Total Mycosporine-like Amino Acids Research Articles

UV-absorbing mycosporine-like amino acids in the eyes of temperate marine and freshwater fish species

Ultraviolet radiation (UVR) is the photochemically most reactive waveband of incident solar irradiation. Despite high absorption in aquatic environments, UVR causes numerous biochemical, genetic, and cytotoxic effects in aquatic organisms. To counteract UVR stress, many of those species are able to synthesize, accumulate, or acquire UV-sunscreen compounds for photoprotection from their diet. The most abundant UV sunscreens in marine and freshwater organisms are mycosporine-like amino acids (MAAs), which exhibit high molar extinction coefficients in the UVR range along with a strong photo- and heat stability. In this study, we investigated the qualitative and quantitative MAA distribution patterns in the eyes of 39 fish species, mainly from the temperate northern hemisphere (Baltic Sea, Northern Atlantic), using state-of-the-art analytical methods. The fish eyes of the most investigated species (33 taxa) contained MAAs, between one and seven different compounds. The MAAs palythine, asterina-330, palythene, and usujirene were present (as previously reported), and three new compounds, aplysiapalythine A, porphyra-334, and shinorine, were identified. Total MAA concentrations covered a wide range from trace amounts to > 4.2 mg g−1 dry weight, thereby providing the first quantitative data on MAAs in fish eyes. The highest MAA contents were measured in Sprattus sprattus, which are comparable to those of intertidal red seaweeds. The trophic transfer of MAAs from primary producers via zooplankton to the fish is discussed, along with the localization in the fish eye as well as possible additional functions.

The Role of Nitrate Supply in Bioactive Compound Synthesis and Antioxidant Activity in the Cultivation of Porphyra linearis (Rhodophyta, Bangiales) for Future Cosmeceutical and Bioremediation Applications.

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.

Mycosporine-like Amino Acids in Palmaria palmata (Rhodophyta): Specific Implication of Usujirene in Photoprotection.

The effect of UV radiation on the accumulation of mycosporine-like amino acids (MAAs) and pigments was investigated on red macroalga Palmaria palmata cultivated for 21 days. The data were combined with the effect of NaNO3 to further investigate the synthesis of these nitrogenous compounds. A progressive decrease in both total MAA and pigment contents was observed, with a positive effect of nitrate supply. Usujirene was the only MAA exhibiting a significantly increasing content when exposed to UV radiation, changing from 9% to 24% of the total MAA's contribution, with no variation observed with NaNO3. This suggests a specific induction or synthesis pathway of usujirene for photoprotection, while the synthesis of other MAAs could have been limited by an insufficient amount of UV radiation and/or irradiance. The photoprotective ability of some MAAs could have been impacted by nitrogen starvation over time, resulting in a limited synthesis and/or potential use of MAAs as a nitrogen source for red macroalgae. The data confirmed the multiple effects of environmental factors on the synthesis of MAAs while providing new insights into the specific synthesis of usujirene, which could find an application in the cosmetics sector as natural sunscreen or an anti-ageing agent.

Rapid Screening for Mycosporine-like Amino Acids (MAAs) of Irish Marine Cyanobacteria and Their Antioxidant Potential

The present study evaluated 53 Irish marine cyanobacteria intending to identify potential producers of mycosporine-like amino acids (MAAs) to meet the increasing demand for replacing chemical sunscreen with bio-sunscreen. The biodiscovery analysis using absorption spectra of methanolic extracts identified eight cyanobacteria as potential MAAs producers with a specific content of 0.114–0.511 A* mg DW−1. Leptolyngbya tenuis SABC010201 was found to possess notably higher MAAs content. LC-MS analysis identified a total of eight different types of known MAAs (mycosporine-glutamicol, mycosporine-glutaminol-glucoside, mycosporine-serinol, mycosporine-taurine, palythine, palythine-threonine-sulphate, porphyra-334, and usujirene) in eight cyanobacteria, while four compounds were considered unknown UV-absorbing compounds with specific mass and absorption maximum. For example, two unknown compounds with, respectively, [M-H]- values of 219.0557 and 289.0730 and lambda max of 314 and 326 nm, were detected in three cyanobacteria Leptolyngbya tenuis SABC010201, Phormidium angustissimum SABC020801, and Schizothrix sp. SABC022401. These two unknown compounds were named M-314 and M-326, respectively. Antioxidant activities of total MAAs of all cyanobacteria showed considerable amounts of DPPH, FRAP, and ORAC activities. Considering the specific MAAs content and antioxidant activities, Leptolyngbya africana SABC021601 was considered the best producer of MAAs.

