RESUMEN
Diabetic retinopathy (DR) is one of the most prevalent secondary complications associated with diabetes. Specifically, Type 1 Diabetes Mellitus (T1D) has an immune component that may determine the evolution of DR by compromising the immune response of the retina, which is mediated by microglia. In the early stages of DR, the permeabilization of the blood-retinal barrier allows immune cells from the peripheral system to interact with the retinal immune system. The use of new bioactive molecules, such as 3-(2,4-dihydroxyphenyl)phthalide (M9), with powerful anti-inflammatory activity, might represent an advance in the treatment of diseases like DR by targeting the immune systems responsible for its onset and progression. Our research aimed to investigate the molecular mechanisms involved in the interaction of specific cells of the innate immune system during the progression of DR and the reduction in inflammatory processes contributing to the pathology. In vitro studies were conducted exposing Bv.2 microglial and Raw264.7 macrophage cells to proinflammatory stimuli for 24 h, in the presence or absence of M9. Ex vivo and in vivo approaches were performed in BB rats, an animal model for T1D. Retinal explants from BB rats were cultured with M9. Retinas from BB rats treated for 15 days with M9 via intraperitoneal injection were analyzed to determine survival, cellular signaling, and inflammatory markers using qPCR, Western blot, or immunofluorescence approaches. Retinal structure images were acquired via Spectral-Domain-Optical Coherence Tomography (SD-OCT). Our results show that the treatment with M9 significantly reduces inflammatory processes in in vitro, ex vivo, and in vivo models of DR. M9 works by inhibiting the proinflammatory responses during DR progression mainly affecting immune cell responses. It also induces an anti-inflammatory response, primarily mediated by microglial cells, leading to the synthesis of Arginase-1 and Hemeoxygenase-1(HO-1). Ultimately, in vivo administration of M9 preserves the retinal integrity from the degeneration associated with DR progression. Our findings demonstrate a specific interaction between both retinal and systemic immune cells in the progression of DR, with a differential response to treatment, mainly driven by microglia in the anti-inflammatory action. In vivo treatment with M9 induces a switch in immune cell phenotypes and functions that contributes to delaying the DR progression, positioning microglial cells as a new and specific therapeutic target in DR.
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Diabetes Mellitus Tipo 1 , Retinopatía Diabética , Modelos Animales de Enfermedad , Microglía , Animales , Retinopatía Diabética/tratamiento farmacológico , Retinopatía Diabética/patología , Retinopatía Diabética/inmunología , Ratas , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Diabetes Mellitus Tipo 1/inmunología , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/complicaciones , Ratones , Microglía/efectos de los fármacos , Microglía/metabolismo , Retina/efectos de los fármacos , Retina/patología , Retina/metabolismo , Células RAW 264.7 , Masculino , Benzofuranos/farmacología , Benzofuranos/uso terapéutico , Inmunomodulación/efectos de los fármacos , Inflamación/tratamiento farmacológico , Inflamación/patología , Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Experimental/complicaciones , Ratas Endogámicas BBRESUMEN
The spread of Chikungunya virus is a major public health concern in the Americas. There were >120,000 cases and 51 deaths in 2023, of which 46 occurred in Paraguay. Using a suite of genomic, phylodynamic, and epidemiologic techniques, we characterized the ongoing large chikungunya epidemic in Paraguay.
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Fiebre Chikungunya , Virus Chikungunya , Epidemias , Humanos , Virus Chikungunya/genética , Paraguay/epidemiología , Sudáfrica , Fiebre Chikungunya/epidemiología , Filogenia , GenotipoRESUMEN
Diatoms are responsible for the fixation of ca. 20% of the global CO2 and live associated with bacteria that utilize the organic substances produced by them. Current research trends in marine microbial ecology show which diatom and bacteria interact mediated through the production and exchange of infochemicals. Polyunsaturated aldehydes (PUA) are organic molecules released by diatoms that are considered to have infochemical properties. In this work, we investigated the possible role of PUA as a mediator in diatom-bacteria interactions. To this end, we compare the PUA profile of a newly isolated oceanic PUA producer diatom, Cyclotella cryptica, co-cultured with and without associated bacteria at two phosphate availability conditions. We found that the PUA profile of C. cryptica cultured axenically was different than its profile when it was co-cultured with autochthonous (naturally associated) and non-autochthonous bacteria (unnaturally inoculated). We also observed that bacterial presence significantly enhanced diatom growth and that C. cryptica modulated the percentage of released PUA in response to the presence of bacteria, also depending on the consortium type. Based on our results, we propose that this diatom could use released PUA as a specific organic matter sign to attract beneficial bacteria for constructing its own phycosphere, for more beneficial growth.
