Health Benefits and Pharmacological Effects of Porphyra Species

Effects of pan- and air fryer-roasting on volatile and umami compounds and antioxidant activity of dried laver (Porphyra dentata)

This study aimed to investigate the impact of pan- and air fryer-roasting on the volatiles, umami compounds, antioxidant activity, and sensory attributes of dried laver (Porphyra dentata). To assess the influence of time and temperature, pan-roasting was conducted at temperatures of 250, 300, and 350 °C for 5, 10, and 15 s, respectively. For air fryer-roasting, dried laver was roasted at 160, 170, and 180 °C for 2, 4, and 6 min, respectively. In both roasting methods, the levels of 1,5-octadien-3-ol and 1-octen-3-ol significantly decreased (p < 0.05) with increased time and temperature. The Equivalent Umami Concentration ranged from 94.89 to 518.09 g MSG/100 g. The antioxidant activity significantly increased (p < 0.05) with higher roasting temperatures and longer durations, whereas pigment content significantly decreased. The browning index increased by 64% and 43% for the pan and air frying methods, respectively. The samples pan-roasted at 300 °C for 15 s obtained the highest sensory scores.

The application of marine polysaccharides to antitumor nanocarriers

Nanotechnology has revolutionized the diagnosis, monitoring and treatment of biomedical diseases, in which nanocarriers have greatly improved the targeting and bioavailability of antitumor drugs. The marine natural polysaccharides fucoidan, chitosan, alginate, carrageenan and porphyran have broad-spectrum bioactivities and unique physicochemical properties such as excellent non-toxicity, biocompatibility, biodegradability and reproducibility, which have placed them as a principal focus in the nanocarrier field. Nanocarriers based on different types of marine polysaccharides are distinctive in addressing antitumor therapeutic challenges such as targeting, environmental responsiveness, drug resistance, tissue toxicity, enhancing diagnostic imaging, overcoming the first-pass effect and innovative 3D binding. Additionally, they all share the possibility of relatively easy chemical modification, while their separation into well-defined derivatives provide innovative structure-activity relationship possibilities. Liposomes, nanoparticles and polymer-micelles constructed from them can efficiently deliver drugs such as paclitaxel, gemcitabine, siRNA and others, which are widely used in radiotherapy, chemotherapy, immunotherapy, nucleic acid therapy and photothermal therapy, yet there are still infinite possibilities for innovation and exploration. This article reviews the recent advances and challenges of marine polysaccharide-based delivery systems as oncology drug nanocarriers.

Recent progress in Porphyra haitanensis polysaccharides: Extraction, purification, structural insights, and their impact on gastrointestinal health and oxidative stress management

Porphyra haitanensis, a red seaweed species, represents a bountiful and sustainable marine resource. P. haitanensis polysaccharide (PHP), has garnered considerable attention for its numerous health benefits. However, the comprehensive utilization of PHP on an industrial scale has been limited by the lack of comprehensive information. In this review, we endeavor to discuss and summarize recent advancements in PHP extraction, purification, and characterization. We emphasize the multifaceted mechanisms through which PHP promotes gastrointestinal health. Furthermore, we present a summary of compelling evidence supporting PHP's protective role against oxidative stress. This includes its demonstrated potent antioxidant properties, its ability to neutralize free radicals, and its capacity to enhance the activity of antioxidant enzymes. The information presented here also lays the theoretical groundwork for future research into the structural and functional aspects of PHP, as well as its potential applications in functional foods.

Polysaccharides from Porphyra haitanensis: A Review of Their Extraction, Modification, Structures, and Bioactivities

Porphyra haitanensis (P. haitanensis), an important food source for coastal residents in China, has a long history of medicinal and edible value. P. haitanensis polysaccharides are some of the main active ingredients in P. haitanensis. It is worth noting that P. haitanensis polysaccharides have a surprising and satisfactory biological activity, which explains the various benefits of P. haitanensis to human health, such as anti-oxidation, immune regulation, anti-allergy, and anticancer properties. Hence, a systematic review aimed at comprehensively summarizing the recent research advances in P. haitanensis polysaccharides is necessary for promoting their better understanding. In this review, we systematically and comprehensively summarize the research progress on the extraction, purification, structural characterization, modification, and biological activity of P. haitanensis polysaccharides and address the shortcomings of the published research and suggest area of focus for future research, providing a new reference for the exploitation of polysaccharides from P. haitanensis in the fields of medicine and functional foods.

Environmental heterogeneity caused by large-scale cultivation of Pyropia haitanensis shapes multi-group biodiversity distribution in coastal areas

The response of marine biodiversity to mariculture has long been a research focus in marine ecology. However, the effects of seaweed cultivation on biological community assembly are poorly understood, especially in diverse communities with distinct ecological characteristics. In this study, we used environmental DNA metabarcoding to investigate the spatial distribution patterns of bacterial, protistan, and metazoan diversity, aiming to reveal the mechanisms of community assembly in the Pyropia haitanensis cultivation zone along the Fujian coast, China. We found that, compared with the biological communities in control zones, those in P. haitanensis cultivation zones exhibited stronger geographic distance-decay patterns and displayed more complex and stable network structures. Deterministic processes (environmental selection) played a more important role in the assembly of bacterial, protistan, and metazoan communities in P. haitanensis cultivation zones, especially metazoan communities. Variance partitioning analysis showed that environmental variables made greater contributions to the diversity of the three types of communities within the P. haitanensis cultivation zones than in the control zones. Partial least squares path modeling analysis identified nitrate‑nitrogen (NO3-N), pH, particulate organic carbon (POC), and dissolved organic carbon (DOC) as the key environmental variables affecting biodiversity. Overall, the environmental heterogeneity caused by the large-scale cultivation of P. haitanensis could be the crucial factor influencing the composition and structure of various biological communities. Our results highlight the importance of the responses of multi-group organisms to the cultivation of seaweed, and provide insights into the coexistence patterns of biodiversity at the spatial scale.

Optimizing the Extraction of Bioactive Compounds from Porphyra linearis (Rhodophyta): Evaluating Alkaline and Enzymatic Hydrolysis for Nutraceutical Applications

Porphyra sensu lato is one of the most economically significant and widely cultured and consumed algae in the world. Porphyra species present excellent nutraceutic properties due to their bioactive compounds (BACs). This research aimed to find the most efficient aqueous extraction method for BACs by examining alkaline and enzymatic hydrolysis. Alkaline hydrolysis with 2.5% sodium carbonate (SC) and at 80 °C proved optimal for extracting all BACs (phycobiliproteins, soluble proteins, polyphenols, and carbohydrates) except mycosporine-like amino acids (MAAs), which were best extracted with water only, and at 80 °C. Enzymatic hydrolysis, particularly with the 'Miura' enzymatic cocktail (cellulase, xylanase, glycoside hydrolase, and β-glucanase), showed superior results in extracting phycoerythrin (PE), phycocyanin (PC), soluble proteins, and carbohydrates, with increases of approximately 195%, 510%, 890%, and 65%, respectively, compared to the best alkaline hydrolysis extraction (2.5% SC and 80 °C). Phenolic content analysis showed no significant difference between the 'Miura' cocktail and 2.5% SC treatments. Antioxidant activity was higher in samples from alkaline hydrolysis, while extraction of MAAs showed no significant difference between water-only and 'Miura' treatments. The study concludes that enzymatic hydrolysis improves the efficiency of BACs extraction in P. linearis, highlighting its potential for the nutraceutical industry, and especially with respect to MAAs for topical and oral UV-photoprotectors.

