Browsing by Author "Barros, Piedade"
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- Antifungal activity of Imidazolidin-4-ones of the antimalarial primaquinePublication . Ferraz, Ricardo; Fernandes, Rúben; Vieira, Mónica; Barros, Piedade; Gomes, Paula; Prudêncio, CristinaThe 5-Isopropyl-3-[4-(6-methoxy-quinolin-8-ylamino)-pentyl]-2,2-dimethyl-imidazolidin-4-one (ValPQacet) was sinthesized through acylation of the anti-malarial primaquine with α-valine and subsequent reaction of the resulting -aminoamide with propanone (Sheme 1).Imidazolidin-4-ones of the anti malarial primaquine are being sinthesized to develop new variants in order to improve more effective treatments against malaria . Recently it has been observed that primaquine derivates could have effect in a new kind of yeast . To study the fungicidal activity against Candida albicans, Candida tropicalis, Issatchenkia orientalis, Sacharomyces cerevisae, the ValPQacet was put in the form of the hydrochloride salt. The minimal inhibitory concentration (MIC) could be determined for all yeast in the concentration range assayed. Also was determined MIC’s of primaquine hydrochloride salt for all yeast, and this shows that the parent drug is less active than our compound. Further studies are being performed to determine viability and cellular injury with this drugs.
- Chronic toxicity of valproic acid in daphnia magnaPublication . Machado, Beatriz; Prudêncio, Cristina; Ferraz, Ricardo; Barros, PiedadeEnvironmental exposure to pharmaceuticals, have negative effects on the health of ecosystems and humans and numerous pharmaceuticals have been identified on surface watersall around the world. After administration, medicines are absorbed, metabolized,and excreted to the sewer system, but many are refractory to the traditional wastewater treatment and become widely distributed in freshwater riversand lakes. Valproic acid is a short-chain fatty acid,clinically used as a broad-spectrum antiepileptic drug, in neurological diseases, whose adverse effects in aquatic organisms are not fully studied. Daphnia magnaisa planktonic crustacean found in lakes and ponds and is one of the most used organisms in aquatic toxicology studies. The adverse effects of pharmaceuticals in Daphni ahave consequences in all the ecosystem. The aim of this study is to evaluate the influence of valproic acid in the reproduction of Daphnia magna. The chronic toxicity study had a duration of 21 days. It was evaluated the effect of five different concentrations of valproic acid(0,4 mg/L, 0,6 mg/L, 0,8 mg/L, 1,0 mg/L and 1,2 mg/L). The parameters evaluated were age at first, second and third posture; the number and mortality of juveniles of each posture. Valproic acid affected the age of the first posture in all the concentrations, it is notice able a delay comparatively to the control. In relation to the juveniles, all concentrations of valproic acid induced aborted eggs, and this number was higher at the highest concentrations (1,0 mg/L and 1,2 mg/L). The control didn’t have any aborted eggs. At the highest concentrations, juvenile mortality was higher,and postures were smaller than the control. Valproic acid interfere with the reproduction of Daphnia magna, causing a delay in reproduction and affecting the number and viability of the offspring.
- Citotoxicity of marine cyanobacteria from the portuguese coast agains breast cancer cellsPublication . Costa, Margarida; Leão, Pedro; Ribeiro, Maria João; Costa-Rodrigues, João; Garcia, Mónica; Barros, Piedade; Fernandes, Helena; Vasconcelos, Vítor; Martins, RosárioThe marine environment possesses an unmeasured chemical and biological diversity, being considered an extraordinary resource for the discovery of new therapeutic drugs. Between others, marine cyanobacteria have emerged as a prominent source of bioactive secondary metabolites with a promising anticancer potential, as the described and intensively studied dolastatins.
- Cytotoxic activity of marine cyanobacteria against cancer cell linesPublication . Ribeiro, Maria João; Costa, Margarida; Leão, Pedro; Barros, Piedade; Vasconcelos, Vítor; Martins, RosárioMarine cyanobacteria possess an extensive capacity to produce compounds that were found to induce biological activities against cell lines and organisms. Many of the marine cyanobacteria compounds already described were found to induce toxicity against cancer cells.
