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Massive accumulations of invasive brown algae Rugulopteryx okamurae are exacerbating environmental and socio-economic issues on the Mediterranean and potentially Atlantic coasts. These golden tides, likely intensified by global change processes such as changes in wind direction and intensity and rising temperatures, pose increasing challenges to coastal management. This study employs the Normalized Difference Vegetation Index (NDVI), with values above 0.08 from Level-2 Sentinel-2 imagery, to effectively monitor these strandings along the coastline of Los Lances beach (Tarifa, Spain) in the Strait of Gibraltar Natural Park from 2018 to 2022. Los Lances beach is one of the most affected by the R. okamurae bioinvasion in Spain. The analysis reveals that wind direction determines the spatial distribution of biomass accumulated on the shore. The highest average NDVI values in the western patch were observed with south-easterly winds, while in the eastern patch, higher average NDVI values were recorded with south-westerly, westerly and north-westerly winds. The maximum coverage correlates with elevated temperatures and minimal rainfall, peaking between July and October. Leveraging these insights, we propose a replicable methodology for the early detection and strategic pre-shore collection of biomass, which could facilitate efficient coastal cleanup strategies and enhance biomass utility for biotechnological applications. This approach promises cost-effective adaptability across different geographic areas impacted by golden tides.

Porphyra sensu lato is one of the most economically significant and widely cultured and consumed algae in the world. Porphyra species present excellent nutraceutic properties due to their bioactive compounds (BACs). This research aimed to find the most efficient aqueous extraction method for BACs by examining alkaline and enzymatic hydrolysis. Alkaline hydrolysis with 2.5% sodium carbonate (SC) and at 80 °C proved optimal for extracting all BACs (phycobiliproteins, soluble proteins, polyphenols, and carbohydrates) except mycosporine-like amino acids (MAAs), which were best extracted with water only, and at 80 °C. Enzymatic hydrolysis, particularly with the ‘Miura’ enzymatic cocktail (cellulase, xylanase, glycoside hydrolase, and β-glucanase), showed superior results in extracting phycoerythrin (PE), phycocyanin (PC), soluble proteins, and carbohydrates, with increases of approximately 195%, 510%, 890%, and 65%, respectively, compared to the best alkaline hydrolysis extraction (2.5% SC and 80 °C). Phenolic content analysis showed no significant difference between the ‘Miura’ cocktail and 2.5% SC treatments. Antioxidant activity was higher in samples from alkaline hydrolysis, while extraction of MAAs showed no significant difference between water-only and ‘Miura’ treatments. The study concludes that enzymatic hydrolysis improves the efficiency of BACs extraction in P. linearis, highlighting its potential for the nutraceutical industry, and especially with respect to MAAs for topical and oral UV-photoprotectors.

Porphyra sensu lato has economic importance for food and pharmaceutical industries due to its significant physiological activities resulting from its bioactive compounds (BACs). This study aimed to determine the optimal nitrate dosage required in short-term cultivation to achieve substantial BAC production. A nitrate experiment using varied concentrations (0 to 6.5 mM) revealed optimal nitrate uptake at 0.5 mM in the first two days and at 3 and 5 mM in the last five days. Polyphenols and carbohydrates showed no differences between treatments, while soluble proteins peaked at 1.5 and 3 mM. Total mycosporine-like amino acids (MAAs) were highest in algae incubated at 5 and 6.5 mM, and the highest antioxidant activity was observed in the 5 mM, potentially related to the MAAs amount. Total carbon and sulfur did not differ between treatments, while nitrogen decreased at higher nitrate. This discovery highlights the nuanced role of nitrate in algal physiology, suggesting that biological and chemical responses to nitrate supplementation can optimize an organism’s health and its commercially significant bioactive potential. Furthermore, given its ability to absorb high doses of nitrate, this alga can be cultivated in eutrophic zones or even in out-/indoor tanks, becoming an excellent option for integrated multi-trophic aquaculture (IMTA) and bioremediation.

The Antarctic Peninsula is experiencing one of the highest warming rates globally. In polar regions, macroalgae thrive under extreme environmental conditions, which could worsen because of future climate change scenarios, including increased ultraviolet exposure, extremely low light availability, and fluctuating temperatures, particularly in the intertidal zones. To investigate the potential role of photoprotective and antioxidant mechanisms in response to future increases in sea surface temperatures caused by climate change, we conducted laboratory experiments using three intertidal macroalgae model species: Adenocystis utricularis (Ochrophyta, Phaeophyceae), Pyropia endiviifolia (Rhodophyta, Bangiophyceae), and Monostroma hariotii (Chlorophyta, Ulvophyceae). These algae were collected in Punta Artigas (King George Island, Antarctica) and acclimated at 2°C for 48 h. They were then assessed in laboratory experiments for up to 5 days under two treatments: (1) control conditions at 2°C and (2) elevated tem.perature conditions at 8°C, representing the most negative increment in SSTs estimated by the end of the 21st century. Carbon, nitrogen, pigments (chlorophylls and carotenoids), mycosporine-like amino acids (MAAs), and phenolic compounds were quantified after 3 and 5 days of exposure. For M. hariotii, elevated temperatures led to an increase in the C/N ratio, total antioxidant capacity, and levels of nitrogen, total carotenoids, chlorophyll-a, pigments (chlorophyll-b and violaxanthin), and phenolic compounds. For A. utricularis, elevated temperatures led to elevated C/N ratio and levels of chlorophyll-a and carotenoids (fucoxanthin and β-carotene). For P. endiviifolia, elevated temperatures resulted in elevated levels of carotenoids (lutein and β-carotene), phenolic compounds, and MAAs (porphyra-334, shinorine, and palythine). Thus, our study suggests that increasing water temperatures due to global warming can enhance the photoprotective abilities of three Antarctic intertidal macroalgae (M. hariotii, A. utricularis, and P. endiviifolia), with each species showing specific responses.

The use of functional feeds in aquaculture is currently increasing. This study aimed to assess the combined impact of dietary green microalgae Chlorella fusca and ethanol-inactivated Vibrio proteolyticus DCF12.2 (CVP diet) on thick-lipped grey mullet (Chelon labrosus) juvenile fish. The effects on intestinal microbiota and the transcription of genes related to metabolism, stress, and the immune system were investigated after 90 days of feeding. Additionally, the fish were challenged with Aeromonas hydrophila and polyinosinic–polycytidylic acid (poly I:C) to evaluate the immune response. Microbiota analysis revealed no significant differences in alpha and beta diversity between the anterior and posterior intestinal sections of fish fed the control (CT) and CVP diets. The dominant genera varied between the groups; Pseudomonas and Brevinema were most abundant in the CVP group, whereas Brevinema, Cetobacterium, and Pseudomonas were predominant in the CT group. However, microbial functionality remained unaltered. Gene expression analysis indicated notable changes in hif3α, mhcII, abcb1, mx, and tnfα genes in different fish organs on the CVP diet. In the head kidney, gene expression variations were observed following challenges with A. hydrophila or poly I:C, with higher peak values seen in fish injected with poly I:C. Moreover, c3 mRNA levels were significantly up-regulated in the CVP group 72 h post-A. hydrophila challenge. To conclude, incorporating C. fusca with V. proteolyticus in C. labrosus diet affected the microbial species composition in the intestine while preserving its functionality. In terms of gene expression, the combined diet effectively regulated the transcription of stress and immune-related genes, suggesting potential enhancement of fish resistance against stress and infections.