Bromoform, mycosporine-like amino acids and phycobiliprotein content and stability in Asparagopsis armata during long-term indoor cultivation

As the commercial use of seaweed for natural product extraction calls for abundant, uniform biomass, this study focused on the production and the variability of the harvested biomass of valuable compounds produced by a commercially relevant red algal species, Asparagopsis armata. Its tetrasporophyte stage was retrieved from two Irish localities and grown for over 2 years in indoor cultures at 13 °C and 17 °C, and bromoform, mycosporine-like amino acids and phycobiliprotein contents were monitored over time. Growth rates at different temperatures were specific to isolates, and one isolate failed to grow at 17 °C. All compounds of interest were detected by the end of the 2-year cultivation period, and most of them were produced at an exponential rate at 13 °C but not at the higher temperature. At 13 °C, bromoform reached concentrations of 10.00 ± 0.55 mg g−1, total mycosporine-like amino acids of 2.65 ± 0.10 mg g−1, phycoerythrin of 11.46 ± 0.35 mg g−1 and phycocyanin of 72.13 ± 1.74 mg g−1 in Irish isolates. The observed variability in compound content was statistically significant but not large enough to impede commercial utilization. Bromoform content in cultivated samples was almost 6-fold higher than in field-collected samples though natural bromoform variability remains to be elucidated. Our findings suggest that the tetrasporophytic phase of A. armata is a suitable candidate for indoor cultivation; abundant and homogeneous biomass composition can be obtained which can be further optimized by growth temperature.

Occurrence of Mycosporine-like Amino Acids (MAAs) from the Bloom-Forming Cyanobacteria Aphanizomenon Strains.

Mycosporine-like amino acids (MAAs) are widespread in various microbes and protect them against harsh environments. Here, four different Aphanizomenon species were isolated from severely eutrophic waterbodies, Lake Dianchi and the Guanqiao fishpond. Morphological characters and molecular phylogenetic analysis verified that the CHAB5919, 5921, and 5926 strains belonged to the Aphanizomenon flos-aquae clade while Guanqiao01 belonged to the Aphanizomenon gracile clade. Full wavelength scanning proved that there was obvious maximal absorption at 334 nm through purified methanol extraction, and these substances were further analyzed by HPLC and UPLC-MS-MS. The results showed that two kinds of MAAs were discovered in the cultured Aphanizomenon strains. One molecular weight was 333.28 and the other was 347.25, and the daughter fragment patterns were in accordance with the previously articles reported shinorine and porphyra-334 ion characters. The concentration of the MAAs was calibrated from semi-prepared MAAs standards from dry cells of Microcystis aeruginosa PCC7806 algal powder, and the purity of shinorine and porphyra-334 were 90.2% and 85.4%, respectively. The average concentrations of shinorine and porphyra-334 were 0.307–0.385 µg/mg and 0.111–0.136 µg/mg in Aphanizomenon flos-aquae species, respectively. And there was only one kind of MAAs (shinorine) in Aphanizomenon gracile species.,with a content of 0.003–0.049 µg/mg dry weight among all Aphanizomenon gracile strains. The shinorine concentration in Aphanizomenon flos-aquae was higher than that in Aphanizomenon gracile strains. The total MAAs production can be ranked as Aphanizomenon flos-aquae > Aphanizomenon gracile.

Short-term variations of mycosporine-like amino acids in the carrageenan-producing red macroalga Mazzaella laminarioides (Gigartinales, Rhodophyta) are related to nitrate availability

