Brown Algae Research Articles

Species diversity and distribution of the macro algae from Bach Long Vi Island, Vietnam

Research results on seaweed at four cross-sections of Bach Long Vi Island from 1994 onwards have shown that 129 species of macroalgae belong to 4 phyla. Among them, Cyanobacteria has ten species, accounting for 7.75% of the total number of species; Red seaweed (Rhodophyta) has 70 species (54.26%); Brown seaweed (Ochrophyta/Phaeophyta) has 27 species (20.93%), and Green seaweed (Chlorophyta) has 22 species (17.06%). They belong to 21 orders, 42 families, and 72 seaweed genera. The number of species in the studied transects ranges from 41 species (transect 4) to 99 species (transect 2) and averages 72.25 species/transect. The similarity coefficient of seaweed species at four surveyed transects ranged from 0.26 (between transects 1 and 4) to 0.74 (between transects 2 and 3) and averaged 0.48. Of the 129 known species, there were 44 species only distributed in the intertidal zone, accounting for 34.10% of the total number of species; 108 species are only distributed in the subtidal zone (83.72%) and 26 species are distributed in both intertidal and subtidal zones (20.15%); most species distributed from the low intertidal zone downward and are concentrated mainly in the low intertidal zone and the upper range of the subtidal zone. In terms of structure, the number of taxa ranges from 2 (Cyanophyta) to 12 (Rhodophyta). On average, 5.25 orders/phylum; of families from 4 (Cyanophyta, Ochrophyta) to 25 (Rhodophyta) and 10.5 families/order; of genera from 6 (Cyanophyta) to 42 (Rhodophyta) and 18; of species from 10 (Cyanophyta) to 70 (Rhodophyta) and 32.25. The average number of species/genera is quite large (32.25). However, some genera have only one species (Hydrocoryne, Asparagopsis, Parvocaulis, etc.), and some other genera have a more significant number of species (Dictyota: 10 species; Hypnea: 8 species; Peyssonnelia: 5 species, etc.). Among the families, some have only one genus (Peyssonneliaceae, Scytosiphonaceae, Codiaceae, etc.), but others have more genera (Dictyotaceae: 5, Boodleaceae: 4, Sargassaceae: 2, etc.). The total number of orders of the four phyla (Cyanophyta, Rhodophyta, Ochrophyta, and Chlorophyta) is 21. Of which, Cyanophyta has 2 orders, accounting for 9.5% of the total number of recorded orders: Rhodophyta (12 and 57.1%), Ochrophyta (4 and 19%), and Chlorophyta (3 and 14.4%).

Chemical composition and carbohydrates of seaweed Sargassum sp. with different drying methods

Sargassum sp., a brown seaweed abundant in Semau Island, East Nusa Tenggara, Indonesia, has potential as an alternative feed source in animal nutrition due to its rich chemical composition. This study aimed to determine Sargassum sp.'s chemical and carbohydrate composition using different drying methods to evaluate its suitability as livestock feed. A Completely Randomized Design (CRD) with three treatments—sun drying, oven drying at 60°C, and air drying—and five replications were employed. Using standard proximate analysis, fresh seaweed samples were dried according to the treatments and analyzed for dry matter, organic matter, crude protein, crude fat, crude fiber, and carbohydrate content. The results showed that the drying method significantly affected (P < 0.05) the dry matter, moisture content, ash content, organic matter, crude protein, and crude fat of Sargassum sp. but had no significant effect (P > 0.05) on crude fiber and carbohydrate content. Air-dried samples exhibited the highest crude protein content (6.38%) compared to sun-dried (4.71%) and oven-dried (4.94%) samples, indicating better preservation of protein at lower temperatures. Crude fat content was highest in sun-dried samples (0.56%) and lowest in air-dried samples (0.24%). Carbohydrate content ranged from 52.83% to 54.00% across all treatments without significant differences. These findings suggest that air drying is the most effective method for retaining the nutritional components of Sargassum sp., enhancing its potential as a valuable ingredient in animal feed formulations. The drying method significantly influences Sargassum sp. seaweed's chemical composition. Air drying preserves key nutritional components, making it the recommended method for processing Sargassum sp. for use in animal nutrition.

