Search Results (195)

Background: Alginate is a naturally occurring anionic polysaccharide extracted from brown marine algae and widely explored for biomedical applications due to its biocompatibility and functional versatility. This study aims to extract and compare alginates from two Red Sea brown algae, Turbinaria ornata (TA) and Hormophysa cuneiformis (HA), and to evaluate how structural differences influence their therapeutic properties. Methods: Alginate was isolated by sequential acid–alkaline extraction and characterized using FTIR, XRD, TGA, elemental analysis, and HPLC. Biological activities were assessed through antioxidant, anti-inflammatory, antidiabetic, neuroprotective, and hepatoprotective assays, supported by molecular docking and gene ontology interaction analysis. Results: Distinct physicochemical variations were observed between HA and TA. TA exhibited stronger antioxidant (IC₅₀ = 25.89 µg/mL), anti-inflammatory (COX-1 IC₅₀ = 69.61 µg/mL), antidiabetic (α-amylase IC₅₀ = 45.14 µg/mL), and hepatoprotective activities (IC₅₀ = 118.21 µg/mL), whereas HA displayed superior neuroprotective potential through butyrylcholinesterase inhibition (IC₅₀ = 39.01 µg/mL). Molecular docking supported the in vitro findings by confirming interactions with key protein targets associated with oxidative stress and metabolic pathways. Conclusions: Structural variation between species-derived alginates directly impacts their biological activities. TA represents a promising candidate for metabolic and anti-inflammatory therapies, while HA may be more suitable for neuroprotective interventions. These results emphasize the importance of source-specific alginate selection for developing targeted pharmaceutical applications. Full article

Background: The Kingdom of Saudi Arabia is adjacent to two vital marine ecosystems; the semi-enclosed Arabian Gulf and the largely landlocked Red Sea. Dinoflagellates are repeatedly found in these bodies of marine water, which serve as significant routes for cargo ships. Through these ships and ballast water, invasive dinoflagellate species and their cysts are introduced. They compete with indigenous species for nutrients and space, cause massive fish kill-off and disturb the ecological balance and biodiversity. To address these threats, the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) set forth guidelines intended to curtail the dissemination of such detrimental organisms. The Kingdom of Saudi Arabia was one of the co-signatory countries to this Convention. Methods of detection and monitoring include microscopy, molecular characterization and remote sensing, which are employed for the detection and monitoring of these harmful algae, in order to avert disasters such as fish die-offs. The results of several reports confirmed the presence of number of dinoflagellates in both the Arabian Gulf and the Red Sea, some of which are toxin producers, with certain species being highlighted as invasive species whose presence requires a high level of alert. Discussion: The monitoring, the change in engineering of cargo ships and the introduction of advanced surveillance methods, together with the proper treatments of ballast water, are all important security elements that ensure the safe disposal of ballast water without introducing harmful species. Full article

Colaconema daviesii has been described as an epi-endophyte of red algae. However, it has also been observed in vitro to colonize thalli of Macrocystis pyrifera, a giant kelp classified as a foundational organism of coastal marine ecosystems. This study aimed to determine, through co-cultivations, how C. daviesii affects the early stages of M. pyrifera, specifically gametophyte and sporophyte development. Determined were growth, oogonia formation, and gametophyte fertility, as well as sporophyte growth rate and survival. The results showed that the presence of C. daviesii negatively altered oogonia production and gametophyte fertility. Moreover, the survival of young sporophytes in co-cultures decreased. These findings demonstrate that the early developmental stages of M. pyrifera could be susceptible to infestation by a filamentous red alga, with negative consequences on fitness. Full article

Earth hosts a remarkable diversity of life, with oceans covering over 70% of its surface and supporting the greatest abundance and variety of species, including a vast range of seaweeds. Among these, red seaweeds (Rhodophyta) represent the most diverse group and are particularly rich in bioactive compounds. Grateloupia turuturu Yamada and Porphyra umbilicalis Kütz. are two species with significant biotechnological and functional food potential. They contain high levels of phycobiliproteins, sulfated polysaccharides (e.g., carrageenan, agar, porphyran), mycosporine-like amino acids (MAAs), phenols, minerals, and vitamins, including vitamin B12 (rare among non-animal sources). Several analytical methods, such as spectrophotometry, chromatography, and mass spectrometry, have been used to characterize their chemical composition. In vitro and in vivo studies have demonstrated their antioxidant, anti-inflammatory, neuroprotective, immunostimulatory, anti-proliferative, and photoprotective effects. These bioactive properties support its application in the food, pharmaceutical, and cosmetic sectors. Given the growing demand for sustainable resources, these algae species stand out as promising candidates for aquaculture and the development of functional ingredients. Their incorporation into novel food products, such as snacks and fortified dairy and meat products, underscores their potential to support health-promoting diets. This review highlights G. turuturu and P. umbilicalis chemical richness, bioactivities, and applications, reinforcing their value as sustainable marine resources. Full article