Ultrasound-assisted fermentation of Porphyra yezoensis sauce at different growth stages using Lactiplantibacillus plantarum: Metabolic response and biological activity

This study first employed ultrasonic-assisted fermentation of seaweed foot material with Lactiplantibacillus plantarum to produce Porphyra yezoensis sauce. The aim was to examine L. plantarum's growth and metabolism of nutritional components at different growth stages under low- (133.99 W/L) and high-ultrasonic power densities (169.17 W/L). After 24-h fermentation, L. plantarum exhibited a 21.32 % increase in the sonicated P. yezoensis sauce at 133.99 W/L and the logarithmic growth phase compared to that at 169.17 W/L. In addition, compared to the non-sonicated sauce, total phenolic and flavonoid contents increased by around 58 % and 27 % in sonicated sauce at 133.99 W/L, reaching 92.38 mg GEA/g DW and 111.08 mg RE/g DW, respectively. Principal Component Analysis (PCA) of the evaluation criteria for different fermentation stages under 133.99 W/L power ultrasonication revealed that the P. yezoensis sauce generated more phenolic compounds and exhibited stronger antioxidant capabilities in the sonicated sample at the logarithmic phase of L. plantarum. Compared to the traditional treated P. yezoensis sauce, the content of free amino acids was significantly increased in sonicated sauce, especially for logarithmic phase. Finally, GC-IMS analysis demonstrated that the ultrasonication at logarithmic phase released more volatile compounds compared to the non-sonicated sauce. This led to a reduction in the fishy odour of the Porphyra yezoensis sauce and an improved release of favourable flavour compounds.

In vitro-simulated intestinal flora fermentation of Porphyra haitanensis polysaccharides obtained by different assisted extractions and their fermented products against HT-29 human colon cancer cells

Herein, we studied the in vitro-simulated intestinal flora fermentation of Porphyra haitanensis polysaccharides (PHPs) with microwave, ultrasonic, ultra-high pressure-assisted extraction and the protective effect of their fermented products against HT-29 human colon cancer cells. The results showed that PHPs were largely degraded at the 18 h stage of ascending colon fermentation, further greatly increasing the contents of reducing sugars and short-chain fatty acids (p < 0.05). Particularly, the PHPs subjected to ultra-high pressure-assisted extraction (UHP-PHP) showed the highest reducing sugar content of 1.68 ± 0.01 mg mL-1 and butyric acid content of 410.77 ± 7.99 mmol mL-1. Moreover, UHP-PHP showed a better effect in increasing the ratio of Bacteroidetes/Firmicutes and decreasing the abundance of Proteobacteria and Escherichia coli. PHPs could protect against HT-29 cells by increasing the ROS levels in a concentration-dependent manner, especially UHP-PHP fermented in a descending colon for 24 h. This was related to the up-regulated apoptosis-related genes (Bax and Bak), down-regulated protein expression of Bcl-2 and activation of the p-AKT protein, thereby promoting the apoptosis of HT-29 cells. Our results can facilitate the modification of PHPs and their practical application in the development of intestinal health improving products.

Structure and Antidiabetic Activity of a Glycoprotein from Porphyra haitanensis

A novel antidiabetic glycoprotein (PG) was isolated and purified from Porphyra haitanensis, and its structure and inhibiting activity on α-amylase and α-glucosidase were analyzed. The purity of the PG was 95.29 ± 0.21%, and its molecular weight was 163.024 ± 5.55 kDa. The PG had a tetramer structure with α- and β-subunits, and it contained 54.12 ± 0.86% protein (with highly hydrophobic amino acids) and 41.19% ± 0.64% carbohydrate (composed of galactose). The PG was linked via an O-glycosidic bond, exhibiting an α-helical structure and high stability. In addition, the PG inhibited the activities of α-amylase and α-glucosidase, by changing the enzyme's structure toward the PG's structure in a noncompetitive inhibition mode. Molecular docking results showed that the PG inhibited α-amylase activity by hydrophobic interaction, whereas it inhibited α-glucosidase activity by hydrogen bonds and hydrophobic interaction. Overall, the PG was linked to polysaccharides via O-glycosidic bonds, showing an α-helical configuration and a hydrophobic effect, which altered the configuration of α-amylase and α-glucosidase and exerted hypoglycemic activity. This study provides insights into analyzing the structure and antidiabetic activity of glycoproteins.

Research Advances in Plant Protein-Based Products: Protein Sources, Processing Technology, and Food Applications

Plant proteins are high-quality dietary components of food products. With the growing interest in sustainable and healthy food alternatives, plant proteins have gained significant attention as viable substitutes for animal-based proteins. Understanding the diversity of protein sources derived from plants, novel processing technology, and multiple applications is crucial for developing nutritious and sustainable plant protein-based products. This Review summarizes the natural sources of traditional and emerging plant proteins. The classifications, processing technologies, and applications of plant protein-based products in the food industry are explicitly elucidated. Moreover, the advantages and disadvantages of plant protein-based food products are revealed. Strategies such as protein fortification and complementation to overcome these shortcomings are critically discussed. We also demonstrate several issues that need to be addressed in future development.

Anti-inflammatory effect of polydeoxyribonucleotides (PDRN) extracted from red alga (Porphyra sp.) (Ps-PDRN) in RAW 264.7 macrophages stimulated with Escherichia coli lipopolysaccharides: A comparative study with commercial PDRN

Polydeoxyribonucleotide (PDRN) is a DNA-derived drug extracted from the sperm cells of Oncorhynchus mykiss or O. keta. PDRN exhibits wound healing and anti-inflammatory activities by activating adenosine A2A receptor and salvage pathways. However, commercial PDRN products (e.g., Placentex, Rejuvenex, and HiDr) have limitations as they are exclusively extracted O. mykiss and O. keta, which are expensive and can only be used as extraction sources during a specific period when their sperm cells are activated. Therefore, this study aimed to extract PDRN from Porphyra sp. (Ps-PDRN) and investigate whether it has anti-inflammatory activity through a comparative study with commercial product. The results indicated that Ps-PDRN had an anti-inflammatory effect on Escherichia coli lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophages. It inhibited nitric oxide production and inducible nitric oxygen synthase protein expression by suppressing phosphorylation of p38 and ERK, without cytotoxicity. Furthermore, Ps-PDRN promoted cell proliferation and collagen production in human dermal fibroblast. In conclusion, our study confirms that Ps-PDRN exhibits both anti-inflammatory and cell proliferative effects. These results indicated that Ps-PDRN has the potential as a bioactive drug for tissue engineering.