Keypoints Chlorella fusca grows and synthesizes metabolites of biotechnological interest in UW Protein and lipid content increased to 50.5% and 16.7% in 75% UW and 100% UW concentrations TN, DOC, and BOD5 reduction efficiency increased with the exposure time.

Presently, the Strait of Gibraltar is undergoing an unprecedented invasion of the alien alga Rugulopteryx okamurae of North Pacific origin. According to the scarce literature, the algae first settled in the south shore, probably following commercial exchanges with French ports where it was accidentally introduced together with Japanese oysters imported for mariculture. There is no certainty, however, that the algae first colonized the south shore of the Strait and, from there, spread to the north. It could well have been the opposite. Whatever the case, it spread all over the Strait and surrounding areas with amazing rapidity. Human-mediated vectors (algae attached to ship hulls or fishing nets, for example) can be behind the spread from the shore initially settled to the algae-free shore on the opposite side. But it could also have happened by means of hydrodynamic processes without direct human intervention. This possibility is assessed in this paper by revisiting historical current meter profiles collected in the Strait of Gibraltar searching for secondary cross-strait flows. All the stations present an intermediate layer of northward cross-strait velocity near the interface of the mean baroclinic exchange along with a surface layer above of southward velocity, whose lower part also overlaps the interface zone. The first one would back the south-to-north transport of algal fragments, the second one, the north-to south. In both cases, algae must reach the depth of the interface. The vertical velocity field in the area, which far exceeds the small sedimentation velocity of the algae, allows their vertical displacements throughout the water column. Its endurance to survive under the weak or no light conditions that will prevail during the cross-strait transport and its capability of reactivating the metabolism after this unfavorable period, offers chances for colonizing the opposite shore. Therefore, the propagation of the algae by hydrodynamic processes, without human intervention, cannot be ruled out.

Global climate change is expected to have detrimental effects on coastal ecosystems, with impacts observable at the local and regional levels, depending on factors such as light, temperature, and nutrients. Shifts in dominance between primary producers that can capitalize on carbon availability for photosynthesis will have knock-on effects on marine ecosystems, affecting their ecophysiological responses and biological processes. Here, we study the ecophysiological vulnerability, photoacclimation capacity, and tolerance responses as ecophysiological responses of the intertidal kelp Lessonia spicata (Phaeophyceae, Laminariales) during a year through different seasons (autumn, winter, spring, and summer) in the Pacific Ocean (central Chile). Six different daily cycle experiments were carried out within each season. A battery of different biochemical assays associated with antioxidant responses and in-vivo chlorophyll a fluorescence parameter showed that during spring and summer, there was an increase in photosynthetic capacity in the macroalgae, although their responses varied depending on light and nutrient availability in the course of the year. Lessonia spicata showed maximal photosynthesis and a similar photoinhibition pattern in summer compared to the other seasons, and the contents of nitrate and phosphorous in seawater were less in winter. Thus, high irradiance during spring and summer displayed a higher maximal electron transport rate (ETRmax), irradiance of saturation (Ek), non-photochemical quenching (NPQmax), nitrogen and carbon contents, and photoprotector compound levels. Antioxidant activity increased also in summer, the seasonal period with the highest oxidative stress conditions, i.e., the highest level of hydrogen peroxide (H2O2). In contrast, under low irradiance, i.e., wintertime conditions, L. spicata demonstrated lower concentrations of the photosynthetic pigments such as chlorophyll a and carotenoids. Our study suggests that macroalgae that are subjected to increased irradiance and water temperature under lower nutrient availability mediated by seasonal changes (expected to worsen under climate change) respond with higher values of productivity, pigment contents, and photoprotective compounds. Thus, our findings strengthen the available evidence to predict that algae in the order Laminariales, specifically L. spicata (kelp), could better proliferate, with lower vulnerability and greater acclimation, than other marine species subject to future expected conditions associated with climate change.

Anthropogenic impacts on water resources, especially by ​​nutrient discharge, is a worldwide problem in marine coastal areas. In this context, seaweed cultivation in aquaculture wastewater can be considered as an alternative for effluent mitigation, where the biomass becomes a source of valuable compounds. The current study examined the potential use of the seaweeds Ulva pseudorotundata and Ulva rigida to remove nutrients to treat effluents from the culture of Chelon labrosus. Two experiments were conducted under pilot-scale conditions to evaluate the nutrient uptake, photosynthetic activity, and biomass production of the seaweed species cultivated under 50 and 100% effluent concentrations. Photosynthetic parameters were determined by in vivo chlorophyll a fluorescence associated to photosystem II 3 times a day to estimate photosynthetic performance and seaweed physiology throughout the experiment: optimal quantum yield (Fv/Fm), in situ and ex situ electron transport rate (ETR), photosynthetic efficiency (αETR), saturation irradiance (Ek), and the maximum non-photochemical quenching (NPQmax). To evaluate seaweed metabolism and biomass compounds, elemental and biochemical composition were analyzed in the beginning and end of each experiment. Results regarding the nutrient source showed that both species removed more than 65% of ammonium after 3 hours of experimentation. At the end of the experiments, up to 94.8% of the initial ammonium was sequestered from the effluent. Additionally, after 5 days of cultivation under 50% fish effluent both Ulva species were able to remove more than 85% of the nitrate. Although a decrease in uptake efficiency was observed in cultures with 100% fish effluent, at the end of the experiment more than 440 µmol L-1 of nitrate was removed, considering all treatment conditions. The biomass values showed that growth rates of seaweed cultivated in 100% effluent were higher than those obtained in 50% effluent. Moreover, when cultivated in the 100% effluent concentration, a significant increment in protein content was detected in both Ulva species. Our results contribute to the understanding of biofiltration and photosynthetic performance of two different Ulva species in order to improve growth optimization, enhancement of biofiltration capacity and also to boost management practices of seaweed cultivation in aquaculture effluent treatment systems.