- Cytotoxicity of marine cyanobacteria extracts on osteosarcoma cellsPublication . Costa-Rodrigues, João; Costa, M. M.; Costa, S.; Garcia, M.; Fernandes, M. H.; Vasconcelos, V.; Barros, Piedade; Martins, RosárioMarine cyanobacteria have been identified as a rich source of secondary metabolites with potential pharmacological applications. Anti-inflammatory, antibacterial and anticancer activities are some examples of properties described for cyanobacteria compounds, being the cytoxicity against cancer cell lines one of the most documented. The Laboratory of Ecotoxicology Genomics and Evolution (LEGE) — CIIMAR, Porto, Portugal, possesses a large collection of cyanobacteria strains isolated from the Portuguese coast. In order to investigate the interest of genera such as Cyanobium, Synechocystis, Synechococcus, Leptolyngbya and Pseudoanabaena which are genera that have been largely overlooked in terms of bioactivity, we have been screening their ability to induce cytotoxicity on human cancer cell lines. Assays have been conducted with a crude extract obtained by a dichloromethane and methanol extraction of freeze dried biomass and three fractions obtained using Si column chromatography with a gradient from 100% hexane, to 100% ethyl acetate to 100% methanol. The cytotoxicity of cyanobacteria crude extract and fractions has been evaluated by the MTT assay at 24, 48 and 72 h. Here we present the results concerning the cytotoxicity of 24 cyanobacteria strains on the osteosarcoma cell line MG63. The results show both inhibitory and stimulatory effects on cell growth within the same cyanobacteria strain. However, five cyanobacteria strains were found to induce a decrease in cell viability that reached the 80% within the ethyl acetate fraction, which makes this fraction interesting for the isolation and characterization of new bioactive compounds.
- Cytotoxicity of picocyanobacteria strains of the genera Cyanobium on osteosarcoma cellsPublication . Martins, Rosário; Costa, Margarida; Garcia, Mónica; Barros, Piedade; Costa-Rodrigues, João; Vasconcelos, Vítor; Fernandes, MariaMarine cyanobacteria have been recognized as an important source of bioactive compounds. The cytotoxicity on cancer cell lines has been extensively explored and several cyanobacteria metabolites are already described as potential anticancer compounds or are considered useful templates for the design of new anticancer drugs. The majority of compounds have been isolated from filamentous or colonial cyanobacteria that growth in high densities along shores. In contrast, picoplanktonic forms have rarely been explored since, for these strains, there is a need for culture for biomass production. From our LEGE cyanobacteria culture collection we selected a panel of seven strains of the picocyanobacteria genera Cyanobium in order to explore it’s potential as anticancer agents. Strains were cultured under laboratory conditions. Freeze-dried biomass was extracted using methanol and dichloromethane to a crude extract and then fractionated using hexane, ethyl acetate and methanol. The cytotoxicity of crude extracts and fractions was evaluated in the osteosarcoma cell line MG63 by the reduction of the bromide 3-(4,5-dimetil-tiazol-2-il)-2,5-difenil-tetrazolio (MTT) and confirmed by the lactate dehydrogenase (LDH) assay. From the results, four of the seven Cyanobium strains were found to induce a significant decrease in cell viability. The highest percentage of inhibition of tumor cells growth was observed within the ethyl acetate, which is therefore, promising in terms of isolation of bioactive compounds
- Detecting toxic dinoflagellates (Dinophysis spp.) using electrochemical genosensorsPublication . Pereira, Eduarda; Barros, Piedade; Cruz, Agostinho; Santos, MarleneAquatic environments are important economic and ecological sources for human activities (e.g. fisheries, tourism, agriculture and aquaculture). However, the increase in those practices has, over the years, compromised the integrity of these ecosystems. Runoffs of terrestrial nutrients (from, for example, agricultural and industrial waste) and higher surface temperatures are believed to have transformed these ecosystems into favourable habitats for algae growth and proliferation. As a result, the frequency in phytoplankton microalgae blooms is rising worldwide. These microorganisms are mostly harmless, however certain species, namely belonging to dinoflagellates (e.g., Dinophysis spp.) produce toxins that pose a potential risk for human health. Therefore, the need for technological developments towards fast and precise detection of these toxin-producing microalgae is critical to prevent socioeconomical damages and assess the ecological status of marine ecosystems. In this work, an analytical approach based on an electrochemical genosensor device was developed to create a low-cost platform able to detect two dinoflagellate species from the genus Dinophysis: D. acuminata and D. acuta, which are lipophilic toxin producers responsible of diarrhetic shellfish poisoning (DSP) in humans. The design of this DNA-based sensor consists of several steps including: i) Sensing phase: consisted by a mixed self-assembled monolayer (SAM) composed by a linear DNA capture probe(DNA-CP) and mercaptohexanol (MCH) onto disposable screen-printed gold electrodes (SPGE) surface; ii) Hybridization of complementary DNA sequence (DNA target) by using a sandwich format assay with enzymatic labels and iii) Electrochemical detection by chronoamperometry using an enzymatic scheme to amplify the electrochemical signal. The best analytical conditions were used to study the relationship between electrochemical signal and DNA target concentration, to produce the best electrochemical genosensor device.