Extraction and Characterization of Cellulose Nanocrystals from Brown Seaweed Dictyota Bartayresiana, J.V. Lamouroux

Extraction and Characterization of Cellulose Nanocrystals from Brown Seaweed Dictyota Bartayresiana, J.V. Lamouroux

Abiotic Factors Modulating Metabolite Composition in Brown Algae (Phaeophyceae): Ecological Impacts and Opportunities for Bioprospecting of Bioactive Compounds

Brown algae are vital structural elements and contributors to biodiversity in marine ecosystems. These organisms adapt to various environmental challenges by producing primary and secondary metabolites crucial for their survival, defense, and resilience. Besides their ecological role, these diverse metabolites have potential for biotechnological applications in industries including pharmaceuticals, cosmetics, and food. A literature review was conducted encompassing studies from 2014–2024, evaluating the effects of hydrodynamics, temperature, light, nutrients, seasonality, and salinity on the chemical profiles of various Phaeophyceae algae species. Thirty original articles spanning 69 species from the Sargassaceae, Dictyotaceae, Fucaceae, and Scytosiphonaceae families were analyzed and systematically arranged, with a focus on methodologies and key findings. This review furthers ecological discussions on each environmental factor and explores the biotechnological potential of metabolites such as polysaccharides, fatty acids, phenolics, diterpenes, and pigments. The information in this work is beneficial for metabolite bioprospecting and in vitro cultivation models as well as indoor and outdoor cultivation studies.

Effect of Phlorethol from the Brown Alga Costaria costata (Turn.) Saund. (Order Laminariales) on Gametes and Embryogenesis of the Sea Urchin Strongylocentrotus intermedius (A. Agassiz, 1864)

The effect of a fraction of phlorethol (CcPh), one of the polyphenolic compounds isolated from the brown alga Costaria costata (Turn.) Saund (Laminariales), on gametes and embryogenesis of the sea urchin Strongylocentrotus intermedius (A. Agassiz, 1864) was studied. Using a model of developing sea urchin embryos, it was shown that phlorethol at concentrations ≤700 µg/mL did not exert cytotoxic effect on early developmental stages (from zygote to 16-celled stage blastomere). The embryotoxic effect of phlorethol, causing death of 50% of embryos, was expressed in a concentration (I) range of 50 I ≤ 100 µg/mL only after 24 h of incubation, in the blastula stage. When exposed to concentrations of ≥100 µg/mL, embryos that survived to the blastula stage did not develop further and died after 36 h of incubation. Under the effect of phlorethol, the fertilizing capacity of sea urchin spermatozoa and oocytes reduced. The concentration of phlorethol inhibiting fertilization by 50% (IC50) when acting on sperm was 1.28±0.38 µg/mL and when acting on oocytes was 3.83±0.82 µg/mL. Thus, phlorethol reduces the fertilizing capacity of sea urchin gametes at concentrations much lower than embryotoxic concentrations and can potentially find practical application as part of new contraceptive drugs for mammals and humans.

Production and ecological function of fucoidans from marine algae in a changing ocean.

Fucoidans have multiple biological and biomedical functions, e.g., antibacterial, antiviral, immunomodulatory, inflammatory, and growth-promoting effects. Recent studies show that they also have essential ecological functions whereas our understanding in this field is very superficial. This study first reviewed the fucoidans content in algae and the highest content of 13.3 % in Undaria pinnatifida sporophyll and the lowest content of 0.1 % in Alaria angusta were found. Field investigation demonstrates that light, temperature, salinity, and nutrient can affect fucoidan production in algae; while more laboratory experiments need to be carried out to verify these conclusions. Brown algae can excrete 8-31 % of their net carbon fixation into seawater in the form of fucoidans. Fucoidans are highly recalcitrant to bacterial degradation and thus the carbon in fucoidans can be stored for centuries. Therefore, fucoidans can play an essential role in carbon sequestration. Ocean afforestation with brown algae may be an effective approach to remove atmospheric CO2 since fucoidans have a high carbon content while seldom need any nitrogen or phosphorus. Fucoidans production in a warming and CO2 enriched ocean was also discussed. This study provides new insight into production and ecological functions of fucoidans, indicating their role in carbon sequestration and climate change alleviation.