In recent years, a clear emphasis has been placed on replacing fishmeal and fish oil in aquafeeds with other alternative ingredients, including algae, particularly in low trophic omnivorous fish species. This work aimed at evaluating the effects of moderate dietary supplementation with the green microalga Chlorella fusca on growth, metabolism, and digestive functionality in juvenile thick-lipped grey mullet (Chelon labrosus). Fish were fed a control diet (CT) or a diet containing 15% C. fusca (C-15) biomass during 90 days. C. labrosus fed with the C-15 diet showed higher growth performance (in terms of final weight and length, weight gain, and specific growth rate) than the control group. Somatic indices and muscle proximate composition were similar at the end of the feeding trial. Regarding fatty acids profile, C. fusca-fed fish showed a selective retention of docosahexaenoic acid (DHA) in the liver, and arachidonic acid (ARA), eicosapentaenoic acid (EPA), and DHA in the muscle. Dietary inclusion of this microalga significantly increased intestinal total alkaline protease, leucine aminopeptidase, and alkaline phosphatase activities in specimens fed with C-15 diet. Furthermore, intestine histological analysis revealed the absence of damage signs on gut morphology in fish fed the microalgae supplemented diet. Thick-lipped grey mullets fed the C-15 diet increased plasma glucose and decreased plasma lactate. Overall, the effects observed on liver (lipid metabolism, glycolysis and glycogenolysis) enzyme activities, together with adequate fatty acid profile, metabolic response, and gut morphology, and a significant increase in the intestinal mucosa’s digestive and absorptive capacity, could explain the positive effects on growth performance obtained in fish fed the microalgae-supplemented diet. In conclusion, the results obtained showed that C. fusca is suitable as dietary ingredient for feeding thick-lipped grey mullet juveniles.

Given the potential of microalgae as new aquafeed ingredients, this study focuses on using a blend of microalgae, Tisochrysis lutea, Nannochloropsis gaditana, and Scenedesmus almeriensis, as a dietary ingredient for feeding Sparus aurata juveniles. The growth performance, carcass composition, tissue fatty acid profile, and intestinal microbiota were evaluated after a 30 day-feeding period. A microalgae-free diet was used as control, and three experimental diets were formulated containing 5%, 15%, and 25% of the microalgae blend (MB-5%, MB-15%, and MB-25%, respectively). After 7, 15, and 30 days of feeding experimental diets, biological samples were taken. Growth performance and nutrient utilization were not significantly modified at the end of the experiment. Microalgae inclusion tended to decrease body lipids and affected the fatty acid profile, especially MB-25 diet increased DHA levels. Diet MB-25 promoted appropriate microbial diversity, favoring the presence of probiotic bacteria, such as Lactobacillus, and significantly influencing the fatty acid composition and lipid metabolism in fish. In conclusion, using a short pulse of dietary administration of 25% microalgal blend in S. aurata modulates the intestinal microbiota and lipid composition while maintaining growth performance.

This study aimed to evaluate the combined effect of dietary Chlorella fusca and ethanol-inactivated Vibrio proteolyticus DCF12.2 (C + V diet) in Chelon labrosus juveniles, highlighting their nutritional, physiological, and morphological effects. The results showed that the combined dietary inclusion of C. fusca and V. proteolyticus significantly enhanced growth performance and feed utilization compared to the control group. The C + V diet increased the fish lipid quality index (FLQ), n-3 polyunsaturated fatty acids, and n-3/n-6 ratio, which might be beneficial in terms of human nutrition. The C + V diet considerably increased carbohydrate metabolic activity by statistically boosting plasma glucose. The dietary inclusion of C. fusca in conjunction with V. proteolyticus increased metabolic enzyme activity as well as intestinal absorption capacity compared to that found in the control group. In conclusion, the experimental diet was suitable for feeding C. labrosus, increasing their growth and the nutritional characteristics of the muscle and intestine, without causing tissue damage.

Marine macroalgae are considered an untapped source of healthy natural metabolites and their market demand is rapidly increasing. Intertidal macroalgae present chemical defense mechanisms that enable them to thrive under changing environmental conditions. These intracellular chemicals include compounds that can be used for human benefit. The aim of this study was to test cultivation protocols that direct seaweed metabolic responses to enhance the production of target antioxidant and photoprotective biomaterials. We present an original integrated multi-trophic aquaculture (IMTA) design, based on a two-phase cultivation plan, in which three seaweed species were initially fed by fish effluents, and subsequently exposed to various abiotic stresses, namely, high irradiance, nutrient starvation, and high salinity. The combined effect of the IMTA’s high nutrient concentrations and/or followed by the abiotic stressors enhanced the seaweeds’ content of mycosporine-like amino acids (MAAs) by 2.3-fold, phenolic compounds by 1.4-fold, and their antioxidant capacity by 1.8-fold. The Sun Protection Factor (SPF) rose by 2.7-fold, and the chlorophyll and phycobiliprotein synthesis was stimulated dramatically by an order of magnitude. Our integrated cultivation system design offers a sustainable approach, with the potential to be adopted by emerging industries for food and health applications.

The biochemical composition, molecular diversity, and two different bioactivities of Asparagopsis armata and Rugulopteryx okamurae (two alien species with different invasive patterns in the southern Iberian Peninsula) were analyzed through spectrophotometric methods and Fourier transform ion cyclotron mass spectroscopy (FT-ICR-MS). A total of 3042 molecular formulas were identified from the different extracts. The dH2O extracts were the most molecularly different. A. armata presented the highest content of nitrogenous compounds (proteins, CHON) and sulphur content, whereas R. okamurae was rich in carbonated compounds (total carbon, lipids, CHO, and CHOP). Antioxidant capacity and phenolic content were higher in R. okamurae than in A. armata. Antimicrobial activity was detected from both species. A. armata showed capacity to inhibit human and fish pathogens (e.g., Staphylococcus aureus or Vibrio anguillarum), whereas R. okamurae only showed inhibition against human bacteria (Staphylococcus aureus and Cutibacterium acnes). In R. okamurae, molecules with a great number of pharmaceutical activities (e.g., anti-inflammatory or antitumoral), antibacterial, biomaterial, and other utilities were found. The main molecules of A. armata had also pharmaceutical applications (e.g., antimalarian, antithrombotic, anti-inflammatory, or antiarthritis). The valorization of these species can help to counteract the environmental effects of the bioinvasions.

