Browsing by Author "Gouveia, Vera L. M."
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- Avaliação do potencial farmacológico de metabolitos secundários de Cystoseira abies-marinaPublication . Gouveia, Vera L. M.; Barreto, Maria do Carmo; Seca, Ana Maria LoureiroA 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.
- Bioactive meroditerpenes from Cystoseira abies-marina, collected from the coast of S. Miguel islandPublication . Gouveia, Vera L. M.; Seca, Ana M. L.; Barreto, Maria do Carmo; Silva, Artur M. S.; Kijjoa, AnakeMany 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.
- Cystoseira abies-marina life cycle : comparative study of its polar profile by RP-HPLC-DAD-MSPublication . Seca, Ana M. L.; Lopes, Diana; Gouveia, Vera L. M.; Silva, Artur M. S.; Pinto, Diana C. G. A.Macroalgae, are largely used in food, pharmaceutical and cosmetics industries. Cystoseira abies-marina (S.G. Gmelin) C. Agardh is a brown macroalgae (Phaeophyta) which belongs to Cystoseira genus and is distributed in the Mediterranean, Macaronesian Region and the coast of Africa. In the Azores lslands, it grows abundantly in the intertidal zone where it is pioneer and attains large size. Since intertidal seaweeds are exposed to extreme stress conditions (temperatura, UV, water levei) in addition to herbivory and fouling, they develop protective mechanisms, some of which involve the biosynthesis of metabolites with properties that may be useful to man (e.g. natural antioxidants, antifouling agents, novel UV sunscreens). The dichlormethane extract of C. abies-marina from Azares was studied revealing the presence of meronorditerpenoids with cytotoxic and antioxidant activities. In this research the antioxidant activity and chemical composition of the ethyl acetate fraction of C. abies-marina methanolic extract was studied. C. abies-marina was collected in two phases of its life cycle üuvenile phase and mature phase). […].
- Cytotoxic meroterpenoids from the macroalga Cystoseira abies-marinaPublication . Gouveia, Vera L. M.; Seca, Ana M. L.; Barreto, Maria do Carmo; Neto, Ana I.; Kijjoa, Anake; Silva, Artur M. S.Two new meronorsesquiterpenes (cystoazorones A and B) and two new meroditerpenes (cystoazorols A and B), along with benzoic acid were isolated from the brown macroalga Cystoseira abies-marina. The structures of the new compounds were established by 1D and 2D NMR as well as HRMS spectral analysis. The in vitro cytotoxicity and antioxidant activity of the isolated compounds were also evaluated. Cystoazorones A and B, and cystoazorol A exhibited in vitro growth inhibitory activity against HeLa cells. The HeLa cell line in log phase was found to be more sensitive to cystoazorol A than when it was in lag phase. Cystoazorol A also showed a selectivity index higher than taxol, which was used as a positive control. Cystoazorols A and B were found to be the strongest antioxidants among the compounds tested.
- Di- and Sesquiterpenoids from Cystoseira Genus: structure, intra-molecular transformations and biological activityPublication . Gouveia, Vera L. M.; Seca, Ana M. L.; Barreto, Maria do Carmo; Pinto, Diana C. G. A.Natural products have been the single most productive source of leads for the development of drugs, because of the great variety of their chemical structures. Previous chemical investigation of members of the genus Cystoseira resulted in the discovery of various bioactive secondary metabolites. The secondary metabolites isolated and characterized are very interesting, both from the biological activity and structural complexity points of view, which make this genus an attractive target for further investigations. The present review covers the research progress on natural products isolated from this genus since January 1995 until now, concerning the isolation and structural elucidation of the secondary metabolites from Cystoseira species. In this contribution significant biological properties are briefly discussed. Simultaneously, we gradually construct an intra-molecular pathway that logically interrelates the isolated compounds.
- The edible Fucus spiralis life-cycle : GC-MS profile analysisPublication . Seca, Ana M. L.; Aguiar, Nuno F. B.; Gouveia, Vera L. M.; Silva, Artur M. S.; Pinto, Diana C. G. A.Fucus spiralis Linnaeus, known in Azores as "Fava-do-mar'' is an edible brown macroalga (Ochrophyta (Phaeophyceae)) which can be found on rocks at upper intertidal leveis, where it forms a patchy zone. It is the only member of the genus Fucus that can be found in Azores and its receptacles are eaten as a local delicacy. Nutritionally, it is very rich in fiber (crude content 63.9% dw) contains important minerais Na, K, Mg, Ca and low content in lipids (5.2%). This edible seaweed is also rich in secondary metabolites, such as phlorotannins, sterols and fatty acids, which are associated with several biological activities. From the human health point ofview, all the above mentioned constituents are of extreme importance and show the potential of F. spiralis as a nutraceutical product. […].
- Purification and structural characterization of compounds isolated from Cystoseira abies-marinaPublication . Gouveia, Vera L. M.; Seca, Ana M. L.; Barreto, Maria do Carmo; Silva, Artur M. S.; Kijjoa, AnakeAlthough 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.