Chemical Composition and Antioxidant Potential of Five Algae Cultivated in Fully Controlled Closed Systems.

In this study, the chemical composition and antioxidant profile of five edible macroalgae, Fucus vesiculosus, Palmaria palmata, Porphyra dioica, Ulva rigida, and Gracilaria gracilis, cultivated in fully controlled closed systems, were determined. Protein, carbohydrates, and fat contents ranged between 12.4% and 41.8%, 27.6% and 42.0%, and 0.1% and 3.4%, respectively. The tested seaweeds presented considerable amounts of Ca, Mg, K, Mn, and Fe, which reinforce their favorable nutritional profile. Regarding their polysaccharide composition, Gracilaria gracilis and Porphyra dioica were rich in sugars common to agar-producing red algae, and Fucus vesiculosus was composed mainly of uronic acids, mannose, and fucose, characteristic of alginate and fucoidans, whereas rhamnose and uronic acid, characteristic of ulvans, predominated in Ulva rigida. Comparatively, the brown F. vesiculosus clearly stood out, presenting a high polysaccharide content rich in fucoidans, and higher total phenolic content and antioxidant scavenging activity, determined by DPPH and ABTS. The remarkable potential of these marine macroalgae makes them excellent ingredients for a wide range of health, food, and industrial applications.

A commercial blend of macroalgae and microalgae promotes digestibility, growth performance, and muscle nutritional value of European seabass (Dicentrarchus labrax L.) juveniles.

Algae can leverage aquaculture sustainability and improve the nutritional and functional value of fish for human consumption, but may pose challenges to carnivorous fish. This study aimed to evaluate the potential of a commercial blend of macroalgae (Ulva sp. and Gracilaria gracilis) and microalgae (Chlorella vulgaris and Nannochloropsis oceanica) in a plant-based diet up to 6% (dry matter basis) on digestibility, gut integrity, nutrient utilization, growth performance, and muscle nutritional value of European seabass juveniles. Fish (11.3 ± 2.70 g) were fed with isoproteic, isolipidic, and isoenergetic diets: (i) a commercial-type plant-based diet with moderate fishmeal (125 g kg-1 DM basis) and without algae blend (control diet; Algae0), (ii) the control diet with 2% algae blend (Algae2), (iii) the control diet with 4% algae blend (Algae4), and (iv) the control diet with 6% algae blend (Algae6) for 12 weeks. The digestibility of experimental diets was assessed in a parallel study after 20 days. Results showed that most nutrients and energy apparent digestibility coefficients were promoted by algae blend supplementation, with a concomitant increase in lipid and energy retention efficiencies. Growth performance was significantly promoted by the algae blend, the final body weight of fish fed Algae6 being 70% higher than that of fish fed Algae0 after 12 weeks, reflecting up to 20% higher feed intake of algae-fed fish and the enhanced anterior intestinal absorption area (up to 45%). Whole-body and muscle lipid contents were increased with dietary algae supplementation levels by up to 1.79 and 1.74 folds in Algae 6 compared to Algae0, respectively. Even though the proportion of polyunsaturated fatty acids was reduced, the content of EPA and DHA in the muscle of algae-fed fish increased by nearly 43% compared to Algae0. The skin and filet color of juvenile European seabass were significantly affected by the dietary inclusion of the algae blend, but changes were small in the case of muscle, meeting the preference of consumers. Overall results highlight the beneficial effects of the commercial algae blend (Algaessence®) supplementation in plant-based diets for European seabass juveniles, but feeding trials up to commercial-size fish are needed to fully assess its potential.

Bioprospecting antibiotic properties in photodynamic therapy of lipids from Codium tomemtosum and Chlorella vulgaris.

The growing resistance from pathogens against antibiotics has increased the research for new compounds and strategies with antibacterial potential. Lipids from algae are emerging as natural and potent bioactive molecules with interesting results regarding the inactivation of bacteria, viruses, and fungi. The combination of algae lipids with innovative strategies, such as antibacterial photodynamic therapy (aPDT) can enhance their antimicrobial potential. In this work, we aimed to evaluate the antibacterial potential in aPDT of total lipid extracts and polar lipid fractions from the green macroalga, Codium tomentosum, and the green microalga, Chlorella vulgaris on a Gram-positive bacteria Staphylococcus aureus. Total lipid extracts and polar lipid fractions were characterized by LC-MS. The results revealed that the total extracts of algae promote S. aureus inhibition after light irradiation, with a decrease of ca. 6 log10 (CFU/mL) after 15 min of treatment with both extracts of algae. The polar lipid fractions, composed by phospholipids, glycolipids and betaine lipids, from C. tomentosum and C. vulgaris also revealed antibacterial potential in combination with aPDT, but a decrease of ca. 6 log10 (CFU/mL) was reached at 60 min of treatment, later than with the total extracts. These results unveil algae lipids as antibacterial compounds in combination with aPDT displaying an alternative from natural origin to tackle pathogen resistance.

