Red Algae Research Articles

Edible-algae base composite film containing gelatin for food packaging from macroalgae, Gracilaroid (Gracilaria fisheri).

Conventional petroleum-based packaging films cause severe environmental problems. In the present study, bio-edible film was introduced as being safe to replace petroleum-based polymers. A food application for edible sachets and a composite edible film (EF) from marine algae, Gracilaria fisheri (GF) extract, were proposed. Carbohydrates were the most prevalent component in fresh GF fronds. Under neutral conditions comprising 90 °C for 40 min, the structure of the extract was determined by Fourier transform infrared to be a carrageenan-like polysaccharide. Glycerol was the best plasticizer for EF formation because it had the highest tensile strength (TS). The integration of gelatin into the algal composite film with gelatin (CFG) was validated to be significant. The best casting temperatures for 2 h were 70 and 100 °C among the four tested temperatures (25, 60, 70 and 100 °C). Temperatures did not result in any significant (P ≤ 0.05) differences in any character (color values, TS, water vapor permeability, oxygen transmission, thickness and water activity), except elongation at break. Visually, the CFG had a slightly yellow appearance. The best-to-worst order of film stability in the three tested solvents was oil, distilled water (DW) and ethanol. Its stability in ethanol (0-100%), temperature of DW (30-100 °C) and pH (3-7 in DW) demonstrated inverse relationships with the concentration or different conditions, except for pH 8-10 in DW. All treatments were significantly (P ≤ 0.05) different. The novel material made from polysaccharides from algae, G. fisheri, was used to improve EF. The edible sachet application is plausible from the EF. © 2024 Society of Chemical Industry.

Enhancing marine algae composites with cellulose nanofibrils for sustainable nutrient management

Enhancing marine algae composites with cellulose nanofibrils for sustainable nutrient management

Report on <i>Phaeophila dendroides</i> (Crouan) Batters Endophytic in <i>Rosenvingea intricata</i> (J. Ag.) Boergs.

Phaeophila dendroides (Crouan) Batters is reported here for the first time from North India from Chilka Lake. While the species is known as an endophyte in several marine algae belonging to Chlorophyta and Rhodophyta and a few marine Spermatophyta, it is reported here for the first time in a Phaeophyta in Roservingea intricata (J. Ag.) Boergs. The endophyte from Chilka Lake is described in some detail.

Extraction, Purification, Structural Characteristics, and Biological Activities of Seaweed Polysaccharides: A Review

AbstractThis paper presents a thorough review of the extraction, purification, structural characterization, and biological activities of polysaccharides obtained from seaweed. The focus is on the polysaccharide compositions of green algae, brown algae, and red algae, which are systematically compared and analyzed. It has been discovered that while there are similarities in the extraction and purification processes of seaweed polysaccharides, there are also significant differences and unique features in their structural characteristics and biological activities. These differences are not only reflected in the chemical composition of the polysaccharides but are also closely related to their sources and extraction methods. The relationship between the structure and activity of seaweed polysaccharides will aid in comprehending the biological activity mechanism of marine organisms. This review provides a theoretical basis and practical guidance for the development of new types of marine drugs or functional foods.

Antifungal Activities of Biogenic Silver Nanoparticles Mediated by Marine Algae: In Vitro and In Vivo Insights of Coating Tomato Fruit to Protect against Penicillium italicum Blue Mold.

