Ulva Rigida Research Articles

The effect of foliar application of Ulva rigida extract on the growth and biochemical parameters of wheat plants

Many research studies have shown the importance of seaweed extract in agriculture. Marine macroalgae are rich in diverse compounds like lipids, proteins, carbohydrates, phytohormones, amino acids, osmoprotectants and minerals. In this study, we have tried to characterize Moroccan macroalgae species Ulva rigida collected from the coastal area of Akhfenir in order to evaluate their potential to improve growth plant. The proximate composition, mineral element (Ca, K, Mg, Na and Cl), pigments, amino acid, proteins, lipids, polyphenol contents were determined in liquid extract obtained from green seaweed (SWE) Ulva rigida. Results show that the application of SWE at different concentrations (0,12.5, 25, 50%) significantly enhanced growth parameters, especially with 25% of seaweed liquid extract. Therefore, algal treatment by foliar application is proved to be an effective technique to improve the growth of wheat plants. This study provides important information on the characterization, identification and utilization of seaweed resources for agriculture as biostimulants.

Environmental-friendly pretreatment and process optimization of macroalgal biomass for effective ethanol production as an alternative fuel using Saccharomyces cerevisiae

Abstract Fossil fuel depletion and gas limitations require tremendous efforts to the production of renewable energy from environmental-friendly and sustainable sources. The third-generation bioethanol from non-lignocellulosic biomass of macroalgae is an effective candidate for renewable and sustainable fuel–making that mainly involves pretreatment, enzyme hydrolysis, and microbial fermentation. Therefore, the purpose of this research was to develop a consolidated process for the effective conversion of macroalgal biomass into third-generation bioethanol. The pretreatment of two macroalgae biomasses (namely Ulva rigida and Ulva intestinalis) was optimized using a steam explosion, compared with ultrasonication, to maximize the fermentable reducing sugars yield. A condition of pressure at 25 psi and pretreatment time of 15 min by steam explosion pretreatment of U. intestinalis was the best condition for maximizing fermentable reducing sugars up to 5.41 g/L, generating 86.6 kJ/L of energy. In subsequent enzyme hydrolysis of pretreated biomass, using commercial cellulose enhanced the fermentable reducing sugars up to 6.18 g/L. Fermentation of the hydrolysate using yeast Saccharomyces cerevisiae produced 0.12 g–ethanol/g–fermentable reducing sugar in a short time with ethanol productivity of 2.54 mg–ethanol/g–fermentable reducing sugar/h. Interestingly, the produced ethanol can be converted into energy up to 21.91 kJ/L. This study demonstrates the macroalgal biomass is a suitable feedstock of non-lignocellulosic biomass for third-generation bioethanol production and the developed process confirmed the practical, low-cost, and non-polluting conversion of macroalgal biomass into bioethanol based renewable energy.

Profiling the activity of edible European macroalgae towards pharmacological targets for type 2 diabetes mellitus

ABSTRACT In traditional medicine marine extracts are extensively used as therapies for diabetes. With the increasing rate of incidence of type 2 diabetes mellitus and rising cost of treatments, we investigated the anti-diabetic properties of extracts of common edible seaweeds in Europe including their ability to inhibit alpha-glucosidase and dipeptidyl peptidase 4 (DPP-4) enzymatic activity, block sodium glucose transporter-2 (SGLT-2) activity and stimulate glucagon-like peptide-1 (GLP-1) secretion and synthesis. The most promising seaweed extracts were tested for anti-hyperglycaemic activity in vivo. Some brown seaweed (Phaeophyceae) extracts had inhibitory effects on alpha-glucosidase ranging from 13.9 ± 0.2% to 89.5 ± 0.4% (p < 0.001). However, none of the seaweed extracts was able to block SGLT-2 activity. Ethanol extracts of the kelp Alaria esculenta and water extracts of Laminaria digitata strongly inhibited DPP-4 activity by 91.3 ± 0.1% and 90.0 ± 0.2%, respectively (p < 0.001), while ethanol extracts of Ulva rigida (Chlorophyta) had the greatest potential to stimulate GLP-1 secretion and GLP-1 synthesis (p < 0.001). A water extract of Porphyra linearis (Rhodophyta) significantly reduced the overall glycaemic excursion during an oral glucose tolerance test in normal mice (p < 0.05). These results demonstrate future potential for common edible seaweeds to be used as medicinal foods or bio-therapeutics to tackle type 2 diabetes mellitus by targeting GLP-1 secretion, DPP-4 activity or alpha-glucosidase activity.