Dietary supplementation with Gracilaria gracilis by-products modulates the immune status and oxidative stress response of gilthead seabream (Sparus aurata) stimulated with Photobacterium damselae subsp. piscicida.

This study evaluated the effects of agar waste (AW) dietary supplementation, obtained from the seaweed Gracilaria gracilis cultivated under two different spectral lights, neutral (NT) and blue (BL), on haematological parameters, inflammatory response, and antioxidant biomarkers of gilthead seabream (Sparus aurata). Three diets were prepared: i) a basal diet (CTR), ii) a diet supplemented with 2.5% NT, and iii) a diet supplemented with 2.5% BL. After 15 days of feeding, fish were injected with PBS (placebo) or inactivated Photobacterium damselae subsp. piscicida (stimulated) and sampled at 4 h and 24 h post-stimulus. Results indicated that fish fed NT and BL supplemented diets had lower Ht value and mean corpuscular volume (MCV) than fish fed the CTR diet, regardless of the stimulus and the sampling time. No differences in mean corpuscular haemoglobin (MCH) were found between fish fed the different diets, while the mean corpuscular haemoglobin concentration (MCHC) increased in fish fed AW supplemented diets compared to fish fed the CTR diet, regardless of the stimulus and the sampling time. In response to inflammation, fish fed the NT diet displayed higher neutrophils count in blood when compared to the CTR group, regardless of the stimulus and sampling time. Thrombocyte count was higher in fish fed NT and BL diets than in the CTR group, especially in the stimulated fish (Diet*injection (D*I), P = 0.004). An increase in plasma protease activity was detected in fish fed NT or BL diets in both placebo and stimulated fish regardless of the sampling time. Hepatic catalase activity was higher in fish fed the NT and BL than in the CTR group, particularly in the stimulated fish (D*I, P < 0.001). In addition, both stimulated and placebo fish that received the BL diet showed an increase in hepatic GR activity compared to the CTR group, regardless of the sampling time. Dietary supplementation with AW by-products obtained from G. gracilis cultured under NT and BL conditions showed to improve the inflammatory and antioxidant mechanisms in gilthead seabream in response to a UV-killed bacterial stimulus, having valuable applications for the sustainable use of seaweed toward improving the health and welfare of cultured fish.

The Red Seaweed Grateloupia turuturu Prevents Epidermal Dysplasia in HPV16-Transgenic Mice.

The role of dietary profiles in promoting or reducing the risk of multiple types of cancer is increasingly clear, driving the search for balanced foods and nutraceuticals. The red seaweed Grateloupia turuturu has been used as human food showing a balanced nutritional profile. This study aims to test in vivo chemopreventive effects of G. turuturu against cutaneous pre-malignant lesions in transgenic mice for the human papillomavirus type 16 (HPV16). Forty-four female HPV+/- or HPV-/- mice received a standard diet or were supplemented with 10% G. turuturu for 22 consecutive days. Cutaneous lesions (ear and chest skin) were identified histologically. Complementarily, the weights and histology of internal organs as well as blood biochemical and DNA integrity parameters were also assessed. G. turuturu consistently reduced the incidence of epidermal dysplasia induced by HPV16 on both cutaneous sites. Moreover, biochemical, DNA integrity and histological analyses confirmed G. turuturu edibility as no signs of toxicity were found. Dietary supplementation with G. turuturu is an effective and safe chemopreventive strategy in this model.

Domesticated Populations of Codium tomentosum Display Lipid Extracts with Lower Seasonal Shifts than Conspecifics from the Wild-Relevance for Biotechnological Applications of this Green Seaweed.