In an attempt to reduce such decay induced by pathogenic causes, several studies investigated the effectiveness of nanoparticles (NPs) that play a vital role in saving food products, especially fruits. Current research delves into biogenic silver nanoparticles (using marine alga Turbinaria turbinata (Tt/Ag-NPs) and their characterization using FT-IR, TEM, EDS, and zeta potential. Some pathogenic fungi, which cause fruit spoilage, were isolated. We studied the impact of using Tt/Ag-NPs to protect against isolated fungi in vitro, and the influence of Tt/Ag-NPs as a coating of tomato fruit to protect against blue mold caused by Penicillium italicum (OR770486) over 17 days of storage time. Five treatments were examined: T1, healthy fruits were used as the positive control; T2, healthy fruits sprayed with Tt/Ag-NPs; T3, fruits infected with P. italicum followed by coating with Tt/Ag-NPs (pre-coating); T4, fruits coated with Tt/Ag-NPs followed by infection by P. italicum (post-coating); and T5, the negative control, fruits infected by P. italicum. The results displayed that Tt/Ag-NPs are crystalline, spherical in shape, with size ranges between 14.5 and 39.85 nm, and negative charges. Different concentrations of Tt/Ag-NPs possessed antifungal activities against Botrytis cinerea, Rhodotorula mucilaginosa, Penicillium expansum, Alternaria alternate, and Stemphylium vesicarium. After two days of tomatoes being infected with P. italicum, 55% of the fruits were spoilage. The tomato fruit coated with Tt/Ag-NPs delayed weight loss, increased titratable acidity (TA%), antioxidant%, and polyphenol contents, and decreased pH and total soluble solids (TSSs). There were no significant results between pre-coating and post-coating except in phenol contents increased in pre-coating. A particular focus is placed on the novel and promising approach of utilizing nanoparticles to combat foodborne pathogens and preserve commodities, with a spotlight on the application of nanoparticles in safeguarding tomatoes from decay.

Metabolic changes of the red marine alga Gracilariopsis tenuifrons elicited by high PAR in laboratory

Metabolic changes of the red marine alga Gracilariopsis tenuifrons elicited by high PAR in laboratory

Recent advances in in vitro and in vivo studies on Kappaphycus alvarezii and its derivatives.

The marine red algae Kappaphycus alvarezii (KA), commonly known as cottonii, is a valuable resource with diverse applications. Research has primarily focused on its primary metabolites such as amino acids, proteins, plant hormones etc. Additionally, KA also produces secondary metabolites under stress, some of which exhibit antioxidant and antibacterial properties. This review provides a comprehensive overview of recent in vitro and in vivo research on KA, delving into their therapeutic effects and potential pharmaceutical applications. The study followed a through literature survey in three databases. From the obtained literature, the studies fitting the criteria were reviewed. The study explores the underlying mechanisms behind the algae's diverse characteristics. The results show that KA is a valuable resource for potential therapeutic applications, but a deeper exploration of its various metabolites and rigorous research are necessary for a thorough understanding of its capabilities.

Accumulation and Quantitative Assessment of Terrigenous Organic Matter in Upper Oligocene to Lower Miocene Marine Source Rocks of the Qiongdongnan Basin.

The intense collision between marine and terrestrial agents results in the dual-source (marine and terrigenous) characteristics of marine source rocks. Our research quantitatively assessed terrestrial organic matter and revealed the crucial role of terrestrial organic materials in the organic matter enrichment of lower Miocene to upper Oligocene marine source rocks in the Qiongdognnan Basin. The quantitative assessment was achieved using partial least-squares analysis with eight biomarker parameters associated with n-alkanes, isoprenoids, bicadinanes, taraxerane, tricyclic terpanes, and gammacerane. Differential unloading of terrestrial organic materials based on sedimentary facies of the delta-marginal sea system were observed through oleanane and bicadinane contents. It should be noted that the diagnostic ratio of oleanane was excluded from the quantitative analysis due to the dual influence from differential unloading and contact with seawater of the terrestrial organic materials. Calculation results show that the terrestrial organic matter was highest in the delta front at 70%, followed by prodelta at 59% and inner shallow marine at 57%. From the late Oligocene to the early Miocene, the proportion of terrestrial organic matter in marine source rocks continuously increased, with the highest average value observed in the second member of the Sanya Formation at 69% and the lowest occurring in the third member of the Lingshui Formation at 46%. Increasing terrestrial organic material inputs and preservation driven by the East Asian summer monsoon provided first-order control of the accumulation of organic carbon in the Qiongdongnan Basin during late Oligocene to early Miocene, rather than the bioproductivity of marine algae. The redox conditions of the water column determine the enrichment extent of organic matter.