Determination of total iodine content in edible seaweeds: Application of inductively coupled plasma-atomic emission spectroscopy

Iodine is an essential element necessary for the synthesis of thyroid hormones, and its deficiency is a common problem worldwide. To avoid iodine insufficiency, the intake of this element must be properly evaluated concerning its adequate intake (AI), which is estimated at 90, 150, and 200 μg per day, for children, adults, and pregnant women, respectively. One of the most abundant resources available for iodine is the consumption of edible seaweeds. In this work, ten species of edible seaweeds: one green (Ulva rigida), five red (Chondracanthus teedei var. lusitanicus, Chondrus crispus, Gracilaria gracilis, Grateloupia turuturu, Osmundea pinnatifida), and four brown species (Bifurcaria bifurcata, Fucus vesiculosus, Saccorhiza polyschides, Undaria pinnatifida), collected from the near-pristine Portuguese seashore, were analyzed for iodine content. The iodine concentration was determined by optimized microwave-assisted extraction in aqua regia (AR), followed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis. The method was validated by using the standard reference material (kelp) obtaining a maximum recovery of 100 ± 15%. The studied species contained a wide range of iodine concentrations, ranging from 33 ± 3 μg g−1 dry weight (dw) (U. rigida), up to 302 ± 26 μg g−1 dw (O. pinnatifida), 352 ± 21 μg g−1 dw (F. vesiculosus) and 391 ± 24 μg g−1 dw (B. bifurcata). The results show that the analyzed seaweeds can serve as a beneficial resource for iodine, however, their consumption must be balanced in a way that does not exceed the adequate estimated iodine intake for population groups.

Foliose Ulva Species Show Considerable Inter-Specific Genetic Diversity, Low Intra-Specific Genetic Variation, and the Rare Occurrence of Inter-Specific Hybrids in the Wild.

Foliose Ulva spp. have become increasingly important worldwide for their environmental and financial impacts. A large number of such Ulva species have rapid reproduction and proliferation habits, which explains why they are responsible for Ulva blooms, known as “green tides”, having dramatic negative effects on coastal ecosystems, but also making them attractive for aquaculture applications. Despite the increasing interest in the genus Ulva, particularly on the larger foliose species for aquaculture, their inter‐ and intra‐specific genetic diversity is still poorly described. We compared the cytoplasmic genome (chloroplast and mitochondrion) of 110 strains of large distromatic foliose Ulva from Ireland, Brittany (France), the Netherlands and Portugal. We found six different species, with high levels of inter‐specific genetic diversity, despite highly similar or overlapping morphologies. Genetic variation was as high as 82 SNPs/kb between Ulva pseudorotundata and U. laetevirens, indicating considerable genetic diversity. On the other hand, intra‐specific genetic diversity was relatively low, with only 36 variant sites (0.03 SNPs/kb) in the mitochondrial genome of the 29 Ulva rigida individuals found in this study, despite different geographical origins. The use of next‐generation sequencing allowed for the detection of a single inter‐species hybrid between two genetically closely related species, U. laetevirens, and U. rigida, among the 110 strains analyzed in this study. Altogether, this study represents an important advance in our understanding of Ulva biology and provides genetic information for genomic selection of large foliose strains in aquaculture.

Ultrasound assisted extraction of selected edible macroalgae: Effect on antioxidant activity and quantitative assessment of polyphenols by liquid chromatography with tandem mass spectrometry (LC-MS/MS)