Choline chloride-based solvents as alternative media for alginate extraction from brown seaweed

Choline chloride-based solvents as alternative media for alginate extraction from brown seaweed

Ameliorative effects of Turbinaria ornata extract on hepatocellular carcinoma induced by diethylnitrosamine in-vivo.

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths and the fifth most common cancer worldwide. Brown algae appeared to be a rich source of efficient and safe agents against many life-threatening diseases like cancer. Thus, the scope of this study was to investigate the therapeutic effects of Turbinaria ornata against experimentally induced HCC in a rat model. Accordingly, forty male albino rats were divided into four groups. HCC was induced by intraperitoneal injection with diethylnitrosamine (DENA) followed by carbon tetrachloride (CCL4). After four weeks of DENA + CCL4 injection and two weeks of treatment with Turbinaria ornata, rats were sacrificed to collect hepatic tissue and blood samples for histopathological observations and various biochemical markers such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), alpha-fetoprotein (AFP), urea, creatinine, albumin (ALB), and alkaline phosphatase (ALP). Rats that were injected for four weeks with DENA + CCL4 showed a significant increase in AFP levels, transforming growth factor-beta (TGF-β) and tumor necrosis factor-alpha (TNF-α), as well as a high percentage of malignant changes in hepatic tissues. The extension of malignant changes in the rat liver tissues was markedly reduced using Turbinaria ornata, as the treatment displayed liver patterns similar to that of the normal control rats. Furthermore, rats with HCC fed with Turbinaria ornata extract for two weeks showed decreasing levels of TGF-β and TNF-α. These findings demonstrate that Turbinaria ornata supplement can prevent HCC development in hepatic rats; however, the exact mechanism requires further investigation.

Degradation of low-molecular-weight fucoidans by human intestinal microbiota and their regulation effect on intestinal microbiota and metabolites during in vitro fermentation

Fucoidan, a sulfated polysaccharide from brown algae, has been shown to improve gut microbiota balance and function. However, the relationship between molecular weight of fucoidan and colonic fermentation characteristics is still unclear. Here, the interaction between different-molecular-weight fucoidans and intestinal microbiota was analyzed via an in vitro fecal fermentation model. Results showed that fucoidan and its 2 low-molecular-weight derivatives (Dfuc1 and Dfuc2) could be utilized by intestinal microbiota after 48 h of fermentation, and among them, Dfuc2 exhibited the highest utilization efficiency of 30.1%, followed by Dfuc1 (24.5%) and fucoidan (14.4%). Notably, the components glucose, mannose and galactose, but not fucose, in different-molecular-weight fucoidans could be utilized. Moreover, intestinal microbiota could degrade Dfuc1 and Dfuc2 to produce oligosaccharide fragments, such as fucose-hexose disaccharide. In addition, fucoidan, Dfuc1 and Dfuc2 displayed different prebiotic effects on the intestinal microbiota community. Native fucoidan preferred to promote Bacteroides and Lactococcus, and low-molecular-weight fucoidans tended to promote Parabacteroides and Lactobacillus. Furthermore, metabolites analysis showed that fucoidan, Dfuc1 and Dfuc2 had similar promoting effects on acetic acid and propionic acid, and had no effect on butyric acid. But they could regulate carbohydrate metabolic pathways and amino acid pathways to varying degrees and with decreasing molecular weight, more differential metabolites were found. Thus, Dfuc2 with a lower molecular weight has more potential to become a potential prebiotics to improve intestinal health.

Egyptian seaweed resources from the South Sinai coast to develop alginate-based biohybrid composites for enhanced lead(II) removal from industrial wastewater