Impacts of microplastic and seawater acidification on unicellular red algae: Growth response, photosynthesis, antioxidant enzymes, and extracellular polymer substances

Microplastics (MPs) pollution and seawater acidification have increasingly become huge threats to the ocean ecosystem. Their impacts on microalgae are of great importance, since microalgae are the main primary producers and play a critical role in marine ecosystems. However, the impact of microplastics and acidification on unicellular red algae, which have a unique phycobiliprotein antenna system, remains unclear. Therefore, the impacts of polystyrene-MPs alone and the combined effects of MPs and seawater acidification on the typical unicellular marine red algae Porphyridium purpureum were investigated in the current study. The result showed that, under normal seawater condition, microalgae densities were increased by 17.75-41.67 % compared to the control when microalgae were exposed to small-sized MPs (0.1 μm) at concentrations of 5-100 mg L-1. In addition, the photosystem II and antioxidant enzyme system were not subjected to negative effects. The large-sized MPs (1 μm) boosted microalgae growth at a low concentration of MPs (5 mg L-1). However, it was observed that microalgae growth was significantly inhibited when MPs concentration increased up to 50 and 100 mg L-1, accompanied by the remarkably reduced Fv/Fm value and the elevated levels of SOD, CAT enzymes, phycoerythrin (PE), and extracellular polysaccharide (EPS). Compared to the normal seawater condition, microalgae densities were enhanced by 52.11-332.56 % under seawater acidification, depending on MPs sizes and concentrations, due to the formed CO2-enrichment condition and appropriate pH range. PE content in microalgal cells was significantly enhanced, but SOD and CAT activities as well as EPS content markedly decreased under acidification conditions. Overall, the impacts of seawater acidification were more pronounced than MPs impacts on microalgae growth and physiological responses. These findings will contribute to a substantial understanding of the effects of MPs on marine unicellular red microalgae, especially in future seawater acidification scenarios.

First report of antioxidant potential of peptide fraction derived from Colaconema formosanum (Rhodophyta) protein hydrolysates

Foods that contain natural antioxidants can improve people's health and performance and make them more resistant to environmental stressors like diseases, lousy living conditions, and heat stress. Marine algae are well known for their function as an antioxidant. Colaconema formosanum is a new rhodophyte discovered in Taiwan and its bioactive activities are rarely studied. This work aims to prepare the protein hydrolysate fraction with antioxidant properties in C. formosanum using single enzyme or complex enzyme hydrolysis. Afterward, a 3 kDa molecular weight cut-off (MWCO) was used for centrifugation, and then fractionation was carried out using Strong Cation Exchange (SCX) Chromatography. The quantification of antioxidant activity was performed using the DPPH test. The results showed that the thermolysin hydrolysate (IC50 1.48 ± 0.92 mg/mL) and the combination of trypsin-thermolysin hydrolysates (IC50 1.37 ± 0.84 mg/mL) had the highest antioxidant activity. The fractionation procedure with strong cation exchange (SCX) yielded fraction C from thermolysin hydrolysates, which exhibited the most significant antioxidant activity with an IC50 value of 0.47 ± 0.02 mg/mL. The fraction 4 derived from trypsin-thermolysin hydrolysates exhibited the most potent antioxidant activity (IC50: 0.34 ± 0.002 mg/mL). No previous reports have been made about the antioxidant properties of the hydrolysate fractions derived from C. formosanum proteins. Consequently, these findings could serve as a foundation for exploring peptides that have potential therapeutic sources for reducing oxidative stress.

Effects of dietary seaweed on obesity-related metabolic status: a systematic review and meta-analysis of randomized controlled trials.

