Search Results (624)

In the marine red alga Pyropia yezoensis, filamentous phases of the life cycle, e.g., the conchocelis (sporophyte) and conchosporangium (conchosporophyte), proliferate by tip growth. In this study, we investigated the possible involvement of phosphoinositide turnover and actin polymerization in the spontaneous initiation and tip growth of new branches in isolated single-celled conchocelis cells using pharmacological treatments. Treatment with LY294002 and U73122, specific inhibitors of phosphoinositide-phosphate 3-kinase and phospholipase C, respectively, reduced side-branch formation and inhibited the elongation of branches. In addition, two inhibitors of the actin cytoskeleton, cytochalasin B (CCB) and latrunculin B (LAT-B), had similar effects on tip growth. However, CCB did not alter the branching rate of single-celled conchocelis, whereas LAT-B did. As CCB and LAT-B affect actin polymerization through different mechanisms, this result suggests differences in the contributions of actin polymerization to branch initiation versus tip growth. These findings demonstrate the critical and diverse functional roles played by phosphoinositide turnover and actin polymerization in the regulation of the initiation and maintenance of tip growth in the conchocelis phase of P. yezoensis. Full article

Microbial extracellular polymeric substances (EPSs) are emerging as sustainable alternatives to conventional corrosion inhibitors due to their eco-friendly nature, biodegradability, and functional versatility. Secreted by diverse microorganisms including bacteria, fungi, archaea, and algae, EPSs are composed mainly of polysaccharides, proteins, lipids, and nucleic acids. These biopolymers, chiefly polysaccharides and proteins, are accountable for surface corrosion prevention through biofilm formation, allowing microbial survival and promoting their environmental adaptation. Usually, EPS-mediated corrosion inhibitions can take place via different mechanisms: protective film formation, metal ions chelation, electrochemical property alteration, and synergy with inorganic inhibitors. Even though efficacious EPS corrosion prevention has been demonstrated in several former studies, the application of such microbial inhibitors remains, so far, a controversial topic due to the variability in their composition and compatibility toward diverse metal surfaces. Thus, this review outlines the microbial origins, biochemical properties, and inhibition mechanisms of EPSs, emphasizing their advantages and challenges in industrial applications. Advances in synthetic biology, nanotechnology, and machine learning are also highlighted and could provide new opportunities to enhance EPS production and functionality. Therefore, the adoption of EPS-based corrosion inhibitors represents a promising strategy for environmentally sustainable corrosion control. Full article

Antipredator defenses of bloom-forming cyanobacteria species maximize their fitness but can reduce carbon and energy transfer efficiency to higher trophic levels, making them a key regulator of plankton communities in eutrophic waters. We investigated the grazing responses of the tropical cladoceran Moina micrura to different strains of the cyanobacteria Microcystis aeruginosa and Planktothrix isothrix, using a good food source (green algae Mono-raphidium capricornutum) as a control. Both Microcystis strains grow as unicellular and are microcystins producers; however, this cyanotoxin was not detected on the filamentous Planktothrix strains. M. micrura ingested all cyanobacteria at reduced rates compared to single diets with Monoraphidium. In mixed diets, food type had a significant effect on grazing responses, which differed interspecifically. Planktothrix was more grazed than Microcystis strains. Feeding selectivity on Monoraphidium was negatively affected by the increase of cyanobacteria in the diet. We observed varied responses across treatments, ranging from feeding inhibition to different degrees of tolerance toward cyanobacteria, particularly in non-microcystin-producing species. We also highlight the selectivity of small tropical cladocerans, a pattern that is not yet well documented. These findings emphasize that studies incorporating phyto- and zooplankton with a history of coexistence can provide more meaningful insights into natural ecosystem dynamics. Full article

Floridoside (2-O-D-glycerol-α-D-galactopyranoside) is a natural product typically found in red algae. It serves as the algae’s carbon reserve and is produced as a protective response against osmotic and heat stress. Both floridoside and its acylated derivatives have been associated with modulating redox homeostasis and inflammatory responses. Therefore, we aimed to evaluate whether the newly synthesized floridoside phosphotriesters (1b–1d, 1f–1h) and acylated floridoside derivative (1e) can modulate the oxidative burst in stimulated human neutrophils. Synthetic strategies included the glycosylation of the thioglycoside donor with glycerol derivatives, having NIS/TfOH as the promoter. Phosphorylation was achieved with POCl₃ in the presence of pyridine. The compounds were analysed for their cytotoxicity, with 1b and 1h being cytotoxic at 50 μM, while the others showed no cytotoxicity in the tested concentrations. The detection of the neutrophils’ oxidative burst was performed using multiple probes [luminol, aminophenyl fluorescein (APF), and Amplex Red (AR)] to evaluate reactive species levels. Compound 1e prevented the oxidative burst in activated human neutrophils (IC₅₀ = 83 ± 7 μM). All the other tested compounds were ineffective in inhibiting APF and AR oxidation under the present experimental conditions. These findings highlight the potential of floridoside-based derivatives as candidates for targeting inflammatory pathways. Full article