The effect of solar UV radiation exposure and NO3– supply on mycosporine-like amino acids (MAAs) accumulation in the carrageenan-producing red macroalga Mazzaella laminarioides in a short-term period was studied. Apical segments of M. laminarioides tetrasporophytes were exposed to three treatments of solar radiation (PAR [P], PAR+UV-A [PA], and PAR+UV-A+UV-B [PAB]) under 0.38 mM NO3– or without NO3– supply. Samples were taken at the following local times: 8:00 (initial value), 13:00, and 18:00, and at 8:00 on the following day. Short-term variations in total MAA content were observed, being this variation accounted by the interaction of radiation, time exposure, and NO3– treatments. The highest MAAs content (above 3 mg g−1 DW) was observed at 13:00 under PA (without NO3−) and PAB (with NO3–), and at 18:00 under PA (with NO3–) and PAB (with NO3–) treatments. Four MAAs were identified: asterina-330, shinorine, palythine, and mycosporine-glycine. The content and percentage of each MAA varied during the experimental time. While the accumulation of shinorine and palythine varied according to NO3– supply, mycosporine-glycine did it according to the interaction of time exposure and radiation treatment. The short-term (hours) variations in total MAAs content and the concentration of each MAA as a response to the high solar irradiance received could be a prerequisite in intertidal species to thrive in a highly variable environment.

Assessment of the photoprotective potential and toxicity of Antarctic red macroalgae extracts from Curdiea racovitzae and Iridaea cordata for cosmetic use

Botanical and marine extracts have been used in cosmetic products as natural antioxidants or UV-absorbers to reduce the use of organic UV filters. However, despite the high UV exposure of Antarctic macroalgae that induces the production of photoprotective compounds, the use of marine macroalgae extracts for photoprotection has been little explored. Thus our objective was to assess the photoprotective potential and the toxicity of extracts from two red macroalgae Curdiea racovitzae and Iridaea cordata. Chemical characterization was based on the qualitative and quantitative analyses of mycosporine-like amino acids (MAAs) by high performance liquid chromatography coupled to mass spectrometry. Photoprotective properties were assessed by UV spectrophotometry and photostability assay. Antioxidant capacity was studied by DPPH and superoxide radical scavenging assays. UVB and UVA photoprotection was assessed in keratinocytes by cell viability analysis after UVB irradiation and quantification of intracellular reactive oxygen species (ROS) induced by UVA, respectively. Toxicity was estimated by cytotoxicity, phototoxicity and HET-CAM (Hen's egg test-chorioallantoic membrane) assays. Red algae extracts had high concentrations of MAAs, mainly consisted of palythine. The extracts absorbed in the UVB and UVA-II and were photostable. The C. racovitzae extract showed antioxidant activity against superoxide radicals. In addition, the C. racovitzae (1.0 and 0.5 mg/mL) and I. cordata (1.0 mg/mL) extracts had an UVB photoprotection similar to benzophenone-3, which was dependent on the total MAAs concentration. Besides, the C. racovitzae extract decreased ROS generation by 31 and 24% at 100 and 50 μg/mL, respectively. Furthermore, it was more effective in reducing ROS generation than quercetin and Helioguard 365®. Finally, both extracts were considered to be non-cytotoxic, non-phototoxic and non-irritant. Therefore, the C. racovitzae extract is a good candidate to be added to anti-aging and sunscreen formulations in order to protect against oxidative stress and to improve the absorption spectra of UV filters.

Temporal variation in pigment and mycosporine-like amino acid composition of the red macroalga Palmaria palmata from Brittany (France): hypothesis on the MAA biosynthesis pathway under high irradiance

Changes in pigment (chlorophyll-a, carotenoids and phycobiliproteins) and mycosporine-like amino acid (MAA) composition were studied in the red edible macroalga Palmaria palmata, harvested between February 2018 and February 2019 at 2 sites from Brittany (France). The results occuring in natural conditions revealed a high seasonal variability that can be related to a combination of environmental parameters, including light, nutrients, temperature, salinity and pH, which may have synergistic or antagonistic effects. A decrease in pigments was observed in summer, matching with the increase in irradiance at the same period. On the contrary, the increase in light from February to May has caused an increase in the total MAA content, confirming the UV-photoprotective role attributed to these compounds. Analysis of the results coupled with the biosynthesis pathway suggests that some MAAs are favoured in the occurrence of high irradiance. In this sense, asterina-330 was synthetized only between March and July and not the rest of the year, supporting its importance in photoprotection. In addition, analysis revealed that nutrient availibility could have a significant influence on MAAs since their synthesis seemed to be limited in summer, despite significant exposure to light. However, this decrease could be due to another potential role of MAAs as a nitrogen source for macroalgae. Thus, the diversity of these compounds and the different synthesis pathways could be explained by different roles including photo-protection and nitrogen source, making MAA multi-purpose protective agents which could play a key role in the adaptation of this species to its changing environment.

