Structural characterization and immunomodulating assessment of ultra-purified water extracted fucoidans from Saccharina latissima, Alaria esculenta and Laminaria hyperborea.

Fucoidans, a group of high molecular weight polysaccharides derived mainly from brown algae, are characterized by their high fucose content, degree of sulfation (DS), and intra- and interspecific structural variation. Fucoidans are increasingly recognized due to various reported bioactivities, potentially beneficial for human health. To unlock their potential use within biomedical applications, a better understanding of their structure-functional relationship is needed. To achieve this, systematic bioactivity studies based on well-defined, pure fucoidans, and the establishment of standardized, satisfactory purification protocols are required. We performed a comprehensive compositional and structural characterization of crude and ultra-purified fucoidans from three kelps: Saccharina latissima (SL), Alaria esculenta (AE) and Laminaria hyperborea (LH). Further, the complement-inhibiting activity of the purified fucoidans was assessed in a human whole blood model. The purification process led to fucoidans with higher DS and fucose and lower concentrations of other monosaccharides. Fucoidans from SL and LH resembles homofucans, while AE is a heterofucan rich in galactose with comparably lower DS. Fucoidans from SL and LH showed complement-inhibiting activity in blood and blood plasma, while no inhibition was observed for AE under the same conditions. The results emphasize the importance of high DS and possibly fucose content for fucoidans' bioactive properties.

Psychrosphaera algicola sp. nov. and Paraglaciecola algarum sp. nov., and reclassification of Pseudoalteromonas elyakovii, Pseudoalteromonas flavipulchra, and Pseudoalteromonas profundi as later heterotypic synonyms of P. distincta, P. maricaloris, and P. gelatinilytica.

Two Gram-negative, obligately aerobic, rod-shaped bacteria, strains G1-22T and G1-23T, were isolated from the phycosphere of a marine brown alga. Both strains exhibited catalase- and oxidase-positive activities. Strain G1-22T displayed optimal growth at 25 °C, pH 8.0, and 2.0-3.0% (w/v) NaCl, while strain G1-23T exhibited optimal growth at 25 °C, pH 8.0, and 4.0% NaCl. Ubiquinone-8 was identified as the sole isoprenoid quinone in both strains. As major fatty acids (> 5%), strain G1-22T contained C16 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), C12 : 1 3-OH, and C10 : 0 3-OH, while strain G1-23T contained C16 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), and C14 : 0. Phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were major polar lipids in both strains. Strains G1-22T and G1-23T had DNA G+C contents of 40.2 and 38.9 mol%, respectively. Phylogenetic analyses based on 16S rRNA and genome sequences revealed that strains G1-22T and G1-23T formed distinct phylogenetic lineages within the genera Psychrosphaera and Paraglaciecola, respectively. Strain G1-22T showed closest relatedness to Psychrosphaera ytuae MTZ26T with 97.8% 16S rRNA gene sequence similarity, 70.2% average nucleotide identity (ANI), and a 21.5% digital DNA-DNA hybridization (dDDH) value, while strain G1-23T was most closely related to Paraglaciecola aquimarina KCTC 32108T with 95.6% 16S rRNA gene sequence similarity, 74.6% ANI, and a 20.1% dDDH value. Based on phenotypic and molecular characteristics, strains G1-22T and G1-23T are proposed to represent two novel species, namely Psychrosphaera algicola sp. nov. (type strain G1-22T=KACC 22486T=JCM 34971T) and Paraglaciecola algarum sp. nov. (type strain G1-23T=KACC 22490T=JCM 34972T), respectively. Additionally, based on the comparison of whole genome sequences, it is proposed that Pseudoalteromonas elyakovii, Pseudoalteromonas flavipulchra, and Pseudoalteromonas profundi are reclassified as later heterotypic synonyms of Pseudoalteromonas distincta, Pseudoalteromonas maricaloris, and Pseudoalteromonas gelatinilytica, respectively.

Resistance of Nile tilapia fed with Padina boergesenii extract to Pseudomonas putida infection.