Temperature affects the morphology, physiology, and distribution of marine macroalgae, as supported by studies that used long-term data from herbaria. In the present study, sea surface temperature (SST), latitudinal distribution, and La Niña or El Niño years were correlated to the morphology of two macroalgal species of the Mexican Pacific: Ceratodictyon tenue and C. variabile. Twenty-four morphological characteristics were evaluated, and 95 samples from 1965 to 2013 in the Escuela Nacional de Ciencias Biológicas herbarium were reviewed. In 2017, 2023, and 2024, 12 specimens were sampled at three locations. Low positive correlations were found between thallus diameter and SST for C. tenue, while low positive correlations were detected for thallus length and medullary cell diameter vs. SST and medullary cell length vs. year for C. variabile. Significant relationships were found between the thallus length and cortical cell diameter of C. variabile with latitude and SST. It is concluded that SST contributes to changes in morphology, but is not the only factor that affects them. For the first time in a tropical area, the present study explores whether there is a relationship between SST, latitudinal distribution, and El Niño and La Niña years and the morphology of a genus of red algae. Full article

Late Pleistocene coastal deposits on the southeastern coast of Formentera (Es Ram–Es Estufadors) provide a high-resolution record of sea-level and climatic fluctuations associated with Marine Isotope Stage (MIS) 5. Three distinct beach levels (Sef-1, Sef-2, Sef-3) were identified, corresponding to substages MIS 5e, 5c, and possibly 5a, based on sedimentological features, fossil assemblages, and Optically Stimulated Luminescence (OSL) dating. The oldest beach level (Sef-1) is attributed to MIS 5e (ca. 128–116 ka) and is characterised by the widespread presence of thermophilic Senegalese fauna—including Thetystrombus latus, Conus ermineus, and Linatella caudata—which mark the onset of this interglacial phase and are associated with two peaks in relative sea-level highstand. A subsequent cooling event during MIS 5d is recorded by the development of thin palaeosols and the disappearance of these warm-water taxa. The second beach level (Sef-2) reflects renewed sea-level rise and warmer conditions during MIS 5c, with abundant macrofauna and red algae. The transition to MIS 5b (~97 ka) is marked by a significant sea-level drop (down to –60 m), cooler climate, and enhanced colluvial sedimentation linked to increased runoff and erosion. In total, 54 macrofaunal species were identified—16 from Sef-1 and 46 from Sef-2—highlighting ecological shifts across substages. These results improve our understanding of coastal response to sea-level oscillations and paleoenvironmental dynamics in the western Mediterranean during the Late Pleistocene. Full article

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

This study examines the environmental challenges posed by azo-dye pollutants and aluminum industrial waste. Aluminum oxide nanoparticles (P/Al₂O₃-NPs) were produced using a green method that utilized pharmaceutical packaging waste as an aluminum source and marine algae extract (Padina pavonica) as reducing and stabilizing agents and that was characterized by XRD, EDX, SEM, TEM, and zeta potential. Batch biosorption studies were performed to assess the effectiveness of P/Al₂O₃-NPs in removing CR dye from aqueous solutions. The results demonstrate that the particle sizes range from 58.63 to 86.70 nm and morphologies vary from spherical to elliptical. FTIR analysis revealed Al–O lattice vibrations at 988 and 570 cm⁻¹. The nanoparticles displayed a negative surface charge (−13 mV) and a pH_zpc of 4.8. Adsorption experiments optimized parameters for CR dye removal, achieving 97.81% efficiency under native pH (6.95), with a dye concentration of 30 mg/L, an adsorbent dosage of 0.1 g/L, and a contact time of 30 min. Thermodynamic studies confirmed that the process is exothermic and spontaneous. Kinetic data fit well with the pseudo-second-order model, while equilibrium data aligned with the Langmuir isotherm. The adsorption mechanism involved van der Waals forces, hydrogen bonding, and π–π interactions, as supported by the influence of pH, isotherm data, and FTIR spectra. Overall, the study demonstrates the potential of eco-friendly P/Al₂O₃-NPs to efficiently remove CR dye from aqueous solutions. Full article