Quantitative and Qualitative HPLC Analysis of Mycosporine-Like Amino Acids Extracted in Distilled Water for Cosmetical Uses in Four Rhodophyta.

Mycosporine-like amino acids (MAAs) have gained considerable attention as highly active photoprotective candidates for human sunscreens. However, more studies are necessary to evaluate the extraction efficiencies of these metabolites in cosmetic compatible solvents, as well as, their subsequent HPLC analysis. In the present study, MAA extraction using distilled water and 20% aqueous methanol in four Rhodophyta was investigated. Different re-dissolution solvents and a C8 and C18 columns were tested for the HPLC analysis. Porphyra-334, shinorine, palythine, palythine-serine, asterina-330, and palythinol were identified by HPLC/ESI-MS. The separation of these MAAs were improved employing the C8-column, and using methanol as re-dissolution solvent. Regarding total MAAs concentrations, no differences between the two solvents were found. The highest MAA amounts were observed injecting them directly in the HPLC. According to these results, distilled water could be an excellent extraction solvent for MAAs. Nevertheless, the re-dissolution in pure methanol after dryness would be the best option for the qualitative analysis of the most common MAAs in these red algae. Our results entail important implications regarding the use of red macroalgae as promising candidates as environment-friendly sources of natural sunscreens.

Stress metabolite pattern in the eulittoral red alga Pyropia plicata (Bangiales) in New Zealand – mycosporine-like amino acids and heterosides

Intertidal rocky shore ecosystems are affected by steep environmental gradients such as fluctuating solar irradiation and salinity along the marine-terrestrial interface. The eulittoral red alga Pyropia plicata (Bangiales) is endemic and abundant to coastal regions of New Zealand and almost unstudied in terms of ecophysiological performance under radiation and salinity stress. Therefore, the acclimation potential of this species against enhanced ultraviolet radiation (UVR) and osmotic stress was evaluated in a combination of field and laboratory experiments with an emphasis on stress metabolite concentrations (UV-sunscreens, organic osmolytes). Samples of P. plicata were collected at the same site in the intertidal zone of Wellington, New Zealand over three seasons (April–November 2016) and used in independent UV and salt stress experiments under controlled conditions. The mycosporine-like amino acids (MAA) shinorine and porphyra-334 were the quantitatively dominant UV-sunscreen compounds, and the total concentrations varied over the year between 5 and 14 mg g−1 dry weight (DW), but neither UVR nor PAR had a significant impact on the total or individual MAA concentrations. A UV radiation stress experiment was conducted, but the total MAA concentrations of 6–8 mg g−1 DW did not change, neither did the contents of shinorine (~ 3 mg g−1 DW) nor that of porphyra-334 (4–5 mg g−1 DW). This suggests, that P. plicata has sufficiently high UV-sunscreen amounts and hence does not respond to changes in UV radiation. Pyropia plicata contained three heterosides (floridoside, D- and L-isofloridoside), which act as organic osmolytes. Seasonally the total concentrations of these compounds varied between 203 and 1226 mmol kg−1 DW, with L-isofloridoside quantitatively dominating all samples. A salt stress experiment showed an increase in the total heteroside concentrations in P. plicata with increasing salinities. However, floridoside was the most up-regulated heteroside under hypersaline conditions indicating its key role in osmotic acclimation. Our data indicate that P. plicata always contains various stress metabolites in consistently high concentrations which mitigate against environmental changes typical of the intertidal zone of New Zealand.

Enhancement of the Production of Bioactive Microalgal Metabolites by Ultraviolet Radiation (UVA 365 nm).

Two marine microalgae, Nitzschia closterium and Isochrysis zhangjiangensis, treated for 9 days with photosynthetically active radiation (PAR), were subjected to 3 days of ultraviolet light band A at 365 nm (UVA365) followed by a 3 day post-UVA PAR treatment. Compared with the control that only had PAR treatment, UVA365 treatment significantly ( p < 0.05) increased the amounts of total xanthophylls in N. closterium and I. zhangjiangensis by up to 3.53- and 1.23-fold, respectively, after 3 days of UVA365 irradiation. In particular, UVA365 treatment markedly ( p < 0.05) increased two major bioactive xanthophyll pigments, fucoxanthin in N. closterium and diadinoxanthin in I. zhangjiangensis, by up to 1.97- and 1.52-fold, respectively. UVA365 treatment significantly ( p < 0.05) increased the accumulation of another bioactive microalgal metabolite, total mycosporine-like amino acids, in N. closterium and I. zhangjiangensis by up to 1.40- and 1.30-fold, respectively. UVA365 irradiation has potential as an efficient approach for enhancing the production of valuable microalgal metabolites.

