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Macroalgae are sources of bioactive compounds that are interesting from both a chemical and a medical point of view. Although their use in biomedicine has increased significantly in recent years, tests conducted to date have been mostly related to species from temperate latitudes, with the potential application of Antarctic biodiversity being minor. The wide variety of algae species present on Antarctic coastal areas can be a source of new antioxidants. Bearing this in mind, the brown macroalgae Desmarestia antarctica (DA) and the red Iridaea cordata (IC) were selected for the preparation of aqueous extracts with the aim of analyzing their antioxidant activity. This analysis was performed by determining reducing power, total phenolic content, and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity. Furthermore, both extracts were employed to synthesize gold and silver nanoparticles. The nanomaterials were fully characterized by means of UV-Visible spectroscopy, transmission electron microscopy, Z potential measurements, and Fourier transform infrared spectroscopy, which confirmed the formation of stable, spherical nanoparticles with mean diameters of 13.7 ± 3.1 and 17.5 ± 3.7 nm for Ag@DA and Ag@IC and 12.6 ± 1.9 and 12.3 ± 1.6 nm for Au@DA and Au@IC. Antioxidant assays were performed after the synthesis of the nanomaterials to evaluate their possible synergistic effect with the extracts. The results suggest that polysaccharides and proteins may play a key role in the process of reduction and stabilization. Finally, for the sake of comparison, the results obtained for the Antarctic macroalgae Desmarestia menziesii and Palmaria decipiens have also been considered in the present work. Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia | Ref. ED431C 2017/46-GRC Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia | Ref. ED431C 2018/54 -GRC

Made available in DSpace on 2019-10-04T12:36:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Leishmaniasis is considered a neglected disease and affects billions around the world, currently presenting few therapeutic options, which makes the development of new antileishmanial drugs urgent. Secondary metabolites from marine and terrestrial organisms are important sources of new chemical entities. Herein, the potential activity of crude extracts and fractions from the Antarctic macroalga Iridaea cordata (Turner) Bory de Saint-Vincent was studied against promastigote and intracellular amastigotes forms of Leishmania amazonensis. The cytotoxicity of the active fractions was evaluated on macrophages and 3T3 BALB/c fibroblasts. The chemical profile of volatile substances was analyzed using the GC-MS technique. The fractions IC-FE (IC50-AMA = 23.6 +/- 3.4 mu g mL(-1); SI > 11) and IC-FF (IC50-AMA = 12.4 +/- 1.2 mu g mL(-1); SI > 24) showed promising activity against amastigotes and higher selectivity to the parasite rather than to the mammalian host cells, when compared to the reference drug amphotericin B (IC50-AMA = 5.9 +/- 0.3 mu g mL(-1); SI = 3.9). Their estimated LD50 in rodents are also higher than that in amphotericin B (LD50 IC-FE = 594.5 +/- 25.87 mg kg(-1); LD50 IC-FE = 580.1 +/- 11.84 mg kg(-1); LD50 amphoter = 172.20 +/- 2.40 mg kg(-1)). The chemical profile of these fractions showed the presence of phthalates, esters, ketones, fatty acids, and carboxylic acids, which might be contributing alone or synergistically to the observed antileishmanial activity. Consequently, I. cordata might be used to identify new antileishmanial compounds. Univ Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, BR-14040903 Ribeirao Preto, SP, Brazil Univ Estadual Paulista, Dept Anal Clin, Fac Ciencias Farmaceut, BR-14800903 Araraquara, SP, Brazil Univ Sao Paulo, Inst Quim, BR-05508000 Sao Paulo, SP, Brazil Univ Estadual Paulista, Dept Anal Clin, Fac Ciencias Farmaceut, BR-14800903 Araraquara, SP, Brazil FAPESP: 2017/03552-5 FAPESP: 2016/06931-4 CNPq: 407588/2013-2

Many species of macroalgae along the western Antarctic Peninsula have a high coverage of filamentous algal endophytes. A previous field study showed that endophyte presence negatively impacts growth and survival in some Antarctic algae, but can have no impact on others. We examined nine species of common macroalgal hosts from the area surrounding Palmer Station, Antarctica, to examine fine-scale impacts of endophyte presence on host physiology. Physiological parameters were selected based on their potential to influence fitness of host algae. These included photosynthetic parameters, thallus toughness and susceptibility to grazers in those species previously known to be chemically defended. We found that few macroalgal hosts are impacted by the presence of endophytes and that these impacts are not consistent across all physiological parameters. Iridaea cordata and Pachymenia sp. were the only species among the nine examined that demonstrated physiological stress in the presence of endophytes. Out of four ...