In the last decades, the use of algae in biotechnology and food industries has experienced an exponential growth. Codium tomentosum is a green macroalgae with high biotechnological potential, due to its rich lipidome, although few studies have addressed it. This study aimed to investigate the seasonal changes in lipid and pigment profiles of C. tomentosum, as well as to screen its antioxidant activity, in order to evaluate its natural plasticity. Samples of C. tomentosum were collected in two different seasons, early-autumn (September/October) and spring (May), in the Portuguese coast (wild samples), and in a land-based integrated multitrophic aquaculture (IMTA) system (IMTA samples). Total lipid extracts were analysed by LC-MS, GC-MS, and HPLC, and antioxidant activity was screened through free radical scavenging potential against DPPH and 2,20-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radicals. Wild samples showed a high seasonal variability, modifying their lipidome and pigment profiles according to environmental shifts, while IMTA samples showed a relatively stable composition due to early-stage culturing in controlled conditions. The lipids that contributed the most to seasonal discrimination were glycolipids (monogalactosyl diacylglycerol - MGDG and digalactosyl diacylglycerol - DGDG) and the lyso forms of phospholipids and glycolipids. Lipid extracts showed antioxidant activity ranging from 61 ± 2 to 115 ± 35 µmol Trolox g-1 of lipid extract in DPPH assay and from 532 ± 73 to 927 ± 92 µmol Trolox g-1 of lipid extract in ABTS assay, with a more intense antioxidant activity in wild spring samples. This study revealed that wild specimens of C. tomentosum presented a higher plasticity to cope with seasonal environmental changes, adjusting their lipid, pigment, and bioactivity profiles, while IMTA samples, cultured under controlled conditions, displayed more stable lipidome and pigment compositions.

Dietary Supplementation with the Red Seaweed Porphyra umbilicalis Protects against DNA Damage and Pre-Malignant Dysplastic Skin Lesions in HPV-Transgenic Mice.

Some diet profiles are associated with the risk of developing cancer; however, some nutrients show protective effects. Porphyra umbilicalis is widely consumed, having a balanced nutritional profile; however, its potential for cancer chemoprevention still needs comprehensive studies. In this study, we incorporated P. umbilicalis into the diet of mice transgenic for the human papillomavirus type 16 (HPV16), which spontaneously develop pre-malignant and malignant lesions, and determined whether this seaweed was able to block lesion development. Forty-four 20-week-old HPV+/- and HPV-/- mice were fed either a base diet or a diet supplemented with 10% seaweed. At the end of the study, skin samples were examined to classify HPV16-induced lesions. The liver was also screened for potential toxic effects of the seaweed. Blood was used to study toxicological parameters and to perform comet and micronucleus genotoxicity tests. P. umbilicalis significantly reduced the incidence of pre-malignant dysplastic lesions, completely abrogating them in the chest skin. These results suggest that P. umbilicalis dietary supplementation has the potential to block the development of pre-malignant skin lesions and indicate its antigenotoxic activity against HPV-induced DNA damage. Further studies are needed to establish the seaweed as a functional food and clarify the mechanisms whereby this seaweed blocks multistep carcinogenesis induced by HPV.

Physicochemical Changes of Air-Dried and Salt-Processed Ulva rigida over Storage Time.

The impact of air-drying at 25 °C, brining at 25%, and dry-salting (at 28% and 40%) on the quality and nutritional parameters of Ulva rigida were evaluated over six months of storage. Overall, the main changes occurred in physical aspects during storage time, with U. rigida intensifying its yellow/browning tones, which were more evident in salt-treated samples. The force necessary to fracture the seaweed also increased under all the preservative conditions in the first month. Conversely, the nutritional parameters of U. rigida remained stable during the 180 days of storage. All processed samples showed a high content of insoluble and soluble fibers, overall accounting for 55%-57% dw, and of proteins (17.5%-19.2% dw), together with significant amounts of Fe (86-92 mg/kg dw). The total fatty acids pool only accounted for 3.9%-4.3% dw, but it was rich in unsaturated fatty acids (44%-49% total fatty acids), namely palmitoleic (C16:1), oleic (C18:1), linoleic (C18:2), linolenic (C18:3), and stearidonic (18:4) acids, with an overall omega 6/omega 3 ratio below 0.6, a fact that highlights their potential health-promoting properties.

Marine macroalgae as a dietary source of genoprotection in gilthead seabream (Sparus aurata) against endogenous and exogenous challenges.