Phlorotannins play a role in biological functions to protect the cells against UV and oxidative damage in brown algae. We hypothesized that these compounds can function as photo-protectors and antioxidants in skin care formulations. Two types of extracts (water (FV-WE) and 67% v/v ethanol (FV-EE)) from Fucus vesiculosus were obtained with a phlorotannin content between 7−14% in dry extract. Exposure to sun light during growth was included as a factor on the phlorotannin content but did not influence the phlorotannin content. However, green colored F. vesiculosus had lower total phenolic content (TPC) (FV-WE = 6.9 g GAE 100 g−1 dw, FV-EE = 7.8 g GAE 100 g−1 dw) compared to those with a yellow/brownish color (FV-WE = 10.4–13.7 g GAE 100 g−1 dw, FV-EE = 11.2–14.0 g GAE 100 g−1 dw). UVA and UVB photo protective capabilities of the extracts through different biological effective protection factors (BEPFs) were evaluated using in vitro methods; the Mansur method for sun protection factor (SPF) and calculation of effective solar absorption radiation (%ESAR) to determine SPF and UVA protection factor (UVA-PF) of the extract and in seaweed enriched lotion. The SPF was negligible, when evaluating FV-WE in lotion (10 and 20% w/w). Moreover, %ESAR of the FV-WE showed SPF and some UVA-PF, but not enough to give sufficient SPF in lotions (10% w/w). It was concluded that the concentration of UV protecting compounds in the extracts was too low to and that further fractionation and purification of phlorotannins is needed to increase the SPF.

Solar radiation effects on the ecophysiology and biochemical responses of the brown macroalga Macrocystis pyrifera (L.) C. Agardh were evaluated using a mesocosm approach in Southern Chile. Treatments with different radiation attenuations were simulated with three vertical attenuation coefficients: (1) total (Kd = 0.8 m−1), (2) attenuated (Kd = 1.2 m−1), and (3) low (Kd = 1.6 m−1) radiation levels. Nutrient concentration and temperature did not show differences under the three light conditions. Photosynthetic activity was estimated by in vivo chlorophyll a (Chla) fluorescence under the three light treatments as an isolated physical factor in both in situ solar radiation in the field. This was achieved using a pulse amplitude-modulated (PAM) fluorometera—Diving PAM (in situ). Photosynthetic activity and biochemical composition were measured in winter during two daily cycles (1DC and 2DC) in different parts of the thalli of the plant: (1) canopy zone, (2) middle zone, and (3) down zone, associated with different depths in the mesocosm system. Nevertheless, the in situ electron transport rate (ETRin situ) was higher in the exposed thalli of the canopy zone, independent of the light treatment conditions. The concentration of phenolic compounds (PC) increases in the down zone in the first daily cycle, and it was higher in the middle zone in the second daily cycle. The Chla increased in the morning time under total and attenuated radiation in the first daily cycle. Solar radiation increasing at midday prompted the photoinhibition of photosynthesis in the canopy zone but also an increase in productivity and phenol content. Therefore, light attenuation in the water column drove key differences in the photo-physiological responses of M. pyrifera, with the highest productivity occurring in thalli positioned in the canopy zone when exposed to solar irradiance.

This study aimed to characterize the intestinal microbiota of wild thick-lipped grey mullets (Chelon labrosus) and explore its potential functionality on the host. Intestinal contents of anterior and posterior sections from wild fish were collected and DNA was extracted. Subsequently, the V3–V4 regions of 16S rRNA were sequenced using the Illumina technology and results were analyzed by bioinformatics pipeline. The functional profile of the microbial community was analyzed using PICRUSt software. Shannon and Simpson diversity indices were significantly higher in the posterior section of wild specimens. The overall taxonomic composition suggests a certain homogeneity in the anterior section of the intestine and heterogeneity in the posterior section. Due to this, no statistical differences were detected at any level among both intestinal sections. Predicted functions of intestinal microbiota showed the most abundant were those related to amino acid metabolism, carbohydrate metabolism, energy metabolism, membrane transport, and cell replication and repair. Furthermore, the analysis revealed microbial functional genes related to the elimination of environmental toxins.

The potential of marine dissolved organic matter (DOM) for free radical scavenging has been extensively evaluated, however, the quantitative assessment of the antioxidant potential has been recently measured for the first time. The linkage of the DOM antioxidant potential to its molecular composition has not yet been examined. Following this line, this article takes a step forward by assessing, throughout a polarity-mediated fractionation, (1) the antioxidant capacity and phenolic content and (2) the molecular characterization of DOM in a more exhaustive manner. (3) The DOM antioxidant potential and phenolic content was linked to the molecular composition of DOM, which was molecularly characterized using ultrahigh resolution Fourier transform Ion Cyclotron Resonance mass spectrometry (FT-ICR MS). Antioxidant activity and phenolic content were quantified by the free radical 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS⋅) and the Folin-Ciocalteu methods, respectively. We considered three types of different natural DOM samples: the deep North Pacific Ocean, the oligotrophic surface of the North Pacific Ocean and porewater from the sulfidic tidal flats of the Wadden Sea. Bulk porewater and its individual polarity fractions presented the highest antioxidant activity and phenolic content. DOM from the water column samples had lower antioxidant activity and phenolic content than porewater, but exceeded what it is commonly found in macroalgae, microalgae, fruits and vegetables with cosmeceutical purposes. Our values were similar to published values for terrestrial DOM. The variations in bioactivity were dependent on polarity and molecular composition. The high resolution and high mass accuracy used to determine the molecular composition of marine DOM and the chemometric and multistatistical analyses employed have allowed to distinguish molecular categories that are related to the bioactive potential. As a future perspective, we performed cytotoxicity tests with human cells and propose marine DOM as a natural ingredient for the development of cosmeceutical products.

The thick-lipped grey mullet (Chelon labrosus) is a nominee fish species for aquaculture diversification in Spain because it is an omnivore and euryhaline species, but limited knowledge about the nutritional attributes of this species is available. This study aimed to characterize the chemical composition of wild and cultured fish. The muscle proximate composition, and fatty acid and amino acid profiles were assessed. The cultivated specimens showed a higher lipid content and lower protein and ash contents compared with the wild specimens. The predominant tissue fatty acids in both the wild and cultivated fish were palmitic acid (16:0), oleic acid (18:1n-9) and docosahexaenoic acid (DHA, 22:6n-3). A higher content of arachidonic acid (ARA, 20:4n-6), eicosapentaenoic acid (20:5n-3) and DHA were detected in the muscle of wild mullets, while the fish supplied with commercial pellets showed higher quantities of monounsaturated fatty acids, and lower quantities of saturated fatty acids and polyunsaturated fatty acids (PUFAs). Regarding PUFAs, n-3 fatty acids were predominant in wild mullets, while n-6 and n-9 were more abundant in farmed fish. In terms of amino acid composition, except for histidine in wild specimens, the amino acid amounts were higher than the FAO/WHO standard. In conclusion, C. labrosus may contribute to improving the dietary intake of highly polyunsaturated n-3 fatty acids, with a benefit to human health, owing to that fact that a 100-g fillet portion of cultivated and wild C. labrosus can provide 770 mg and 1160 mg of EPA and DHA, respectively, which exceeds the 250 mg dietary daily intake recommended by the FAO/WHO.