Unraveling the Diverse Profile of N-Acyl Homoserine Lactone Signals and Their Role in the Regulation of Biofilm Formation in Porphyra haitanensis-Associated Pseudoalteromonas galatheae

N-acyl homoserine lactones (AHLs) are small, diffusible chemical signal molecules that serve as social interaction tools for bacteria, enabling them to synchronize their collective actions in a density-dependent manner through quorum sensing (QS). The QS activity from epiphytic bacteria of the red macroalgae Porphyra haitanensis, along with its involvement in biofilm formation and regulation, remains unexplored in prior scientific inquiries. Therefore, this study explores the AHL signal molecules produced by epiphytic bacteria. The bacterium isolated from the surface of P. haitanensis was identified as Pseudoalteromonas galatheae by 16s rRNA gene sequencing and screened for AHLs using two AHL reporter strains, Agrobacterium tumefaciens A136 and Chromobacterium violaceum CV026. The crystal violet assay was used for the biofilm-forming phenotype. The inferences revealed that P. galatheae produces four different types of AHL molecules, i.e., C4-HSL, C8-HSL, C18-HSL, and 3-oxo-C16-HSL, and it was observed that its biofilm formation phenotype is regulated by QS molecules. This is the first study providing insights into the QS activity, diverse AHL profile, and regulatory mechanisms that govern the biofilm formation phenotype of P. galatheae. These findings offer valuable insights for future investigations exploring the role of AHL producing epiphytes and biofilms in the life cycle of P. haitanensis.

Exploring and strengthening the potential of R-phycocyanin from Nori flakes as a food colourant

This study aimed to purify, characterise and stabilise the natural food colourant, R-phycocyanin (R-PC), from the red algae Porphyra spp. (Nori). We purified R-PC from dried Nori flakes with a high purity ratio (A₆₁₈/A₂₈₀ ≥ 3.4) in native form (α-helix content 53%). SAXS measurements revealed that R-PC is trimeric ((αβ)₃) in solution. The thermal denaturation of α-helix revealed one transition (T_m at 52 °C), while the pH stability study showed R-PC is stable in the pH range 4-8. The thermal treatment of R-PC at 60 °C has detrimental and irreversible effects on R-PC colour and antioxidant capacity (22 % of residual capacity). However, immobilisation of R-PC within calcium alginate beads completely preserves R-PC colour and mainly retains its antioxidant ability (78 % of residual capacity). Results give new insights into the stability of R-PC and preservation of its purple colour and bioactivity by encapsulation in calcium alginate beads.

Anti-Hypercholesterolemia Effects of Edible Seaweed Extracts and Metabolomic Changes in Hep-G2 and Caco-2 Cell Lines

Hypercholesterolemia is a major risk for the development of cardiovascular diseases (CVDs), the main cause of mortality worldwide, and it is characterized by high levels of circulating cholesterol. The drugs currently available for hypercholesterolemia control have several side effects, so it is necessary to develop new effective and safer therapies. Seaweeds serve as sources of several bioactive compounds with claimed beneficial effects. Eisenia bicyclis (Aramé) and Porphyra tenera (Nori) are edible seaweeds that were previously recognized as rich in bioactive compounds. In the present study, we aim to evaluate the anti-hypercholesterolemia effect of these two seaweed extracts and their health potential. Both extracts, but more efficiently Aramé extract, have liver 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) inhibitory activity as well as the capability to reduce approximately 30% of cholesterol permeation through human Caco-2 cells by simulating the intestinal lining, which is a target for hypercholesterolemia treatments. An untargeted metabolomic assay on human intestinal Caco-2 and liver Hep-G2 cell lines exposed to Aramé and Nori extracts revealed changes in the cells' metabolism, indicating the extracts' health beneficial effects. The metabolic pathways affected by exposure to both extracts were associated with lipid metabolism, such as phospholipids, and fatty acid metabolism, amino acid pathways, cofactors, vitamins, and cellular respiration metabolism. The effects were more profound in Aramé-treated cells, but they were also observed in Nori-exposed cells. The metabolite modifications were associated with the protection against CVDs and other diseases and to the improvement of the cells' oxidative stress tolerance. The results obtained for the anti-hypercholesterolemia properties, in addition to the revelation of the positive impact on cell metabolism, offer an important contribution for further evaluation of these seaweed extracts as functional foods or for CVD prevention.

A propitious role of marine sourced polysaccharides: Drug delivery and biomedical applications

Numerous compounds, with extensive applications in biomedical and biotechnological fields, are present in the oceans, which serve as a prime renewable source of natural substances, further promoting the development of novel medical systems and devices. Polysaccharides are present in the marine ecosystem in abundance, promoting minimal extraction costs, in addition to their solubility in extraction media, and an aqueous solvent, along with their interactions with biological compounds. Certain algae-derived polysaccharides include fucoidan, alginate, and carrageenan, while animal-derived polysaccharides comprise hyaluronan, chitosan and many others. Furthermore, these compounds can be modified to facilitate their processing into multiple shapes and sizes, as well as exhibit response dependence to external conditions like temperature and pH. All these properties have promoted the use of these biomaterials as raw materials for the development of drug delivery carrier systems (hydrogels, particles, capsules). The present review enlightens marine polysaccharides providing its sources, structures, biological properties, and its biomedical applications. In addition to this, their role as nanomaterials is also portrayed by the authors, along with the methods employed to develop them and associated biological and physicochemical properties designed to develop suitable drug delivery systems.

A novel antioxidant protein of non-phycobiliprotein family derived from marine red alga Porphyra haitanensis

BACKGROUND

Oxidation has been reported as the one of the deterioration reactions of proteins in aquatic products. Searching for new bioactive substances from marine algae has been one of the main areas in food science and additives.

RESULTS

In this study, a novel protein from the red alga Porphyra haitanensis was determined after ammonium sulfate precipitation and gel filtration chromatography. It closely corresponded to the antioxidant activity and was identified as an uncharacterized protein with a molecular mass of 43 kDa, designated Ph43. Bioinformatic analysis revealed that Ph43 is a novel protein of non-phycobiliprotein family with putative chordin domains and rich in α-helical conformation. Recombinant protein (rPh43) was expressed in Escherichia coli as a Hig-tagged protein using a pET-22b vector system and purified by affinity high-performance liquid chromatography. Spectroscopy analysis revealed that there were no structural differences between rPh43 and natural recovered Ph43. Moreover, rPh43 showed equal/higher antioxidant activity compared with Ph43. rPh43 has the potential for application as a natural antioxidant for food stabilization.

CONCLUSION

Our results identified a novel antioxidant protein with molecular mass of 43 kDa derived from Porphyra haitanensis that belongs to the non-phycobiliprotein family. © 2023 Society of Chemical Industry.