Chronic pain affects approximately 20% of the global adult population, posing significant healthcare and economic challenges. Effective management requires addressing both biological and psychosocial factors, with emerging therapies such as antioxidants and marine algae offering promising new treatment avenues. Marine algae synthesize bioactive compounds, including polyphenols, carotenoids, and sulfated polysaccharides, which modulate oxidative stress, inflammation, and neuroimmune signaling pathways implicated in pain. Both preclinical and clinical studies support their potential application in treating inflammatory, neuropathic, muscular, and chronic pain conditions. Notable constituents include polyphenols, carotenoids (such as fucoxanthin), vitamins, minerals, and sulfated polysaccharides. These compounds modulate oxidative stress and inflammatory pathways, particularly by reducing reactive oxygen species (ROS) and downregulating cytokines such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Brown and red algae produce phlorotannins and fucoidans that alleviate pain and inflammation in preclinical models. Carotenoids like fucoxanthin demonstrate neuroprotective effects by influencing autophagy and inflammatory gene expression. Algal-derived vitamins (C and E) and minerals (magnesium, selenium, and zinc) contribute to immune regulation and pain modulation. Additionally, sulfated polysaccharides suppress microglial activation in the central nervous system (CNS). Marine algae represent a promising natural source of bioactive compounds with potential applications in pain management. Although current evidence, primarily derived from preclinical studies, indicates beneficial effects in various pain models, further research is necessary to confirm their efficacy, safety, and mechanisms in human populations. These findings advocate for the continued exploration of marine algae as complementary agents in future therapeutic strategies. Full article

The exploitation of underutilised resources is critical for achieving a sustainable society, and non-edible seaweeds are promising candidates. This study focused on the red alga Portieria hornemannii from Okinawa, Japan, a seaweed with a distinctive aroma, and determined its volatile organic compounds (VOCs) and halogenated secondary metabolites using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) at various extraction temperatures. HS-SPME-GC-MS analysis revealed 52 VOCs in Okinawan P. hornemannii, including predominant compounds α-pinenyl bromide (IUPAC name: 2-bromomethyl-6,6-dimethylbicyclo [3.1.1]hept-2-ene; halogenated monoterpene), myrcene disulfide (3-(6-methyl-2-methylidenehept-5-enylidene)dithiirane), and 5,6-dimethyl-1H-benzimidazole, the content of which in the extract increased with increasing extraction temperature from 30 to 60 °C. On the other hand, the β-myrcene (7-methyl-3-methyleneocta-1,6-diene) content, which likely contributes majorly to the distinct fresh odour of the algae, declined as the temperature increased. Furthermore, the proportion of β-myrcene obtained using SPME was significantly higher than that extracted using solvent liquid extraction (SLE) (7.20% in SPME at 30 °C vs. 0.09%, respectively). However, SLE-GC-MS provided a different P. hornemannii volatile profile, allowing for the acquisition of more furan-, alcohol-, ester-, and carboxylic acid-containing compounds. These data provide valuable information, such as a systematic analytical framework for volatiles profiling in the marine macroalgae P. hornemannii, with potential applicability in the development of food and fragrance products. Full article

The depletion of the ozone layer and climate change have increased exposure to ultraviolet (UV) radiation, driving the search for natural photoprotective agents. Marine macroalgae, particularly Gracilaria sp. (Rhodophyta) and Sargassum polyceratium (Ochrophyta), are rich in UV-absorbing bioactives, such as mycosporine-like amino acids (MAAs) and fucoxanthin, offering natural alternatives to synthetic sunscreens. This study aimed to develop and optimize a nanoemulsion incorporating both algal extracts, with MAAs and fucoxanthin strategically distributed in the aqueous and oil phases, respectively, to enhance synergistic broad-spectrum UV protection. MAAs were quantified in Gracilaria sp. using UHPLC-DAD, revealing 8.03 mg/g dry weight, primarily composed of shinorine and porphyra-334. Fucoxanthin was identified in S. polyceratium at 0.98 mg/g dry weight. A Box–Behnken design (BBD) was employed to optimize the nanoemulsion, targeting minimal droplet size and optimal ζ potential. The resulting formulation achieved a droplet size less than 100 nm and a ζ potential less than −25.0 mV. In vitro spectrophotometric analysis demonstrated significant photoprotective potential. The nanoemulsion containing only 375 ppm of algal extracts exhibited a UVA ratio of 1.25 and a critical wavelength of 379 nm, meeting the criteria for broad-spectrum protection and outperforming the commercial natural filter Helioguard^®365. These results confirm the efficacy of combining red and brown algae extracts in a nanoemulsion platform to deliver sustainable, low-dose photoprotection. This work presents, for the first time, the incorporation of red and brown algae extracts into a single nanoemulsion system, representing a novel strategy to maximize the combined photoprotective potential of MAAs and fucoxanthin. Ultimately, this investigation contributes to the growing field of marine-derived sunscreens and supports the advancement of “blue beauty” innovations aligned with eco-conscious formulation principles. Full article