Despite vast coastline and huge cultivation of macroalgae in India, bioactive compounds in the edible macroalgae have not been well characterized. Ultrasound assisted extraction and conventional extraction techniques were compared & characterized by extracting three edible macroalgae, viz., Sargassum wightii, Ulva rigida and Gracilaria edulis in methanol. Ultrasound assisted extract (120 min) of S. wightii showed significantly higher (p < 0.05) phenolic (19.27 ± 0.05 mg gallic acid equivalent/g) and flavonoid content (14.94 ± 0.65 mg quercetin equivalent/g) as well as antioxidant activity [evaluated by ferric reducing antioxidant power (8.21 ± 0.02 mg Trolox/g) and by 2,2-Diphenyl-1-picrylhydrazyl (87.79 ± 0.13%RSA) assay] when compared with conventional extraction. G. edulis showed highest yield (4.77 ± 0.24%) with conventional extraction at 120 min. Further, extracts of all macroalgae (ultrasound assisted extraction/120 min) characterized by liquid chromatography with tandem mass spectrometry for bioactives showed highest phloroglucinol (69.86 ± 5.25 mg/kg), fucoxanthin (1.45 ± 0.22 mg/kg) and gallic acid in the S. wighti; highest quercetin (0.07 ± 0.00 mg/kg) and ferulic acid (0.21 ± 0.04 mg/kg) in the U. rigida and the highest vanillin (0.39 ± 0.01 mg/kg) in the G. edulis. Liquid chromatography with tandem mass spectrometry results corroborated higher antioxidant activity seen with the ultrasound assisted extract. This study seems the first report on use of ultrasound assisted extraction for the selected Indian edible macroalgae & quantification of their bioactives. Results are highly relevant to the functional food & nutraceuticals industry for the potential exploitation of these edible macroalgae, especially, the brown seaweed, S. wightii.

Short-term effects of increased CO2, nitrate and temperature on photosynthetic activity in Ulva rigida (Chlorophyta) estimated by different pulse amplitude modulated fluorometers and oxygen evolution.

Short-term effects of pCO2 (700-380 ppm; High carbon (HC) and Low carbon (LC), respectively) and nitrate content (50-5 µM; High nitrogen (HN) and Low nitrogen (LN), respectively on photosynthesis were investigated in Ulva rigida (Chlorophyta) under solar radiation (in-situ) and in the laboratory under artificial light (ex-situ). After six days of incubation at ambient temperature (AT), algae were subjected to a 4 °C temperature increase (AT+4 °C) for 3 d. Both in-situ and ex-situ maximal electron transport rate (ETRmax) and in situ gross photosynthesis (GP), measured by O2 evolution, presented highest values under HCHN, and lowest under HCLN, across all measuring systems. Maximal quantum yield (Fv/Fm), and ETRmax of photosystem (PS) II [ETR(II)max] and PSI [ETR(I)max], decreased under HCLN at AT+4 °C. Ex situ ETR was higher than in situ ETR. At noon, Fv/Fm decreased (indicating photoinhibition), whereas ETR(II)max and maximal non-photochemical quenching (NPQmax) increased. ETR(II)max decreased under AT+ 4 °C in contrast to Fv/Fm, photosynthetic efficiency (α ETR) and saturated irradiance (EK). Thus, U. rigida exhibited a decrease in photosynthesis under acidification, changing LN, and AT+4 °C. These results emphasize the importance of studying the interaction between environmental parameters using in-situ versus ex-situ conditions, when aiming to evaluate the impact of global change on marine macroalgae.

Amino Acid Profile and Protein Quality Assessment of Macroalgae Produced in an Integrated Multi-Trophic Aquaculture System.

Seaweeds are a recognized source of bioactive compounds and techno-functional ingredients. However, its protein fraction is still underexplored. The aim of this study was to determine the total and free amino acid profile and protein content of four seaweeds species (Porphyra dioica, Porphyra umbilicalis, Gracilaria vermiculophylla, and Ulva rigida) produced in an integrated multi-trophic aquaculture system, while assessing their protein quality. Samples were submitted to acid and alkaline hydrolysis (total amino acids) and to an aqueous extraction (free amino acids) followed by an automated online derivatization procedure, and analyzed by reverse phase-high performance liquid chromatography. Protein-, non-protein and total-nitrogen were quantified by the Kjeldahl method. Crude and true protein contents were estimated based on the nitrogen and amino acid composition. Protein quality was assessed based on the amino acids profile. Porphyra species presented the highest protein content compared to the remaining three seaweed species tested. All samples presented a complete profile of essential amino acids and a high quality protein profile, according to World Health Organization and Food and Agriculture Organization standards. Methionine and tryptophan were the first limiting amino acids in all species. Red species (Porphyra and Gracilaria) presented high levels of free alanine, glutamic, and aspartic acids. The results highlight the potential of using seaweeds as an alternative and sustainable source of protein and amino acids for human nutrition and industrial food processing.