Herein, crosslinked-alginate (CAL) was extracted from Egyptian marine biowaste (brown seaweed discarded near seashore of Ras Sedr, Sinai). Novel biohybrid composites were fabricated by hybridizing CAL chains with either carbohydrate polymer (starch, St) or proteinaceous content (albumin, Alb). Physicochemical properties of such biocomposites were characterized using XRD, FTIR, Raman, DLS, SEM and AFM analyses. Compared to CAL, starch as hybridizing agent enthuses existence of stacking-oriented alginate chains of higher amorphicity and lower zeta-potential (-17 mV). Hybridization of alginate matrix with albumin chains yielded high negatively charged (-37.8mV) crystalline biocomposite with smooth surfaces. Performance of St-CAL and Alb-CAL biocomposites toward Pb2+ removal from wastewater was scrutinized. The impact of pH, adsorbate concentration, contact time, and thermodynamic studies on Pb2+ removal using these biocomposites were estimated. Removal efficiency of St-CAL was superior to that of Alb-CAL yielding ~ 70% for 5 succussive runs. Pb2+ adsorption process over St-CAL was spontaneous with exothermic nature at room temperature and followed Freundlich model with pronounced adsorption energy and capacity. Fitness of kinetic models for St-CAL was ranked as pseudo-first-order with escalated intra-particle diffusion rates. Construction of oxygen-rich hybrid carbohydrate systems is willingly applied in future as green cleaner to wastewater from heavy metal ions.

Extraction and characterization of sodium alginate from native Malaysian brown seaweed Sargassum polycystum.

Malaysian seaweed, particularly Sargassum polycystum, has potential for alginate production, yet an extraction protocol for this seaweed remains lacking. This study aimed to optimize the extraction process to maximize alginate yield while characterizing the physicochemical properties of the extracted alginate and its potential applications. An alkali-based extraction method was employed, with key parameters, including alkali concentration, extraction temperature, and time, carefully optimized to yield 30.17 ± 0.76 % (g alginate/100 g dry seaweed biomass) of alginate. Sodium alginate extracted from Sargassum polycystum has a viscosity-average molecular weight of 4.73 ± 0.001 × 104 g/mol and an M/G ratio of 2.87. The physicochemical properties and biochemical composition of the extracted alginate revealed its capacity to be utilized as a natural antioxidant. An alginate-based nanohybrid for polyphenol delivery was developed to explore the potential applications of extracted alginate. This nanohybrid showed favorable properties (size: 415 nm, PDI: 0.3, zeta potential: -44.7 mV), high encapsulation (80.13 %), and loading efficiency (19.21 ± 1.69 %). Alginate coating on the nanohybrid protected polyphenol from premature release, significantly enhancing its antioxidant activity. These findings suggest that alginate extracted from Malaysian Sargassum polycystum could be a valuable natural material for developing controlled-release delivery systems.

Corrigendum to “Instant Controlled Pressure Drop (DIC) as an innovative pretreatment for extraction of natural compounds from the brown seaweed Sargassum muticum (Yendo) Fenshott 1955 (Ochrophytina, Fucales)” [Algal Res. 83 (2024) 103705

Corrigendum to “Instant Controlled Pressure Drop (DIC) as an innovative pretreatment for extraction of natural compounds from the brown seaweed Sargassum muticum (Yendo) Fenshott 1955 (Ochrophytina, Fucales)” [Algal Res. 83 (2024) 103705

Unveiling the Nutritional and Antioxidant Properties of Brown Algae Resources (Dictyota J.V. Lamouroux) from the Bay of Bengal and Arabian Sea, Indian coast

Unveiling the Nutritional and Antioxidant Properties of Brown Algae Resources (Dictyota J.V. Lamouroux) from the Bay of Bengal and Arabian Sea, Indian coast

Determination of antimicrobial activities and DNA protection properties of Scytosiphon lomentaria extracts

Scytosiphon lomentaria is a brown algae that has many promising biological activities in medicine as well as being consumed as food in many countries. This study aims to investigate the antimicrobial, antimutagenic and DNA damage protective activity of S. lomentaria by obtaining hexane, methanol and water extracts. To evaluate the antimicrobial effect of the extracts, minimum inhibitory concentration (MIC) tests were performed on both yeasts and bacteria. The antimutagenic activities of the extracts were investigated by the Ames test, and their protective effects against oxidative DNA damage were investigated by agarose gel electrophoresis using pBR322 plasmid DNA. Antimicrobial results showed that hexane methanol and aqueous extract were more effective on Candia albicans (5, 2.5 and 2.5 mg/mL, respectively) compared to all strains used. All concentrations of the methanol extract exhibited strong antimutagenicity (more than 40% inhibition) on both TA98 and TA100 mutant strains. It was determined that the extracts protected DNA against oxidative DNA damage. The results show that S. lomentaria extracts have antimicrobial activity and DNA protection properties, making them have the potential to be evaluated as new natural resources that can be used in antimicrobial and anticancer formulations