Polychaetes are important marine invertebrates that contribute to sediment bioturbation, nutrient recycling, and food web dynamics. This study examines the diversity and structure of the polychaete assemblages associated with the red algae Corallina officinalis in areas with different levels of anthropogenic pressures of the Northeastern Adriatic Sea. Sampling was performed in the intertidal zones. Altogether, 54 species from 13 families were found, with Syllidae being the most abundant. Polychaete richness, relative abundance and diversity at sampling locations with and without anthropogenic pressures showed no significant difference. Multivariate analyses revealed significant differences in species composition between sites under anthropogenic pressures and those without, with key species such as Sphaerosyllis pirifera, Syllis rosea, Syllis prolifera, Syllis gerundensis, and Platynereis dumerilii playing significant roles. Syllis rosea was the most abundant in locations without anthropogenic pressures, while S. pirifera was the most abundant in locations under anthropogenic pressures. These results suggest that while polychaete communities are resilient, anthropogenic pressures are causing shifts in species composition. This pattern is consistent with the results of related studies, indicating a broader ecological trend. The shifts observed here should raise concern among conservation ecologists, underscoring the importance of long-term monitoring to understand and mitigate the impacts of human activities on coastal ecosystems. Full article

Bromophenols (BPs), particularly those derived from marine sources, are known for their potent radical scavenging activity, effectively neutralizing reactive oxygen species (ROS). However, their exact mechanism of action remains largely unexplored, limiting our understanding of their potential as natural antioxidants. In this study, the antiradical mechanisms of two BP derivatives (1 and 2), previously isolated from the marine red alga Polysiphonia urceolata, were systematically investigated using thermodynamic and kinetic calculations. Both compounds demonstrated potent hydroperoxyl radical (HOO^•) scavenging activity in polar and lipid environments, with rate constants surpassing those of the well-known antioxidant standards Trolox and BHT. In lipid media, BP 2 exhibited approximately 600-fold greater activity than BP 1, with rate constants of 9.75 × 10⁵ and 1.64 × 10³ M⁻¹ s⁻¹, respectively. In contrast, both BPs showed comparable activity in aqueous media, with rate constants of 3.46 × 10⁸ and 9.67 × 10⁸ M⁻¹ s⁻¹ for 1 and 2, respectively. Mechanistic analysis revealed that formal hydrogen atom transfer (f-HAT) is the predominant pathway for radical scavenging in both lipid and polar environments. These findings provide critical insights into the antiradical mechanisms of natural BPs and underscore the potential of BP 1 and BP 2 as highly effective hydroperoxyl radical scavengers under physiological conditions. Full article

The diffusive availability of CO₂ for photosynthesis is orders of magnitude lower in water than in air. This, and the low affinity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) for CO₂, implies that most marine photoautotrophs (cyanobacteria, microalgae, macroalgae and marine angiosperms or seagrasses) would be severely restricted were they to rely only on dissolved CO₂ for their photosynthetic performance. On the other hand, the ~120 times higher concentration of bicarbonate (HCO₃⁻) makes this inorganic carbon (Ci) form more available for utilisation by marine photosynthesisers. The most common way in marine macrophytes to utilise HCO₃⁻ is to convert it to CO₂ within acidic micro-zones of diffusion boundary layers (DBLs), including the cell walls, as catalysed by an outwardly acting carbonic anhydrase (CA). This would then generate an intra-chloroplastic (or for cyanobacteria intra-carboxysomal) CO₂-concentrating mechanism (CCM). Some algae (e.g., the common macroalgae Ulva spp.) and most cyanobacteria and microalgae feature direct HCO₃⁻ uptake as the most efficient CCM, while others (e.g., some red algae growing under low-light conditions) may rely on CO₂ diffusion only. We will in this contribution summarise our current understanding of photosynthetic carbon assimilation of submerged marine photoautotrophs, and in particular how their ‘biophysical’ CCMs differ from the ‘biochemical’ CCMs of terrestrial C₄ and Crassulacean Acid Metabolism (CAM) plants (for which there is very limited evidence in cyanobacteria, algae and seagrasses). Full article

Among algae that synthesize paralytic shellfish toxins (PSTs), Alexandrium tamarense is a widely distributed and highly dangerous species with significant impacts on the marine environment and human health. Therefore, establishing fast and reliable monitoring technology for Alexandrium tamarense is crucial. Developing effective detection and early warning systems for toxic red tides is of paramount importance. Conventional detection methods, such as microscopy and molecular biology, are complex and time-consuming, requiring specialized personnel and equipment, which makes them unsuitable for on-site rapid testing. In this study, we successfully developed polyclonal and monoclonal antibodies targeting Alexandrium tamarense using colloidal gold immunochromatography technology. Based on these antibodies, we created colloidal gold test strips capable of detecting Alexandrium tamarense in water samples. These test strips enable rapid detection of the target algae in aquatic environments and semi-quantitative estimation of algal concentrations using a colorimetric card. They can quickly determine whether the concentration of red tide algae has reached a critical level, allowing for timely preventive measures. This innovation holds significant practical value and broad application potential. Full article