Alzheimer’s disease (AD) is characterized by β-amyloid plaques, neurofibrillary tangles, neuroinflammation, and oxidative stress—pathological features that pose significant challenges for the development of therapeutic interventions. Given these challenges, this review comprehensively evaluates the neuroprotective mechanisms of bioactive compounds derived from red algae, including polysaccharides and phycobiliproteins, which are considered a promising source of natural therapeutics for AD. Red algal constituents exhibit neuroprotective activities through multiple mechanisms. Sulfated polysaccharides (e.g., carrageenan, porphyran) suppress NF-κB-mediated neuroinflammation, modulate mitochondrial function, and enhance brain-derived neurotrophic factor (BDNF) expression. Phycobiliproteins (phycoerythrin, phycocyanin) and peptides derived from their degradation scavenge reactive oxygen species (ROS) and activate antioxidant pathways (e.g., Nrf2/HO-1), thus mitigating oxidative damage. Carotenoids (lutein, zeaxanthin) improve cognitive function through the inhibition of acetylcholinesterase and pro-inflammatory cytokines (TNF-α, IL-1β), while phenolic compounds (bromophenols, diphlorethol) provide protection by targeting multiple pathways involved in dopaminergic system modulation and Nrf2 pathway activation. Emerging extraction technologies—including microwave- and enzyme-assisted methods—have been shown to optimize the yield and maintain the bioactivity of these compounds. However, the precise identification of molecular targets and the standardization of extraction techniques remain critical research priorities. Overall, red algae-derived compounds hold significant potential for multi-mechanism AD interventions, providing novel insights for the development of therapeutic strategies with low toxicity. Full article

The diversity of structural types of carrageenans (CRGs)—sulfated polysaccharides of red algae—determines their different biological activities. The different types of CRGs (kappa, lambda, kappa/beta-CRGs) were isolated from the red algae of the Pacific coast. Molecular docking was performed to determine potential interactions of CRGs with the receptor-binding domain (RBD) of SARS-CoV-2 and its cellular receptor—angiotensin—converting enzyme type 2 (ACE2). CRGs interacted with ACE2 and RBD via hydrogen bonding and ionic interactions. The strongest binding affinity of CRGs and ACE2 was observed for kappa-CRG. Molecular docking was confirmed by results studying the effects of CRGs against SARS-CoV-2 in vitro. The ability of CRGs, as well as the complex CRG with sea urchin echinochrome (Ech), to inhibit SARS-CoV-2 replication in Vero E6 cells was studied using cytopathic effect (CPE) inhibition and RT-PCR assays. The simultaneous treatment of cells with CRGs and the virus revealed that kappa-CRG exhibited the most significant antiviral effect among all the polysaccharides, with a selective index (SI) of 33. The kappa-CRG/Ech complex exhibited the highest virucidal effect on SARS-CoV-2 particles with an SI above 70 (more than two times higher than that of CRG and Ech) and reduced viral RNA levels by 45% (IC = 45%). Our results illustrate that CRGs and kappa-CRG/Ech complex can act as protective agents against SARS-CoV-2. Full article