The aim of this research was to estimate the immunopotentiation effect of brown algae Padina boergesenii water extract on Nile tilapia, Oreochromis niloticus through resistance to Pseudomonas putida infection. Gas Chromatography Mass Spectrometry was utilized to characterize the seaweed phytoconstituents. One hundred and twenty-six fish were divided in triplicates into two equal groups corresponding to two diet variants that used to feed Nile tilapia for 20 successive days: a basal (control), and P. boergesenii water extract supplemented group. Fish samples were collected at 10-days intervals throughout the experiment. Serum biochemical constituents, total antioxidant capacity (TAC), and some immune related genes expression of the spleen and intestinal tissues of experimental fish were studied, as well as histological examination of fish immune tissues. Moreover, following 20 days of feeding, the susceptibility of Nile tilapia to P. putida infection was evaluated to assess the protective effect of the used extract. The findings indicated that the studied parameters were significantly increased, and the best immune response profiles were observed in fish fed P. boergesenii water extract for 20 successive days. A bacterial challenge experiment using P. putida resulted in higher survival within the supplemented fish group than the control. Thus, the lowered post-challenge mortality of the fish may be related to the protection provided by the stimulation of the innate immune system, reduced oxidative stress by higher activity of TAC, and elevated levels of expression of iterleukin-1beta (IL-1ß), beta-defensin (ß-defensin), and natural killer-lysin (NKl). Moreover, the constituents of the extract used showed potential protective activity for histological features of the supplemented fish group when compared to the control. Collectively, this study presents a great insight on the protective role of P. boergesenii water extract as an additive in Nile tilapia feed which suggests its potential for improving the immune response against P. putida infection.

2,7-Phloroglucinol-6,6'-bieckol from Ecklonia cava ameliorates nanoplastics-induced premature endothelial senescence and dysfunction.

Nanoplastics (NPs), plastic particles ranging from 1 to 100 nm are ubiquitous environmental pollutants infiltrating ecosystems. Their small size and widespread use in various products raise concerns for human health, particularly their association with cardiovascular diseases (CVD). NPs can enter the human body through multiple routes, causing oxidative stress, and leading to the senescence and dysfunction of endothelial cells (ECs). Although there are potential natural compounds for treating CVD, there is limited research on preventing CVD induced by NPs. This study investigates the efficacy of Ecklonia cava extract (ECE) in preventing NPs-induced premature vascular senescence and dysfunction. Exposure of porcine coronary arteries (PCAs) and porcine coronary ECs to NPs, either alone or in combination with ECE, demonstrated that ECE mitigates senescence-associated ß-galactosidase (SA-ß-gal) activity induced by NPs, thus preventing premature endothelial senescence. ECE also improved NPs-induced vascular dysfunction. The identified active ingredient in Ecklonia cava, 2,7'-Phloroglucinol-6,6'-bieckol (PHB), a phlorotannin, proved to be pivotal in these protective effects. PHB treatment ameliorated SA-ß-gal activity, reduced oxidative stress, restored cell proliferation, and decreased the expression of cell cycle regulatory proteins such as p53, p21, p16, and angiotensin type 1 receptor (AT1), well known triggers for EC senescence. Moreover, PHB also improved NPs-induced vascular dysfunction by upregulating endothelial nitric oxide synthase (eNOS) expression and restoring endothelium-dependent vasorelaxation. In conclusion, Ecklonia cava and its active ingredient, PHB, exhibit potential as therapeutic agents against NPs-induced premature EC senescence and dysfunction, indicating a protective effect against environmental pollutants-induced CVDs associated with vascular dysfunction.

Bioadsorption of crude petroleum oil from seawater using the marine alga Hormophysa triquetra mediated silver nanoparticles.

The biosynthesis of silver nanoparticles, both economically and environmentally advantageous, uses algae extracts. In the current work, we extracted the marine brown alga Hormophysa triquetra (C. Agardh) kützing and used it to make silver nanoparticles (HAgNPs) which are characterized via UV-visible spectrophotometers, Transmission Electron Microscopy (TEM), Zeta potential, and FTIR then used them in the bio adsorption of crude petroleum oil from seawater, comparing them with H. triquetra aqueous extract. UV scan of the phycosynthesized silver nanoparticles achieved the highest absorption at 369 nm. TEM showed that the synthesized HAgNPs occur with smooth, spherical, and semispherical forms with sizes ranging from 12.04 to 20.67 nm, zeta potential illustrated that HAgNPs were charged with -22.1, The H. triquetra aqueous extract's FTIR examination identified several active groups like - OH, -C=C-, NO, -CH, CCl, -C ≡ C-H: CH which are responsible for the bioadsorption of crude petroleum oil. When extracting crude petroleum oil from seawater, HAgNPs worked better than its aqueous extract. The maximum removal % for light n-alkanes (Ln-alk), heavy n-alkanes (Hn-alk), and PAHs were 70.4 %, 71.63 %, and 75.38 % respectively for H. triquetra aqueous extract with adsorption capacity 889, 511, 273 µg/g at salinity 36 % and pH 5, while in case of HAgNPs the results were 75.81 %, 77.15 %, and 80.56 %, respectively with adsorption capacity 957, 550, 292 µg/g at the same salinity and pH.

