield, viscosity, and gel strength. The properties of the hard-shell capsules, including dimensions, capsule weight, disintegration time, and moisture content, were analyzed. The yield was 25%, and the viscosity and gel strength of carrageenan were 45 cP and 175 gf, respectively. Carrageenan contains 13% moisture, 8% ash, and 8% cellulose. Semi-refined carrageenan produced by this treatment was used to prepare hard-shell capsules. The capsule made from semi-refined carrageenan had a body length of 18 mm, capsule length of 10 mm, capsule weight of 0.9 grams, disintegration time of 10 min, and moisture content of 12%.

Structure, emulsifying and embedding characteristics of soy protein isolate induced by the complexation of carrageenan with different charge groups

Soy protein isolate (SPI) offers high protein, nutritional benefits, and versatile functionality but requires modification due to its environmental sensitivity and functional limitations. To expand the functional characteristics and application scope of SPI, three types of carrageenan (Car) was used to form complexes with SPI. With the addition of carrageenan, the turbidity of SPI at its isoelectric point significantly decreased, and the turbidity curve shifted toward the acidic range. Structural analysis showed that λ-carrageenan significantly reduced the hydrophobicity of SPI from 218 to 150 when combined to SPI at a Car/SPI ratio of 1:5 (P < 0.05). Fourier transform infrared spectra revealed that the electrostatic interaction between ι-carrageenan and SPI was the strongest at a ratio of 1:5. The emulsion stabilized by κ-Car/SPI complexes had the smallest creaming index, with a creaming index of 46.6% after 7 days of storage, which was 33.3% lower than the creaming index of the SPI emulsion (P < 0.05). The ι-Car/SPI complexes exhibited the highest encapsulation efficiency for curcumin, with a value of 80.1%, which was 25.3% higher than the SPI (P < 0.05). This study could provide solutions for the modification of SPI and enhance its application in the food industry.

Marine Polysaccharides Carrageenans Enhance Eryptosis and Alter Lipid Order of Cell Membranes in Erythrocytes.

Carrageenans of ι-, κ- and λ-types were incubated with washed erythrocytes (hematocrit 0.4%) at 0-1-5-10 g/L for either 24 h or 48 h. Incubation was followed by flow cytometry-based quantitative analysis of eryptosis parameters, including cell volume, cell membrane scrambling and reactive oxygen species (ROS) production, lipid peroxidation markers and confocal microscopy-based evaluation of intracellular Ca2+ levels, assessment of lipid order in cell membranes and the glutathione antioxidant system. Confocal microscopy was used to assess carrageenan cellular internalization using rhodamine B isothiocyanate-conjugated carrageenans. All three types of carrageenans were found to trigger eryptosis. Pro-eryptotic properties were type-dependent and λ-carrageenan had the strongest impact inducing phosphatidylserine membrane asymmetry, changes in cell volume, Ca2+ signaling and oxidative stress characterized by ROS overproduction, activation of lipid peroxidation and severe glutathione system depletion. Eryptosis induction by carrageenans does not require their uptake by erythrocytes. Changes in physicochemical properties of cell membrane were also type-dependent. No carrageenan-induced generation of superoxide and hydroxyl radicals was observed in cell-free milieu. Our findings suggest that ι-, κ- and λ-types trigger eryptosis in a type-dependent manner and indicate that carrageenans can be further investigated as potential eryptosis-regulating therapeutic agents.

Understanding the rheological properties from linear to nonlinear regimes and spatiotemporal structure of mixed kappa and reduced molecular weight lambda carrageenan gels