- Detection of alexandrium minutum dinoflagellate in environmental samples using electrochemPublication . Morais, Stephanie L.; Barros, Piedade; Santos, Marlene; Delerue-Matos, Cristina; Gomes, Andreia C.; Barroso, M. FátimaDinoflagellates are aquatic microorganisms that inhabit both salt and fresh waters. These microorganisms are mostly harmless, however, under certain conditions, some species rapidly re produce forming water blooms that not only discolor the waters but also compromise the health of every organism in the vicinity, as some dinoflagellates produce potent toxins deemed unsafe for human health (e.g. Alexandrium minutum). In this work, a disposable electrochemical genosensor for the detection of the toxic dinoflagellate Alexandrium minutum was developed. The analytical plat form methodology consisted in a sandwich format heterogeneous hybridization of complementary DNA sequences assay. The 70 bp A. minutum-specific targeting probe, the 45 bp fluorescein isothi ocyanate-labelled signaling DNA probe and the 25 bp thiolated-DNA-capture probe were designed, after analyzing public databases. To maximize the complementary DNA hybridization and to avoid the formation of strong secondary structures, a mixed mercaptohexanol (MCH) and self-assembled monolayer (SAM) A. minutum-specific DNA-capture probe was immobilized onto disposable screen-printed gold electrodes (SPGE). Using chronoamperometric measurements, the enzymatic amplification of the electrochemical signal was obtained with a concentration range from 0.12 to 1.0 nM, a LD of 24.78 pM with a RSD < 5.2 %. This electrochemical genosensor was successfully applied to the selective analysis of the targeted A. minutum specific region of denatured genomic DNA, ex tracted from toxic dinoflagellates present in the Atlantic Ocean.
- Development of electrochemical genosensors for the detection of toxic dinoflagellate alexandrium spp.Publication . Morais, Stephanie L.; Barros, Piedade; Santos, Marlene; Delerue-Matos, Cristina; Gomes, Andreia Castro; Barroso, M. FátimaMicroalgae represent a photosynthetic microorganisms’ group that inhabit both salt and fresh waters. These microorganisms, namely several species of dinoflagellates (e.g. Alexandrium spp.)1 , are mostly harmless; however, some species produce toxins classified as unsafe to human health. The uncontrolled proliferation of such species results in a hazardous occurring event designated harmful algal blooms (HAB). The effects of these episodes can lead to severe ecological and socio-economic impacts (e.g. decrease of the local tourism, fishing and port activities, the contamination or death of the nearby wildlife, discoloration of the beach coasts). Therefore, the need for a rapid, selective and in real time detection device that can monitor the presence of these microalgae in aquaculture waters is critical to prevent human, ecological and economical losses. In this work, an analytical approach based on electrochemical genosensor techniques was developed to create a low cost platform able to detect the dinoflagellates: Alexandrium minutum and Alexandrium ostenfledii. The design of this genosensor consisted of several steps including: i) Sensing phase: Creation of a mixed self assembled monolayer (SAM) composed by a linear DNA capture probe (DNA-CP) and mercaptohexanol (MCH) onto screen-printed gold electrodes (SPGE) surface; ii) Heterogenous hybridization of complementary DNA sequence (DNA target) by using a sandwich format assay with enzymatic labels and iii) Electrochemical detection by chronoamperometry using an enzymatic scheme to amplify the electrochemical signal (Figure 1). The best analytical conditions were used to study the relationship between electrochemical signal and DNA target concentration.
- Differential toxicity responses of green algae and cyanobacteria to formamidePublication . Moreira, Teresa; Sousa, Maria; Barros, PiedadeFormamide is used as a softener for paper and gums, as na ionizing solvent and in the manufacture of hydrocyanic acid and formic esters.