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Diatomeas , Diatomeas/química , Aldehídos/farmacología , Aldehídos/química , Océanos y Mares , Bacterias , Biología MarinaRESUMEN
BACKGROUND: The pathogenesis of mild cognitive impairment (MCI) is multifactorial and includes the presence of genetic variants such as the ε4 allele of the apolipoprotein E gene (APOE-ε4). Association between the APOE-ε4 carrier status and deleterious structural and functional changes on magnetic resonance imaging (MRI) has been previously described in individuals with Alzheimer's disease. However, the central nervous system changes may possibly develop in earlier stages of cognitive impairment, as reflected in MCI. OBJECTIVE: The objective of the study was to determine the association between APOE-ε4 carrier status and qualitative changes on MRI (medial temporal and parietal atrophy), as well as the detection of white matter hyperintensities (WMH) in older adults with MCI, in the memory clinic of a tertiary care hospital in Mexico City. METHODS: A cross-sectional study of 72 adults aged 60 years or above who underwent an exhaustive clinical, neuroimaging, and neuropsychological evaluation. Multivariate logistic regression models were constructed to determine the association between APOE-ε4 carrier status and qualitative/quantitative changes on MRI. RESULTS: Mean age was 75.2 years (± 7.2) and 64% were female. Twenty-one participants were cognitively normal and 51 had MCI. Almost 56% were APOE-ε4 carriers and were associated with medial-temporal atrophy according to the Scheltens scale (odds ratio [OR]: 20.0, 95% confidence intervals [CI]: 3.03-131.7), parietal atrophy according to the Koedam's score (OR: 6.3; 95% CI 1.03-39.53), and WMH according to the Fazekas scale (OR: 11.7, 95% CI: 1.26-108.2), even after adjusting for age, educational level, and cardiovascular risk factors. CONCLUSION: The APOE-ε4 carrier status was associated with medial temporal and parietal atrophy, as well as WMH. Our findings support the hypothesis suggesting the contribution of this genotype to neurodegeneration and cerebral vascular pathology.
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Enfermedad de Alzheimer , Disfunción Cognitiva , Anciano , Enfermedad de Alzheimer/genética , Apolipoproteína E4/genética , Disfunción Cognitiva/genética , Estudios Transversales , Femenino , Humanos , Persona de Mediana Edad , NeuroimagenRESUMEN
Polyunsaturated aldehydes (PUAs) are bioactive molecules suggested as chemical defenses and infochemicals. In marine coastal habitats, diatoms reach high PUA production levels during bloom episodes. Two fractions of PUA can usually be analyzed: pPUA obtained via artificial breakage of collected phytoplankton cells and dissolved PUA already released to the environment (dPUA). In nature, resource supply arises as a main environmental controlling factor of PUA production. In this work, we monitored the vertical distribution and daily variation of pPUA associated with large-size phytoplankton and dPUA, at three sites located in the Alborán Sea from mesotrophic to oligotrophic waters. The results corroborate the presence of large-size PUA producers in oligotrophic and mesotrophic waters with a significant (58%-85%) diatom biomass. In addition to diatoms, significant correlations between pPUA production and dinoflagellate and silicoflagellate abundance were observed. 2E,4E/Z-Heptadienal was the most abundant aldehyde at the three sites with higher values (17.1 fg·cell-1) at the most oligotrophic site. 2E,4E/Z-Decadienal was the least abundant aldehyde, decreasing toward the oligotrophic site. For the first time, we describe the daily fluctuation of pPUA attributable to cellular physiological state and not exclusively to taxonomical composition. Our results demonstrate the persistence of threshold levels of dPUA deep in the water column, as well as the different chromatographic profiles of dPUA compared with pPUA. We propose different isomerization processes that alter the chemical structure of the released PUAs with unknown effects on their stability, biological function, and potential bioactivity.