Blends of different carrageenan types have proven to be useful in tuning carrageenan gels' rheological properties. However, understanding the influence of a reduced molecular weight on the gelation of mixed carrageenan gels is still limited. Here, the gelation of mixed kappa-(KC) and reduced molecular weight lambda-(LC) carrageenan systems at different mixing ratios was evaluated using rheology from linear to nonlinear regimes via large amplitude oscillatory shear (LAOS), small-angle X-ray scattering (SAXS), pulsed nuclear magnetic resonance (NMR) and particle tracking. A single-step increase in moduli was seen for mixed kappa-lambda carrageenan (KCLC) gels with decreasing temperature while LC demonstrated nongelling behavior. The LAOS response of KCLC mixed gels showed the characteristic signature of strain-stiffening corresponding to the difference in the size and dynamics of the aggregates. The cross-sectional size revealed by SAXS and dynamics of the aggregates revealed by pulsed-NMR demonstrate that KCLC gels has higher segmental mobility and formed small aggregates that reduce with decreasing the KC fraction whereas pure KC gels formed large and rigid aggregates. Thus, the spatiotemporal features of the aggregates are considered to be the origin of the strain-stiffening in mixed gels under large deformation. Moreover, the microscopic properties of the KCLC gels evaluated using particle tracking revealed a homogenous network suggesting the formation of a swollen KC network in the LC solution. Hence, our findings provide insights into the rheological behavior and network structure design of KC and reduced molecular weight LC mixed gels.

Low-cost and eco-friendly PVA/carrageenan membrane to efficiently remove cationic dyes from water: Isotherms, kinetics, thermodynamics, and regeneration study

Methylene blue (MB), a common dye in the textile industry, has a multitude of detrimental consequences on humans and the environment. Accordingly, it is necessary to remove dyes from water to guarantee our health and sustainable ecosystem. In this study, we developed polyvinyl alcohol (PVA)-based hydrogel adsorbents with high adsorption capacity by adding three types of carrageenan (kappa, iota, and lambda) to remove MB from water. Thanks to the functional groups, the PVA/carrageenan membranes dramatically increased the removal efficiency (kappa, 98.8%; iota, 97.0%; lambda, 95.4%) compared to the pure PVA membrane (6.3%). Among the three types of PVA/carrageenan membranes, the PVA/kappa-carrageenan membrane exhibited the best adsorption capacity of 147.8 mg/g. This result implies that steric hindrance was considerably significant, given that kappa carrageenan has only one sulfate group in the repeating unit, whereas iota and lambda carrageenan composite PVA membranes possess two and three sulfate groups. Apart from the maximum adsorption capacity, this study addressed a variety of characteristics of PVA/carrageenan membranes such as the effects of initial MB concentration, kappa carrageenan weight percentage, contact time, adsorbent dosage, and temperature on the adsorption performance. In addition, the kinetic and thermodynamic studies were also carried out. Lastly, the reusability of the PVA/carrageenan membrane was verified by the 98% removal efficiency maintained after five adsorption-desorption cycles.

Static stability of partially crystalline emulsions stabilized by milk proteins: Effects of κ-carrageenan, λ-carrageenan, ι-carrageenan, and their blends

In addition to good whippability, partially crystallized emulsions (PCEs) represented by whipping creams and ice creams must also have prolonged long shelf-life. Carrageenan, the most commonly used thickener for production of PCEs, mainly comes in three commercial forms that may exert different effects on storage stability. In the present study, κ-carrageenan (κ-C), λ-carrageenan (λ-C), ι-carrageenan (ι-C), and their blends (κ-C + λ-C, κ-C + ι-C, λ-C + ι-C, and κ-C + λ-C + ι-C) were included as stabilizers of PCEs to investigate effects of such carrageenans on their static stability. The results indicated that in comparison with λ-C and ι-C, κ-C formed stronger three-dimensional networks with casein micelles, and effectively inhibited droplet flocculation of PCEs by improving zeta potentials (−19.93 mV) and reducing contribution of hydrophobic interactions (0.34 mg/mL) and disulfide bonds (0.34 mg/mL). Interestingly, combination of different types of carrageenans (especially κ-C + λ-C, λ-C + ι-C, and κ-C + λ-C + ι-C) also enhanced the electronegativity (−19.73 to −21.43 mV) and reduced the hydrophobic interactions (0.44–0.53 mg/mL) and disulfide bonds (0.03–0.34 mg/mL), which contributed to preventing fat droplets from flocculation during storage. After a storage of 2 months, the emulsions formulated with κ-C, κ-C + λ-C, λ-C + ι-C, and κ-C + λ-C + ι-C exhibited low levels of watering-off (10.03–11.35% of creaming index) and agglomeration (676.00–1012.50 mPa·s of viscosity).