DNA integrity and stability are essential to organisms' health and survival. However, it has been neglected in what concerns to fish farming, disregarding the potential impact of endogenous/ exogenous factors. As marine macroalgae constitute a source of natural compounds with a large spectrum of biological activities, this study, situated in the interface of nutritional-genetic research and development of algae practical applications, aimed to evaluate the genoprotective properties of a macroalgae-enriched diet (total percentage of 5%, incorporating equal percentages of Ulva rigida, Gracilaria gracilis and Fucus vesiculosus) in gilthead seabream (Sparus aurata). Protection was assessed in relation to a basal genome integrity and against an exogenous genotoxic challenge (cyclophosphamide; CP). Fish were reared for 30 days with the supplemented diet, being then injected with CP and sampled at days 3 and 10 post-injection (p.i.). To evaluate whether the favorable effects remain after the end of supplementation, a fish subgroup previously fed with algae-enriched diet was submitted to a diet reversion at day 3 p.i., being thereafter fed with the standard diet. Genetic damage was evaluated through the erythrocytic nuclear abnormalities (ENA) and comet assays and complemented by the assessment of the antioxidant system. Results pointed out that algae-enriched feed exhibits anti-genotoxic properties, mostly expressed in relation to the exogenous pressure, manifest in relation to DNA strand breaks and chromosomal lesions, also reducing oxidative DNA damage. Nonetheless, blood antioxidants were only punctually altered by the supplemented diet (e.g. catalase and glutathione-S-transferase). Analyzing the effect persistence, it was perceived that 7 days without algae uptake was enough to partially reduce the protection efficacy. Overall, these findings are promising towards the benefits of macroalgae inclusion in fish diet, and thus, to invigorate mariculture activity and the commercial use of algae, also providing new insights on the DNA protection mechanisms.

Effect of Oven-Drying on the Recovery of Valuable Compounds from Ulva rigida, Gracilaria sp. and Fucus vesiculosus.

The effect of oven-drying at 25, 40 and 60 °C was evaluated on three macroalgae of relevance in Europe, namely Ulva rigida, Gracilaria sp. and Fucus vesiculosus, with respect to quality aspects, including their potential to be exploited as a source of valuable compounds. Notably, as compared to freeze-drying, oven-drying at 25 °C promoted the extraction of chlorophylls and carotenoids from U. rigida, as well as those of phycoerythrin and chlorophyll a from Gracilaria sp., while 40 °C favored the recovery of fucoxanthin and pheophytin a from F. vesiculosus. On the other hand, the use of oven-drying had a negative impact on the extraction of phenolic compounds from this alga, also diminishing the antioxidant activity of the resulting extracts. Instead, the impact of oven-drying of raw material on the recovery of specific polysaccharides differed among the macroalgae. While the amounts of ulvans and fucoidans obtained from macroalgae dried at higher temperatures tended to be superior, the recovery of agar was not affected with the drying temperatures applied to Gracilaria sp. The overall results showed that oven-drying might serve as a good alternative to stabilize Ulva rigida, Gracilaria sp. and Fucus vesiculosus, especially if extraction of pigments and polysaccharides is aimed, thought the appropriate temperature applied must be adapted for each macroalgae.

Screening of Ulva rigida, Gracilaria sp., Fucus vesiculosus and Saccharina latissima as Functional Ingredients.

The intent of the present work was to evaluate the potential of four macroalgae prevalent in Europe, namely Ulva rigida, Gracilaria sp., Fucus vesiculosus and Saccharina latissima, for application in functional foods, either in the direct form or as extracts. Accordingly, nutritional composition, the content of phytochemical antioxidants, and the inhibitory ability of key enzymes with impacts on obesity and diabetes (α-glucosidase and pancreatic lipase) or on arterial pressure (angiotensin-I converting enzyme), were evaluated. Overall, protein, lipid, ash and fiber contents of the macroalgae ranged from 9⁻24% dw, 0.5⁻3.0% dw, 20⁻32% dw, and 37⁻45% dw, respectively, making them good candidates for nutritional supplementation of several foods, particularly due to their mineral and fiber contents. In addition, brown macroalgae, in particular F. vesiculosus, stood out for its superior phenolic content, which was reflected by its high antioxidant ability and inhibition towards α-glucosidase activity (0.032 mg/mL of hydroacetonic extract inhibited 50% of the enzyme activity).

Searching for antigenotoxic properties of marine macroalgae dietary supplementation against endogenous and exogenous challenges.

The functional characterization of marine macroalgae toward their potential to strength genome protection is still scarce. Hence, the aim of this study was to assess the antigenotoxic potential of Ulva rigida, Fucus vesiculosus, and Gracilaria species in Drosophila melanogaster following dietary exposure and adopting the somatic mutation and recombination test (SMART). All macroalgae displayed a genoprotection activity, namely against an exogenous challenge (streptonigrin). The action against subtler endogenous pressures was also noted indicating that supplementation level is a critical factor. Gracilaria species provided ambivalent indications, since 10% of G. vermiculophylla inhibited the egg laying and/or larvae development, while 10% of G. gracilis promoted spontaneous genotoxicity. The effects of U. rigida were modulated (in intensity) by the growing conditions, demonstrating higher genoprotection against streptonigrin-induced damage when grown in an aquaculture-controlled system, while the effectiveness against spontaneous genotoxicity was more apparent in specimens grown under wild conditions. In contrast, F. vesiculosus did not produce significant differences in its potential under varying growing conditions. Overall, these findings shed some light on the macroalgae ability toward genome protection, contributing to the development of algaculture industry, and reinforcing the concept of functional food and its benefits.