Screening of a Novel Lactiplantibacillus plantarum MMB-05 and Lacticaseibacillus casei Fermented Sandwich Seaweed Scraps: Chemical Composition, In Vitro Antioxidant, and Volatile Compounds Analysis by GC-IMS

Lactic acid fermentation is a promising method for developing sandwich seaweed scraps. The objectives of this study were to investigate the effect of fermentation with Lactiplantibacillus plantarum MMB-05, Lactiplantibacillus casei FJAT-7928, mixed bacteria (1:1, v/v) and control on the physicochemical indexes, in vitro antioxidant activity, and volatile compounds of Porphyra yezoensis sauce. Sensory evaluation was also performed. The results indicated that all lactic acid bacteria strains grew well in P. yezoensis sauce after 72 h of fermentation, with the viable cell counts of L. plantarum MMB-05 exceeding 10.0 log CFU/mL, the total phenolic content increasing by 16.54%, and the lactic acid content increasing from 0 to 44.38 ± 0.11 mg/mL. Moreover, the metabolism of these strains significantly increased the content of umami, sweet and sour free amino acids in P. yezoensis sauce. The total antioxidant capacity of L. plantarum MMB-05, L. casei FJAT-7928, mix and control groups increased by 594.59%, 386.49%, 410.27%, and 287.62%, respectively. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis suggested that aldehydes and ketones accounted for the largest proportion, and the relative contents of acids and alcohols in P. yezoensis sauce increased significantly after lactic acid bacteria fermentation. In addition, the analysis of dynamic principal component analysis (PCA) and fingerprinting showed that the volatile components of the four treatment methods could be significantly distinguished. Overall, the L. plantarum MMB-05 could be recommended as an appropriate starter for fermentation of sandwich seaweed scraps, which provides a fundamental knowledge for the utilization of sandwiched seaweed scraps.

Porphyra tenera Protects against PM2.5-Induced Cognitive Dysfunction with the Regulation of Gut Function

To evaluate the biological effects of Porphyra tenera (P. tenera), we tried to confirm the possibility that the intake of P. tenera could modulate cognitive and intestinal functions in PM_2.5-induced cognitive decline mice. P. tenera attenuated PM_2.5-induced learning and memory impairment through antioxidant and anti-inflammatory effects by regulating the mitochondrial function and TLR-initiated NF-κB signaling. In addition, P. tenera effectively alleviated Aβ production/tau phosphorylation by inhibiting the JNK phosphorylation. Also, the bioactive constituents of P. tenera determined the sulfated galactan, mycosporine-like amino acids (MAAs), and chlorophyll derivatives. Moreover, the bioactive compounds of P. tenera by gut fermentation protected against gut dysbiosis and intestinal tight junction damage with a decrease in inflammatory response and short-chain fatty acid production. Based on these results, our findings suggest that P. tenera with sulfated galactan and MAAs is a potential material for cognitive function improvement.

Inhibitory Effects of Polyphenols-Rich Components From Three Edible Seaweeds on Inflammation and Colon Cancer in vitro

Polyphenols from edible seaweeds display various health benefits which have not been adequately studied. This study aimed to characterize the composition of extractable polyphenol-rich components (EPCs) and non-extractable polyphenol-rich components (NEPCs) from three edible seaweeds (i.e., Laminaria japonica, Ulva lactuca, and Porphyra tenera) and evaluate their anti-inflammatory capacities in activated macrophages and anticancer properties in colon cancer cells. Both EPCs and NEPCs from three edible seaweeds against lipopolysaccharides (LPS) stimulated nitric oxide in activated macrophages. Immunoblotting and qRT-PCR indicated that EPCs and NEPCs regulated the expression levels of proinflammatory enzymes, proinflammatory cytokines, and antioxidant enzymes in macrophages. Furthermore, EPCs and NEPCs lowered the viability of colon cancer cells, while normal colon cells were not affected. Additionally, EPCs and NEPCs induced cellular apoptosis and led to G0/G1 cell cycle arrest in HCT116 cells. Overall, these results provide a rationale for future animal and human studies designed to examine the anti-inflammatory and chemopreventive capacities of polyphenols-rich components from L. japonica, U. lactuca, and P. tenera.

Lab-scale photobioreactor systems: principles, applications, and scalability

Phototrophic microorganisms that convert carbon dioxide are being explored for their capacity to solve different environmental issues and produce bioactive compounds for human therapeutics and as food additives. Full-scale phototrophic cultivation of microalgae and cyanobacteria can be done in open ponds or closed photobioreactor systems, which have a broad range of volumes. This review focuses on laboratory-scale photobioreactors and their different designs. Illuminated microtiter plates and microfluidic devices offer an option for automated high-throughput studies with microalgae. Illuminated shake flasks are used for simple uncontrolled batch studies. The application of illuminated bubble column reactors strongly emphasizes homogenous gas distribution, while illuminated flat plate bioreactors offer high and uniform light input. Illuminated stirred-tank bioreactors facilitate the application of very well-defined reaction conditions. Closed tubular photobioreactors as well as open photobioreactors like small-scale raceway ponds and thin-layer cascades are applied as scale-down models of the respective large-scale bioreactors. A few other less common designs such as illuminated plastic bags or aquarium tanks are also used mainly because of their relatively low cost, but up-scaling of these designs is challenging with additional light-driven issues. Finally, this review covers recommendations on the criteria for photobioreactor selection and operation while up-scaling of phototrophic bioprocesses with microalgae or cyanobacteria.

Photosynthetic Protein-Based Edible Quality Formation in Various Porphyra dentata Harvests Determined by Label-Free Proteomics Analysis

The influence of harvest time on the photosynthetic protein quality of the red alga Porphyra dentata was determined using label-free proteomics. Of 2716 differentially abundant proteins that were identified in this study, 478 were upregulated and 374 were downregulated. The top enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) pathways were metabolic processes and biosynthetic pathways such as photosynthesis, light harvesting, and carbon fixation in photosynthetic organisms. Nine important photosynthetic proteins were screened. Correlations among their expression levels were contrasted and verified by western blotting. PSII D1 and 44-kDa protein levels increased with later harvest time and increased light exposure. Specific photoprotective protein expression accelerated P. dentata growth and development. Biological processes such as photosynthesis and carbon cycling increased carbohydrate metabolism and decreased the total protein content. The results of the present study provide a scientific basis for the optimization of the culture and harvest of P. dentata.