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Aldehídos/química , Ácidos Grasos Insaturados/química , Biomasa , Clorofila/química , Diatomeas/química , Dinoflagelados/química , Eutrofización , Ácidos Grasos Insaturados/farmacología , Mar Mediterráneo , Fitoplancton/química , Fitoplancton/clasificación , Microbiología del AguaRESUMEN
Jellyfish is a compartment in the marine food web that often achieves high increases of biomass and that it is starting to be explored for several human potential uses. In this paper, a recently rediscovered large jellyfish, Rhizostoma luteum, is studied for the first time to describe its organic compounds for the isolation and production of bioactive compounds in several fields of food, cosmetics, or biomedical industries. The biogeochemical composition (Carbon, Nitrogen and Sulfur content), protein and phenols content, together with their antioxidant activity, and the analysis of lipid content (identifying each of the fatty acids presented) was analyzed. The results presented here suggested this jellyfish has the highest antioxidant activity ever measured in a jellyfish, but also with high content in polyunsaturated fatty acids (PUFAs), including the essential fatty acid linoleic. The large natural biomass of Rhizostoma luteum in nature, the wide geographical spread, the fact that already its life cycle has been completed in captivity, establishes a promising positive association of this giant jellyfish species and the isolation of bioactive compounds for future use in marine biotechnology.
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Antioxidantes/farmacología , Productos Biológicos/farmacología , Suplementos Dietéticos , Ácidos Grasos Insaturados/farmacología , Escifozoos , Animales , Antioxidantes/química , Antioxidantes/aislamiento & purificación , Productos Biológicos/química , Productos Biológicos/aislamiento & purificación , Biomasa , Biotecnología/métodos , Ácidos Grasos Insaturados/química , Ácidos Grasos Insaturados/aislamiento & purificación , Cadena Alimentaria , HumanosRESUMEN
Increases in seawater temperature are expected to have negative consequences for marine organisms. Beyond individual effects, species-specific differences in thermal tolerance are predicted to modify species interactions and increase the strength of top-down effects, particularly in plant-herbivore interactions. Shifts in trophic interactions will be especially important when affecting habitat-forming species such as seagrasses, as the consequences on their abundance will cascade throughout the food web. Seagrasses are a major component of coastal ecosystems offering important ecosystem services, but are threatened by multiple anthropogenic stressors, including warming. The mechanistic understanding of seagrass responses to warming at multiple scales of organization remains largely unexplored, especially in early-life stages such as seedlings. Yet, these early-life stages are critical for seagrass expansion processes and adaptation to climate change. In this study, we determined the effects of a 3 month experimental exposure to present and predicted mean summer SST of the Mediterranean Sea (25°C, 27°C, and 29°C) on the photophysiology, size, and ecology (i.e., plant-herbivore interactions) of seedlings of the seagrass Posidonia oceanica. Warming resulted in increased mortality, leaf necrosis, and respiration as well as lower carbohydrate reserves in the seed, the main storage organ in seedlings. Aboveground biomass and root growth were also limited with warming, which could hamper seedling establishment success. Furthermore, warming increased the susceptibility to consumption by grazers, likely due to lower leaf fiber content and thickness. Our results indicate that warming will negatively affect seagrass seedlings through multiple direct and indirect pathways: increased stress, reduced establishment potential, lower storage of carbohydrate reserves, and increased susceptibly to consumption. This work provides a significant step forward in understanding the major mechanisms that will drive the capacity of seagrass seedlings to adapt and survive to warming, highlighting the potential additive effects that herbivory will have on ultimately determining seedling success.