Comparative structure and evolution of the organellar genomes of Padina usoehtunii (Dictyotales) with the brown algal crown radiation clade.

BACKGROUND: Organellar genomes have become increasingly essential for studying genetic diversity, phylogenetics, and evolutionary histories of seaweeds. The order Dictyotales (Dictyotophycidae), a highly diverse lineage within the Phaeophyceae, is long-term characterized by a scarcity of organellar genome datasets compared to orders of the brown algal crown radiation (Fucophycidae). RESULTS: We sequenced the organellar genomes of Padina usoehtunii, a representative of the order Dictyotales, to investigate the structural and evolutionary differences by comparing to five other major brown algal orders. Our results confirmed previously reported findings that the rate of structural rearrangements in chloroplast genomes is higher than that in mitochondria, whereas mitochondrial sequences exhibited a higher substitution rate compared to chloroplasts. Such evolutionary patterns contrast with land plants and green algae. The expansion and contraction of the inverted repeat (IR) region in the chloroplast correlated with the changes in the number of boundary genes. Specifically, the size of the IR region influenced the position of the boundary gene rpl21, with complete rpl21 genes found within the IR region in Dictyotales, Sphacelariales and Ectocarpales, while the rpl21 genes in Desmarestiales, Fucales, and Laminariales span both the IR and short single copy (SSC) regions. The absence of the rbcR gene in the Dictyotales may indicate an endosymbiotic transfer from the chloroplast to the nuclear genome. Inversion of the SSC region occurred at least twice in brown algae. Once in a lineage only represented by the Ectocarpales in the present study and once in a lineage only represented by the Fucales. Photosystem genes in the chloroplasts experienced the strongest signature of purifying selection, while ribosomal protein genes in both chloroplasts and mitochondria underwent a potential weak purifying selection. CONCLUSIONS: Variations in chloroplast genome structure among different brown algal orders are evolutionarily linked to their phylogenetic positions in the Phaeophyceae tree. Chloroplast genomes harbor more structural rearrangements than the mitochondria, despite mitochondrial genes exhibiting faster mutation rates. The position and the change in the number of boundary genes likely shaped the IR regions in the chloroplast, and the produced structural variability is important mechanistically to create gene diversity in brown algal chloroplast.

Sulfur release behavior and sulfur fixation mechanism during biomass microwave co-pyrolysis of Ascophyllum and rice straw.

Co-pyrolysis with low-sulfur biomass is expected to improve the yield and quality of bio-fuels, without the usage of calcium-based desulfurizer. Sulfur transformation during microwave fluidized-bed co-pyrolysis between terrestrial and marine biomass (Ascophyllum, AS; Rice straw, RS) was investigated. Sulfur release was promoted during biomass co-pyrolysis, but it was inhibited during pyrolysis between AS and low-sulfur char. Thermal cracking of biomass was promoted during co-pyrolysis between biomass, accelerating the combination of H atoms and -SH radicals. Introduction of low-sulfur bio-char (CA) inhibited the generation of bio-char and the release of sulfur. Released sulfur was captured by -OH/C = C functional groups on bio-char through dehydration reactions/addition reactions, forming mercaptan in bio-char. Furthermore, introduction of microwave and bio-char promoted the cyclization and aromatization reaction, converting mercaptan to thiophene and improving the thermal stability of solid sulfur, and thus increasing in-situ sulfur fixation rate.

Direct Itaconate Production from Brown Macroalgae Using Engineered Vibrio sp. dhg.