Macroalgae belong to a diverse group of organisms that could be exploited for biomolecule application. Among the biocompounds found in this group, mycosporine-like amino acids (MAAs) are highlighted mainly due to their photoprotection, antioxidant properties, and high photo and thermo-stability, which are attractive characteristics for the development of cosmeceutical products. Therefore, here we revise published data about MAAs, including their biosynthesis, biomass production, extraction, characterization, identification, purification, and bioactivities. MAAs can be found in many algae species, but the highest concentrations are found in red macroalgae, mainly in the order Bangiales, as Porphyra spp. In addition to the species, the content of MAAs can vary depending on environmental factors, of which solar radiation and nitrogen availability are the most influential. MAAs can confer photoprotection due to their capacity to absorb ultraviolet radiation or reduce the impact of free radicals on cells, among other properties. To extract these compounds, different approaches can be used. The efficiency of these methods can be evaluated with characterization and identification using high performance liquid chromatography (HPLC), associated with other apparatus such as mass spectrometry (MS) and nuclear magnetic resonance (NMR). Therefore, the data presented in this review allow a broad comprehension of MAAs and show perspectives for their inclusion in cosmeceutical products.

This study presents the validation of a high-performance liquid chromatography diode array detector (HPLC-DAD) method for the determination of different mycosporine-like amino acids (MAAs) in the red alga Bostrychia scorpioides. The investigated MAAs, named bostrychines, have only been found in this specific species so far. The developed HPLC-DAD method was successfully applied for the quantification of the major MAAs in Bostrychia scorpioides extracts, collected from four different countries in Europe showing only minor differences between the investigated samples. In the past, several Bostrychia spp. have been reported to include cryptic species, and in some cases such as B. calliptera, B. simpliciuscula, and B. moritziana, the polyphyly was supported by differences in their MAA composition. The uniformity in the MAA composition of the investigated B. scorpioides samples is in agreement with the reported monophyly of this Bostrychia sp.

In the last 10 years, a great number of publications (both regular papers and reviews) have been published on the interesting molecules—mycosporine-like amino acids (MAAs). Despite significant advances in the research of MAAs, current overviews in the recent publications involving MAA research still need reporting. The aim of this Special Issue is to join, as an interdisciplinary approach, the photochemical and photobiological aspects, with emphasis on new natural resources to obtain both algae and zooplankton MAAs, advances in methodology of extraction and chemical identification of new MAAs. Finally, this Special Issue reviews the bioactivities of MAAs including UVR screen, antioxidant, immunostimulant, growth factor, DNA protection, inhibition of collagenase, elastase and hyaluronidase, and anti-photoaging, among others, and their potential use as nutracosmeceutic molecules (i.e., oral and topic photoprotector).

Fluctuations in solar radiation are one of the key factors affecting productivity and survival in habitat forming coastal macroalgae, in this regard, photoacclimation has a direct impact on the vulnerability and the capacity of seaweed to withstand, for instance, radiation excess. Here, we study ecophysiological responses through photosynthetic activity measurements under time-dependent (one year) fluctuations in solar radiation in the brown macroalga L. spicata. The responses presented seasonal patterns, with an increase in photosynthetic capacity during summer, expressed in greater maximal electron transport rate (ETRmax) and diminished thermal dissipation (NPQmax). Moreover, we studied photoprotective compounds (phenolic compounds) and total antioxidant capacity, which demonstrated an increase during periods of high solar radiation. In addition, content of photosynthetic pigment (Chla, Chlc and Carotenoids) increased under greater solar irradiance. The L. spicata can accumulate as reservoir photoprotective and antioxidant substances to withstand periods of high solar irradiance. All ecophysiological and biochemical responses in L. spicata indicate high photoacclimation and low vulnerability in the species, especially during with greater levels of solar irradiance.

In recent years, research on natural products has gained considerable attention, particularly in the cosmetic industry, which is looking for new bio-active and biodegradable molecules. In this study, cosmetic properties of cyanobacteria and red macroalgae were analyzed. The extractions were conducted in different solvents (water, ethanol and two combinations of water:ethanol). The main molecules with antioxidant and photoprotective capacity were mycosporine-like amino acids (MAAs), scytonemin and phenolic compounds. The highest contents of scytonemin (only present in cyanobacteria) were observed in Scytonema sp. (BEA 1603B) and Lyngbya sp. (BEA 1328B). The highest concentrations of MAAs were found in the red macroalgae Porphyra umbilicalis, Gelidium corneum and Osmundea pinnatifida and in the cyanobacterium Lyngbya sp. Scytonema sp. was the unique species that presented an MAA with maximum absorption in the UV-B band, being identified as mycosporine-glutaminol for the first time in this species. The highest content of polyphenols was observed in Scytonema sp. and P. umbilicalis. Water was the best extraction solvent for MAAs and phenols, whereas scytonemin was better extracted in a less polar solvent such as ethanol:dH2O (4:1). Cyanobacterium extracts presented higher antioxidant activity than those of red macroalgae. Positive correlations of antioxidant activity with different molecules, especially polyphenols, biliproteins and MAAs, were observed. Hydroethanolic extracts of some species incorporated in creams showed an increase in the photoprotection capacity in comparison with the base cream. Extracts of these organisms could be used as natural photoprotectors improving the diversity of sunscreens. The combination of different extracts enriched in scytonemin and MAAs could be useful to design broad-band natural UV-screen cosmeceutical products.

UV-absorbing compounds, such as mycosporine-like amino acids (MAAs), are a group of secondary metabolites present in many marine species, including red seaweeds. In these organisms, the content and proportion of the composition of MAAs vary, depending on the species and several environmental factors. Its high cosmetic interest calls for research on the content and composition of MAAs, as well as the dynamics of MAAs accumulation in seaweeds from different latitudes. Therefore, this study aimed to survey the content of UV-absorbing MAAs in three Subantarctic red seaweeds during a seasonal cycle. Using spectrophotometric and HPLC techniques, the content and composition of MAAs of intertidal Iridaea tuberculosa, Nothogenia fastigiate, and Corallina officinalis were assessed. Some samples were also analyzed using high-resolution mass spectrometry coupled with HPLC-ESI-MS in order to identify more precisely the MAA composition. I. tuberculosa exhibited the highest MAA values (above 1 mg g−1 of dried mass weight), while C. officinalis showed values not exceeding 0.4 mg g−1. Porphyra-334 was the main component in N. fastigiata, whereas I. tuberculosa and C. officinalis exhibited a high content of palythine. Both content and composition of MAAs varied seasonally, with high concentration recorded in different seasons, depending on the species, i.e., winter (I. tuberculosa), spring (N. fastigiata), and summer (C. officinalis). HPLC-ESI-MS allowed us to identify seven different MAAs. Two were recorded for the first time in seaweeds from Subantarctic areas (mycosporine-glutamic acid and palythine-serine), and we also recorded an eighth UV-absorbing compound which remains unidentified.

