Thiago Nogueira de Vasconcelos Reis

The in Vitro Biological Activity of the Brazilian Brown Seaweed Dictyota mertensii against Leishmania amazonensis

Seaweeds present a wide variety of interesting bioactive molecules. In the present work we evaluated the biological activity of the dichloromethane/methanol (2:1) extract (DME) from the brown seaweed Dictyota mertensii against Leishmania amazonensis and its cytotoxic potential on mammalian cells. The extract showed significant inhibitory effect on the growth of promastigote forms (IC50 = 71.60 μg/mL) and low toxicity against mammalian cells (CC50 = 233.10 μg/mL). The DME was also efficient in inhibiting the infection in macrophages, with CC50 of 81.4 μg/mL and significantly decreased the survival of amastigote forms within these cells. The selectivity index showed that DME was more toxic to both promastigote (SI = 3.25) and amastigote (SI = 2.86) forms than to macrophages. Increased NO production was observed in treated macrophages suggesting that besides acting directly on the parasites, the DME also shows an immunomodulatory effect on macrophages. Drastic ultrastructural alterations consistent with loss of viability and cell death were observed in treated parasites. Confocal microscopy and cytometry analyzes showed no significant impairment of plasma membrane integrity, whereas an intense depolarization of mitochondrial membrane could be observed by using propidium iodide and rhodamine 123 staining, respectively. The low toxicity to mammalian cells and the effective activity against promastigotes and amastigotes, point to the use of DME as a promising agent for the treatment of cutaneous leishmaniasis.

Quantification and classification of the main environmental impacts on a Halodule wrightii seagrass meadow on a tropical island in northeastern Brazil

Multiple stress mechanisms have caused a worldwide decrease in seagrasses, which are vulnerable to environmental and/or anthropogenic pressure. The loss of seagrass meadows of Halodule wrightii is reported for the littoral of Itamaracá Island (Northeastern Brazil). The present study identified the main anthropogenic factors that negatively influenced over the abundance and distribution of seagrass meadows between July and September 2007 at the Jaguaribe and Pilar Beaches, Eastern littoral of Itamaracá. Anthropogenic impact included the discharge of untreated sewage through fluvial channels, urban and commercial development along the coast, the anchoring of motorized and non-motorized boats, diverse fishing techniques and the dumping of solid waste. The data indicates that the Pilar is an environment with a higher impact index (71.43%) when compared with the Jaguaribe (57.14%), standing out the number of boats with a central motor, the total number of boats, the presence of shellfish gatherers and coastal urban development. The present study reinforces the need for defining management and conservation measures for this ecosystem, which has high ecological and economic value.

Antioxidant activity of three seaweeds from tropical reefs of Brazil: potential sources for bioprospecting

We report the first screening for antioxidant activity (AOX) of three dominant seaweeds from low intertidal reefs of Brazil. Sargassum furcatum, Bryothamnion triquetrum, and Osmundaria obtusiloba were extracted with dichloromethane and methanol (2:1), and AOX was measured by five UV-vis microplate spectrophotometric methods: DPPH (2,2-diphenyl-1-picryhydrazyl) and ABTS (2,2-azinobis (3-ethylbenzthiazoline-6-sulfonic acid)) free radical scavenging, metal chelating capacity, total phenolic compounds using reducing power by Folin-Ciocalteu and FRAP (ferric reducing antioxidant power). All studied species showed high AOX, even at very low extract concentrations. We can attribute these results to the stressful environment in which these seaweeds live, high hydrodynamics, air exposure during low spring tides, intense solar radiation, and other factors that may contribute to oxidative stress, featuring O. obtusiloba as a new source of natural antioxidants.

Macroalgal responses to coastal urbanization: relative abundance of indicator species

This study aimed to evaluate and compare the intertidal macroalgae community from reef structures subject to different urbanization degrees. Samplings were made in 11 beaches from the Pernambuco coast, northeastern Brazil. The sites were classified according to the level of urbanization into three classes of increasing urbanization pressure: non urbanized (NU), in urbanization process (UP), and consolidated urbanization (UC). Macroalgae were identified in situ non-destructively. A total of 53 taxa were identified, 41 of these were macroalgae. Significant differences were observed in the composition of macroalgae according to the urbanization levels, with Palisada perforata, Gelidiella acerosa, and Caulerpa spp. dominating NU and UP sites, whereas Chondracanthus acicularis, Bryopsis sp., and Ulva spp. dominated UC sites. This work shows that urbanization can have a strong effect on the structure of rocky intertidal macroalgal assemblages and highlights some macroalgae species that can be used as bioindicators for assessing the impact of urbanization on coastal shores.

FENOLOGIA DE Amansia multifida E Vidalia obtusiloba (CERAMIALES, RHODOPHYTA) EM RECIFE DE UMA PRAIA DO NORDESTE ORIENTAL DO BRASIL

As rodoficeas Amansia multifida e Vidalia obtusiloba ocorrem principalmente nos recifes costeiros das regioes tropicais. As especies sao produtoras de substâncias farmaceuticas, como analgesicas, antibioticas e antioxidantes, com expressivo potencial biotecnologico. Em vista disso, os aspectos fenologicos das populacoes de A. multifida e V. obtusiloba que ocorrem nos recifes da Praia de Boa Viagem, em Recife, foram analisados visando auxiliar o manejo e conservacao destes recursos marinhos. Aleatoriamente, 15 especimes de cada taxon foram coletados mensalmente de dezembro/2013 a novembro/2014, para analisar as fases reprodutivas e padroes de crescimento. Os resultados sugerem que a fase tetrasporofitica predomina sobre a gametofitica em ambos os taxons. Em relacao a Amansia multifida, apenas a fase tetrasporofitica e os especimes nao ferteis foram encontrados. Em Vidalia obtusiloba foram registradas as fases gametofiticas, cistocarpica, tetrasporofitica e nao fertil. Quantitativamente foi analisado um total de 180 especimes durante o periodo estudado, dos quais 14 especimes sao da fase gametofitica masculina e cinco sao da fase feminina com cistocarpo. A preponderância da fase tetrasporofitica sobre as demais fases e um evento observado em outras especies de Rhodophyta.