Recovery of pigments from Ulva rigida

Pigments, such as chlorophylls and carotenoids, have important applications in various fields, such as colorants in food, cosmetic or textile industries and in biomedical applications. Both pigments have an important role in the photosynthetic process and can be found in the marine green macroalgae genus Ulva. In this work, an integrated downstream process was developed to extract chlorophylls and carotenoids from those macroalgae. The solid-liquid extraction was optimized. For that, several conditions were tested, namely the use of different mechanical processes (maceration, microwave- or ultrasound- assisted extraction), type of solvent, number of consecutive extractions, solid-liquid ratio, and the design of the extraction process using a mechanical treatment. Using the extract obtained, a liquid-liquid extraction system composed of ethanol, hexane, and water was then studied. Different mixture points within the biphasic region were tested in terms of their ability to selectively separate chlorophylls and xanthophylls to opposite phases in a single step. The optimization and implementation of a simple, fast and efficient downstream process to separate both classes of pigments such as chlorophylls and xanthophylls from green macroalgae is reported. It could be applied to fractionate other extracts with similar compositions obtained from other natural sources.

Hypoxia and Acidification, Individually and in Combination, Disrupt Herbivory and Reduce Survivorship of the Gastropod, Lacuna vincta

Acidification and deoxygenation are two consequences of climate change that also co-occur in eutrophied coastal zones and can have deleterious effects on marine life. While the effects of hypoxia on marine herbivores have been well-studied, how ocean acidification combined with hypoxia affects herbivory is poorly understood. This study examined how herbivory and survival by the gastropod Lacuna vincta grazing on the macroalgae Ulva rigida was influenced by hypoxia and ocean acidification, alone and in combination, with and without food limitation. Experiments exposed L. vincta to a range of environmentally realistic dissolved oxygen (0.7 – 8 mg L-1) and pH (7.3 – 8.0 total scale) conditions for 3 – 72 h, with and without a starvation period and quantified herbivory and survival. While acidified conditions (pH < 7.4) reduced herbivory when combined with food limitation, low oxygen conditions (< 4 mg L-1) reduced herbivory and survival regardless of food supply. When L. vincta were starved and grazed in acidified and hypoxic conditions, respectively, herbivory was additively and synergistically reduced, respectively, with low oxygen having a more inhibitory effect than low pH. Shorter exposure times (9, 6, and 3 h) were required to reduce grazing at lower DO levels (~2.4, ~1.6, and ~0.7 mg L-1, respectively). Herbivory ceased entirely following a three-hour exposure to DO of 0.7 mg L-1 suggesting that episodes of diurnal hypoxia disrupt grazing by these gastropods. The suppression of herbivory in response to acidified and hypoxic conditions could create a positive feedback loop that promotes ‘green tides’ whereby reduced grazing facilitates the overgrowth of macroalgae that cause nocturnal acidification and hypoxia, further disrupting herbivory and promoting the growth of macroalgae. Such feedback loops could have broad implications for estuarine ecosystems where L. vincta is a dominant macroalgal grazer and will intensify as climate change accelerates.

Valuing Bioactive Lipids from Green, Red and Brown Macroalgae from Aquaculture, to Foster Functionality and Biotechnological Applications.

Marine edible macroalgae have functional proprieties that might improve human health and wellbeing. Lipids represent a minor fraction of macroalgae, yet with major interest as main carriers of omega 3 polyunsaturated fatty acids and intrinsic bioactive properties. In this study, we used lipid extracts from the green macroalgae Ulva rigida and Codium tomentosum; the red Gracilaria gracilis, Palmaria palmata and Porphyra dioica; and the brown Fucus vesiculosus, produced in a land-based integrated multitrophic aquaculture (IMTA) system. We determined the lipid quality indices based on their fatty acid profiles and their bioactivities as putative antioxidant, anti-inflammatory and antiproliferative agents. The results reveal to be species-specific, namely U. rigida displayed the lowest atherogenicity and thrombogenicity indices. Palmaria palmata and F. vesiculosus lipid extracts displayed the lowest inhibitory concentration in the free radical scavenging antioxidant assays. Ulva rigida, C. tomentosum, P. palmata and P. dioica inhibited COX-2 activity by up to 80%, while P. dioica and P. palmata extracts showed the highest cytotoxic potential in the MDA-MB-231 breast cancer cells. This work enhances the valorization of macroalgae as functional foods and promising ingredients for sustainable and healthy diets and fosters new applications of high-valued algal biomass, in a species-specific context.