Electrically controlled transdermal drug release of ionic and non-ionic drug from kappa-iota carrageenan cryogel

The goals of this study were to fabricate and characterize the kappa (K) and iota (I) carrageenan (CAR) cryogel matrix for electrically controlled transdermal ionic namely diclofenac (DCNa) and non-ionic namely theophylline (Theo) delivery. The CAR cryogels were prepared by freeze-drying method based on the effects of CAR types which were different sulfate ester group content in the structure, K-CAR concentrations, and blending K and I-CAR. According to the results, the increasing K-CAR concentrations affected to reduce the swelling behavior and pore size of cryogels. However, the swelling behavior was increased and pore size was decreased with blending K/I-CAR. The release mechanism of DCNa and Theo was a non-fickian and fickian diffusion depending on drug types, cryogels composition, and applied electric potentials. The amount of drug release was decreased with increasing K-CAR concentrations and decreased with a blending K/I-CAR. However, the amount of drug release was increased with increasing electric potential, especially an anionic drug. The amount of DCNa was higher than that of Theo with and without applied electric potential. The maximum amount of drug release was 78.06 and 58.78% for DCNa and Theo, respectively. Thus, the CAR cryogel is suitable for controlled release of ionic and non-ionic drug with and without applied electric field.

Carrageenan as a macromolecular crowding agent in human umbilical cord derived mesenchymal stromal cell culture

Cell sheet tissue engineering requires prolonged in vitro culture for the development of implantable devices. Unfortunately, lengthy in vitro culture is associated with cell phenotype loss and substantially higher cost of goods, which collectively hinder clinical translation and commercialisation of tissue engineered medicines. Although macromolecular crowding has been shown to enhance and accelerate extracellular matrix deposition, whilst maintaining cellular phenotype, the optimal macromolecular crowding agent still remains elusive. Herein, we evaluated the biophysical properties of seven different carrageenan molecules at five different concentrations and their effect on human umbilical cord-derived mesenchymal stromal cell morphology, viability, metabolic activity, proliferation, extracellular matrix deposition and surface marker expression. All types of carrageenan (CR) assessed demonstrated a hydrodynamic radius increase as a function of increasing concentration; high polydispersity; and negative charge. Two iota CRs were excluded from further analysis due to poor solubility in cell culture. Among the remaining five carrageenans, the lambda medium viscosity type at concentrations of 10 and 50 μg/ml did not affect cell morphology, viability, metabolic activity, proliferation and expression of surface markers and significantly increased the deposition of collagen types I, III and IV, fibronectin and laminin. Our data highlight the potential of lambda medium viscosity carrageenan as a macromolecular crowding agent for the accelerated development of functional tissue engineered medicines.

Carrageenans as Sustainable Water-Processable Binders for High-Voltage NMC811 Cathodes.

Poly(vinylidene fluoride) (PVDF) is the most common binder for cathode electrodes in lithium-ion batteries. However, PVDF is a fluorinated compound and requires toxic N-methyl-2-pyrrolidone (NMP) as a solvent during the slurry preparation, making the electrode fabrication process environmentally unfriendly. In this study, we propose the use of carrageenan biopolymers as a sustainable source of water-processable binders for high-voltage NMC811 cathodes. Three types of carrageenan (Carr) biopolymers were investigated, with one, two, or three sulfonate groups (SO3-), namely, kappa, iota, and lambda carrageenans, respectively. In addition to the nature of carrageenans, this article also reports the optimization of the cathode formulations, which were prepared by using between 5 wt % of the binder to a lower amount of 2 wt %. Processing of the aqueous slurries and the nature of the binder, in terms of the morphology and electrochemical performance of the electrodes, were also investigated. The Carr binder with 3SO3- groups (3SO3-Carr) exhibited the highest discharge capacities, delivering 133.1 mAh g-1 at 3C and 105.0 mAh g-1 at 5C, which was similar to the organic-based PVDF electrode (136.1 and 108.7 mAh g-1, respectively). Furthermore, 3SO3-Carr reached an outstanding capacity retention of 91% after 90 cycles at 0.5C, which was attributed to a homogeneous NMC811 and a conductive carbon particle dispersion, superior adhesion strength to the current collector (17.3 ± 0.7 N m-1 vs 0.3 ± 0.1 N m-1 for PVDF), and reduced charge-transfer resistance. Postmortem analysis unveiled good preservation of the NMC811 particles, while the 1SO3-Carr and 2SO3-Carr electrodes showed damaged morphologies.