Itaconate is a promising platform chemical with broad applicability, including the synthesis of poly(methyl methacrylate). Most studies on microbial itaconate production entail the use of crop-based feedstock, which imposes constraints due to its limited supply. Brown macroalgae have recently gained attention as next-generation biomass owing to their high biomass productivity and carbohydrate content and amenability to mass production. Therefore, the use of macroalgae for itaconate production warrants exploration. In this study, the direct production of itaconate from brown macroalgae was demonstrated using engineered Vibrio sp. dhg, which has emerged as an efficient platform host for brown macroalgal biorefineries. Specifically, to enhance production, cis-aconitate decarboxylase (Cad) from Aspergillus terreus was heterologously expressed and isocitrate dehydrogenase (icd) was deleted. Notably, the resulting strain, VIC, achieved itaconate titers of 2.5 and 1.5 g/L from a mixture of alginate and mannitol (10 g/L of each) and 40 g/L of raw Saccharina japonica (S. japonica), respectively. Overall, this study highlights the utility of brown macroalgae as feedstock, as well as that of Vibrio sp. dhg as a platform strain for improving itaconate bioproduction.

Refined linkage analysis of the sulphated marine polysaccharide fucoidan of Cladosiphon okamuranus with a focus on fucose.

Methylation followed by depolymerization and gas chromatography (GC) is an effective methodology for the linkage analysis of polysaccharides, including fucoidan, a sulphated algal polysaccharide. However, this sample material demands attention to experimental details to prevent aberrations in the analytical result. The use of deficient bases for methylation, the presence of water, analyte degradation during hydrolysis, and coelution of the target analytes during gas chromatography create doubts about published results. We therefore investigated critical parameters of the method and carefully optimized the steps of the protocol to ensure the integrity of the results for the fucose monomers. Fucoidan from Cladosiphon okamuranus was used as reference sample to determine the glycosidic bonds, and sulphate positions in the monomer. Fucoidan in protonated form was methylated in a strictly water-free environment using lithium dimsyl as base and methyl iodide for methylation. The methylated polymer was isolated by solid phase extraction, which was crucial to recover also the highly sulfated fraction. Hydrolysis was conducted with trifluoroacetic acid. To separate all target analytes in GC-FID/MS, a stationary phase with high cyanopropyl content (HP-88) was required, as the commonly employed phenyl siloxane phases result in co-elution, which distorts the result severely.

A Comparative Analysis of the Anti-Tumor Activity of Sixteen Polysaccharide Fractions from Three Large Brown Seaweed, Sargassum horneri, Scytosiphon lomentaria, and Undaria pinnatifida.

Searching for natural products with anti-tumor activity is an important aspect of cancer research. Seaweed polysaccharides from brown seaweed have shown promising anti-tumor activity; however, their structure, composition, and biological activity vary considerably, depending on many factors. In this study, 16 polysaccharide fractions were extracted and purified from three large brown seaweed species (Sargassum horneri, Scytosiphon lomentaria, and Undaria pinnatifida). The chemical composition analysis revealed that the polysaccharide fractions have varying molecular weights ranging from 8.889 to 729.67 kDa, and sulfate contents ranging from 0.50% to 10.77%. Additionally, they exhibit different monosaccharide compositions and secondary structures. Subsequently, their anti-tumor activity was compared against five tumor cell lines (A549, B16, HeLa, HepG2, and SH-SY5Y). The results showed that different fractions exhibited distinct anti-tumor properties against tumor cells. Flow cytometry and cytoplasmic fluorescence staining (Hoechst/AO staining) further confirmed that these effective fractions significantly induce tumor cell apoptosis without cytotoxicity. qRT-RCR results demonstrated that the polysaccharide fractions up-regulated the expression of Caspase-3, Caspase-8, Caspase-9, and Bax while down-regulating the expression of Bcl-2 and CDK-2. This study comprehensively compared the anti-tumor activity of polysaccharide fractions from large brown seaweed, providing valuable insights into the potent combinations of brown seaweed polysaccharides as anti-tumor agents.

Projected loss of brown macroalgae and seagrasses with global environmental change.

Although many studies predict extensive future biodiversity loss and redistribution in the terrestrial realm, future changes in marine biodiversity remain relatively unexplored. In this work, we model global shifts in one of the most important marine functional groups-ecosystem-structuring macrophytes-and predict substantial end-of-century change. By modelling the future distribution of 207 brown macroalgae and seagrass species at high temporal and spatial resolution under different climate-change projections, we estimate that by 2100, local macrophyte diversity will decline by 3-4% on average, with 17 to 22% of localities losing at least 10% of their macrophyte species. The current range of macrophytes will be eroded by 5-6%, and highly suitable macrophyte habitat will be substantially reduced globally (78-96%). Global macrophyte habitat will shift among marine regions, with a high potential for expansion in polar regions.