Temporal and spatial variability of mycosporine-like amino acids and pigments in three edible red seaweeds from western Ireland

The content of photosynthetic pigments (chlorophyll a and phycobiliproteins) and UV-absorbing mycosporine-like amino acids (MAAs) was investigated in three commercially important red macroalgae, Palmaria palmata, Chondrus crispus, and Porphyra dioica, with respect to seasonal changes at three locations in Galway Bay (western Ireland). Several parameters, including light, temperature, salinity, and nutrients, were measured over a 12-month sampling period, in an attempt to correlate changes in the content of compounds with variations in environmental factors. Pigments followed a distinct seasonal pattern, similar for the three species, which correlated in most cases with changes of seasonal environmental factors. As irradiance and temperature decreased in autumn, chlorophyll a and phycobiliprotein concentrations increased and remained high throughout winter, typically reaching maximum levels by late winter, early spring. By contrast, an increase in total MAA contents in all species was induced by increasing daily light doses and irradiance levels, from winter to spring, but without clear significant correlations with light and/or temperature. This could be explained by the low nutrient concentrations observed in summer months, limiting the synthesis and accumulation of MAAs, even when exposed to high irradiance levels. Nutrient availability, in particular nitrate, appears to be a limiting factor for the red algal species under investigation to synthetize MAA compounds when exposed to extreme light/irradiance stress. This study provides therefore the first available account of the seasonal variability of pigments and MAAs in these three commercially and ecologically important edible red seaweeds from Ireland.

Mycosporine-like amino acids vs carrageenan yield in Mazzaella laminarioides (Gigartinales; Rhodophyta) under high and low UV solar irradiance

:The effects of increased solar photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) on biomass, mycosporine-like amino acid (MAA) content, and carrageenan yield were studied for 14 days in tank-cultivated tetrasporophytes and gametophytes of Mazzaella laminarioides from the Magellan Strait. The initial values of carrageenan yield were similar between gametophytes and tetrasporophytes, whereas the MAA content was higher in gametophytes than that in tetrasporophytes. After 14 days of exposure to different combinations of solar radiation (PAR, PAR + UV-A, and PAR + UV-A + UV-B) and two irradiance levels (high and low), differences between gametophytes and tetrasporophytes of M. laminarioides in growth rate (GR), MAA, and carrageenan yield were observed. Higher GRs were observed in gametophytes than in tetrasporophytes under all radiation and irradiance treatments. A significant decrease in total MAA content was observed in both reproductive phases, with these decreases being more evident in gametophytes under all radiation and irradiance treatments (20 to 30% decrease compared with the initial value). Changes in the proportion of each MAA were also observed. The asterina-330 and palythine content decreased in gametophytes in all radiation and irradiance treatments, whereas tetrasporophytes exhibited an increase of these MAAs, mainly under PAR + UV-A at low irradiance. The carrageenan yield decreased in tetrasporophytes in all radiation treatments, whereas gametophytes exhibited an increase in this parameter under UV radiation at high irradiance. These results suggest that both reproductive phases have different strategies to cope with light stress, mainly under high UVR. Furthermore, both reproductive phases are adapted to high solar radiation, and the differences between gametophytes and tetrasporophytes could result from the vertical distribution on shore and from intrinsic differences related to ploidy level.

Effect of UV-B Radiation and Desiccation Stress on Photoprotective Compounds Accumulation in Marine Leptolyngbya sp.