Carrageenan in Seaweed (Eucheuma sp.) and Use of Carrageenan in Fishery Food Products: A Review

Carrageenan is a hydrocolloid compound found in red seaweed (Rodhophyta). Carrageenan-producing sources are Eucheuma cottonii seaweed with kappa carrageenan type and Eucheuma spinoum with iota carrageenan type. Kappa carrageenan is widely used in food products because its availability is very abundant in nature compared to iota and lambda carrageenan types. The boiling method with an alkaline solution is a method that is often used in extracting carrageenan. Carrageenan has properties as a stabilizer, thickener, gelling agent, and emulsifier. Carrageenan is widely applied in the food and non-food sector. In food products, carrageenan functions as a food additive, thickener, and emulsifier, and can increase the protein and fiber content of a food product.

Analysis of yield and types of carrageenan from different strains at Kupang Bay seaweed production center, East Nusa Tenggara

Kappaphycus alvarezzi is a species widely cultivated by the seaweed farmers surrounding Kupang Bay since the early 2000s. K. alvarezzi is sold as raw materials for the carrageenan industry as its hydrocolloid properties are used as emulsion and suspension stabilizers in the food and pharmaceutical industries. This study determines the yield and identifies the type of carrageenan from algal farms at Kupang Bay. Samples are collected from five production centers, then extracted at the Wet Laboratory at the Undana Faculty of Animal Husbandry, Marine and Fisheries in Kupang; and the extracted carrageenan is then analyzed using infrared spectroscopy at the Laboratory of the Faculty of Advanced and Multidisciplinary Technology Universitas Airlangga in Surabaya. The results showed that the highest yield of carrageenan was seaweed from Sulamu (25.72%) then, followed by Oenaek (19.6%), Tablolong A (13.48%), South Semau (11%), and Tablolong B as the lowest yield (9.6% ). Both the presence of functional groups such as D-galactose-4-sulphate and 3,6 anhydro D-galactose groups and the absence of D-galactose-2-sulfate and the 3,6 anhydrogalactose-2-sulfate group, concluded that the type of carrageenan produced in Kupang Bay is the kappa carrageenan.

Variations on primary metabolites of the carrageenan-producing red algae Sarcopeltis skottsbergii from Chile and Sarcopeltis antarctica from Antarctic Peninsula

Several studies reported that gametophytes and tetrasporophytes of Gigartinaceae produce different carrageenan types, as observed in Sarcopeltis species although they have isomorphic haploid and diploid phases. Cystocarpic and non-fertile plants of Sarcopeltis (ex Gigartina) skottsbergii produced kappa-carrageenans, while tetrasporophytes produced lambda-carrageenans, and yields were higher in cystocarpic and sterile specimens than in tetrasporophytes. However, comparison on the other primary metabolites among different life history phases still needed to be investigated. Then, we tested the hypothesis if the variation on primary metabolites (pigments, proteins and carbohydrates) are related to the life history phases of Sarcopeltis antarctica and Sarcopeltis skottsbergii, and/or are influenced by abiotic factors. Primary metabolites of S. antarctica varied according to the life-history phases: non-fertile specimens presented higher phycobiliprotein concentrations, tetrasporophytes presented higher chlorophyll a concentrations, and cystocarpic specimens presented higher concentrations of proteins, polysaccharides and floridean starch. However, primary metabolites of S. skottsbergii varied in response to some abiotic factors (nutrients, temperature and salinity), since principal component analysis evidenced two groups; one was related by the higher nitrate and phosphate concentrations, and the other was related to the higher temperatures and lower salinities. Concentrations of floridean starch, low molecular weight carbohydrates, and polysaccharides are higher in S. antarctica than in S. skottsbergii, which could be related to the protective role of these compounds against salinity variation and low temperatures faced in the Antarctic extreme environments.

Conducting poly(3,4-ethylenedioxythiophene) materials with sustainable carrageenan counter-ions and their thermoelectric properties

We prepared a conducting polymer with naturally occurring polymers kappa- and lambda-carrageenan as counter-ions; the materials produced show good conductivity and thermoelectric properties that make them attractive for a range of functionalities.