Phycobiliproteins: Structural aspects, functional characteristics, and biotechnological perspectives

Phycobiliproteins (PBPs) are fluorescent proteins of various colors, including fuchsia, purple-blue and cyan, that allow the capture of light energy in auxiliary photosynthetic complexes called phycobilisomes (PBS). PBPs have several highly preserved structural and physicochemical characteristics. In the PBS context, PBPs function is capture luminous energy in the 450-650 nm range and delivers it to photosystems allowing photosynthesis take place. Besides the energy harvesting function, PBPs also have shown to have multiple biological activities, including antioxidant, antibacterial and antitumours, making them an interesting focus for different biotechnological applications in areas like biomedicine, bioenergy and scientific research. Nowadays, the main sources of PBPs are cyanobacteria and micro and macro algae from the phylum Rhodophyta. Due to the diverse biological activities of PBPs, they have attracted the attention of different industries, such as food, biomedical and cosmetics. This is why a large number of patents related to the production, extraction, purification of PBPs and their application as cosmetics, biopharmaceuticals or diagnostic applications have been generated, looking less ecological impact in the natural prairies of macroalgae and less culture time or higher productivity in cyanobacteria to satisfy the markets and applications that require high amounts of these molecules. In this review, we summarize the main structural characteristics of PBPs, their biosynthesys and biotechnological applications. We also address current trends and future perspectives of the PBPs market.

Macroalgal Proteins: A Review

Population growth is the driving change in the search for new, alternative sources of protein. Macroalgae (otherwise known as seaweeds) do not compete with other food sources for space and resources as they can be sustainably cultivated without the need for arable land. Macroalgae are significantly rich in protein and amino acid content compared to other plant-derived proteins. Herein, physical and chemical protein extraction methods as well as novel techniques including enzyme hydrolysis, microwave-assisted extraction and ultrasound sonication are discussed as strategies for protein extraction with this resource. The generation of high-value, economically important ingredients such as bioactive peptides is explored as well as the application of macroalgal proteins in human foods and animal feed. These bioactive peptides that have been shown to inhibit enzymes such as renin, angiotensin-I-converting enzyme (ACE-1), cyclooxygenases (COX), α-amylase and α-glucosidase associated with hypertensive, diabetic, and inflammation-related activities are explored. This paper discusses the significant uses of seaweeds, which range from utilising their anthelmintic and anti-methane properties in feed additives, to food techno-functional ingredients in the formulation of human foods such as ice creams, to utilising their health beneficial ingredients to reduce high blood pressure and prevent inflammation. This information was collated following a review of 206 publications on the use of seaweeds as foods and feeds and processing methods to extract seaweed proteins.

Inhibition of porphyra polysaccharide on xanthine oxidase activity and its inhibition mechanism

Xanthine oxidase (XO) is a purine catabolic enzyme related to hyperuricemia and gout. Porphyra polysaccharide (PP) is a kind of sulfated polysaccharide with potent biological activity. Herein, the interaction mechanism between PP and XO was studied by enzyme kinetics and multi-spectroscopy methods for the first time. Inhibition kinetics assay showed that PP reversibly inhibited XO activity in a mixed competitive manner with an IC₅₀ of 10.53 ± 0.69 mg/ml. Fluorescence titration studies and thermodynamic parameter calculations revealed that PP could spontaneously bind to XO through hydrophobic interactions, with a class of binding site. Circular dichroism analysis demonstrated that PP induced secondary structure rearrangement and conformational change of XO. Molecular docking further revealed that PP inserted into the hydrophobic cavity of XO, occupying the catalytic center, leading to the inhibition of XO activity. This study may provide new insights into the inhibitory mechanism of PP as a promising XO inhibitor.

Probing the stability of the food colourant R-phycoerythrin from dried Nori flakes

This study aimed to characterise the stability of R-phycoerythrin (R-PE), a vivid natural colourant with emerging potential for application in the food industry. High-quality (A₅₆₀/A₂₈₀ ≥ 5), native (α-helix content 75%) R-PE was purified from commercial dried Nori (Porphyra sp.) flakes. Thermal unfolding revealed two transitions (at 56 and 72 °C), ascribed to different protein subunits. Contrary to elevated temperature, high-pressure (HP) treatment showed significant advantages: The R-PE unfolding was partly reversible and the colour bleaching was minimal. Binding of Cu²⁺ (6.3 × 10⁵ M^-1) and Zn²⁺ (1.7 × 10³ M^-1) influenced conformational changes in the protein tetrapyrrole chromophore without affecting R-PE structure and stability (colour). The results give new insights into the stability of R-PE suggesting its usefulness for the replacement of toxic synthetic dyes. Preservation of the red colour of R-PE could be considered in fortified food and beverages by HP processing. R-PE may act as a biosensor for Cu²⁺ in aquatic systems.

Marine Natural Products and Coronary Artery Disease

Coronary artery disease is the major cause of mortality worldwide, especially in low- and middle-income earners. To not only reduce angina symptoms and exercise-induced ischemia but also prevent cardiovascular events, pharmacological intervention strategies, including antiplatelet drugs, anticoagulant drugs, statins, and other lipid-lowering drugs, and renin-angiotensin-aldosterone system blockers, are conducted. However, the existing drugs for coronary artery disease are incomprehensive and have some adverse reactions. Thus, it is necessary to look for new drug research and development. Marine natural products have been considered a valuable source for drug discovery because of their chemical diversity and biological activities. The experiments and investigations indicated that several marine natural products, such as organic small molecules, polysaccharides, proteins, and bioactive peptides, and lipids were effective for treating coronary artery disease. Here, we particularly discussed the functions and mechanisms of active substances in coronary artery disease, including antiplatelet, anticoagulant, lipid-lowering, anti-inflammatory, and antioxidant activities.

Evaluation of the Relationship Between Bioactive Components in Seaweeds and Advanced Glycation End-Products Inhibitory Activities Using Principal Component Analysis

This study comprehensively presents the relationship between the bioactive substance of 70% (v/v) aqueous ethanol extract of 38 species of seaweeds (SWEs), and anti-glycation activities. The contents of bioactive substance of SWEs, such as total phenolic, total flavonoid and condensed tannins, were determined through a colorimetric analysis. Among the tested species, Ecklonia bicyclis, Ishige foliacea, and Cladophora urightiana var. minor had the highest amount of total phenolic (255.75 mg GAE/g DW), total condensed tannins (63.36 mg CE/g DW), and total flavonoid content (85.26 mg CE/g DW), respectively. Anti-glycation properties of SWEs were evaluated through advanced glycation end-products (AGEs) formation, AGEs-collagen cross-link formation, and AGEs-collagen cross-link breaking assay. Brown algae species exhibited a more prominent inhibitory activity on AGEs formation and AGEs-collagen cross-links, and the breaking of AGEs-collagen cross-links compared to that exhibited by aminoguanidine and ALT-711 (positive controls). Using principal component analysis, we confirmed that the AGEs formation inhibitory property and AGEs-collagen cross-links breaking activity were closely correlated with total phenolic and the condensed tannin contents contained in SWEs. Therefore, the bioactive substances such as phenolics and condensed tannins in seaweeds can be used as predictive indices in selecting compounds for the development of a therapeutic agent that prevents diabetic complications related to the AGEs. In addition, our results suggest that brown algae species, which contains more bioactive substances than green and red algae species, can be utilized as a promising natural resource for the prevention and alleviation of AGEs-related diabetic complications as AGE inhibitor and cross-links breaker.