Chemical constituents from a marine medicinal brown alga-derived Xylaria acuta SC1019.

In this study, a marine medicinal brown alga Sargassum cristaefolium-derived fungal strain Xylaria acuta SC1019 was isolated and identified. Column chromatography of the extracts from liquid- and solid-fermented products of the fungal strain was carried out, and led to the isolation of twenty-one compounds. Their structures were characterized by spectroscopic analysis, and the absolute configurations were further established by single X-ray diffraction analysis or modified Mosher's method as nine previously undescribed compounds, namely xylarilactones A-C (1-3), ent-gedebic acid 8-O-α-D-glucopyranoside (4), 5R-hydroxylmethylmellein 11-O-α-D-glucopyranoside (5), ent-hymatoxin E 16-O-α-D-mannopyranoside (6), 19,20-epoxycytochalasin S (7), 19,20-epoxycytochalasin T (8), and (2R)-butylitaconic acid (9), along with twelve known compounds 10-21. All the isolates were subjected to anti-inflammatory and anti-angiogenic assays. Compounds 1, 5, 7, 10, and 17 showed moderate nitric oxide production inhibitory activities in lipopolysaccharide-activated BV-2 microglial cells with IC50 values of 19.55 ± 0.35, 16.10 ± 0.57, 15.20 ± 0.87, 11.76 ± 0.49, and 11.30 ± 0.32 µM, respectively, as compared to curcumin (IC50 = 2.69 ± 0.34 µM) without any significant cytotoxicity. Compounds 7, 8, and 21 displayed potent anti-angiogenic activities by suppressing the growth of human endothelial progenitor cells with IC50 values of 0.44 ± 0.01, 0.47 ± 0.03, and 0.53 ± 0.01 µM, respectively, as compared to sorafenib (IC50 = 5.50 ± 1.50 µM).

Optimizing extraction methods by a comprehensive experimental approach and characterizing polyphenol compositions of Ecklonia radiata.

Brown seaweed Ecklonia radiata harbors valuable polyphenols, notably phlorotannins, prized for their health benefits. This study optimized phlorotannin extraction via conventional solvent extraction and ultrasound-assisted extraction methods, utilizing variable concentrations of ethanol. Employing fractional factorial designs, key variables were identified. Steepest ascent/descent method and central composite rotatable designs refined optimal conditions, enhancing phlorotannin and polyphenol yields, and antioxidant capacities. Under optimized conditions, phlorotannin contents reached 2.366 ± 0.01 and 2.596 ± 0.04 PGE mg/g, total polyphenol contents peaked at 10.223 ± 0.03 and 10.836 ± 0.02 GAE mg/g. Robust antioxidant activity was observed: DPPH and OH radical scavenging capacities measured 27.891 ± 0.06 and 17.441 ± 0.08 TE mg/g, and 37.498 ± 1.12 and 49.391 ± 0.82 TE mg/g, respectively. Reducing power capacities surged to 9.016 ± 0.02 and 28.110 ± 0.10 TE mg/g. Liquid chromatography-mass spectrometry (LC-MS) and high-performance liquid chromatography (HPLC) analyses revealed enriched antioxidant compounds. Variations in polyphenol profiles were noted, potentially influencing antioxidant capacity nuances. This study illuminated the potential of E. radiata potential as a polyphenol source and offers optimized extraction methods poised to benefit various industries.

Mass spectrometric characterization of aminophospholipids containing N-(2-hydroxyethyl)glycine in kombu algae extracts.

RATIONALE: 1,2-Diacyl-sn-glycero-3-phospho-O-[N-(2-hydroxyethyl)glycines] (PHEGs) are a class of rare aminophospholipids found specifically in brown algae, including kombu seaweed. Despite their potential importance in algal physiology, a comprehensive mass spectrometry (MS) characterization, useful to understand their biological behaviour, is still lacking. METHODS: To establish the structural regiochemical features of PHEGs, we employed hydrophilic interaction liquid chromatography (HILIC). Following separation, the isolated band of PHEGs was analyzed using MS techniques. This included multistage tandem MS experiments, performed in both positive and negative electrospray ionization modes at low and high resolution. RESULTS: By comparing MS/MS and MS3 spectra acquired in negative ion mode, the regiochemical rules for PHEG identification were established. The most abundant PHEG species in kombu seaweed, from both Laminaria ochroleuca (European Atlantic) and Laminaria longissima (Japan), was identified as PHEG 20:4/20:4. Less abundant species included PHEG 20:4/20:5 and hydroxylated forms of both PHEG 20:4/20:4 (i.e. 40:8;O) and 20:4/20:5 (40:9;O). The presence of a lyso PHEG 20:4 was consistently detected but at very low levels. CONCLUSIONS: This study employed MS analysis to elucidate the regiochemical patterns of PHEGs in kombu seaweed. We identified PHEG 20:4/20:4 as the dominant species, along with several less abundant variants, including hydroxylated forms. These findings provide valuable insights into the potential roles and metabolism of PHEGs in brown algae, paving the way for further investigation into their biological functions.