Asunto(s)
Alismatales/fisiología , Cambio Climático , Herbivoria , Plantones , Aclimatación , Biomasa , Ecosistema , Cadena Alimentaria , Mar Mediterráneo , Hojas de la Planta/crecimiento & desarrollo , Estaciones del Año , Agua de Mar , TemperaturaRESUMEN
The chemical study of the bryozoan Schizomavella mamillata has led to the isolation of six new 5-alkylresorcinol derivatives, schizols A-F (1-6), whose structures were established by spectrocospic means. Schizol A (1) exhibits a (E)-6-phenylnon-5-enyl moiety linked to the C-5 of a resorcinol ring, while in schizol B (2) the substituent at C-5 contains an unusual 1,2-dihydrocyclobutabenzene moiety. Schizols C (3) and D (4) have been characterized as the 1-sulfate derivatives of 1 and 2, respectively, and schizols E (5) and F (6) are the corresponding 1,3-disulfates. Schizol A (1) has been synthetized from 3,5-dimethoxybenzaldehyde through a sequence involving a Wittig reaction for the construction of the C-1',C-2' bond and a Julia-Kocienski olefination for the synthesis of the C-5',C-6' double bond. In the ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)) antioxidant assay, the natural compounds schizol A (1) and schizol B (2) showed higher radical scavenging activity than the Trolox standard.
Asunto(s)
Antioxidantes/farmacología , Organismos Acuáticos , Briozoos , Resorcinoles/farmacología , Animales , Antioxidantes/química , Espectroscopía de Resonancia Magnética , Resorcinoles/química , Relación Estructura-ActividadRESUMEN
Twelve new meroditerpenoids, 1-12, along with eight known compounds, have been isolated from the brown alga Cystoseira usneoides collected off the coast of Tarifa (Spain). The structures of the new metabolites have been established by spectroscopic techniques. All of the new compounds consist of a toluhydroquinone-derived nucleus linked to a regular diterpenoid moiety, which can either be acyclic or contain an ether ring. Most structural diversity arises from the presence of different oxygenated functionalities and unsaturations along the two terminal isoprenoid units of the diterpene backbone. Twelve of the isolated meroditerpenes have been tested in antioxidant assays. All of them have shown radical-scavenging activity. The most active compounds were cystodiones G (1) and H (2), 11-hydroxyamentadione (15), and amentadione (16), which exhibited antioxidant activities in the range of 77-87% that of the Trolox standard. In anti-inflammatory assays, cystodiones G (1) and M (6), cystone C (9), 11-hydroxyamentadione (15), and amentadione (16) showed significant activity as inhibitors of the production of the proinflammatory cytokine TNF-α in LPS-stimulated THP-1 human macrophages.
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Antiinflamatorios/aislamiento & purificación , Antiinflamatorios/farmacología , Antioxidantes/aislamiento & purificación , Antioxidantes/farmacología , Diterpenos/aislamiento & purificación , Diterpenos/farmacología , Phaeophyceae/química , Antiinflamatorios/química , Antioxidantes/química , Diterpenos/química , Humanos , Lipopolisacáridos/farmacología , Macrófagos/efectos de los fármacos , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Extractos Vegetales/farmacología , España , Terpenos/química , Factor de Necrosis Tumoral alfaRESUMEN
The use of a copper-iron mixed oxide as a heterogeneous catalyst for the efficient synthesis of α-acyloxy-1,4-dioxanes and 1,4-dithianes employing t-butyl peroxyesters is reported. The preparation and characterization of the catalyst are described. The effect of the heteroatoms and a plausible mechanism are discussed. The method is operationally simple and involves low-cost starting materials affording products in good to excellent yields.
RESUMEN
Diatoms, a major component of the large-sized phytoplankton, are able to produce and release polyunsaturated aldehydes after cell disruption (potential PUAs or pPUA). These organisms are dominant in the large phytoplankton fraction (>10 µm) in the Strait of Gibraltar, the only connection between the Mediterranean Sea and the Atlantic Ocean. In this area, the hydrodynamics exerts a strong control on the composition and physiological state of the phytoplankton. This environment offers a great opportunity to analyze and compare the little known distribution of larger sized PUA producers in nature and, moreover, to study how environmental variables could affect the ranges and potential distribution of these compounds. Our results showed that, at both tidal regimes studied (Spring and Neap tides), diatoms in the Strait of Gibraltar are able to produce three aldehydes: Heptadienal, Octadienal and Decadienal, with a significant dominance of Decadienal production. The PUA released by mechanical cell disruption of large-sized collected cells (pPUA) ranged from 0.01 to 12.3 pmol from cells in 1 L, and from 0.1 to 9.8 fmol cell⻹. Tidal regime affected the abundance, distribution and the level of physiological stress of diatoms in the Strait. During Spring tides, diatoms were more abundant, usually grouped nearer the coastal basin and showed less physiological stress than during Neap tides. Our results suggest a significant general increase in the pPUA productivity with increasing physiological stress for the cell also significantly associated to low nitrate availability.