Iridaea cordata cultivated in the presence of UVB radiation (UVBR) was studied using transmission electron microscopy. Apical segments were cultivated in 0.97 Wm −2 of UVBR for 40 days, 3 h a day, and compared to a negative control (UVBR absent). UVBR caused modifications, mainly in the cortical cells, including an increased number of cell wall-producing vesicles, in addition to thicker and denser cellular walls, compared to the control. Additionally, cells were observed with an irregular contour and without defined organelles. The increase of cell-wall thickness could be interpreted as an acclimation to UVBR, which could lead to protection from this radiation. © 2010 Elsevier Ltd. All rights reserved.

This study describes the effects of different intensities of UVB radiation on growth and morphology of early development stages of Iridaea cordata in germlin...

Carbon is acquired through photosynthetic and non-photosynthetic processes in marine algae. However, little is known about the biochemical regulation of these metabolic pathways along the thallus of seaweeds. Consequently, the objective of this study was to assess the distribution of in vivo carboxylation pathways and to relate them to the in vitro activity of ribulose 1,5-bisphosphate carboxylase/oxygenase (RUBISCO), phosphoenolpyruvate carboxykinase (PEPCK), and phosphoenolpyruvate carboxylase (PEPC) in the Phaeophyte Laminaria setchellii, the Chlorophyte Ulva lactuca, and the Rhodophyte Iridaea cordata. Chlorophyll-a levels did not vary in U. lactuca and I. cordata. However, pigment levels were significantly lower in the meristematic region of L. setchellii probably as a result of a lack of differentiation of the chloroplasts in this region. Similarly, net photosynthesis did not vary in the thallus of U. lactuca and I. cordata, while it increased from the stipe and meristem towards the lamina of L. setchellii. In contrast to photosynthesis, light-independent carbon fixation rates were significantly greater in the meristematic region of L. setchellii suggesting a compensating mechanism for carbon incorporation in photosynthetically limited tissue. The activity of RUBISCO and PEPCK followed a pattern similar to that of in vivo carboxylation processes indicating that in vivo carbon assimilation is regulated by the activity of the carboxylating enzymes throughout the thallus of L. setchellii La incorporación de carbono en algas marinas se lleva a cabo mediante procesos fotosintéticos y no-fotosintéticos. Sin embargo, poco se sabe sobre la regulación bioquímica de estas rutas metabólicas en el tejido de algas marinas. En consecuencia, el objetivo de este estudio fue el de evaluar la distribución de la carboxilación in vivo y relacionarlas a la actividad in vitro de ribulosa 1,5-bisfosfato carboxilasa/oxigenasa (RUBISCO), fosfoenolpiruvato carboxikinasa (PEPCK) y fosfoenolpiruvato carboxilasa (PEPC) en la Phaeophyta Laminaria setchellii, la Chlorophyta Ulva lactuca y la Rhodophyta Iridaea cordata. Los niveles de clorofila-a no variaron en U. lactuca e I. cordata. Sin embargo, los niveles de pigmentos fueron significativamente menores en la región meristemática de L. setchellii probablemente debido a una falta de diferenciación de los cloroplastos de esta región. De una manera similar, la fotosíntesis neta no varió en el talo de U. lactuca e I. cordata, mientras que se incrementó desde el estipe y el meristemo hacia la lámina de L. setchellii. En contraste con la fotosíntesis, la fijación de carbono en oscuridad fue significantemente mayor en la zona meristemática de L. setchellii sugiriendo un mecanismo para la compensación de la incorporación de carbono en tejido fotosintéticamente limitado. La actividad enzimática de RUBISCO y PEPCK se comportó de una manera similar a los procesos carboxilantes in vivo, indicando que la fotosíntesis y la fijación de carbono en oscuridad son reguladas por la actividad de las enzimas carboxilantes a lo largo del talo de L. setchellii