Marine biofouling, the process of marine microorganisms, algae, and invertebrates attaching to and forming biofilms on ship hulls, underwater infrastructure, and marine equipment in ocean environments, severely impacts shipping and underwater operations by increasing fuel consumption, maintenance costs, and corrosion risks, and by threatening marine ecosystem stability via invasive species transport. This study reports the development of a hydrogel-metal-organic framework (MOF)-quorum sensing inhibitor (QSI) antifouling coating on 304 stainless steel (SS) substrates. Inspired by mussel adhesion, a hydrophilic bionic hydrogel was first constructed via metal ion coordination. The traditional metal ion source was replaced with a zeolitic imidazolate framework-8 (ZIF-8) loaded with 2-(5H)-furanone (HF, a QSI) without altering coating formation. Physicochemical characterization using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), the Brunauer–Emmett–Teller (BET) method, and the diffraction of x-rays (XRD) confirmed successful HF loading into ZIF-8 with intact crystal structures. Antifouling tests showed HF@ZIF-8 enhanced antibacterial inhibition against Staphylococcus aureus (97.28%) and Escherichia coli (>97%) and suppressed Chromobacterium violaceum CV026 pigment synthesis at 0.25 mg/mL (sub-growth concentration). The reconstructed PG/PVP/PEI/HF@ZIF-8 coating achieved 72.47% corrosion inhibition via synergistic anodic protection and physical shielding. This work provides a novel green approach for surface antifouling and drag reduction, highlighting MOF-loaded QSIs as promising additives to enhance the antifouling performance of hydrogel coatings, anti-corrosion performance, and QSI performance for sustainable marine engineering applications. Full article

Alginate oligosaccharide (AOS), a degradation product of alginate derived from marine brown algae, has attracted significant attention due to its potent ability to modulate gut microbiota and enhance human health. This review aims to systematically introduce current evidence on the interactions between AOS and gut microbial communities, focusing on how AOS improves health through regulating gut microbiota. Initially, the structural factors of AOS that influence their functions are highlighted, including molecular weight, monomer composition, terminal structure, and chemical modifications. Importantly, AOS primarily exerts beneficial effects by adjusting gut microbiota community and outputs, which include the promotion of probiotics, the inhibition of pathogens, the balance of microbiota composition, and the increase of short-chain fatty acid production. Moreover, the discovered mechanisms underlying AOS-mediated health promotion via microbiota modulation are detailed comprehensively, specifically emphasizing intestinal barrier maintenance, antioxidation, dual-regulation of immune and inflammatory responses, pathogenic infection inhibition, metabolic improvement, uric acid excretion promotion, anti-tumor effects, and anti-skin aging. Such beneficial effects make AOS valuable in keeping healthy, preventing disorders, and intervening in diseases. Despite these findings and research progress, there are yet limitations in studying AOS–gut microbiota interactions, such as precise microbiota-targeted structural optimization, personalized nutritional interventions based on microbial characteristics, and broadening the horizon of microbiota-derived metabolic metabolomic profiles. In conclusion, advancing our understanding of the gut microbiota-centered mechanisms of AOS would probably facilitate novel nutritional strategy development for health promotion. Full article

Allelochemicals are recognized as promising algaecides due to their environmental safety. Para-tert-butylcatechol (TBC) and L-lysine exhibit significant potential in suppressing harmful algal blooms (HABs); however, their combined effects and algae inhibition mechanisms remain unelucidated. Therefore, this study systematically investigated the growth inhibition of Microcystis aeruginosa by TBC and L-lysine individually and in combination, while simultaneously examining their combined effects on algal growth, cell membrane integrity, photosynthetic activity, antioxidant responses, and microcystin production. The results revealed a significant interactive effect between TBC (0.04 mg/L) and L-lysine (1 mg/L), achieving over 90% growth inhibition within 96 h. The combined treatment significantly inhibited M. aeruginosa growth through impaired photosynthetic efficiency and elevated oxidative stress. Compared to the control group, the treatment group exhibited a continuous decline in chlorophyll-a content, phycobiliprotein levels, F_v/F_m, YII, α, and rETR_max, while phosphoenolpyruvate carboxylase (PEPC) activity decreased by 96.48% by day 8. And antioxidant enzymes, including superoxide dismutase (SOD) and reduced glutathione (GSH), showed a progressive increase in activity. In addition, the structure and integrity of the cell membrane of M. aeruginosa were damaged after treatment, and the conductivity of the treatment groups increased continuously from 2.32 to 4.63 μs/cm. In addition, under combined treatment, intra- and extracellular microcystin levels initially increased (peaking at day 2) but sharply declined thereafter, becoming significantly lower than controls by day 8. These findings highlight the potential of combining TBC and L-lysine as an eco-friendly and cost-effective strategy for mitigating M. aeruginosa-dominated harmful algal blooms. Full article