Asunto(s)
Aldehídos/química , Diatomeas/química , Aldehídos/metabolismo , Animales , Océano Atlántico , Biomasa , Clorofila/química , Clorofila/metabolismo , Citometría de Flujo , Alimentos , Cromatografía de Gases y Espectrometría de Masas , Región Mediterránea , Fitoplancton , Análisis de Componente Principal , Estaciones del Año , Agua de Mar/químicaRESUMEN
Seagrasses are plants adapted to the marine environment that inhabit shallow coastal waters, where they may be exposed to direct sunlight during low tides. These plants have photoprotection mechanisms, which could include the use of phenolic secondary metabolites. In this study, rosmarinic acid (RA) and the flavonoids of Zostera noltei from the Bay of Cadiz (Spain) have been analyzed, first to define suitable conditions of leaves (i.e., fresh, dried, or frozen) for quantitative analysis, and then to explore the potential correlation between the phenolic profile of the leaves and sunlight exposure using an in situ experimental approach. Compared with fresh leaves, the contents of RA and flavonoids were significantly lower in air-dried and freeze-dried leaves. Freezing caused highly variable effects on RA and did not affect to flavonoid levels. On the other hand, the content of RA was significantly higher in plants that emerged during low tides than in plants permanently submerged, while plants underneath an artificial UV filter experienced a progressive reduction in RA content. However, the major flavonoids did not show a clear response to sunlight exposure and were unresponsive to diminished UV incidence. The results showed a positive correlation of RA with direct sunlight and UV exposure of leaves, suggesting that this compound contributes to the photoprotection of Z. noltei.
RESUMEN
Differences in phenolic composition across different ontogenic stages can be crucial in determining the interaction outcomes between plants and their surrounding biotic environment. In seagrasses, specific phenolic compounds have rarely been analyzed and remain unexplored in ontogenic stages other than non-reproductive adults. Furthermore, it is generally accepted that plants would prioritize defense (e.g., through increased phenolic content) on tissues or stages that are critical for plant fitness but how this affects nutritional quality or plant resources has been scarcely explored. We analyzed how phenolic composition, N and C content and carbohydrate resources varied among different life stages (i.e. old and young leaves of reproductive and non-reproductive plants, and leaves of seedlings) in the seagrass Posidonia oceanica. We identified five phenolic compounds, whose structures were established as hydroxycinnamate esters of tartaric acid. Also, our results show that in all examined ontogenic stages phenolic compounds have the same qualitative composition but inflorescences exhibit higher contents than vegetative tissues. We did not find a reduction in stored resources in reproductive plants, pointing to some kind of compensatory mechanism in the production or storage of resources. In contrast, seedlings seemed to have less phenolic compounds than reproductive plants, perhaps due to limited resources available to allocate to phenolic production. Our results demonstrate how different ontogenic stages change their investment in specialized phenolic compounds prioritizing different functions according to the needs and limitations of that stage.
Asunto(s)
Alismatales , Alismatales/química , Fenoles , Hojas de la Planta , PlantonesRESUMEN
Phthalides are a group of compounds with relevant biological activities in different areas such as cytotoxicity, anti-stroke activity, neuroprotection, and inflammation, among others. In this study we designed and synthesized a series of 3-arylphthalide derivatives in order to identify their antioxidant and anti-inflammatory activities. The synthetic methodology was established in terms of atom and step economy through a dehydrative coupling reaction between 3-hydroxyphthalide and different properly functionalized arene rings. The evaluation of the antioxidant activity was performed by the ABTS assay and for the anti-inflammatory activity the inhibition of LPS-induced nitric oxide (NO) production in microglial cells Bv.2 and macrophage cells RAW 264.7 was measured. The synthesized compound 3-(2,4-dihydroxyphenyl)phthalide (5a) showed better antioxidant activity than the Trolox standard and caused strong inhibition of NO production in LPS-stimulated Bv.2 and RAW 264.7 cells. In addition, compound 5a reduced the expression of the pro-inflammatory cytokines Il1b and Il6 in RAW 264.7 cells. These results, which are the first account of the anti-inflammatory activity of 3-arylphthalides, suggest that compound 5a could be a promising candidate for more advanced anti-inflammatory studies.