Gracilaria species are the main source of agar worldwide. Since laboratory cultivation is an important means of sustaining such production, this study aimed to assess the influence of two fundamental strategies of physiological algae adjustment, photoacclimation and photomorphogenesis, on G. birdiae physiology. Specifically, the effects of different spectral light qualities on reproduction, growth, and pigment content in two distinct photoperiods (8 and 14 hours) were examined. Tetrasporophytes and gametophytes were submitted to different light qualities: white, green, red, and blue over the course of nine weeks. At the end of this period, chlorophyll a, allophycocyanin, phycocyanin, and phycoerythrin contents were analysed. Gametophytes showed reproductive structures only under monochromatic radiation. A stimulatory effect on tetrasporangium differentiation was mainly observed under red light, but this high fertility was negatively correlated with growth rate, i.e. algae cultivated under red light showed the lowest growth rate. However, while growth rates were higher in algae exposed to white light, they were similar to those observed in algae subjected to green light and 14 hours of daylight. PE was the predominant pigment, irrespective of light quality. Phycocyanin and phycoerythrin concentration increased when algae were cultivated under green and blue light. Therefore, considering future management prospects for G. birdiae mariculture, we suggest that red light could be utilized as a reproductive inductor to produce tetraspores. Furthermore, if the aim is to achieve high phycoerythrin content, continuous blue light could be applied during a short photoperiod. Indeed, the combination of different wavelengths could allow better economic resource exploitation.

Cystoseira tamariscifolia thalli collected from rocky shores and rockpools in winter and summer in Southern Spain were incubated for 7 days in UV transparent cylindrical vessels under outdoor conditions. Photosynthetic activity estimated as in vivo chlorophyll α fluorescence of photosystem II, photosynthetic pigments, antioxidant activity (DPPH assay), phenolic compounds and total internal C and N contents were determined after short-term (3 d) and mid-term (7 d) periods. Maximum quantum yield of PSII (Fv/Fm) was significantly higher in field-collected algae and after 7 d incubation in winter than in summer. In rocky shores and rockpools thalli, maximum electron transport rate (ETRmax) and photosynthetic efficiency (αETR) were much higher in summer than in winter. ETR of outdoor-grown thalli (in situ ETR) showed a daily pattern, with a decrease at noon in both winter and summer (3rd and 7th days). We found much higher antioxidant activity in thalli collected in summer than in winter. However, the concentration of internal UV screen substances (polyphenols) was higher in winter than in summer, whereas the release of phenolic compounds was lower. The highest capacity of acclimation in C. tamariscifolia found in summer and RS with emersion periods was explained by the highest dynamic photoinhibition, energy dissipation (non-photochemical quenching) and antioxidant activity (EC50).

This study was designed to evaluate the potential use of algal extracts in cosmeceuticals, including factors related to biosecurity. The aqueous crude extracts of Hydropuntia cornea and Gracilariopsis longissima showed a good photoprotective capacity (Sun Protection Factor, SPF) due to, among other reasons, the presence of five types of mycosporine-like amino acids (MAAs) detected by high pressure liquid chromatography-photodiode array detector (HPLC-PDA) and electrospray ionization mass spectrometry (ESI-MS) (Palythine, Asterina-330, Shinorine, Porphyra-334, and Palythinol). The toxicity of the extracts was evaluated by the MTT assay, which is based on the metabolic reduction of MTT [3-(4,5-dimethylthiazol-2yl)-diphenyl tetrazolium bromide] by the action of the mitochondrial enzyme succinate dehydrogenase. This assay was carried out in vitro in three cell lines: one related to the immune system (murine macrophages of the immune system: RAW264.7) and two human cell lines related to the skin (gingival fibroblasts: HGF, and immortalized human keratinocytes: HaCaT). Both extracts showed no cytotoxic activity in both types of human cells, whereas they showed cytotoxicity in murine tumor cells of the immune system (macrophages: RAW264.7). On the other hand, the immunological activity in the murine macrophage RAW264.7 was studied at a concentration lower than 100 μg mL−1 and lower than the EC50, and evaluated by the production of pro-inflammatory compounds through an immunosorbent assay linked to enzymes such as tumor necrosis factor-α (TNF-α) or anti-inflammatory/proinflammatory enzymes such as interleukin-6 (IL-6). Both algae extracts induced the biosynthesis of TNF-α and IL-6. The production of TNF-α was much higher than that observed in the control (at a concentration of the aqueous extract higher than 5 μg mL−1). These results support the theory that the extracts of H. cornea and G. longissima actively induce the production of cytokines. In summary, the extracts of these species did not show cytotoxicity in human cells, and they present with immunomodulatory and photoprotection capacity.

The safety and stability of synthetic UV-filters and the procedures for evaluating the photoprotective capability of commercial sunscreens are under continuous review. The influence of pH and temperature stressors on the stability of certain Mycosporine-like amino acids (MAAs) isolated at high purity levels was examined. MAAs were highly stable at room temperature during 24 h at pH 4.5–8.5. At 50 °C, MAAs showed instability at pH 10.5 while at 85 °C, progressive disappearances were observed for MAAs through the studied pH range. In alkaline conditions, their degradation was much faster. Mycosporine-serinol and porphyra-334 (+shinorine) were the most stable MAAs under the conditions tested. They were included in four cosmetically stable topical sunscreens, of which the Sun Protection Factor (SPF) and other Biological Effective Protection Factors (BEPFs) were calculated. The formulation containing these MAAs showed similar SPF and UVB-BEPFs values as those of the reference sunscreen, composed of synthetic UV absorbing filters in similar percentages, while UVA-BEPFs values were slightly lower. Current in vitro data strongly suggest that MAAs, as natural and safe UV-absorbing and antioxidant compounds, have high potential for protection against the diverse harmful effects of solar UV radiation. In addition, novel complementary in vitro tests for evaluation of commercial sunscreens efficacy are proposed.

Aquatic macrophyte biomass, diaspore bank distribution and their relationship to spatial variability of depth, nutrients (nitrite, nitrate, ammonium and soluble reactive phosphorus) as well as sediment granulometry in an athalassohaline lake have been studied during one wet hydrological year. The results indicate that species growing in the lake show different spatial distribution patterns throughout the lake. Indirect gradient analysis (canonical analysis) results showed a first axis defined as a function of Ulva flexuosa Wulfen biomass which is, in turn, positively correlated with interstitial ammonium and Soluble Reactive Phosphorus (SRP). The second axis was mainly established due to Lamprothamnium papulosum (Wallr.) J. Groves biomass which correlated positively to depth and negatively to interstitial ammonium and SRP. These results revealed a NESW eutrophic gradient allowing the U. Flexuosa biomass proliferation. This phenomenon could increase the shadow effect over the rest of the macrophytes inhabiting this shallow lake. Moreover, the eutrophic harmful effect on the macrophyte physiology and over the diaspore bank could have important consequences in the survival of such important populations. The results reported in this study show the need for studies as the base to select sampling points for monitoring this wetland.