Chemically modified seaweed polysaccharides: Improved functional and biological properties and prospective in food applications.

Seaweed polysaccharides are natural biomacromolecules with unique physicochemical properties (e.g., good gelling, emulsifying, and film-forming properties) and diverse biological activities (e.g., anticoagulant, antioxidant, immunoregulatory, and antitumor effects). Furthermore, they are nontoxic, biocompatible and biodegradable, and abundant in resources. Therefore, they have been widely utilized in food, cosmetics, and pharmaceutical industries. However, their properties and bioactivities sometimes are not satisfactory for some purposes. Modification of polysaccharides can impart the amphiphilicity and new functions to the biopolymers and change the structure and conformation, thus effectively improving their functional properties and biological activities so as to meet the requirement for targeted applications. This review outlined the modification methods of representative red algae polysaccharides (carrageenan and agar), brown algae polysaccharides (fucoidan, alginate, and laminaran), and green algae polysaccharides (ulvan) that have potential food applications, including etherification, esterification, degradation, sulfation, phosphorylation, selenylation, and so on. The improved functional properties and bioactivities of the modified seaweed polysaccharides and their potential food applications are also summarized.

Improving the shelf life of minced beef by Cystoseira compressa polysaccharide during storage.

A polysaccharide extracted from the brown alga Cystoseira compressa (CCPS) was evaluated as a food additive to extend the shelf-life of raw beef meat. The antioxidant potential of CCPS was demonstrated by its inhibition of ß-carotene bleaching (64.28 %), superoxide radicals (70.12 %), and hydroxyl radicals (93 %) at a concentration of 10 mg/ml. The polysaccharide also showed antibacterial activity with MIC values between 6.25 mg/ml and 50 mg/ml against five foodborne pathogenic bacteria. Furthermore, CCPS exhibited excellent functional, foaming, and emulsifying properties. Furthermore, microbiological and chemical effects of CCPS at concentrations equivalent to 1 MIC (CCPS-1), 2 MIC (CCPS-2), and 4 MIC (CCPS-3) were conducted. Chemical analyses showed that treated beef had significantly reduced TBARS levels below 2 mg MDA/kg at day 14. The treatment also decreased carbonyl groups, improved heme iron transformation, inhibited microbial growth (p < 0.05), and kept MetMb levels below 40 % by day 14. Moreover, two multivariate approaches, principal component analysis (PCA) and hierarchical cluster analysis (HCA), were effectively used to analyze the results characterizing the main attributes of the stored meat samples. In conclusion, these findings demonstrated that CCPS could be employed as a functional and bioactive component in the meat industry.

Physiochemical changes, metabolite discrepancies of brown seaweed-derived sulphated polysaccharides in the upper gastrointestinal tract and their effects on bioactive expression.

Brown seaweed-derived polysaccharides, notably fucoidan and laminarin, are known for their extensive array of bioactivities and physicochemical properties. However, the effects of upper digestive tract modification on the bioactive performance of fucoidan and laminarin fractions (FLFs) sourced from Australian native species are largely unknown. Here, the digestibility and bioaccessibility of FLFs were evaluated by tracking the dynamic changes in reducing sugar content (CR), profiling the free monosaccharide composition using LC-MS, and comparing high-performance gel permeation chromatography profile variation via LC-SEC-RI. The effects of digestive progression on bioactive performance were assessed by comparing the antioxidant and antidiabetic potential of FLFs and FLF digesta. We observed that molecular weight (Mw) decreased during gastric digestion indicating that FLF aggregates were disrupted in the stomach. During intestinal digestion, Mw gradually decreased and CR increased indicating cleavage of glycosidic bonds releasing free sugars. Although the antioxidant and antidiabetic capacities were not eliminated by the digestion progression, the bioactive performance of FLFs under a digestive environment was reduced contrasting with the same concentration level of the undigested FLFs. These data provide comprehensive information on the digestibility and bioaccessibility of FLFs, and shed light on the effects of digestive progression on bioactive expression.

