DCFQE - Comunicações a Conferências / ConferenceItem
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Browsing DCFQE - Comunicações a Conferências / ConferenceItem by Author "Barreto, Maria do Carmo"
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- Anti-aging activity of Lobophora variegata ethanolic and methanolic extracts and their fractionsPublication . Rosa, Gonçalo P.; Costa, Ana C.; Medeiros, D.; Seca, Ana M. L.; Barreto, Maria do CarmoSeaweed have promising applications within food, cosmetic and health industries, which led to an increased interest in studying these organisms [1]. In several coastal areas, thousands of tons of macroalgae are cast on beaches and shorelines and it would be very interesting if this biomass could be managed, allowing the extraction of added-value compounds. In this context, polar extracts (methanol and ethanol) of a macroalgal beach cast sample mainly composed of “Lobophora variegate” were prepared and the anti-aging and antioxidant activities were evaluated. The preliminary results showed interesting results, and thus these crude extracts were then fractionated sequentially by their solubility in dichloromethane, acetone and ethyl acetate, resulting in 4 semi-pure fractions each, which were also tested. Fractions A1.1.1 and A1.2.3 were very good tyrosinase inhibitors (IC₅₀ = 37.87 and 24.01 μg/mL, respectively) and fractions A1.1.2 and A1.2.2 presented very good inhibition of elastase (IC₅₀ = 44.76 and 20.86 μg/mL, respectively). However, none of the fractions was active against collagenase. These results show that further purifications of these fractions can lead to the isolation of bioactive added-value compounds.
- Antioxidant and anticholinesterasic activities of Morella faya (Aiton) Wilbur extractsPublication . Silva, Bruno J. C.; Seca, Ana M. L.; Moreno-Rodriguez, L.; Barreto, Maria do CarmoMorella faya (Aiton) Wilbur (Myricaceae), formerly Myrica faya, is a shrub or small tree native to Macaronesia, Spain and Portugal and invasive in Hawai'i [1]. In the present study, bioactivities of extracts from leaves and bark collected in S. Miguel, Azores, were determined. Extracts were prepared by sequentially extracting the dry material with dichloromethane and acetone at room temperature. The antioxidant activity of the extracts was determined by the DPPH radical scavenging and FeCl3 reduction assays, total phenolics by the Folin-Ciocalteau method and in vitro anticholinesterasic (anti-AChE) activity by a modification of the Ellman method [2]. The dichloromethane extracts did not present any of these activities between 4.9 and 1250 µg/mL. Both acetone extracts presented a high antioxidant activity. For the DPPH scavenging activity, EC50= 17.7 ± 0.13 and 16.9 ± 0.36 µg/mL for leaves and bark, respectively and 4.5 ± 1.1 µg/mL for quercetin (positive control). In the FeCl3reduction assay, EC50 values were 3.8 ± 0.40 and 3.9 ± 0.16 µg/mL for leaves and bark respectively, and 0.995 ± 0.06 µg/mL for gallic acid (positive control). The acetone extracts also showed anti-AChE activity, stronger for the bark, with IC50= 82.9 ± 6.16 µg/mL and weaker for the leaves, with IC50= 333.0 ± 27.3 µg/mL, which are interesting values for whole extracts. Anti-AChE activity was inversely proportional to the amount of phenolic compounds, 639.3 ± 17.8 mg GAE/g of leaf extract and 95.3 ± 6.55 mg GAE/g of bark extract, therefore the compounds responsible for this effect do not belong to this group. The antioxidant activity cannot be explained by the amount of these compounds alone, since it was quite similar for both acetone extracts and did not therefore reflect the differences in polyphenol content.
- Antitumor activities of invasive allien species from the AzoresPublication . Bettencourt, Ana; Pereira, Joana M.; Costa, Ana C.; Seca, Ana M. L.; Barreto, Maria do Carmo
- 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.
- Chemical and biological studies from an Azorean macroalga: Ulva rigidaPublication . Silva, Madalena; Vieira, Luís M. M.; Almeida, Ana Paula; Silva, Artur M. S.; Kijjoa, Anake; Seca, Ana M. L.; Barreto, Maria do CarmoNew 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).
- Cosmeceutical Potential of the Green Macroalga Caulerpa ProliferaPublication . Rosa, Gonçalo P.; Seca, Ana M. L.; Barreto, Maria do Carmo; Pinto, Diana C. G. A.The present cosmeceutical industry has been gradually shifting its interest from products based on synthetic compounds to macroalgae-based products due to their interesting antiaging properties but also to their lower cytotoxicity and allergens content. Molecules isolated from macroalgae already showed potential as either active cosmetic ingredients or key elements for the consistency of the cosmetic formulation. In this regard, it is of foremost importance to keep studying the chemical composition of different algal species, aiming to find new compounds with cosmeceutical potential. […].
- Cytotoxic, antibacterial, antioxidant, and anticholinesterasic activity of Juniperus brevifolia extractsPublication . Oliveira, Nemésia; Medeiros, Sofia; Barreto, Maria do Carmo; Seca, Ana M. L.; Rosa, José S.The cytotoxic, antibacterial, antioxidant and anticholinesterasic (anti-AChE) activities of the methanol and acetone extracts of Juniperus brevifolia wood and bark were determined. The present study demonstrates that bark extracts of J. brevifolia are the most active and showed good antioxidant activity, lower anti-AChE activity except for the acetone extract, poor cytotoxic and antibacterial activities and absence of activity for Gram (-) bacteria.
- Interaction between glutathione and protopine alkaloidPublication . Barreto, Maria do Carmo; Arrabaça, João Daniel; Pavão, Maria Leonor; Pinto, Ruy EugénioIn previous s.rudies, glutathione decreased the inhibition of mitochondrial NADH dehydrogenase by protopine alkaloid. This fact suggests the possibility of fonnation of a complex between glutathione and protopine, decreasing the effectivc concentration of inhibitor in the reaction medium. Absorption spectra of glutathione in the absence and in the presence o f protopine corroborare this hypothesis. Changes in the UV spectrum of glutathione in the prescnce of protopine were detected, and the rate of change with time was monitored.
- Kaempferol Derivatives from Hedychium gardnerianum : Unveiling the Potential of an Invasive PlantPublication . Tavares, Wilson R.; Barreto, Maria do Carmo; Seca, Ana M. L.The therapeutic properties of plants and of their secondary metabolites are a current research topic of great interest. Considering that Hedychium species are used in folk medicine around the globe, Hedychium gardnerianum Sheppard ex Ker Gawl., an extremely aggressive invasive plant in Hawaii and in Azores, was selected and phytochemically studied in order to search for natural compounds with interesting biological activities. […].
- Laurus Azorica Leaves : Sesquiterpene Lactones and Antiaging ActivityPublication . Viveiros, Mariana Moniz; Barreto, Maria do Carmo; Seca, Ana M. L.Plants are a relevant source of biologically active compounds for skin protection. Laurus azorica (Seub.) Franco, an endemic species from Azores, was traditionally used as a disinfectant, and the oil from its berries was used to treat wounds. This species is barely studied concerning its chemical constituents and biological activities. In this study, three sesquiterpene lactones, costunolide, 11,13-dehydrosantonin and reynosin, were isolated for the first time on the hexane fraction of the ethanol extract from Laurus azorica leaves by chromatographic techniques. […].