Antioxidant Activity and Tyrosinase of Brown Seaweed Extract Using Ultrasonic and Magnetic Stirrer Extraction Methods

Antioxidant Activity and Tyrosinase of Brown Seaweed Extract Using Ultrasonic and Magnetic Stirrer Extraction Methods

Innovative Approaches to Fucoxanthin Delivery: Characterization and Bioavailability of Solid Lipid Nanoparticles with Eco-Friendly Ingredients and Enteric Coating

Fucoxanthin (FN), a carotenoid derived from brown seaweed and algae, offers significant health benefits. However, its unique structure leads to challenges in stability and bioavailability. To overcome these issues, we successfully encapsulated fucoxanthin in solid lipid nanoparticles (SLNs) utilizing health-safe materials, achieving remarkable results. SLNs exhibited a nanoscale size of 248.98 ± 4.0 nm, along with an impressive encapsulation efficiency of 98.30% ± 0.26% and a loading capacity of 5.48% ± 0.82% in lipid. The polydispersity index (PDI) was measured at 0.161 ± 0.03, indicating a narrow size distribution, while the high negative zeta potential of −32.93 ± 1.2 mV suggests excellent stability. Pharmacokinetic studies conducted in Sprague–Dawley rats revealed an exceptional oral bioavailability of 2723.16% compared to fucoxanthin crystals, likely attributed to the enhanced stability and improved cellular uptake of the SLNs. To further improve bioavailability, we creatively applied enteric coatings to the freeze-dried SLNs, effectively protecting fucoxanthin from gastric degradation, which is supported by in vitro digestion results. These findings underscore the potential of SLNs as a superior delivery system for fucoxanthin, significantly enhancing its therapeutic efficacy and broadening its application in the food and pharmaceutical industries.

Optimization of Bioactive Compound Extraction from Iranian Brown Macroalgae Nizimuddinia zanardini with Ultrasound and Microwave Methods Using Fuzzy Logic

In this study, three extraction methods of bioactive compounds from the brown algae Nizimuddinia zanardini were ranked using the fuzzy weighting system in two stages, ranking between different conditions and choosing the optimal conditions for each extraction method separately. The inputs included extraction yield (EY), antioxidant activity (DPPH), total flavonoid content (TFC), total phenolic content (TPC), total phlorotannin content (TPhC), time, temperature, power, and cost. The top ranks of the first phase output included: Maceration Extraction (ME) with a score of 52.67, Ultrasound-Assisted Extraction (UAE) with a score of 54.31, and Microwave-Assisted Extraction (MAE) with a score of 73.09. The results of the second stage indicated that the lowest and highest extraction yields were obtained using UAE and MAE, respectively. The TFC in the UAE was determined as 103.29 mg QE (Quercetin Equivalent)/g as the lowest value and, in the ME, 140.95 mg QE/g was the highest value. The highest and lowest TPC and TPhC were observed with MAE and UAE, respectively. DPPH decreased in UAE, MAE, and ME, respectively. According to the fuzzy weighted results and considering the purpose of extraction, MAE can be introduced as the optimal method for extracting bioactive compounds from N. zanardini. The findings on extraction methods underscore the potential to reduce costs and improve the yields of bioactive compounds, such as antioxidants and polyphenols, thereby enhancing the economic viability of functional foods and nutraceuticals.