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Congenital neuroblastoma is the most frequent malignant solid tumor in the neonatal period. The clinical presentation is usually either by prenatal diagnosis or by palpation of an abdominal mass. Staging allows classifying it according to risk groups with a different prognosis and treatment. In the neonatal period, it is characterized by a high rate of spontaneous regression and good prognosis (disease-free survival at 5 years greater than 90 %). We present a clinical case of congenital neuroblastoma whose presentation, shock and hypertension, was only described on a previous occasion. Antihypertensive treatment along with systemic chemotherapy produced clinical control and patient improvement.
El neuroblastoma congénito es el tumor sólido maligno más frecuente en el período neonatal. La forma de presentación suele ser por diagnóstico prenatal o por una masa abdominal. Su estadificación permite clasificarlo en grupos de riesgo con pronóstico y tratamiento diferentes. En el período neonatal, se caracteriza por la alta tasa de regresión espontánea y el buen pronóstico (supervivencia libre de enfermedad a los 5 años superior al 90 %). Se presenta un caso clínico de neuroblastoma congénito cuya forma de presentación, shock e hipertensión, solo estaba descrita en otra ocasión antes. El tratamiento antihipertensivo, junto con la quimioterapia sistémica, produjo el control clínico y la mejoría del paciente.
Asunto(s)
Hipertensión/etiología , Neuroblastoma/diagnóstico , Choque/etiología , Enfermedad Aguda , Antihipertensivos/administración & dosificación , Antineoplásicos/administración & dosificación , Humanos , Hipertensión/tratamiento farmacológico , Recién Nacido , Masculino , Neuroblastoma/complicaciones , Neuroblastoma/congénitoRESUMEN
Further research on the constituents of the sponge Axinyssa isabela collected in the Gulf of California has led to the isolation of nine new sesquiterpenes, the eudesmanes axinisothiocyanates M and N (1, 2), the bisabolane axinythiocyanate A (3), and the aristolane derivatives axinysones A-E (4-8) and axinynitrile A (9), together with four known sesquiterpenoids (10-13). The structures of the new metabolites have been established by spectroscopic techniques.The absolute configuration of axinysones A (4) and B (5) has been assigned after esterification with (R)- and (S)-MPA acids. In addition, the unusual nitrile-containing sesquiterpene 9 has been synthesized from (+)-aristolone (14). The cytotoxic activity of the compounds isolated has been tested against three human tumor cell lines.
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Antineoplásicos/aislamiento & purificación , Isotiocianatos/aislamiento & purificación , Poríferos/química , Sesquiterpenos/aislamiento & purificación , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , California , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Isotiocianatos/química , Isotiocianatos/farmacología , Estructura Molecular , Océanos y Mares , Sesquiterpenos/química , Sesquiterpenos/farmacologíaRESUMEN
The new cembrane diterpenes leptodienone A (2) and leptodienone B (3) and the known compounds lopholide, lophodiol B, lophodione, and lophotoxin (1) have been isolated from the gorgonian Leptogorgia laxa collected in the Gulf of California. The structures of the new metabolites have been established by spectroscopic techniques. The in vitro cytotoxicity of the new compounds has been tested against three human tumor cell lines.