The effect of increased UV radiation on photosynthesis estimated as in vivo chlorophyll fluorescence i.e. optimal quantum yield (Fv/Fm) and electron transport rate (ETR) in the green filamentous alga Zygnemopsis decussata (Streptophyta, Zygnematales) growing in the high mountain lake "La Caldera" (Sierra Nevada, Spain) at 3050 m altitude was evaluated. Two sets of in situ experiments were conducted: (1) On July 2006, Fv/Fm was measured throughout the day at different depths (0.1, 0.25, 0.5 and 1 m) and in the afternoon, ETR and phenolic compounds were determined. In addition, in order to analyze the effect of UV radiation, Fv/Fm was determined in algae incubated for 3 days at 0.5m under three different light treatments: PAR+UVA+UVB (PAB), PAR+UVA (PA) and PAR (P). (2) On August 2007, Fv/Fm was determined under PAB, PA and P treatments and desiccation/rehydration conditions. Fv/Fm decreased in algae growing in surface waters (0.1 m) but also at 1 m depth compared to that at 0.5 m depth. The decrease of Fv/Fm at noon due to photoinhibition was small (less than 10%) except in algae growing at 1 m depth (44%). The maximal electron transport rate was 3.5-5 times higher in algae growing at 0.25-0.5 m respectively than that at 0.1 and 1 m depth. These results are related to the accumulation of phenolic compounds: i.e. the algae at 0.25-0.5 m presented respectively about a 3-5 times higher concentration of phenolic compounds than that of algae at 0.1-1 m depth. The protection mechanisms seem to be stimulated by UVB radiation, since Fv/Fm was higher in the presence of UVB (PAB treatment) compared to PA or P treatments. UVA exerts the main photoinhibitory effect, not only at midday, but also in the afternoon. UVB radiation also had a protective effect in algae grown under desiccation conditions for three days. During re-hydration, the rapid increase of Fv/Fm (after 1 h) was higher in the UVB-grown algae than in algae grown under UVA radiation. After 5 h, Fv/Fm values were similar in algae submitted to desiccation/rehydration under PAB and P treatments as they were in the control (submerged algae). The combined effect of desiccation and UVA produced the greatest decrease of photosynthesis in Z. decussata. Thus UVB, in contrast to other species, may support the recovery process. Z. decussata can acclimate to severe stress conditions in this high mountain lake by the photoprotection mechanism induced by UVB radiation through dynamic photoinhibition and the accumulation of phenolic compounds (UV screen and antioxidant substances).

Porphyra umbilicalis L. Kutzing collected from the upper intertidal zone at Helgoland, North Sea, was exposed to different spectral ranges of UV radiation under both 12/12 h light/dark cycles and continuous irradiation. In light/dark cycles, oscillations of the optimal quantum yield (Fv /Fm) were observed during the experiments, reaching maximal values at the end of the light phase followed by lower values during the dark phase. Decreased Fv /Fm was observed in thalli illuminated with photosynthetic active radiation (PAR) plus UV-A and PAR+UV-A+UV-B, compared with the PAR control, indicating a certain degree of UV-induced photoinhibition. In addition, a decrease in the percentage of change of the linear initial slope and maximum electron transport rate (ETR) estimated from ETR vs. irradiance curves was induced by UV radiation during the light phase. Recovery during the 12 h dark phase was almost completed in UV-A treated plants. PAR+UV-A seemed not to affect the photosynthesis, measured as O2 production. However, a decrease in O2 production was observed in the PAR+UV-A+UV-B treatment, but it recovered to initial values after 48 h of culture. No changes in total content of photosynthetic pigments were observed. However, thallus absorptance and the in vivo absorption cross-section in the PAR range (400-700 nm) normalised to Chl a (a* parameter) fluctuated during light/dark cycles and were positively correlated with changes in the optimum quantum yield, thus indicating that daily pigment reorganisation in the light-harvesting complex may play a key role in the photosynthetic performance of the algae. Both UV-A and UV-B treatments under continuous irradiation induced a significant reduction in the optimal quantum yield, ETR efficiency and photosynthetic oxygen production during the first 36 h to values around 30% of the initial ones. Thus, different protective mechanisms against UV stress can be observed in P. umbilicalis: dynamic photoinhibition when UVA is combined with PAR, followed by full recovery of photosynthesis during the dark phase, and a more pronounced photoinhibition under UV-B, with only partial recovery after longer time periods, in which photosynthetic pigment reorganisation plays an important role.

Ocean acidification may benefit algae that are able to capitalise on increased carbon availability for photosynthesis but is expected to have adverse effects on calcified algae through dissolution. Shifts in dominance between primary producers will have knock-on effects on marine ecosystems and will likely vary regionally, depending on factors such as irradiance (light vs shade) and nutrient levels (oligotrophic vs eutrophic). Thus experiments are needed to evaluate interactive effects of combined stressors in the field. In this study, we investigated the physiological responses of macroalgae near a CO2 seep in oligotrophic waters off Vulcano (Italy). The algae were incubated in situ at 0.2 m depth using a combination of three mean CO2 levels (500, 700-800 and 1200 µatm CO2), two light levels (100 and 70% of surface irradiance) and two nutrient levels of N, P, and K (enriched vs non-enriched treatments) in the non-calcified macroalga Cystoseira compressa (Phaeophyceae, Fucales) and calcified Padina pavonica (Phaeophyceae, Dictyotales). A suite of biochemical assays and in vivo chlorophyll a fluorescence parameters showed that elevated CO2 levels benefitted both of these algae, although their responses varied depending on light and nutrient availability. In C. compressa, elevated CO2 treatments resulted in higher carbon content and antioxidant activity in shaded conditions both with and without nutrient enrichment - they had more Chla, phenolic and fucoxanthin with nutrient enrichment and higher quantum yield (Fv/Fm) and photosynthetic efficiency (αETR) without nutrient enrichment. In P. pavonica, elevated CO2 treatments had higher carbon content, Fv/Fm, αETR, and Chla regardless of nutrient levels - they had higher concentrations of phenolic compounds in nutrient enriched, fully-lit conditions and more antioxidants in shaded, nutrient enriched conditions. Nitrogen content increased significantly in fertilised treatments, confirming that these algae were nutrient

Lanthanides are biologically non-essential elements with wide applications in technology and industry. Their concentration as environmental contaminants is, therefore, increasing. Although non-essential, lanthanides have been proposed (and even used) to produce beneficial effects in plants, even though their mechanisms of action are unclear. Recently, it was suggested that they may replace essential elements. We tested the effect of low concentrations of lanthanides on the common freshwater microalga Desmodesmus quadricauda, grown under conditions of metal ion-deficiency (lower calcium or manganese concentrations). Our goal was to test if lanthanides can replace essential metals in their functions. Physiological stress was recorded by studying growth and photosynthetic activity using a pulse amplitude modulation (PAM) fluorimeter. We found that nutrient stress reduced parameters of growth and chlorophyll fluorescence, such as maximal quantum yield, relative electron transport rate, photon capturing efficiency and light saturation irradiance. After adding low concentrations of five lanthanides, we confirmed that they can produce a stimulatory effect on microalgae, depending on the nutrient (metal) deprivation. In the case of a calcium deficit, the addition of lanthanides partly alleviated the effects, probably by a partial substitution of the element. In contrast, with manganese deprivation (and at even lower concentrations), lanthanides enhanced the toxic effect and severely inhibited growth. These results show that lanthanides can replace essential elements, but their effects on microalgae depend on stress and the physiological state of the microalgae, raising the possibility of environmental impacts at even low concentrations.