A novel edible biocomposite coating based on alginate from the brown seaweed Dictyota mertensii loaded with beeswax nanoparticles extends the shelf life of yellow passion fruit

In this study, an edible biocomposite coating of alginate extracted from the brown seaweed Dictyota mertensii was loaded with beeswax nanoparticles (BDMAB) to extend the shelf life of yellow passion fruit (Passiflora edulis f. flavicarpa). The films were characterized by morphology, moisture content, contact angle, water vapor permeability, solubility, and optical and mechanical properties. Using a 4 × 6 factorial design, coated fruit was evaluated during six storage intervals (0, 2, 4, 6, 8, 10 days) at 22.5 ± 0.5 °C and 65 ± 5 % RH, focusing on respiration rate, weight loss, peel thickness and color, pulp yield and color, soluble solids, titratable acidity, ascorbic acid, phenolics, antioxidant capacity, and sensory acceptance. The BDMAB coating, composed of 67.9 % (w/w) ADM (bleached), 5 % (w/w) glycerol, 8.5 % (w/w) beeswax, and 18.6 % (w/w) Tween 80, significantly (p < 0.05) reduced the respiration rate, minimized weight loss, and preserved quality attributes, such as acidity, ascorbic acid, phenols, and antioxidant capacity. A 3-day extension in shelf life was inferred based on the climacteric peak delay of BDMAB-coated fruits compared with the control. Sensory analysis confirmed the acceptance of BDMAB coating. Therefore, BDMAB biocomposite coatings have great potential for preserving yellow passion fruit and promoting sustainability and conservation.

Expression, Purification, and Characterisation of Recombinant Alginate Lyase (Flammeovirga AL2) for the Bioconversion of Alginate into Alginate Oligosaccharides

Alginate, a polysaccharide found in brown seaweeds, has regularly gained attention for its potential use as a source of bioactive compounds. However, it is structurally complex with a high molecular weight, limiting its application. Alginate oligosaccharides (AOS) are small, soluble fragments, making them more bioavailable. Alginate hydrolysis by enzymes is the preferred method for AOS production. Commercially available alginate lyases are limited, expensive, and sometimes exhibit unsatisfactory activity, making the search for novel alginate lyases with improved activity indispensable. The aims of this study were to codon-optimise, synthesise, express, purify, and characterise a recombinant alginate lyase, AL2, from Flammeovirga sp. strain MY04 and to compare it to a commercial alginate lyase. Expression was successfully performed using Escherichia coli ArcticExpress (DE3) RP cells, and the protein was purified through affinity chromatography. The recombinant enzyme was characterised by pH optimum studies, and temperature optimum and stability experiments. The optimal reaction conditions for AL2 were pH 9.0 and 37 °C, while for the commercial enzyme, the optimal conditions were pH 8.0 and 37 °C. At optimal reaction conditions, the specific activity of AL2 was 151.6 ± 12.8 µmol h−1 mg−1 protein and 96.9 ± 13.1 µmol h−1 mg−1 protein for the commercial alginate lyase. Moreover, AL2 displayed impressive activity in breaking down alginate into AOS. Hence, AL2 shows potential for use as an industrial enzyme for the hydrolysis of alginate into alginate oligosaccharides. Additional studies should be carried out to further characterise this enzyme, improve its purity, and optimise its activity.

Therapeutic Potential of Oligo-Fucoidan in Mitigating Peritoneal Dialysis-Associated Fibrosis

Peritoneal dialysis (PD) serves as a home-based kidney replacement therapy with increasing utilization across the globe. However, long-term use of high-glucose-based PD solution incites repeated peritoneal injury and inevitable peritoneal fibrosis, thus compromising treatment efficacy and resulting in ultrafiltration failure eventually. In the present study, we utilized human mesothelial MeT-5A cells for the in vitro experiments and a PD mouse model for in vivo validation to study the pathophysiological mechanisms underneath PD-associated peritoneal fibrosis. High-glucose PD solution (Dianeal 4.25%, Baxter) increased protein expression of mesothelial–mesenchymal transition (MMT) markers, such as N-cadherin and α-SMA in MeT-5A cells, whereas it decreased catalase expression and stimulated the production of reactive oxygen species (ROS). Furthermore, macrophage influx and increased serum pro-inflammatory cytokines, such as IL-1β, MCP-1, and TNF-α, were observed in the PD mouse model. Interestingly, we discovered that oligo-fucoidan, an oligosaccharide extract from brown seaweed, successfully prevented PD-associated peritoneal thickening and fibrosis through antioxidant effect, downregulation of MMT markers, and attenuation of peritoneal and systemic inflammation. Hence, oligo-fucoidan has the potential to be developed into a novel preventive strategy for PD-associated peritoneal fibrosis.