Browsing by Author "Alves, Maria José"
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- Ação antimicrobiana de extratos fenólicos de cogumelos silvestres contra Neisseria gonorrhoeaePublication . Alves, Maria José; Marques, Azucena; Ferreira, Isabel C.F.R.; Martins, Anabela; Pintado, ManuelaO relatório da OMS publicado em 2001 faz referência à estimativa de que mais de seis milhões de casos de gonorreia (infeção causada pela Neisseria gonorrhoeae) ocorrem a cada ano e com índices crescentes, principalmente nos países em desenvolvimento. Por outro lado, tem-se vindo a verificar uma resistência emergente deste microrganismo aos agentes antimicrobianos comuns no seu tratamento, sendo um grande obstáculo no controle de gonorreia [1,2]. Assim, é urgente a descoberta de novas soluções antimicrobianas no combate a esta infeção. O objetivo do presente trabalho foi avaliar a atividade antimicrobiana de extratos e respetivos compostos fenólicos puros de oito espécies de cogumelos silvestres, provenientes do Nordeste de Portugal, contra Neisseria gonorrhoeae obtida de exsudados da uretra no CHTMAD – Centro Hospitalar de Trás-os-Montes e Alto Douro, Portugal. Para a determinação das concentrações mínimas inibitórias (CMI) de crescimento recorreu-se ao método da microdiluição e ao ensaio colorimétrico com cloreto de p-iodonitrotetrazólio (INT). Os resultados demostraram que todos os extratos testados, na gama de concentrações testadas (10,0 – 20,0 mg/mL), conseguiam inibir completamente o crescimento de Neisseria gonorrhoeae. De todos as espécies testadas, os extratos de Agaricus bisporus, Lactarius deliciosus, Russula delica e Sarcodon imbricatus foram aqueles que apresentaram maior atividade em concentrações de extrato muito reduzidas (CMI= 1,25 mg/mL). O extrato de Leucopaxillus giganteus apresentou uma CMI = 2,5 mg/mL e o de Ramaria botrytis e Agaricus arvenses apresentaram uma CMI de 10 mg/mL. O extrato de Tricholoma portentosum demonstrou ser o de menor atividade contra Neisseria gonorrhoeae, com uma CMI elevada (20 mg/mL). Dos principais compostos fenólicos presentes nos extratos, identificados e quantificados por cromatografia líquida de alta eficiência acoplada a deteção de díodos (HPLC-DAD), os ácidos protocatéquico, p-cumárico e cinâmico inibiram a Neisseria gonorrhoeae para uma concentração de 1mg/mL, não se verificando qualquer atividade antimicrobiana para o ácido p-hidroxibenzóico. De um modo geral, todos os extratos apresentaram atividade antimicrobiana sobre a Neisseria gonorrhoeae, sendo pertinente estudar no futuro a sua toxicidade celular no sentido de avaliar possíveis aplicações clínicas na terapêutica e mesmo na prevenção da gonorreia.
- Ação antimicrobiana de extratos fenólicos de cogumelos silvestres contra Neisseria gonorrhoeaePublication . Alves, Maria José; Marques, Azucena; Ferreira, Isabel C.F.R.; Martins, Anabela; Pintado, ManuelaInfeções pelo gonococo e por clamídia estão entre as doenças sexualmente transmissíveis mais comuns causadas por bactérias no mundo. Por outro lado, tem-se verificado um aumento de resistência da Neisseria gonorrhoeae aos diferentes antimicrobianos usados no mercado, sendo desta forma urgente a descoberta de novas soluções antimicrobianas no combate a esta infeção. Assim, o objetivo do presente trabalho foi avaliar a atividade antimicrobiana de extratos e respetivos compostos fenólicos puros de nove espécies de cogumelos silvestres, provenientes do Nordeste de Portugal, contra Neisseria gonorrhoeae obtida de exsudados da uretra no CHTMAD – Centro Hospitalar de Trás-os-Montes e Alto Douro. Para a determinação das concentrações mínimas inibitórias (CMI) de crescimento recorreu-se ao método da microdiluição e ao ensaio colorimétrico com cloreto de p-iodonitrotetrazólio (INT). De um modo geral, todos os extratos apresentaram atividade antimicrobiana sobre a Neisseria gonorrhoeae, e alguns compostos parecem apresentar boa atividade antimicrobiana para esta bactéria, tornando-se pertinente estudar o mecanismo de ação destes compostos na inibição da bactéria bem como a sua toxicidade celular no sentido de avaliar possíveis aplicações clínicas na terapêutica e mesmo na prevenção da gonorreia.