Sulfated polysaccharides of some seaweeds exhibit neuroprotection via mitigation of oxidative stress, cholinergic dysfunction and inhibition of Zn \u2013 induced neuronal damage in HT-22 cells

BackgroundSulfated polysaccharides from marine algae are known to possess antioxidative activities, however, their therapeutic role in metal-induced neurodegeneration has not been explored. In this study, the neuroprotective potentials of sulfated polysaccharides isolated from Ecklonia maxima (PKPM), Gelidium pristoides (PMNP), Ulva lactuca (PULV), Ulva rigida (PURL) and Gracilaria gracilis (PGCL) against Zn-induced neurodegeneration in rats’ hippocampal neuronal cells (HT-22) were assessed.MethodsCells were cultured and maintained at 37 °C. Control cells did not contain Zinc sulphate (ZnSO4) while other experimental groups contain Zn (50 μM) alone or in combination with sulfated polysaccharides (0.4 or 0.8 mg/mL). Cell viability was assessed using MTT assay while apoptotic assay was also determined using acridine orange and ethidium bromide staining technique. Oxidative stress parameters (superoxide dismutase and catalase activities, glutathione and nitric oxide levels) and acetylcholinesterase activity were also assessed in neuronal cells treated with or without Zn.ResultsZn significantly reduced cell viability to about 50%. However, sulfated polysaccharides improved cell viability to about 95%. The sulfated polysaccharides also prevented late apoptosis and necrosis triggered by Zn. Furthermore, superoxide dismutase and catalase activities including glutathione content were significantly low in cells induced with Zn. Treatment with sulfated polysaccharides triggered a significant increase in antioxidant enzymes and glutathione content as well as a decrease in the activity of acetylcholinesterase in cells treated with Zn.ConclusionPKPM, PGCL, PURL, PULV and PMNP exhibit neuroprotective effects against neuronal damage induced by Zn and this may be attributed to inhibition of apoptosis, oxidative damage and acetylcholinesterase activity. These polysaccharides may be good therapeutic agents to protect neuronal cells against Zn - induced pathological processes associated with Alzheimer’s disease.

Исследование биологии и пищевой ценности Ulva rigida C. Ag., как перспективного объекта марикультуры

The haplodiplobion life cycle with sporic meiosis and isomorphic alternation&#x0D; of generations, the ability for vegetative reproduction, the rapid growth of&#x0D; thallus, a large amount of produced cells, and high specific production make&#x0D; Ulva rigida C. Ag. attractive for marine aquaculture. The paper is devoted to&#x0D; study biological features of Ulva growth and nutritional value under artificial&#x0D; conditions. It is shown how environmental factors affect the germination and&#x0D; formation of new plants. Preliminary data on nutritional value allow us to&#x0D; consider Ulva to low-calorie foods with a rich carbohydrate component. The&#x0D; mineral composition and a high concentration of iodine indicate the feasible&#x0D; usage of Ulva as a functional food ingredient.

Catalytic transformation of the marine polysaccharide ulvan into rare sugars, tartaric and succinic acids

The green macroalga Ulva rigida represents a promising feedstock for biorefinary due to its fast growth and cosmopolitan distribution. The main component of the cell walls of U. rigida is a sulfated glucuronorhamnan polysaccharide known as ulvan. Herein it was found that due to the high (hydrogen)sulfate group content of ulvan, hydrothermal autohydrolysis at 130 °C renders a high percentage of rhamnose (78–79 % recovery from the initial content in the raw material), a rare sugar of high added value. In addition, acid catalysis by a triflate-based graphene oxide under oxygen-free conditions at 180 °C affords moderate amounts of tartaric acid (24–26 %). The same triflate-based graphene oxide catalyst under oxygen pressure yields remarkably high percentages of succinic acid (65 %). The catalyst preserves its activity for at least five consecutive reuses.