Seaweed is a promising source of anti-obesity agents, including polysaccharides, proteins, polyphenols, carotenoids, and n-3 long-chain polyunsaturated fatty acids. The anti-obesity effects of such compounds may be due to several mechanisms, including inhibition of lipid absorption and metabolism, effect on satiety, and inhibition of adipocyte differentiation. The aim of this study was to assess the evidence from human randomized controlled trials for the effects of seaweed on body-weight status as well as lipid and nonlipid parameters in adults with overweight and obesity. Four databases-Medline, Scopus, Web of Science, and Cochrane Library-were searched from December 2022 to June 2023 using the following key words: Seaweed OR fucoxanthin OR alginates OR fucoidans OR phlorotannin's OR macroalgae OR marine algae AND obesity OR overweight OR BMI OR body mass index. Eleven interventional studies (10 parallel and 1 crossover) were extracted. Meta-analysis showed a significant effect, favoring the intervention group for BMI (body mass index) (standardized mean difference [SMD]: -0.40; 95% CI: -0.65 to -0.16 kg/m2; P = 0.0013) and percentage of fat mass (SMD: -1.48; 95% CI: -2.66% to -0.30%, P = 0.0138). The results were seen when refined or extracted brown seaweed (BMI) or only refined brown seaweed (% fat mass) were administered to participants for at least 8 weeks. Moreover, a significant overall effect of seaweed supplementation on total cholesterol (SMD: -7.72; 95% CI: -12.49 to -2.95 mg/dL; P = 0.0015) and low-density-lipoprotein cholesterol (SMD: -7.33; 95% CI: -11.64 to -3.02 mg/dL; P < 0.001) was noted. Any significant effects of seaweed on glucose metabolism were not shown. Edible seaweed supplementation shows potential for managing obesity and disorders of the blood lipid profile when administered to participants for at least 8 weeks. PROSPERO registration no. CRD42022378484 (www.crd.york.ac.uk/PROSPERO).

Critical thermal maxima and oxygen uptake in Elysia viridis, a sea slug that steals chloroplasts to photosynthesize.

Photosynthetic animals produce oxygen, providing an ideal lens for studying how oxygen dynamics influence thermal sensitivity. The algivorous sea slug Elysia viridis can steal and retain chloroplasts from the marine alga Bryopsis sp. for months when starved, but chloroplast retention is mere weeks when they are fed another green alga, Chaetomorpha sp. To examine plasticity in thermal tolerance and changes in net oxygen exchange when fed and starving, slugs fed each alga were acclimated to 17°C (the current maximum temperature to which they are exposed in nature) and 22°C (the increase predicted for 2100) and measured at different points during starvation. We also examined increased illumination to evaluate a potential tradeoff between increased oxygen production but faster chloroplast degradation. Following acclimation, we subjected slugs to acute thermal stress to determine their thermal tolerance. We also measured net oxygen exchange before and after acute thermal stress. Thermal tolerance improved in slugs acclimated to 22°C, indicating they can acclimate to temperatures higher than they naturally experience. All slugs exhibited net oxygen uptake, and rates were highest in recently fed slugs before exposure to acute thermal stress. Oxygen uptake was suppressed following acute thermal stress. Under brighter light, slugs exhibited improved thermal tolerance, possibly because photosynthetic oxygen production alleviated oxygen limitation. Accordingly, this advantage disappeared later in starvation when photosynthesis ceased. Thus, E. viridis can cope with heatwaves by suppressing metabolism and plastically adjusting heat tolerance; however, starvation influences a slug's thermal tolerance and oxygen uptake such that continuous access to algal food for its potential nutritive and oxygenic benefits is critical when facing thermal stress.

Study of Antioxidant, Antimicrobial and Cytotoxic Activities of Ag-Co Bimetallic Nanoparticles Biosynthesized from Red Alga (Amphiroa sp.)

Study of Antioxidant, Antimicrobial and Cytotoxic Activities of Ag-Co Bimetallic Nanoparticles Biosynthesized from Red Alga (Amphiroa sp.)

Red Algae Compounds: Potential Neuroprotective Agents for Neurodegenerative Disorders

This review explores the potential of compounds derived from red algae (Rhodophyta) as promising neuroprotective agents for treating neurodegenerative disorders. Red algae, abundant in marine environments, contain bioactive compounds with diverse chemical structures and functionalities. Sulfated polysaccharides, primarily agar and carrageenans, stand out as the predominant and widely utilized compounds derived from red algae. Additionally, red algae harbor a spectrum of potential molecules such as essential fatty acids, phycobiliproteins, vitamins, minerals, and secondary metabolites. Extensive research has highlighted the diverse biological activities exhibited by these compounds, including anti-oxidative and anti-inflammatory properties. These compounds show various biological activities that have garnered interest in their therapeutic potential for neurodegenerative diseases. This comprehensive review aims to summarize the current knowledge regarding the extraction, characterization, mechanisms of action, and therapeutic applications of Rhodophyta-derived compounds in the context of neuroprotection and treatment of neurodegenerative disorders.