- Alkaloids from fungiPublication . Silva, Jani; Garcia, Juliana; Guimarães, Rafaela; Palito, Cátia; Lemos, André; Barros, Lillian; Alves, Maria JoséThe prospection of unusual sources and undiscovered habitats is valuable in natural product research. Indeed, the fungi kingdom has received special attention since its ability to produce novel and intriguing secondary metabolites with various biological uses. Among secondary metabolites, alkaloid-derived structures present a wide range of bioactivities, including antineurodegenerative, antidepressive, anxiolytic, anti-inflammatory, cytotoxic, and insecticidal properties. Furthermore, various studies showed particular properties of those alkaloids in reducing nicotine addiction and alcohol dependence. Alkaloids are categorized into several groups based on their heterocyclic ring system and biosynthetic precursor, such as indole, isoxazoles, and muscarine. Therefore, this chapter focuses on those fungi’s bioactive alkaloids with emphasis on pharmacokinetics as well as the current analytical approaches for extraction and compound identification. Furthermore, the main biological activities and action mechanisms of these fungus alkaloids will also be discussed.
- Amantagula fruit (Carissa macrocarpa (Eckl.) A.DC.): nutritional and phytochemical characterizationPublication . Souilem, Fedia; Dias, Maria Inês; Barros, Lillian; Calhelha, Ricardo C.; Alves, Maria José; Harzallah-Skhiri, Fethia; Ferreira, Isabel C.F.R.Fruits are one of the most promising food matrices and they have been explored in the discovery of new natural and safer bioactive compounds. Carissa macrocarpa (Eckl.) A. DC. fruits are widely consumed in African countries for the preparation of traditional foodstuff, but also for their beneficially health effects. Thus, as the authors’ best knowledge there are no studies on the chemical and bioactive characterization of these fruits. Therefore, fruits of C. macrocarpa from Tunisia were chemically characterized regarding their nutritional value and bioactive compounds. Furthermore, the hydroethanolic extract of these fruits was evaluated regarding its bioactive properties. The fruit powder sample showed high amounts of sugars and polyunsaturated fatty acids (PUFA). The organic acids and tocopherols’ profiles revealed the presence of five organic acids and two tocopherol isoforms, being quinic acid and α-tocopherol the most abundant. The hydroethanolic extract of the fruits presented high antioxidant, cytotoxic, anti-inflammatory, and antibacterial properties, showing activity against all the bacterial strains studied, also inhibiting the cell growth of all the tested tumor cell lines, with the exception of HepG2, and did not reveal toxicity for the non-tumor cells PLP2. Therefore, the fruits of C. macrocarpa could be included in a daily basis diet as a source of high nutritional quality compounds with high bioactive potential.
- Amaranthus caudatus L. as a source of betacyanins with coloring and antimicrobial properties.Publication . Roriz, Custódio Lobo; Alves, Maria José; Morales, Patricia; Barros, Lillian; Ferreira, Isabel C.F.R.Amaranthus caudatus L. is a plant belonging to the Amaranthaceae family, and is a very interesting crop, since it resists drought, heat, and pests, and adapts readily to new environments. The visual appearance of this plant is a bright red-violet, being betacyanins the compounds responsible for the color, and several bioactivities. Therefore, and despite being considered a good source of nutrients with high quality proteins, vitamins, minerals and bioactive molecules, such as phenolic compounds, A. caudatus can also be commercially exploited as a source of natural colorants. In the last decade, and due to the growing demand of consumers, natural matrices have been used to search natural colorant alternatives, in order to replace the artificial counterparts, which have been revealed some toxic effects. Betacyanins are natural colorants and have been used in the food industry, not only because of the high colouring power, but also due to recognized bioactive properties, such as antioxidant and antimicrobial, among others. Thus, the objective of this work was to obtain an extract rich in betacyanins to be used as food coloring agents, offering an alternative source of these coloring compounds, but at the same time conferring bioactive properties. A dynamic maceration extraction was carried out, being the extracts characterized by HPLC-DAD-ESI/MS regarding betacyanins’ composition. The antibacterial activity was evaluated against a panel of four Gram-positive and five Gram-negative bacteria, and the absence of cytotoxicity was confirmed in a porcine liver primary culture. By the chromatographic analysis it was possible to identify four compounds, being amaranthine (171 ± 1 mg/g extract) and isomaranthine (38 ± 1 mg/g) the two major compounds, and betanin (1.6 ± 0.1 mg/g) and isobetanin (1.3 ± 0.1 mg/g) the minor compounds. The extract presented minimum growth inhibitory concentrations (MICs) ranging from 20-10 mg/mL, with no cytotoxicity. After such promising results, this plant can be a viable alternative to obtain natural colorant ingredients.