Use of technological processing of seaweed and microalgae as strategy to improve their apparent digestibility coefficients in European seabass (Dicentrarchus labrax) juveniles

Algae are natural sources of nutrients, but the presence of anti-nutritional factors often compromises nutrient apparent digestibility coefficients (ADCs) in several fish species. In this study, physical-mechanical and enzymatic technological processing was applied to two seaweeds (Gracilaria gracilis and Ulva rigida) and three microalgae (Nannochloropsis oceanica, Chlorella vulgaris, and Tetraselmis sp.) in order to evaluate its effectiveness in improving nutrient ADC values in diets for European seabass. A practical commercial-based diet was used as reference (REF) and experimental diets were prepared by replacing 30% of REF diet with each test alga used either intact or after processing. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fast performance liquid chromatography (FPLC) analyses revealed that enzymatic processing was more effective than the physical one in changing the protein and peptides composition, increasing the amount of low-molecular-weight compounds in seaweeds and N. oceanica microalgae. Protein digestibility was significantly affected by algae species and in the case of the microalgae by the technological process. Gracilaria gracilis is better digested than U. rigida and physical processing enhanced protein and energy ADC values. Nannochloropsis oceanica and C. vulgaris are better digested than Tetraselmis sp.; the highest protein and energy ADCs were observed in diets containing enzymatically processed N. oceanica (NAN-ENZ) and physically processed C. vulgaris (CHLO-PHY), followed by the diet with physically processed Tetraselmis sp. (TETR-PHY). Results clearly showed that it is possible to increase nutrient accessibility and digestibility of algae by fish, by selecting the most adequate method to disrupt the cell wall. Moreover, the physical-mechanical and enzymatic technological processes used in this study are scalable to the industrial level.

Comparative genoprotection ability of wild-harvested vs. aqua-cultured Ulva rigida coupled with phytochemical profiling

Antigenotoxic properties of plant- and plant-like derived foods may embody nutritional strategies against DNA damage. Marine macroalgae have shown DNA-protective effects, but their nutraceutical potential and the influence of growing conditions on these properties is underexplored. Hence, we aimed to assess the genoprotection potential of wild-harvested vs. aquacultured Ulva rigida on Drosophila melanogaster, following a dietary exposure, in the presence and absence of a genotoxic agent (streptonigrin) using phytochemical profiling. DNA damage was evaluated with a single cell gel electrophoresis (comet) assay improved with endonucleases. An origin-based phytochemical profile was found, with aquacultured algae showing higher relative amounts of fatty alcohols, sterols, sesquiterpenoids and glycerol esters. Although U. rigida from both sources showed a DNA-protective action, especially against streptonigrin-induced genotoxicity, aquacultured algae demonstrated higher potential, which may be linked to the distinctive phytochemical profile. Overall, this study provided scientific evidence for the genoprotective activity of U. rigida and its confirmation as a functional food.

A short pulse of dietary algae boosts immune response and modulates fatty acid composition in juvenileOreochromis niloticus

Considering algae as novel dietary ingredient for aquafeeds, this study evaluates the effects of three algae, Ulva rigida, Crassiphycus corneus (formerly Hydropuntia cornea) and Scenedesmus almeriensis, on non-specific immune response and fatty acid profile in juvenile Nile tilapia (Oreochromis niloticus) after a short dietary administration period (30 days). U. rigida, C. corneus and S. almeriensis diets (UL-25, CC-25 and SC-25 respectively) included 25% dry algae biomass, whereas an algae-free diet was used as control. Biological samples were taken at 7, 15 and 30 days. Diet SC-25 significantly improved respiratory burst, alternative complement (ACH50) and lysozyme activity (p < .05). Regarding tissue fatty acid composition, SC-25 diet reduced the levels of saturated fatty acid in liver and muscle, while increased levels of C20:3n6 and eicosapentaenoic acid (EPA) in liver, and total n-3 content, arachidonic acid (ARA), EPA and docosahexaenoic acid (DHA) in muscle (p < .05). UL-25 and CC-25 groups showed the lowest levels of ARA in liver but increased levels of monounsaturated fatty acids. In conclusion, the results obtained lead us to consider the use of a short pulse of dietary algae is suited for improving the immune response and modulating the tissue fatty acid composition in this fish species.