Potential benefits of dietary seaweeds as protection against COVID-19

The coronavirus disease 2019 (COVID-19) pandemic in Japan is not as disastrous as it is in other Western countries, possibly because of certain lifestyle factors. One such factor might be the seaweed-rich diet commonly consumed in Japan. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which binds to angiotensin-converting enzyme 2 (ACE2) on the cell surface and downregulates ACE2, likely elevating the ratio of angiotensin-converting enzyme (ACE) to ACE2. The overreaction of the immune system, combined with the cytokine storm and ACE dominance, is purported to cause the condition of COVID-19 patients to deteriorate rapidly. Dietary seaweeds contain numerous components, including ACE inhibitory peptides, soluble dietary fibers (eg, fucoidan, porphyran), omega-3 fatty acids, fucoxanthin, fucosterol, vitamins D3 and B12, and phlorotannins. These components exert antioxidant, anti-inflammatory, and antiviral effects directly as well as indirectly through prebiotic effects. It is possible that ACE inhibitory components could minimize the ACE dominance caused by SARS-CoV-2 infection. Thus, dietary seaweeds might confer protection against COVID-19 through multiple mechanisms. Overconsumption of seaweeds should be avoided, however, as seaweeds contain high levels of iodine.

Fish and Shellfish-Derived Anti-Inflammatory Protein Products: Properties and Mechanisms

The interest in utilizing food-derived compounds therapeutically has been rising. With the growing prevalence of systematic chronic inflammation (SCI), efforts to find treatments that do not result in the side effects of current anti-inflammatory drugs are underway. Bioactive peptides (BAPs) are a particularly promising class of compounds for the treatment of SCI, and the abundance of high-quality seafood processing byproducts (SPB) makes it a favorable material to derive anti-inflammatory BAPs. Recent research into the structural properties of anti-inflammatory BAPs has found a few key tendencies including they tend to be short and of low molecular weight (LMW), have an overall positive charge, contain hydrophobic amino acids (AAs), and be rich in radical scavenging AAs. SPB-derived anti-inflammatory BAPs have been observed to work via inhibition of the NF-κB and MAPK pathways by disrupting the phosphorylation of IκBα and one or more kinases (ERK, JNK, and p38), respectively. Radical scavenging capacity has also been shown to play a significant role in the efficacy of SPB-derived anti-inflammatory BAPs. To determine if SPB-derived BAPs can serve as an effective treatment for SCI it will be important to understand their properties and mechanisms of action, and this review highlights such findings in recent research.

Antidepressant-like Effects of Degraded Porphyran Isolated from Porphyra haitanensis

INTRODUCTION

Degraded porphyran is a bioactive polysaccharide extracted from Porphyra haitanensis (P. haitanensis). According to the previous studies, it produced anti-inflammatory activity, but little is known about its effects on depression.

METHODS AND RESULTS

As inflammation is one of the critical factors involved in the development of depression, this study aims to elucidate the potential antidepressant-like effects of degraded porphyran. The results show that acute porphyran treatment decreased the immobility time in despair tests. In addition, subchronic porphyran administration reverses depressive-like behaviors in lipopolysaccharide (LPS)-treated mice. Meanwhile, porphyran inhibits NF-κB/NLRP3 signaling, proinflammatory cytokine release, and microglial activation in the hippocampus. Moreover, chronic porphyran treatment activates hippocampal brain derived neurotrophic factor (BDNF)/TrkB/ERK/CREB signaling pathway in chronic unpredictable mild stress (CUMS) in mice. As a result, neurogenesis and spinogenesis are maintained.

CONCLUSIONS

The findings of the present study indicate that degraded porphyran intake provides a potential strategy for depression treatment, which is mediated by the inhibition of neuroinflammation and the enhancement of neurogenesis and spinogenesis in the central nervous systems.

Production and characterization of a novel beverage from laver (Porphyra dentata) through fermentation with kombucha consortium

A novel functional kombucha using laver was developed by fermentation for 14 d at 25 °C through kombucha consortia of yeast and bacteria. The physicochemical characteristics, antioxidant effects, and nutraceutical properties of laver kombucha from infusion extracts (K-IE) and ultrasound-assisted extracts (K-UAE) were compared with those of black tea (K-BT) and green tea kombucha (K-GT). Tea kombucha showed higher amounts of total phenols and flavonoid content, and ferric reducing antioxidant power (FRAP) while K-UAE exhibited the highest content of organic acid, especially, α- ketoglutaric acid (224.97 mg/100 mL), and acetic acid (564.15 mg/100 mL) with highest titratable acidity, lower pH value and enhanced DPPH scavenging ability. Hence, laver has significant potential to be used as a substrate for developing new fermented beverages through ultrasound-assisted extraction.

Porphyran and oligo-porphyran originating from red algae Porphyra: Preparation, biological activities, and potential applications

Porphyra is one of the most economically important red algae in the world. The functional components extracted from Porphyra such as porphyrans, proteins, lipids, and minerals have strong physiological activities. Porphyran, a sulfated galactan, is composed of alternating 1,4-linked α-l-galactopyranose-6-sulfate (L6S) and 1,3-linked β-d-galactopyranose (G). Porphyran and oligo-porphyran have a series of pharmacological and biological functions, such as antioxidation, anticancer, antiaging, antiallergic, immunomodulatory, hypoglycaemic, and hypolipidemic effects. Thus, red algae Porphyra-derived porphyran and oligo-porphyran have various potential applications in food, medicine, and cosmetic fields. For better application, this review introduces and summarizes the structure and source of porphyran as well as the preparation methods, biological activities, and potential applications of porphyran and oligo-porphyran. Moreover, the future research directions and emphasis of porphyran and oligo-porphyran preparation as well as their functional activities and applications are highlighted and prospected.

Bioremediation of Pyropia-processing wastewater coupled with lipid production using Chlorella sp

Pyropia-processing wastewater (PPW) contains diverse organic nutrients and causes environmental pollution. To explore the nutrient removal efficiency and growth performance of Chlorella sp. on PPW, the cultures were conducted in different culture substrates. Results showed that, after 7 days of incubation, the removal rates of total nitrogen (TN), total phosphorus (TP) and phycobiliprotein (PP) all reached more than 90% by cultivating Chlorella sp. C2 and C. sorokiniana F-275 in PPW. The chemical oxygen demand (COD) removal efficiencies could be over 50%. Meanwhile, the increments of biomass in two tested Chlorella strains were 1.39 and 4.89 times higher than those of BG11 and BBM substrates and the increases in lipid productivity were 1.34 and 10.18- fold, respectively. The C18:3 fatty acid proportions were markedly reduced by 27.89% and 29.10%. These results suggest that Chlorella sp. could efficiently reduce various nutrients in PPW and simultaneously accumulate higher biomass with higher biodiesel characteristics.