Exploring the Bioactive Potential of Marine Algae: Insights from Phytochemical Analysis, GC-MS Profiling, and Antioxidant Evaluation

Exploring the Bioactive Potential of Marine Algae: Insights from Phytochemical Analysis, GC-MS Profiling, and Antioxidant Evaluation

Marine algae oils from Phaeodactylum tricornutum and Laminaria japonica alleviate obesity, insulin resistance, and gut microbiota dysbiosis in high-fat diet-fed mice

The present study was aimed to investigate the effects of Phaeodactylum tricornutum oil (PO) and Laminaria japonica oil (LO) against obesity and other metabolic disorders in a high-fat diet (HFD) induced obese mouse model. The results revealed that PO or LO supplementation significantly reduced HFD-induced body weight gain, hyperlipemia, and fat accumulation in mice. PO or LO supplementation also inhibited SREBP-1-mediated de novo lipogenesis and PPARγ-mediated adipogenesis, as well as enhanced PPARα-mediated fatty acid β-oxidation in the WAT and liver of HFD-fed mice. Moreover, PO or LO supplementation attenuated low-grade chronic inflammation, hyperglycemia and insulin resistance in obese mice. Furthermore, Dietary PO or LO also modulated HFD-induced gut microbiota dysbiosis and increased the SCFAs production. More importantly, our results also manifested that the ameliorative effect of PO and LO against HFD-induced obesity, IR and gut microbiota dysbiosis was comparable, but was superior than that of krill oil and fish oil.

Exploring potential polysaccharide utilization loci involved in the degradation of typical marine seaweed polysaccharides by Bacteroides thetaiotaomicron.

Research on the mechanism of marine polysaccharide utilization by Bacteroides thetaiotaomicron has drawn substantial attention in recent years. Derived from marine algae, the marine algae polysaccharides could serve as prebiotics to facilitate intestinal microecological balance and alleviate colonic diseases. Bacteroides thetaiotaomicron, considered the most efficient degrader of polysaccharides, relates to its capacity to degrade an extensive spectrum of complex polysaccharides. Polysaccharide utilization loci (PULs), a specialized organization of a collection of genes-encoded enzymes engaged in the breakdown and utilization of polysaccharides, make it possible for Bacteroides thetaiotaomicron to metabolize various polysaccharides. However, there is still a paucity of comprehensive studies on the procedure of polysaccharide degradation by Bacteroides thetaiotaomicron. In the current study, the degradation of four kinds of marine algae polysaccharides, including sodium alginate, fucoidan, laminarin, and Pyropia haitanensis polysaccharides, and the underlying mechanism by Bacteroides thetaiotaomicron G4 were investigated. Pure culture of Bacteroides thetaiotaomicron G4 in a substrate supplemented with these polysaccharides were performed. The change of OD600, total carbohydrate contents, and molecular weight during this fermentation were determined. Genomic sequencing and bioinformatic analysis were further performed to elucidate the mechanisms involved. Specifically, Gene Ontology (GO) annotation, Clusters of Orthologous Groups (COG) annotation, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were utilized to identify potential target genes and pathways. Underlying target genes and pathways were recognized by employing bioinformatic analysis. Several PULs were found that are anticipated to participate in the breakdown of these four polysaccharides. These findings may help to understand the interactions between these marine seaweed polysaccharides and gut microorganisms. The elucidation of polysaccharide degradation mechanisms by Bacteroides thetaiotaomicron provides valuable insights into the utilization of marine polysaccharides as prebiotics and their potential impact on gut health. Further studies are warranted to explore the specific roles of individual PULs and their contributions to polysaccharide metabolism in the gut microbiota.