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Antozoos/química , Antineoplásicos/aislamiento & purificación , Diterpenos/aislamiento & purificación , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , California , Diterpenos/química , Diterpenos/farmacología , Ensayos de Selección de Medicamentos Antitumorales , Femenino , Humanos , Estructura Molecular , Terpenos/química , Terpenos/aislamiento & purificación , Terpenos/farmacologíaRESUMEN
The polyunsaturated aldehydes (PUAs) are bioactive metabolites commonly released by phytoplankton species. Based primarily on laboratory experiments, PUAs have been implicated in deleterious effects on herbivores and competing phytoplankton species or in the regulation of the rates of bacterial organic matter remineralization; however, the role of the PUAs at an ecosystem level is still under discussion. Using data of PUA production in natural phytoplankton assemblages over a wide range of conditions, we analyzed macroecological patterns aiming for a comprehensive environmental contextualization that will further our understanding of the control and ecologic role played by these compounds. PUA composition changed from the predominance of decadienal in oligotrophy, octadienal in eutrophy, and heptadienal at intermediate conditions. The production of PUAs per unit biomass also showed a strong relationship with the trophic status, sharply increasing towards oligotrophic conditions and with small-sized cells reaching the highest production rates. High ratios of dissolved inorganic nitrogen to dissolved inorganic phosphorus also promoted PUA production, albeit to a considerably lesser extent. Although the allelopathic use of PUAs to outcompete other phytoplankton or reduce herbivory may be key in some environments and interactions, the macroecological patterns found here, showing higher production towards the poorest waters and among the small species typically populating these environments, support and link at the large scale the hypotheses of the nutrient-derived stress as driver for the production of PUAs together with the use of these compounds as boosters for the nutrient remineralization.
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Aldehídos/metabolismo , Ecosistema , Fitoplancton/metabolismo , Aldehídos/química , BiomasaRESUMEN
Global change, such as warming and ocean acidification, and local anthropogenic disturbances, such as eutrophication, can have profound impacts on marine organisms. However, we are far from being able to predict the outcome of multiple interacting disturbances on seagrass communities. Herbivores are key in determining plant community structure and the transfer of energy up the food web. Global and local disturbances may alter the ecological role of herbivory by modifying leaf palatability (i.e. leaf traits) and consequently, the feeding patterns of herbivores. This study evaluates the main and interactive effects of factors related to global change (i.e. elevated temperature, lower pH levels and associated ocean acidification) and local disturbance (i.e. eutrophication through ammonium enrichment) on a broad spectrum of leaf traits using the temperate seagrass Cymodocea nodosa, including structural, nutritional, biomechanical and chemical traits. The effect of these traits on the consumption rates of the generalist herbivore Paracentrotus lividus (purple sea urchin) is evaluated. The three disturbances of warming, low pH level and eutrophication, alone and in combination, increased the consumption rate of seagrass by modifying all leaf traits. Leaf nutritional quality, measured as nitrogen content, was positively correlated to consumption rate. In contrast, a negative correlation was found between feeding decisions by sea urchins and structural, biomechanical and chemical leaf traits. In addition, a notable accomplishment of this work is the identification of phenolic compounds not previously reported for C. nodosa. Our results suggest that global and local disturbances may trigger a major shift in the herbivory of seagrass communities, with important implications for the resilience of seagrass ecosystems.
Asunto(s)
Alismatales/fisiología , Herbivoria/fisiología , Alismatales/parasitología , Animales , Eutrofización , Cadena Alimentaria , Concentración de Iones de Hidrógeno , Paracentrotus/fisiologíaRESUMEN
Seagrasses are marine plants that play important ecological functions in coastal ecosystems. The species Zostera noltei is widely distributed along the European coasts thriving in a variety of environmental conditions. In this study, the phenolic natural products of Z. noltei have been analyzed quantitatively by using UPLC-MS. Plants from the Natural Park of the Bay of Cadiz (Spain) were shown to contain rosmarinic acid (1) and the flavonoids apigenin-7-0- glucoside (2), luteolin-7-sulfate (7), apigenin-7-sulfate (8), diosmetin-7-sulfate (9), and acacetin-7-sulfate (10). The analysis by UPLC-MS of extracts allowed the quantification of all the compounds and evidenced the intraspecific variations in the profile of natural products among plants collected at different dates and locations within the Bay. The flavonoids 2, and 7-10 were present in all the analyzed samples with a total flavonoid content in the range 12.8-72.3 mg/g dry wt, while rosmarinic acid (1) was only present in some samples, reaching up to 19.6 mg/g dry wt. A distinctive feature of plants from the Bay of Cadiz is the common presence of apigenin-7-sulfate (8) as major flavonoid, differing from plants from other regions whose major flavonoid is diosmetin-7-sulfate (9).