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Avaliação do potencial farmacológico de metabolitos secundários de Cystoseira abies-marina

Publication . Gouveia, Vera L. M.; Barreto, Maria do Carmo; Seca, Ana Maria Loureiro

A pesquisa de Produtos Naturais com propriedades farmacológicas tem vindo a crescer, destacando-se a descoberta de moléculas vindas de organismos marinhos, que devido à sua considerável biodiversidade se reflecte em metabolitos secundários com estruturas únicas e com várias funcionalidades. Este trabalho surge no seguimento de uma investigação feita com algas do mar dos Açores, cujas actividades biológicas se mostraram promissoras. Nesta tese intitulada “Avaliação do potencial farmacológico de metabolitos secundários de Cystoseira abies-marina”, faz-se um estudo fitoquímico e determinam-se algumas actividades biológicas de compostos isolados. No capítulo I apresentam-se os objectivos e faz-se uma descrição das características da alga em estudo, bem como um pequeno resumo da literatura referente aos compostos isolados de algas do género Cystoseira. A elucidação estrutural dos cinco compostos isolados (o ácido benzóico, um composto natural já conhecido, o cystoazores A, o cystoazores B, o cystoazorona A e o cystoazorona B, meroditerpenos isolados pela primeira vez), e as actividades destes compostos (antitumoral, antioxidante, anticolinesterásica e anti-inflamatória) são apresentadas e discutidas no Capitulo II. Os resultados mostram que os compostos cystoazores A, cystoazores B e cystoazorona A apresentam actividade antitumoral, mas com baixa selectividade entre a linhagem tumoral HeLa e a linhagem não tumoral Vero usada como referência. Na actividade antioxidante, nenhum dos compostos testados apresentaram IC50 <500 μg/mL.. Os compostos mais activos como anticolinesterásicos foram o cystoazores A e B, apesar de não terem atingido 50% de inibição da enzima à concentração máxima testada (125 μg/mL). Quanto à actividade anti-inflamatória in vitro, o ácido benzóico e a cystoazorona B foram os únicos que inibiram ambas as formas da cicloxigenase (COX1 e COX2), comportando-se no entanto como pro-inflamatórios em relação à lipoxigenase 15-LOX. No capítulo III são apresentados os detalhes dos procedimentos experimentais utilizados neste trabalho de investigação.

2012-12-07Master thesis

Open access

Bioactive meroditerpenes from Cystoseira abies-marina, collected from the coast of S. Miguel island

Publication . Gouveia, Vera L. M.; Seca, Ana M. L.; Barreto, Maria do Carmo; Silva, Artur M. S.; Kijjoa, Anake

Many substances isolated from marine organisms have demonstrated to possess interesting biological and pharmacological activities and have been used as leads in the development of new pharmaceutical agents. Marine macroalgae are abundant and structuring organisms of the coastal area of all the islands in the Azores Archipelago; some have a markedly seasonal pattern and others are perennial and present during the whole year in the Azorean coasts. One of these is Cystoseira abies-marina which grows abundantly in the coast of the Azores archipelago. Interestingly, it was observed in situ that this alga was not attacked by common predators, such as marine gastropods which led to the suggestion that the great resistance to predation of this species was due to the presence of potentially active compounds, such as antifeedant and/or cytotoxic. Preliminary study on the extracts of Cystoseira abies-marina, collected in S. Miguel Island, showed very promising results for antitumour and antioxidant activities [3]. These results have increased our interest in this alga and led to its phytochemical study. Recently, we have reported the isolation and identification of benzoic acid and two new meronorsesquiterpenes [Cystoazores A (1) and Cystoazores B (2)] from the extracts of this marine alga [4]. Further investigation of this species led to isolation of other two new meroditerpene derivatives (3 and 4). We report here the isolation of the compounds 3 and 4, from Cystoseira abies-marina whose structures were established by 1D and 2D NMR spectral analysis as well as by MS. Additionally, the cytotoxic, anti-inflammatory and antioxidant activities of compounds 1-4 were evaluated and the results will be presented.