Application of MALDI-MS for characterization of fucoidan hydrolysates and screening of endo-fucoidanase activity.

Brown macroalgae synthesize large amounts of fucoidans, sulfated fucose-containing polysaccharides, in the ocean. Fucoidans are of importance for their recently discovered contribution to marine carbon dioxide sequestration and due to their potential applications in biotechnology and biomedicine. However, fucoidans have high intra- and intermolecular diversity that challenges assignment of structure to biological function and the development of applications. Fucoidan-active enzymes may be used to simplify this diversity by producing defined oligosaccharides more applicable for structural refinement, characterization, and structure to function assignment for example via bioassays. In this study, we combined MALDI mass spectrometry with biocatalysis to show that the endo-fucoidanases P5AFcnA and Wv323 can produce defined oligosaccharide structures directly from unrefined macroalgal biomass. P5AFcnA released oligosaccharides from seven commercial fucoidan extracts in addition to unrefined biomass of three macroalgae species indicating a broadly applicable approach reproducible across 10 species. Both MALDI-TOF/TOF and AP-MALDI-Orbitrap systems were used, demonstrating that the approach is not instrument-specific and exploiting their combined high-throughput and high-resolution capabilities. Overall, the combination of MALDI-MS and endo-fucoidanase assays offers high-throughput evaluation of fucoidan samples and also enables extraction of defined oligosaccharides of known structure from unrefined seaweed biomass.

New cytotoxic spatane diterpenoids from marine alga Stoechospermum marginatum.

Three new spatane diterpenoids (1-3) were isolated from the brown alga Stoechospermum marginatum together with three known compounds (4-6). The structures of these compounds were determined by the detailed NMR spectroscopic and Mass spectrometric analyses. All the isolated compounds were screened for their cytotoxic potentials against a panel of four human cancer cell lines, which include DU145 (Prostate), B16F10 (Melanoma), MDA MB-231 (Breast), and HeLa (Cervical) along with a normal cell line (HEK). The screening results indicated that compounds 1, 4 and 5 displayed significant activities against B16F10 [IC50, 6.21 ± 0.14, 5.88 ± 0.21, 5.31 ± 0.24 µM] and MDA MB-231 [9.25 ± 0.61, 4.59 ± 0.14, 4.19 ± 0.13 µM] cell lines, respectively. In view of their significant activity, these compounds 1, 4 and 5 were further taken up for detailed fluorescence assays, scratch assay and flow cytometry analysis, which revealed that they diminished proliferation and arrested cell cycle in the S phase and G2/M phase, which induced cell death by apoptosis. Overall, based on their considerable results, these compounds could serve as lead molecules in the development of anticancer drug candidates.

Exploring Bioactive Components and Assessing Antioxidant and Antibacterial Activities in Five Seaweed Extracts from the Northeastern Coast of Algeria.

The main goal of this study was to assess the bioactive and polysaccharide compositions, along with the antioxidant and antibacterial potentials, of five seaweeds collected from the northeastern coast of Algeria. Through Fourier transform infrared spectroscopy analysis and X-ray fluorescence spectroscopy, the study investigated the elemental composition of these seaweeds and their chemical structure. In addition, this study compared and identified the biochemical makeup of the collected seaweed by using cutting-edge methods like tandem mass spectrometry and ultra-high-performance liquid chromatography, and it searched for new sources of nutritionally valuable compounds. According to the study's findings, Sargassum muticum contains the highest levels of extractable bioactive compounds, showing a phenolic compound content of 235.67 ± 1.13 µg GAE·mg-1 and a total sugar content of 46.43 ± 0.12% DW. Both S. muticum and Dictyota dichotoma have high concentrations of good polyphenols, such as vanillin and chrysin. Another characteristic that sets brown algae apart is their composition. It showed that Cladophora laetevirens has an extracted bioactive compound content of 12.07% and a high capacity to scavenge ABTS+ radicals with a value of 78.65 ± 0.96 µg·mL-1, indicating high antioxidant activity. In terms of antibacterial activity, S. muticum seaweed showed excellent growth inhibition. In conclusion, all five species of seaweed under investigation exhibited unique strengths, highlighting the variety of advantageous characteristics of these seaweeds, especially S. muticum.