Obesity represents a significant global public health issue, contributing to the rising prevalence of metabolic diseases. One treatment for obesity is orlistat, a drug that inhibits pancreatic lipase. It is widely used due to its efficacy in reducing dietary fat absorption. However, patient adherence to this drug is often hindered by its associated adverse effects. As a result, there is an increasing interest in exploring alternative therapeutic options derived from natural sources, such as plants and algae, particularly extracts and their bioactive compounds. These extracts and compounds have shown potential in inhibiting pancreatic lipase and other markers associated with obesity. Nevertheless, they also present certain limitations, including low bioavailability. In this context, combination therapy involving orlistat and these extracts or their compounds has emerged as a promising strategy. This approach aims to enhance the inhibition of pancreatic lipase and other obesity-related markers, thereby improving therapeutic outcomes and reducing adverse effects associated with treatment. The objective of this review is to analyze the available scientific evidence regarding the combined effects of orlistat and extracts or bioactive compounds in inhibiting various markers related to dyslipidemia and obesity, with the goal of proposing combination therapy as a safe and effective therapeutic option. Full article

The conversion of coal to biomethane is an environmentally friendly and sustainable method of coal utilization, and algae is a nutrient additive that enhances the economic sustainability of coal-to-biomethane production. The key regulatory factors and interaction mechanism of methane production were studied by carrying out anaerobic fermentation experiments on coal and microorganisms. Spearman correlation analysis, multiple linear regression, random forest and principal component analysis (PCA) were used to evaluate the effects of 14 coal-quality and microorganism composition parameters on methane production. The results showed that the hemicellulose content of microorganisms was significantly positively correlated with methane production, while total sugar and total fat significantly reduced the gas production. The protein content of microorganisms in a reasonable range could promote methane production. Among the coal-quality parameters, the C/H ratio (β = 0.43) and dry volatile matter (β = 0.17) had a weak positive contribution to methane production, while a high carbonization degree (C% > 80%; vitrinite reflectance > 1.2%) significantly inhibited the fermentation activity. The higher the maturity of the coal, the lower the methane production. The optimal methanogenic performance was concentrated in the combination of a low degree of coalification in coal (PC1 < −1.5) and high hemicellulose in microorganisms (PC2 > 1.8). In this study, a process optimization strategy was put forward, and the combination of low-rank coal with vitrinite reflectance < 0.5%, volatile matter > 35%, microorganisms with hemicellulose > 4.5%, and total sugar < 20% was optimized in an anaerobic fermentation experiment of coal and microorganisms. The results provide theoretical support for the directional control of anaerobic digestion of coal enhanced by microorganisms. Full article

Harmful algal blooms can negatively impact freshwater, estuarine, and coastal marine systems globally and pose serious risks to water quality, human and ecosystem health, and food production. Algae can produce toxic compounds, directly interfere with aquaculture species through (e.g.,) the production of foam or mucilage, as well as causing diseases and disorders in fish, and can result in hypoxic conditions when the bloom senesces. Application of US Environmental Protection Agency (USEPA) registered algaecides can be effective, scalable, and inexpensive, but there is growing interest in plant- or bacterial-derived compounds that do not require the use of chemicals such as hydrogen peroxide or copper. The algaecide C7X1 is a plant-based organic algaecide that proves effective against a wide variety of algae, including harmful algal species such as Microcystis, Heterosigma, and Pseudo-nitzschia. Performance is comparable to other USEPA-registered algaecides, with low to moderate extracellular toxin release and a potential lifetime of weeks in treated waters. The mode of action is inhibition of photosynthesis, suggesting that direct off-target impacts on zooplankton and other organisms would be minimal. Full article