2012-11Conference object

Open access

Purification and structural characterization of compounds isolated from Cystoseira abies-marina

Publication . Gouveia, Vera L. M.; Seca, Ana M. L.; Barreto, Maria do Carmo; Silva, Artur M. S.; Kijjoa, Anake

Although the Azores archipelago is rich in algal communities, only two papers have been published concerning the nutritional and pharmacological potential of this resource in the Azorean sea.[4,5,6] As a brown alga Cystoseira abies-marina grows abundantly in the coast of these islands and has a great resistance to predation, which indicates the presence of potential active compounds[7], we have investigated its secondary metabolites. We report herein isolation and structure elucidation of several compounds from Cystoseira abies-marina, collected at Mosteiros S. Miguel. The structures of the compounds were established by 1D (1H, 13C, DEPTs) and 2D (COSY, HSQC HMBC, NOESY) NMR techniques as well as HRMS.

2012-07Conference object

Open access

Chemical and biological studies from an Azorean macroalga: Ulva rigida

Publication . Silva, Madalena; Vieira, Luís M. M.; Almeida, Ana Paula; Silva, Artur M. S.; Kijjoa, Anake; Seca, Ana M. L.; Barreto, Maria do Carmo

New drugs from natural sources have been targets of the drug discovery program and some bioactive compounds from macroalgae such as sulfated polysaccharides, steroids and diterpens have found their applications in the pharmaceutical industry.[1,2] Consequently, we have investigated the chemical composition and the in vitro antitumor potential of the metabolites isolated from the macroalga Ulva rigida, collected from the Azorean coast, an environmentally healthy habitat with a high level of biodiversity. We hereby describe isolation of isofucosterol (1) and 7(E)-3ẞ-hidroxy-5α, 6α-epoxymegastigmane (2) from the methanol extract of Ulva rigida, collected in May of 2011 in the Sea of St Miguel Island - Azores archipelago. The process of isolation of these metabolites involved chlorophylls elimination by the method previously described[3] and fractionation by column chromatography. The structures of 1 and 2 were established by 1D and 2D NMR spectral analysis and specific rotation as well as comparison of their spectral data with those described in the literature.[4,5] Compounds 1 and 2 were evaluated for their capacity to inhibit the in vitro growth of three human cancer cell lines: MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and A375-C5 (human skin cell line), using the protein binding dye SRB method. The results showed that compound 1 exhibited only a weak activity against MCF-7 (GI50 = 122.2 ± 17.9 μM), NCI-H460 (GI50 = 128.4 ± 32.4 μM), A375-C5 (GI50 = 119.2 ± 28.9 μM), while compound 2 was inactive against all the three cell lines (GI50 >200 μM).

2012-11Conference object

Open access

Chemical study and biological activity evaluation of two Azorean Macroalgae: Ulva rigida and Gelidium microdon

Publication . Silva, Madalena; Vieira, Luís M.; Almeida, Ana Paula; Silva, Artur M. S.; Seca, Ana M. L.; Barreto, Maria do Carmo; Neto, Ana I.; Pedro, Madalena; Pinto, Eugénia; Kijjoa, Anake

The green macroalga Ulva rigida C. Agardh (Chlorophyta) and the red macroalga Gelidium microdon Kützing (Rhodophyta), collected from the Azorean archipelago, were investigated for their secondary metabolites and their in vitro growth inhibitory effect on three human tumor cell lines: MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and A375-C5 (melanoma), as well as for their antifungal and antibacterial activities. The methanol extract of U. rigida furnished isofucosterol (1), 7(E)-3β-hydroxy-5α,6α-epoxymegastigmane (2) and (+)-dehydrovomifoliol (3) while the methanol extract of G. microdon yielded cholesterol (4) and lumichrome (5). The crude extracts of both macroalgae were found to be moderately active against the three cell lines whereas compound 1 showed a weak effect and compound 2 was inactive. The crude extracts of the two macroalgae were found to be moderately active against some fungi and bacteria while compounds 1 and 2 were inactive against all microorganisms tested.

2013-04Journal article

Open access