A Critical Appraisal of the Evidence Supporting Consumer Motivations for Alternative Proteins

Alternative proteins are receiving increased global attention. This burgeoning interest in plants (especially plant-based meat alternatives), insects, algae, and cultured meat has been attributed to their reported health benefits, lower environmental impact and improved animal welfare compared to conventional animal-based meat. Food producers and the media are promoting acceptance of these products, claiming superior nutritional, environmental and ethical credentials and a desirable novel sensory experience. However, the evidence supporting these claims remains unclear. In this review, we summarise the main evidence underlying the nutritional, sensorial, economical, ethical, and environmental reasons reported for the rise in consumer demand for alternative proteins. We found many of these reasons to lack a strong evidence base. For instance, evidence is emerging for the nutritional benefits of plant-based meat alternatives, but present claims are largely based on established evidence for plant-based diets. Significant research gaps remain, especially longitudinal evidence on the sustained effects of replacing conventional animal-based proteins with alternative sources. For many alternative proteins, challenges exist in achieving desirable sensory properties akin to animal-based meat to promote their acceptance by consumers. Overall, fundamental shifts in the food system are required to create a culture in which healthful and sustainable food choices are the norm.

Inhibitory effects of Porphyra dentata extract on 3T3-L1 adipocyte differentiation

This study was aimed to investigate the inhibitory effects of Porphyra dentata (P. dentata) extract on the adipogenesis of 3T3-L1 cells and evaluate its anti-obesity effect. The proliferation of 3T3-L1 cells and differentiation of adipocytes under treatment of P. dentata extract was examined by measuring the cell viability using alamarBlue assay and lipid droplets by Oil Red O staining. Results showed that P. dentata extract has no cytotoxicity effect and lipid droplets formation decreased in a concentration-dependent manner in 3T3-L1 cells. It has been confirmed that transcription factors affecting lipid accumulation and anti-adipogenic effects during cell differentiation are linked to P. dentata extract. We observed that P. dentata shows lowering the mRNA expression of peroxisome proliferator-activated receptor γ2 (PPARγ2), CCAAT/enhancer binding protein α (C/EBPα) that adipogenesis-associated key transcription factors and inhibiting adipogenesis in the early stages of differentiation. Treating the cells with P. dentata did not only suppressed PPARγ2 and C/EBPα but also significantly decreased the mRNA expression of adiponectin, Leptin, fatty acid synthase, adipocyte protein 2, and Acetyl-coA carboxylase 1. Overall, the P. dentata extract demonstrated inhibitory property in adipogenesis, which has a potential effect in anti-obesity in 3T3-L1 cells.

Porphyran-capped silver nanoparticles as a promising antibacterial agent and electrode modifier for 5-fluorouracil electroanalysis

In the present work, the green synthesis of silver nanoparticles (AgNPs) using the sulfated polysaccharide porphyran (PFR) as capping agent and d-glucose as reducing agent is described. PFR was extracted from red seaweed and characterized by employing ¹³C NMR and determination of total sugar, protein, and sulfate contents. The obtained AgNPs-PFR were characterized by using UV-VIS spectroscopy, zeta potential determination, FESEM, and TEM, which demonstrated that PFR was effective at capping the AgNPs, yielding stable suspensions. The AgNPs-PFR presented good antimicrobial properties against Gram-positive and Gram-negative bacterial strains (Staphylococcus aureus and Escherichia coli, respectively). The AgNPs-PFR were also employed as the modifier of carbon paste electrodes, which were efficiently applied as electrochemical sensors for the determination of 5-fluorouracil (5-FU), an important anticancer drug, through square wave voltammetry (SWV). The AgNPs-PFR improved the electrochemical properties of the electrodes, and enhanced their electroanalytical performance. The developed sensing device presented detection and quantification limits equal to 10.7 and 35.8 μmol L-1, respectively, towards 5-FU determination. The proposed electrochemical sensor successfully quantified 5-FU in a real pharmaceutical formulation, confirming its potential as a new promising analytical detection tool for 5-FU quality control purposes.

Purification, characterization and antioxidant activity of polysaccharides from Porphyra haitanensis

In order to study the antioxidant activity of Porphyra haitanensis polysaccharides and the effect of their structure on the antioxidant activity, the Porphyra haitanensis polysaccharide (PHP), prepared by hot water extraction and alcohol precipitation, was separated and purified by Cellulose DEAE-52 ion exchange and Sephadex G-100 column chromatography. Three purified components including PHP1, PHP2 and PHP3 were obtained, and chemical composition analysis and structural characterization were performed. The in vitro free radical scavenging activity of the purified polysaccharide fractions and their ability to relieve oxidative stress in macrophage RAW264.7 were investigated. The results indicated that all the three fractions possessed appreciable DPPH radical, superoxide anion radical, and hydroxyl radical scavenging ability and reducing power. They were also found to effectively reduce the MDA content and ROS level, and to improve the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) in H₂O₂-treated RAW264.7 cells. Among the three polysaccharides, PHP3 possessed the most potent activity. Porphyra haitanensis polysaccharides have potential to develop as natural non-toxic antioxidants and may find application as the ingredients of functional foods.

Anti-Inflammatory Properties and Gut Microbiota Modulation of Porphyra tenera Extracts in Dextran Sodium Sulfate-Induced Colitis in Mice

Porphyra tenera (PT) is a functional seaweed food that has been reported for health benefits such as antioxidant, immunostimulant, anti-inflammation, and hepatoprotective effects. In this study, we investigated the effect of PT extracts on gut microbiota modulation in colitis-induced mice. The mice experiment was designed as three groups including normal mice (CTL), dextran sodium sulfate (DSS)-fed mice, and DSS plus PT extracts-fed mice (PTE). DSS was administrated through drinking water containing DSS for 1 week, and the PT extract was ingested into the gastrointestinal tract in mice. PT extract ameliorated the decreased body weight and colon length and improved disease activity index and pro-inflammatory cytokine expression. In addition, PT extract significantly shifted the gut microbiota of mice. DSS treatment significantly increased the portion of harmful bacteria (i.e., Helicobacter, Mucipirillum, and Parasutterella) and decreased the butyrate producing bacteria (i.e., Acetatifactor, Alistipes, Oscillibacter, and Clostridium_XIVb). PT extract increased the abundance of genera Clostridium_XIVb and also enriched some of predicted metabolic activities such as glyoxylate cycle, ethylmalonyl-CoA pathway, nitrate reduction, creatinine degradation, and glycine betaine metabolism. These results suggest that PT extract may ameliorate the DSS-induced colitis inflammation through regulating the compositions and functions of gut microbiota in mice.