Obesity and metabolic dysfunction-associated steatotic liver disease (MASLD) are major contributors to the rise in metabolic disorders, particularly in developed countries. Despite the need for effective therapies, natural product-based interventions remain underexplored. This study investigated the therapeutic effects of Endarachne binghamiae, a type of brown algae, hot water extract (EB-WE) in ameliorating obesity and MASLD using high-fat diet (HFD)-induced ICR mice for an acute obesity model (4-week HFD feeding) and C57BL/6 mice for a long-term MASLD model (12-week HFD feeding). EB-WE administration significantly reduced body and organ weights and improved serum lipid markers, such as triglycerides (TG), total cholesterol (T-CHO), HDL (high-density lipoprotein), LDL (low-density lipoprotein), adiponectin, and apolipoprotein A1 (ApoA1). mRNA expression analysis of liver and skeletal muscle tissues revealed that EB-WE upregulated Ampkα and Cpt1 while downregulating Cebpα and Srebp1, suppressing lipogenic signaling. Additionally, EB-WE activated brown adipose tissue through Pgc1α and Ucp1, contributing to fatty liver alleviation. Western blot analysis of liver tissues demonstrated that EB-WE enhanced AMPK phosphorylation and modulated lipid metabolism by upregulating PGC-1α and UCP-1 and downregulating PPAR-γ, C/EBP-α, and FABP4 proteins. It also reduced oxidation markers, such as OxLDL (oxidized low-density lipoprotein) and ApoB (apolipoprotein B), while increasing ApoA1 levels. EB-WE suppressed lipid peroxidation by modulating oxidative stress markers, such as SOD (superoxide dismutase), CAT (catalase), GSH (glutathione), and MDA (malondialdehyde), in liver tissues. Furthermore, EB-WE regulated the glucose regulatory pathway in the liver and muscle by inhibiting the expression of Sirt1, Sirt4, Glut2, and Glut4 while increasing the expression of Nrf2 and Ho1. Tentative liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis for EB-WE identified bioactive compounds, such as pyropheophorbide A and digiprolactone, which are known to have antioxidant or metabolic regulatory activities. These findings suggest that EB-WE improves obesity and MASLD through regulation of metabolic pathways, glucose homeostasis, and antioxidant activity, making it a promising candidate for natural product-based functional foods and pharmaceuticals targeting metabolic diseases. Full article

This study investigates the rare seaweed alga Dictyota bartayresiana lamour for biological activity. Antioxidant and antibacterial activities were examined. An MTT assay was carried out to examine cytotoxicity activity against colon cancer cells. The HPTLC analysis was performed for four different extracts, which exhibited clear flavonoid band formation at 254 nm and 366 nm with varied ranges of R_f values: methanolic extract (R_f 0.87), acetone extract (R_f 0.82), and benzene (R_f 0.83). Methanolic Extract Fraction One (MEF1) has a distinct band formation at 366 nm, it is shown to have the highest inhibition (6.20 ± 0.53 mm) against Escherichia coli, and the MTT assay reveals that the aqueous extract of Dictyota bartayresiana extract has an IC₅₀ value of 300 µg/mL. It is divulged that methanolic extract shows the highest phytochemical compound level among the four extracts of Dictyota bartayresiana. A GC/MS analysis was employed to investigate the flavonoid profile of the crude seaweed extract. Although LC/MS is typically preferred for flavonoid analysis due to thermal sensitivity, GC/MS was used in this study owing to time constraints, with optimized conditions to reduce thermal degradation. The GC-MS analysis identified Quinoline and other flavonoids, suggesting potential bioactivity. The cytotoxicity activity of MEF1 shows that the development of a promising drug may be evaluated from a seaweed source. The present study provides excellent insight with the first report of the biologically active compound of Dictyota bartayresiana. Full article

Background/Objectives: This study evaluated the potential of a polysaccharide (PCS) extracted from the brown alga Cystoseira spinosa as an antioxidant and anti-inflammatory agent. Collected off the coast of Alkhoms, Libya, PCS was investigated for its wound-healing and pro-angiogenic properties, addressing the need for natural bioactive compounds in therapeutic applications. Methods: The monosaccharide composition of PCS was analyzed using HPLC-RID, identifying glucuronic acid and xylose as major components. In vitro tests assessed antioxidant activity, while in vivo experiments on 24 rats evaluated wound healing. Rats were divided into four groups: control (saline), standard drug (CYTOL CENTELLA cream), glycerol, and glycerol+PCS. Wound healing was analyzed macroscopically, histologically, and biochemically. The chick chorioallantoic membrane (CAM) model assessed pro-angiogenic effects, and computational analyses explored COX-2 and VEGF pathways. Pharmacokinetic properties were also evaluated. Results: PCS demonstrated significant antioxidant activity and accelerated wound healing after 16 days, with improved wound appearance scores and increased collagen content. Histological analysis confirmed PCS outperformed the standard drug. The CAM model showed PCS increased blood vessel density, length, and junctions while reducing lacunarity. Computational analyses supported involvement of COX-2 and VEGF pathways. Pharmacokinetic assessments indicated good bioavailability, non-inhibition of CYP enzymes, and favorable skin permeability. Conclusions: PCS shows promise as a natural bioactive polymer for wound healing and tissue regeneration. Its antioxidant, anti-inflammatory, and pro-angiogenic properties, combined with favorable pharmacokinetics, highlight its therapeutic potential. This study provides new insights into the mechanisms of C. spinosa polysaccharides and their application in promoting tissue repair. Full article