Increased awareness regarding the harmful effects of ultraviolet (UV)-B radiation has led to the search for new sources of natural UV-B protecting compounds. Mycosporine-like amino acids are one of such promising compounds found in several organisms. Cyanobacteria are ideal organisms for isolation of these compounds due to their compatibility and adaptability to thrive under harsh environmental conditions. In the following investigation, we report the production of shinorine in Leptolyngbya sp. isolated from the intertidal region. Based on the spectral characteristics and liquid chromatography-mass spectrometry analysis, the UV-absorbing compound was identified as shinorine. To the best of our knowledge, this is the first report on the occurrence of shinorine in Leptolyngbya sp. We also investigated the effect of artificial UV-B radiation and periodic desiccation on chlorophyll-a, total carotenoids, and mycosporine-like amino acids (MAAs) production. The UV-B radiation had a negative effect on growth and chlorophyll concentration, whereas it showed an inductive effect on the production of total carotenoids and MAAs. Desiccation along with UV-B radiation led to an increase in the concentration of photoprotective compounds. These results indicate that carotenoids and MAAs thus facilitate cyanobacteria to avoid and protect themselves from the deleterious effects of UV-B and desiccation.

Novel glycosylated mycosporine-like amino acid, 13-O-(β-galactosyl)-porphyra-334, from the edible cyanobacterium Nostoc sphaericum-protective activity on human keratinocytes from UV light

A UV-absorbing compound was purified and identified as a novel glycosylated mycosporine-like amino acid (MAA), 13-O-β-galactosyl-porphyra-334 (β-Gal-P334) from the edible cyanobacterium Nostoc sphaericum, known as “ge xian mi” in China and “cushuro” in Peru. Occurrence of the hexosylated derivative of shinorine (hexosyl-shinorine) was also supported by LC-MS/MS analysis. β-Gal-P334 accounted for about 86.5% of total MAA in N. sphaericum, followed by hexosyl-shinorine (13.2%) and porphyra-334 (0.2%). β-Gal-P334 had an absorption maximum at 334nm and molecular absorption coefficient was 46,700 at 334nm. Protection activity of β-Gal-P334 from UVB and UVA+8-methoxypsoralen induced cell damage on human keratinocytes (HaCaT) was assayed in comparison with other MAA (porphyra-334, shinorine, palythine and mycosporine-glycine). The UVB protection activity was highest in mycosporine-glycine, followed by palythine, β-Gal-P334, porphyra-334 and shinorine in order. β-Gal-P334 had highest protection activity from UVA+8-methoxypsoralen induced cell damage followed by porphyra-334, shinorine, mycosporine-glycine and palythine. We also found an antioxidant (radical-scavenging) activity of β-Gal-P334 by colorimetric and ESR methods. From these findings, β-Gal-P334 was suggested to play important roles in stress tolerant mechanisms such as UV and oxidative stress in N. sphaericum as a major MAA. We also consider that the newly identified MAA, β-Gal-P334 has a potential for use as an ingredient of cosmetics and toiletries.

Characterization and antioxidant functions of mycosporine-like amino acids in the cyanobacterium Nostoc sp. R76DM

Mycosporine-like amino acids (MAAs) are considered efficient photoprotectants against high energy UV-photon flux. The present study is intended to probe the occurrence and synthesis of UV-absorbing MAAs and characterization of their induction, stability and free radical scavenging capacity in the cyanobacterium Nostoc sp. R76DM. HPLC-PDA detection, and LC–MS analysis revealed the occurrence of four different MAAs, palythine (λmax 320nm, m/z 245), Asterina (λmax 331nm, m/z 289), Porphyra (λmax 333nm, m/z 347) and palythene (λmax 359nm, m/z 285) with retention times 2.9, 4.71, 6.29 and 7.05min, respectively. Induction of the synthesis of all MAAs was highly noticeable under UV-B radiation. These MAAs were exceedingly resistant to some physico-chemical factors such as UV-B, temperature, pH and a strong oxidizing agent. Total MAAs were extensively evaluated for their antioxidant properties by 2,2-diphenyl-1-picryl-hydrazyl, ferric reducing antioxidant power, superoxide radical scavenging and reducing power assay. MAAs exhibited significant and dose-dependent in vitro antioxidant and in vivo ROS scavenging potentials. Moreover, the results indicate the vital role of MAAs in life-saving mechanisms of cyanobacteria by virtue of their UV-absorbing/screening and antioxidant function. The results also added up evidence in favor of MAAs for possible use as active ingredients in cosmeceuticals.

Effects of Light and Salinity Stresses in Production of Mycosporine-Like Amino Acids by Gymnodinium catenatum (Dinophyceae).