A Novel Carrageenan Metabolic Pathway in Flavobacterium algicola.

Carbohydrate-active enzymes are important components of the polysaccharide metabolism system in marine bacteria. Carrageenase is indispensable for forming carrageenan catalytic pathways. Here, two GH16_13 carrageenases showed likely hydrolysis activities toward different types of carrageenans (e.g., κ-, hybrid β/κ, hybrid α/ι, and hybrid λ), which indicates that a novel pathway is present in the marine bacterium Flavobacterium algicola to use κ-carrageenan (KC), ι-carrageenan (IC), and λ-carrageenan (LC). A comparative study described the different features with another reported pathway based on the specific carrageenans (κ, ι, and λ) and expanded the carrageenan metabolic versatility in F. algicola. A further comparative genomic analysis of carrageenan-degrading bacteria indicated different distributions of carrageenan metabolism-related genes in marine bacteria. The crucial core genes encoding the GH127 α-3,6-anhydro-d-galactosidase (ADAG) and 3,6-anhydro-d-galactose (d-AHG)-utilized cluster have been conserved during evolution. This analysis further revealed the horizontal gene transfer (HGT) phenomenon of the carrageenan polysaccharide utilization loci (CarPUL) from Bacteroidetes to other bacterial phyla, as well as the versatility of carrageenan catalytic activities in marine bacteria through different metabolic pathways. IMPORTANCE Based on the premise that the specific carrageenan-based pathway involved in carrageenan use by Flavobacterium algicola has been identified, another pathway was further analyzed, and it involved two GH16_13 carrageenases. Among all the characterized carrageenases, the members of GH16_13 accounted for only a small portion. Here, the functional analysis of two GH16_13 carrageenases suggested their hydrolysis effects on different types of carrageenans (e.g., κ, hybrid β/κ, hybrid α/ι-, and hybrid λ-), which led to the identification of another pathway. Further exploration enabled us to elucidate the novel pathway that metabolizes KC and IC in F. algicola successfully. The coexistence of these two pathways may provide improved survivability by F. algicola in the marine environment.

Carrageenan From Kappaphycus alvarezii (Rhodophyta, Solieriaceae): Metabolism, Structure, Production, and Application.

Carrageenan is a polysaccharide derived from red algae (seaweed) with enormous economic potential in a wide range of industries, including pharmaceuticals, food, cosmetics, printing, and textiles. Carrageenan is primarily produced through aquaculture-based seaweed farming, with Eucheuma and Kappaphycus species accounting for more than 90% of global output. There are three major types of carrageenan found in red algae: kappa (κ)-, iota (ι)-, and lambda (λ)-carrageenan. Kappaphycus alvarezii is the most common kappa-carrageenan source, and it is primarily farmed in Asian countries such as Indonesia, the Philippines, Vietnam, and Malaysia. Carrageenan extracted from K. alvarezii has recently received a lot of attention due to its economic potential in a wide range of applications. This review will discuss K. alvarezii carrageenan in terms of metabolic and physicochemical structure, extraction methods and factors affecting production yield, as well as current and future applications.

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

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

Potential Use of Carrageenans against the Limestone Proliferation of the Cyanobacterium Parakomarekiella sesnandensis

Stone biodeterioration by cyanobacteria is a common issue in the field of cultural heritage. As they are considered the first stone colonizers, the need to control their growth has increased. In this study, we evaluated the effectiveness of kappa/iota carrageenans from the red seaweed Chondracanthus teedei var. lusitanicus against the limestone proliferation of the cyanobacterium Parakomarekiella sesnandensis, under laboratory conditions. For this purpose, 200 μL of kappa/iota carrageenans (0.01 g mL−1) were applied into the surface of the limestone replicas prior to their inoculation with P. sesnandensis. Results were evaluated after 4 months of incubation through visual inspection, stereomicroscopy, scanning electron microscopy and colorimetric analyses. The gathered data demonstrated that these types of carrageenans have the potential to reduce the colonization of P. sesnandensis. With one sole application, the aesthetical alterations caused by the proliferation of P. sesnandensis were drastically reduced. This study highlights the need to explore marine-based products, particularly those derived from seaweeds with antimicrobial properties, as alternative methods for biocleaning cultural heritage assets.