Umami free amino acids in edible green, red, and brown seaweeds from the Portuguese seashore

The fifth basic taste—umami—is based on hydrophilic monosodium L-glutamate (L-Glu), and, to a smaller extent, on L-aspartate (L-Asp), which can be found in free form in seaweeds. The umami taste can be elicited by the synergistic effect of 5′-nucleotides, guanosine-5′-monophosphate (GMP), and inosine-5′-monophosphate (IMP). In this work, twelve edible seaweeds, two green (Codium tomentosum, Ulva rigida), six red (Chondracanthus teedei var. lusitanicus, Chondrus crispus, Gracilaria gracilis, Grateloupia turuturu, Nemalion helminthoides, Osmundea pinnatifida), and four brown (Bifurcaria bifurcata, Fucus vesiculosus, Saccorhiza polyschides, Undaria pinnatifida), from the Portuguese seashore, were selected for the analysis of umami amino acids and 5′-nucleotides. To determine the concentrations of umami free compounds, L-Glu, L-Asp, GMP, and IMP, the usual procedure for the preparation of seaweed’s broth was carried out, and the resulting extracts were analyzed by HPLC-DAD. The effect of the seaweed’s pretreatment, oven-dried and lyophilized, was also studied. Results showed that all seaweed species contained free amino acids in broad range, whereas umami 5′-nucleotides were not detected. The lyophilized C. crispus and G. gracilis contained the highest amounts of free L-Glu (627 ± 109 mg (100 g)−1 and 398 ± 67 mg (100 g)−1, respectively) and L-Asp (520 ± 102 mg (100 g)−1 and 270 ± 10 mg (100 g)−1, respectively). Two-factor PCA explained quantitatively (90%) the variance of seaweed species based on umami L-Glu content after different drying techniques applied. The results indicate that lyophilization constitutes a superior procedure for increasing the umami potential in most of the selected seaweeds.

Seasonal plasticity of the polar lipidome of Ulva rigida cultivated in a sustainable integrated multi-trophic aquaculture

Green macroalgae of the genus Ulva, commonly known as sea lettuces, are currently traded worldwide for multiple applications, including human consumption. In this work, we evaluated the seasonal variation of the total content of lipids, esterified fatty acids (FAs) and polar lipids (the major carriers of FAs) at the level of the classes and molecular species of Ulva rigida cultivated in Portugal in a land-based integrated multitrophic aquaculture (IMTA) system. Comparing winter, spring, summer and autumn samples, the lipid content and abundance of unsaturated FAs, namely n-3 polyunsaturated FAs, were highest in winter and lowest in summer. However, regardless of seasonal variations, U. rigida had a low n-6/n-3 ratio in all seasons, which is associated with health benefits. Among the polar lipids, those that varied the most were betaines, glycolipids and phospholipids, including a high number of lysolipid species that increased during autumn and spring. Multivariate analysis using principal component analysis (PCA) showed better discrimination of the four seasons when the dataset on molecular lipid species was used. Knowledge of the seasonal variability of lipid composition in biomass of Ulva rigida can be used to better explore these green macroalgae as a source of bioactive polar lipids with high market value.

Antioxidant Activity Correlated with Chlorophyll Pigments and Magnesium Content of Some Green Seaweeds

The complex valorification of seaweed biomass represents a highly important resource for the pharmaceutical and dermo-cosmetic industry, supplying raw material for the extraction of bioactive substances such as, polysaccharides, vitamins, sterols, aminoacids, polyphenols and minerals. Marine algae represent an indefatigability resource of therapeutic active principles for diseases treatment of magnesium deficiency. The presence of chlorophyll pigments in the green algae confirms the magnesium existence, as central element in molecular structures. The main green algae, as Ulva lactuca and Enteromorpha intestinalis present on the Romanian Black Sea Coast, belong to Chlorophyta sp. In this paper we present a study of antioxidant activity correlated with magnesium content and chlorophyll pigments of the green algae Enteromorpha intestinalis and Ulva rigida (syn. Ulva lactuca) hydroalcoholic extracts. For chlorophyll pigments determination, the UV-Vis spectrometry was used. Magnesium content had been determined by absorption atomic spectrometry method, using HR-CS- AAS ContraA 700 apparatus, Analytik Jena and for total antioxidant capacity of green algae extracts, the photochemiluminescence method had been applied, using Photochem Analytik Jena apparatus. The comparative studies on two marine green algae extracts confirm the high magnesium content correlated with a high level of total antioxidant capacity for both species. The results obtained emphasize the possibility to enlarge the options to use these natural vegetal resources from Black Sea Coast, in different degenerative diseases therapy.