Phenology and the response of photosynthesis to irradiance and temperature gradient in the herbal drug red alga, Chondria armata (Rhodomelaceae, Ceramiales) from Kagoshima, Japan

AbstractSeasonal changes in the size of the herbal drug red alga Chondria armata (Rhodomelaceae, Ceramiales) were investigated in Kagoshima, Japan, which is near the northern distributional limit in the western Pacific. Additionally, its photosynthetic response to irradiance and temperature was examined using dissolved oxygen sensors and a pulse amplitude modulation (PAM)-chlorophyll fluorometer. This alga was observed in tidepools throughout the year; its height and weight were greatest in December and the lowest in April and May. The net photosynthesis of the photosynthesis–irradiance (P–E) curve determined at 28°C quickly saturated at 113 µmol photons m-2 s-1, with minimal inhibition even at 1000 µmol photons m-2 s-1. The gross photosynthesis of the photosynthesis–temperature (P–T) curved over 8 to 40°C, measured at 500 µmol photons m-2 s-1, peaked at 30.1°C and decreased rapidly below 20°C and above 36°C, respectively. Similarly, the effective quantum yield (ΔF/Fm') after a 3-day culture during 4–40°C at 50 µmol photons m-2 s-1 remained stable between 16°C and 32°C but decreased outside of this range. The combined effect of irradiance (200 [low] and 1000 [high] µmol photons m-2 s-1) and temperature (28, 22, and 16°C) revealed that ΔF/Fm' declined during exposure to high irradiance at all temperature treatments. However, it mostly recovered after a subsequent 12-hour period of dim-light acclimation at 28°C and 22°C. In contrast, those at 16°C could not recover, indicating the occurrence of low-temperature light stress. This alga appears to be well-adapted to the irradiance and temperature environment at the study site. However, the winter temperature appears to approach its threshold level, and the occurrence of strong light during the winter might adversely affect the abundance of this alga near its northern distributional limit.

Fermented Gracilaria lemaneiformis polysaccharides alleviate food allergy by regulating Treg cells and gut microbiota

Food allergy has a significant impact on the health and well-being of individuals, affecting both their physical and mental states. Research on natural bioactive compounds, such as polysaccharides extracted from seaweeds, holds great promise in the treatment of food allergies. In this study, fermented Gracilaria lemaneiformis polysaccharides (F-GLSP) were prepared using probiotic fermentation. Probiotic fermentation of Gracilaria lemaneiformis reduces the particle size of polysaccharides. To compare the anti-allergic activity of F-GLSP with unfermented Gracilaria lemaneiformis polysaccharides (UF-GLSP), an OVA-induced mouse food allergy model was established. F-GLSP exhibited a significant reduction in OVA-specific IgE and mMCP levels in allergic mice. Moreover, it significantly inhibited Th2 differentiation and IL-4 production and significantly promoted Treg differentiation and IL-10 production in allergic mice. In contrast, UF-GLSP only reduced OVA-specific IgE and mMCP in the serum of allergic mice. Furthermore, F-GLSP demonstrated a more pronounced regulation of intestinal flora abundance compared to UF-GLSP, significantly influencing the populations of Firmicutes, Bacteroidetes, Lactobacillus, and Clostridiales in the intestines of mice with food allergy. These findings suggest that F-GLSP may regulate food allergies in mice through multiple pathways. In summary, this study has promoted further development of functional foods with anti-allergic properties based on red algae polysaccharides.

Study of Ultrasound Effect on Macrophyte Fouling of Artificial Substrates as a Way to Control Bio-Damage in NPP Water Supply Systems

The results of the study of ultrasound influence on the formation of macrophytoperiphyton on steel and concrete substrates in field conditions (sea water area) are presented. On the example of macroalgae in the conditions of full-scale experiment the ability of ultrasound to complicate, but not completely inhibit the development of plant colonizers is shown. The greatest sensitivity to the impact of ultrasound is shown by red algae. It is recommended to expand the experiments with the use of ultrasound installation of higher power in order to assess the effect of ultrasound on different groups of algae during the operation of NPP.