Mycosporine-like amino acids (MAAs) were analyzed in a Portuguese Gymnodinium catenatum strain when transferred to high salinity and high light conditions. Total MAA concentrations increased progressively between 30 and 36 psu, attaining at 36 psu 2.9-fold the 30 psu treatment. When abruptly transferred to solar light in an outdoor shadowed location, MAA concentration increased steadily along the day for most compounds. After 8h, mycosporine-glycine, palythene and M-319 attained or surpassed 25-fold their initial concentration, while M-370 only attained 4-fold concentration. When transferred from halogen to fluorescent light, polar MAAs such as shinorine and porphyra-334, increased until day two and then declined, while M-370 increase slowly, becoming the dominant compound from the profile after 1week. These experiments put into evidence the relation of palythene with M-319, which was further identified as its acid degradation product, palythine. Acid degradation of M-370 originated M-324, while M-311 seems to be the precursor of M-370. Under high salinity and high light conditions chain formation was altered toward shorter chains or solitary cells. This alteration can represent a morphological stress sign, which in the natural environment could affect average population speed during daily vertical migrations.

The relationship between UV-irradiance, photoprotective compounds and DNA damage in two intertidal invertebrates with contrasting mobility characteristics

The photoprotective role of mycosporine-like amino acids (MAA) against the generation of DNA cyclobutane pyrimidine dimers (CPD) was studied in the sessile intertidal anemone Actinia tenebrosa and the mobile intertidal gastropod Diloma aethiops through 27months at a mid-latitude New Zealand location. MAA were sequestered by A. tenebrosa and D. aethiops from their diet, although maximum total MAA levels in both species were not correlated with seasonal variation in maximum ambient UV-B levels recorded at the collection site. Temporal changes in total MAA in A. tenebrosa showed a six months lag-time in their concentration regarding to the environmental UV-B levels. This lag period corresponded to an observed increase in CPD production from spring to summer; suggesting that MAA do not completely protect the anemone from UV-B during summer. For D. aethiops, total MAA concentrations did not change significantly during the study, although qualitative changes in MAA were apparent. A month lag-time in MAA concentration in D. aethiops and possibly the physical barrier that the shell confers to the animal, can explain reduced CPD levels in comparative terms with A. tenebrosa. Although MAA are used by invertebrates for photoprotection, contrasting mobility characteristics and the presence of physical adaptations can confer them important protection levels during temporal changes of UV-B at mid-latitude places of the Southern Hemisphere.

Short-term ecophysiological and biochemical responses of Cystoseira tamariscifolia and Ellisolandia elongata to environmental changes

Short-term ecophysiological and biochemical responses of Cystoseira tamariscifolia and Ellisolandia elongata to changes in solar irradiance and nutrient levels were analyzed in situ in oligotrophic coastal waters by transferring macroalgae collected at 0.5 and 2.0 m depth and exposing them to 2 irradiance levels (100 and 70% of surface irradiance) and nutrient conditions (nutrient-enriched and non-enriched). Both species were affected by changes in irradiance and nutrient levels. Few interactive effects between these 2 physical stressors were found, suggesting major additive effects on both species. C. tamariscifolia collected at 0.5 m and exposed to 70% irradiance had the highest maximal electron transport rate (ETRmax), saturated irradiance (EkETR) and chl a content and the lowest antioxidant activity. Under the same conditions, E. elongata had increased EkETR, antheraxanthin and β-carotene content. At 100% irradiance, C. tamariscifolia collected at 2.0 m had higher maximal quantum yield (Fv/Fm), photosynthetic efficiency (αETR), ETRmax, maximal non-photochemical quenching (NPQmax), saturation irradiance for NPQ (EkNPQ), and antheraxanthin and polyphenol content increased, whereas in E. elongata only αETR increased. In nutrient-enriched conditions, phenolic compounds, several carotenoids and N con- tent increased in C. tamariscifolia at both depths. E. elongata from 2.0 m depth at 100% irradiance and nutrient-enriched conditions showed increased N content and total mycosporine-like amino acids (MAAs). Our results show rapid photophysiological responses of C. tamariscifolia to varia- tions in in situ irradiance and nutrient conditions, suggesting efficient photoacclimation to envi- ronmental changes. In E. elongata, Fv/Fm and ETRmax did not change in the transplant experiment; in contrast, N content, pigment and MAAs (biochemical variables) changed. The responses of these macroalgae to nutrient enrichment indicate oligotrophic conditions at the study site and environmental stress.