Dietary supplementation of heat-treated Gracilaria and Ulva seaweeds enhanced acute hypoxia tolerance in gilthead sea bream (Sparus aurata).

Intensive aquaculture practices involve rearing fish at high densities. In these conditions, fish may be exposed to suboptimal dissolved O2 levels with an increased formation of reactive O2 species (ROS) in tissues. Seaweeds (SW) contain biologically active substances with efficient antioxidant capacities. This study evaluated the effects of dietary supplementation of heat-treated SW (5% Gracilaria vermiculophylla or 5% Ulva lactuca) on stress bioindicators in sea bream subjected to a hypoxic challenge. 168 fish (104.5 g average weight) were distributed in 24 tanks, in which eight tanks were fed one of three experimental diets for 34 days: (i) a control diet without SW supplementation, (ii) a control diet supplemented with Ulva, or (iii) a control diet with Gracilaria Thereafter, fish from 12 tanks (n=4 tanks/dietary treatment) were subjected to 24 h hypoxia (1.3 mg O2 l-1) and subsequent recovery normoxia (8.6 mg O2 l-1). Hypoxic fish showed an increase in hematocrit values regardless of dietary treatment. Dietary modulation of the O2-carrying capacity was conspicuous during recovery, as fish fed SW supplemented diets displayed significantly higher haemoglobin concentration than fish fed the control diet. After the challenge, survival rates in both groups of fish fed SW were higher, which was consistent with a decrease in hepatic lipid peroxidation in these groups. Furthermore, the hepatic antioxidant enzyme activities were modulated differently by changes in environmental O2 condition, particularly in sea bream fed the Gracilaria diet. After being subjected to hypoxia, the gene expression of antioxidant enzymes and molecular chaperones in liver and heart were down regulated in sea bream fed SW diets. This study suggests that the antioxidant properties of heat-treated SW may have a protective role against oxidative stress. The nature of these compounds and possible mechanisms implied are currently being investigated.

Impact of cultivation of Mastocarpus stellatus in IMTA on the seaweeds chemistry and hybrid carrageenan properties.

The biomass yield potential of Mastocarpus stellatus, a commercially attractive carrageenophyte for foods and pharmaceutics, was investigated by cultivating the seaweeds in the nutrient-rich outflow of a commercial fish farm. Results from two consecutive 4 weeks experiments indicate that the cultivation of this seaweed produces a mean biomass of 21 to 40.6 gDW m(-2) day(-1) depending on the time of the experiment. DRIFT and CP-MAS NMR analyses of seaweeds indicate that cultivation during May affected quantitatively the seaweeds chemistry, and thus the chemical and gelling properties of native extracts of kappa/iota-hybrid carrageenan (KI). Overall, algal growth leads to the production of more sulphated KI, the percentage increase varying between 27% and 44% for the two experiments. However, alkali treatment of seaweeds before extraction reduces the variations in gelling properties of KI induced by the algal growth. This study demonstrates the capacity of growing M. stellatus in an integrated multi-trophic aquaculture system for the sustainable production of high value polysaccharides.

Personality vulnerabilities in adolescent suicidality: The mediating role of psychological distress.

The research literature consistently indicates that self-criticism is related to suicidality. Evidence for the role of dependency, however, is more controversial. This study examines the extent to which these personality vulnerabilities are mediated by psychological distress in the prediction of suicidality. As part of a study of adolescent psychopathology, a sample of 260 Portuguese adolescents (148 [56.9 %] female and 112 [43.1%] male), ranging in age from 15 to 18 years (M = 16.32, SD = 1.19) completed measures of personality, suicidal behavior, and current distress, in counterbalanced order. The measures were: self-criticism and dependency from the Depressive Experiences Questionnaire for Adolescents; two psychological distress scales, social withdrawal from the Youth Self Report and depression from the Center for Epidemiologic Studies of Depression Scale; and a measure of suicidality from the Suicide Behaviors Questionnaire Revised. Structural equation modeling indicated that self-criticism and dependency were both significantly associated with suicidality. Psychological distress, however, as measured by withdrawal and depression, fully mediated these relationships, but did not moderate them. The authors conclude that adolescents with higher levels of self-criticism and dependency are at greater risk for experiencing intense psychological distress-high levels of social withdrawal and depression-that account for their vulnerability to suicide risk.