Anti-cancer effects of Porphyra haitanensis polysaccharides on human colon cancer cells via cell cycle arrest and apoptosis without causing adverse effects in vitro

In this study, the anticancer effects of Porphyra haitanensis polysaccharides (PHPs) on human colon cancer cells and non-cancerous cells were evaluated. PHP was extracted by an ultrasonic/microwave-assisted method, and three fractions of polysaccharides (PHP-F1, PHP-F2 and PHP-F3) were obtained through a DEAE-52 cellulose ion-exchange column. The results of the cytotoxicity test showed that all of the PHP fractions had inhibitory effects on the growth of colon cancer cells HT-29, LoVo and SW-480, but no toxic effects on the normal human cells HaCaT. The fractions PHP-F2 and PHP-F3 had the most significant cytotoxicity on HT-29 cells. Studies on intracellular reactive oxygen species (ROS) levels, cell apoptosis, the apoptosis index (using Hoechst 33342 staining) and analysis of cell cycle arrest using flow cytometry revealed that the fractions PHP-F2 and PHP-F3 could apparently induce oxidative stress and apoptosis in HT-29 cells and cause cell G0-G1 phase arrest. These findings suggest that polysaccharides from P. haitanensis have anticancer effects on human colon cancer cells and therefore might be regarded as new candidates for the prevention and treatment of colon cancers.

Gamma-irradiation degraded sulfated polysaccharide from a new red algal strain Pyropia yezoensis Sookwawon 104 with in vitro antiproliferative activity

Pyropia yezoensis Sookwawon 104 is a newly cultivated strain of red marine algae. The present study aimed to investigate the in vitro antiproliferative activity of sulfated polysaccharide extracted from P. yezoensis Sookwawon 104 (PYSP), as well as that of its low molecular weight (Mw) derivatives. PYSP is a heterogeneous sulfated polysaccharide mainly composed of galactose, glucose and fucose. PYSP was degraded by gamma-irradiation at doses of 20 and 100 kGy to produce two derivatives, named as PYSP-20 and PYSP-100, respectively. Comparison of PYSP, PYSP-20 and PYSP-100 revealed clear differences in their molecular weight (Mw) distributions, and distinct in vitro antiproliferative activities against Hep3B, MDA-MB-231 and HeLa cancer cell lines. PYSP-20 and PYSP-100 exhibited stronger antiproliferative effects than PYSP, suggesting that the reduction in Mw may have increased the in vitro antiproliferative activity. Furthermore, the mRNA expression levels of the antitumor gene P53 and cell cycle-associated genes P21, Cyclin B1 and cyclin dependent kinase 1 (Cdk1) were further analyzed by reverse transcription-quantitative PCR in PYSP-20 and PYSP-100-treated cancer cells. PYSP and its derivatives were shown to inhibit the proliferation of tumor cells by regulating the expression of P53, P21, Cyclin B1 and Cdk1. In conclusion, low-Mw polysaccharide derivatives prepared from P. yezoensis Sookwawon 104 by gamma-irradiation exhibit significant inhibition effects on cancer cell proliferation in vitro and may be a novel source of potential anticancer therapeutic agents.

Effect of in vitro simulated gastrointestinal digestion on the antioxidant activity of the red seaweed Porphyra dioica

Porphyra sp. is one of the most cultivated and commercially valuable species, recognized for its high protein content (up to 47% dry weight) and complete amino acids profile. Based on these characteristics, P. dioica produced in an integrated multitrophic aquaculture system was selected for this study. The aim was to evaluate the effect of in vitro simulated gastrointestinal digestion (SGID) on the antioxidant activity of the hydrolysates generated from dried blades and from the protein isolate (PI) extracted from them. The alkali extraction and isoelectric precipitation (pH 4.5) of P. dioica protein prior SGID allowed isolating/enriching protein, while direct SGID of blades allowed assessing the potential influence of other constituents of the sample on the bioactive properties. Overall, SGID promoted the release of smaller bioactive peptides and their in vitro antioxidant activity, which was assessed by different methods (DPPH and ABTS⁺ scavenging capacity, ORAC and FRAP), was improved compared to the intact samples. Blades submitted to direct SGID presented significantly higher ORAC values compared to PI (2010 ± 136 vs 542 ± 21 µmol TE/g FDS, respectively). For the remaining assays, PI presented more potent antioxidant activity, especially FRAP (131 ± 2 vs 16 ± 1 µmol TE/g FDS) and ABTS⁺ (1244 ± 157 vs 230 ± 15 µmol TE/g FDS). The results indicated that gastrointestinal digestion improved the antioxidant activity of P. dioica-derived hydrolysates, as they presented effective activity against different oxidative mechanisms, thus suggesting health-protecting effects.

Effect of Dietary Nori (Dried Laver) on Blood Pressure in Young Japanese Children: An Intervention Study

BACKGROUND

Few studies have examined the association between seaweed intake and blood pressure in children. We conducted an intervention study to investigate whether seaweed intake affects blood pressure.

METHODS

Subjects were children aged 4 to 5 years attending a preschool in Aichi Prefecture, Japan, in 2010. Among 99 students, 89 (89.9%) were enrolled in our study. Nori (dried laver), an edible seaweed widely consumed in Japan, was used as a dietary intervention. Children in the intervention group were asked to consume 1.76 grams per day of roasted nori in addition to standard meals for 10 weeks. Children in the control group consumed their usual diet. Before the intervention and at the 10th week of the intervention, children's blood pressure was measured three times successively using an automated sphygmomanometer with subjects in a sitting position. Changes in systolic (SBP) and diastolic blood pressure (DBP) were compared between 55 children in the intervention group and 26 in the control group after adjustment for SBP and DBP before the intervention.

RESULTS

Changes in SBP were -8.29 mm Hg in the intervention group and +0.50 mm Hg in the control group (P for difference in change = 0.051). Changes in DBP were -6.77 mm Hg in the intervention group and -0.05 mm Hg in the control group (P = 0.031). In girls, no difference in blood pressure changes was found between the intervention and control groups.

CONCLUSION

Nori intake lowered DBP level in boys. Seaweed intake might have preventive effects on elevated blood pressure in childhood.

Extraction and Modification of Macroalgal Polysaccharides for Current and Next-Generation Applications

Marine macroalgal (seaweed) polysaccharides are highly promising for next-generation applications in several industries. However, despite the reported comprehensive potential of these polysaccharides, commercial products are scarce on the market. Seaweed cultivations are increasing in number and production quantity, owing to an elevated global trend of utilization interest in seaweed. The extraction of polysaccharides from seaweed generally generates low yields, but novel methods are being developed to facilitate and improve the extraction processes. Current areas of applications for seaweed polysaccharides mainly take advantage of the physicochemical properties of certain polysaccharides, such as gelling, thickening and emulsifying. However, many of the numerous bioactivities reported are still only at research level and lack clinical evidence for commercialization. It has been suggested the construction of smaller units may generate better defined molecules that are more suitable for biomedical applications. Enzymatic modification is a promising tool for the generation of more defined, targeted biomolecules. This review covers; structural differences between the most predominant marine algal polysaccharides, extraction processes, modification alternatives, as well as a summary of current and potential next-generation application areas.