The effects of solar ultraviolet (UV) radiation during daily cycles on photosynthesis and two key enzymes involved in carbon incorporation, the carbonic anhydrase, and in inorganic nitrogen reduction, the nitrate reductase, of macroalgae from southern Spain are presented. During daily cycles, photoinhibition in several intertidal macroalgae, expressed as decrease in the effective quantum yield from the morning to noon time, was linearly dependent on the daily integrated irradiance. However, recovery, expressed as the increase in the effective quantum yield from noon to the afternoon, presented a different pattern; full recovery was found below daily integrated irradiance of 1.0 x10(4) kJ m-2. However, recovery reached only 50 % at higher irradiances. The existence of daily photoinhibition and full recovery in intertidal algae suggests that photoinhibition is a photoprotective mechanism against high solar radiation as in higher plants, and that patterns of photoinhibition and recovery are affected by accumulative doses. Activities of carbonic anhidrase and nitrate reductase were determined in three marine macroalgae (Plocamium cartilagineum, Ulva rigida and Fucus spiralis) under full (PAR + UV-A + UV-B) and excluded UV solar radiation (PAR). Under PAR + UV-A + UV-B, peaks of enzyme activity were found in P. cartilagineum during the evening, and accordingly to data previously published for other red macroalgae. This situation was modified by the absence of UV radiation since the increase in the activities was delayed several hours. In the three macroalgae and under full solar radiation, a significant and negative correlation was found only when data from nitrate reductase activity was shifted in time during at least four hours. This correlation is lost in Ulva rigida when UV radiation is excluded. The existence of these daily variations with a negative correlation of both enzyme activities could reflect a complex regulatory link between carbon and nitrogen metabolism under solar radiation. Considering the absence of a significant correlation in U. rigida and the delay observed in maximal activities of P. cartilagineum in the absence of UV, it is suggested that UV radiation acts as an environmental signal involved in the control of cycles. The presence of feedback processes that control nitrogen assimilation as a function of carbon content is proposedEn este trabajo se presenta el efecto de la radiación solar ultravioleta (UV) durante el ciclo diario de luz sobre la actividad fotosintética y la de dos enzimas claves en la incorporación de carbono, la anhidrasa carbónica, y en la reducción de nitrógeno inorgánico, la nitrato reductasa, en macroalgas del sur de España. Durante el ciclo diario de luz, la fotoinhibición, expresada como porcentaje de disminución del rendimiento cuántico efectivo desde la mañana al mediodía, estuvo linear y negativamente correlacionada con la irradiancia integrada diaria. Sin embargo, la recuperación, expresada como porcentaje de incremento del rendimiento cuántico efectivo desde el mediodía hasta el atardecer siguió un patrón diferente. Se observó recuperación completa a irradiancias integradas diarias menores a 1.0 x 10(4) kJ m-2. Sin embargo, a irradiancias diarias mayores, la recuperación fue sólo del 50 %. La existencia de fotoinhibición y de una recuperación diaria completa en macroalgas hace pensar que la fotoinhibición está funcionado como un mecanismo de fotoprotección contra radiaciones solares altas como ocurre en plantas terrestres. Además, los patrones de fotoinhición y recuperación tienen relación con la dosis acumulada diaria. Las actividades enzimáticas (anhidrasa carbónica y nitrato reductasa) fueron determinadas en tres macroalgas marinas (Plocamium cartilagineum, Ulva rigida y Fucus spiralis) bajo radiación solar completa (PAR + UV-A + UV-B) y excluyendo la radiación UV (PAR). Bajo PAR + UV-A + UV-B se observó un máximo en la actividad de ambas enzimas en P. cartilagineum por la tarde, lo que concuerda con datos publicados en otras algas rojas. La situación fue modificada en ausencia de UV ya que el incremento de ambas actividades fue retrasado en el tiempo (varias horas). En las tres macroalgas bajo radiación solar completa se encontró una correlación significativa y negativa sólo cuando los datos de la actividad nitrato reductasa fueron desplazados al menos 4 horas respecto a los de la anhidrasa carbónica. Esta correlación se pierde en Ulva rigida cunado se excluye la radiación UV. La existencia de variaciones diarias y la correlación negativa entre la actividad de ambas enzimas podría reflejar una compleja regulación conjunta entre el metabolismo del carbono y del nitrógeno bajo radiación solar. Debido a que esta correlación se pierde en ausencia de UV en Ulva o los máximos se retrasan en Plocamium, se sugiere que la radiación UV podría ser una señal medioambiental implicada en el control de los ciclos enzimáticos. Se sugiere la existencia de procesos de retroalimentación que controlan el metabolismo del nitrógeno en función del contenido de carbono

The present study was carried out to determine the antitumor and antioxidant activities of the seaweed Durvillaea antarctica. Extraction and purification of polysaccharides from D. antarctica were performed. They were characterized by FT‐IR and GC–MS, identifying isomers of arabinose, fucose, mannose, and galactose. The antioxidant capacity of polysaccharides was analyzed using the ABTS method (14.3 ± 0.5 μmol TE g−1 PS) and the DPPH method (21.82 ± 0.32 μmol TE g−1 PS). The antitumor capacity of polysaccharides was studied by MTT colorimetric assays in human leukemia, colon, breast, and lung cancer cell lines, obtaining the lowest IC50 in colon cancer (19.99 μg mL−1). In the line of healthy human gingival fibroblasts (HGF‐1), an IC50 of 444.39 μg mL−1 was obtained. Flow cytometry in the HL60 cell line showed that polysaccharides at concentrations higher than IC50 inhibited cell proliferation, demonstrating a possible antitumor capacity in vitro. In the proteomic analysis with HGF‐1, nine proteins involved in different biological processes were identified. In conclusion, polysaccharides from D. antarctica could be considered powerful nutraceuticals, mainly against colon cancer. [ABSTRACT FROM AUTHOR]