- Anthocyanin-rich extract obtained from Prunus Spinosa L. by ultrasound assisted extraction for coloring purposesPublication . Leichtweis, Maria Gabriela; Pereira, Carla; Prieto Lage, Miguel A.; Alves, Maria José; Calhelha, Ricardo C.; Barreiro, M.F.; Baraldi, Ilton J.; Ferreira, Isabel C.F.R.; Barros, LillianAnthocyanins are a group of natural pigments presenting a range of colours between red, blue, and violet that are characteristic of various fruits and vegetables. A complex profile of anthocyanins, predominantly cyanidin 3-rutinoside and peonidin 3-rutinoside, was previously identified in Prunus spinosa L. fruit, a bitter and astringent fruit from a wild shrub that is poorly commercially exploited [1]. In this sense, the objective of this work was to develop a natural food colourant based on anthocyanins extracted from the epicarp of P. spinosa fruits. For that purpose, a conventional extraction method, maceration, and a rapid and low-cost ultrasound procedure were applied for the extraction of anthocyanins from this matrix. To achieve the conditions that maximize anthocyanins’ extraction, a response surface methodology was applied using a circumscribed central composite design with three variables and five levels, being the variables time, temperature, and ethanol content, in the case of maceration extraction, whereas for ultrasound assisted extraction, temperature was replaced by ultrasound power. The anthocyanins were identified and quantified by HPLC-DAD-ESI/MS. The optimized extract was assessed in terms of antioxidant and antimicrobial capacity, and hepatotoxicity. Ultrasound assisted extraction was the most efficient method, under optimum conditions of 5.00±0.15 min, 400.00±32.00 W and 47.98±2.88% ethanol, where the extraction yield was 68.60±2.06% (v/v), with a total anthocyanin content of 18.17±1.82 mg/g of dry extract and 11.76±0.82 mg/g of dry epicarp. Regarding bioactivity, the optimized extract showed antioxidant and antimicrobial activity and it did not show hepatotoxic effects in a primary culture of porcine liver cells. To validate its coloring properties, the anthocyanin-rich extract was incorporated into a typical Brazilian confectionery product "beijinho", proving its applicability as food colorant.
- Antibacterial activity of Euterpe oieracea Mart. seeds against clinical isolatesPublication . Alves, Maria José; Pimentel, Maria Helena; Baía, Lilia; Soares, R.P.; Santos, C.R.; Regis, Wiliam C.B.; Ferreira, Isabel C.F.R.Introduction: The use of antibiotics – including the over- and misuse – in human and veterinary practices selected for resistant pathogens led to their emergence and dissemination along with the transmission of resistant bacteria [1]. Due to this problem, there is a need to investigate new strategies to reverse this tendency in order to achieve the appropriate and effective treatment against infections. Aims: The present work aimed to evaluate the antibacterial activity of an aqueous extract prepared from Euterpe Oleracea Mart. (açai) seeds (originated from Brazil [2]), against clinical isolates from “Centro Hospitalar de Trás-os-Montes e Alto Douro- Unidade de Vila Real”, with high resistance profiles to different antibiotics. Material and Methods: The minimal inhibitory concentrations (MIC) of the growth of Gram-positive and Gram-negative bacteria were determined by the colorimetric assay based on the use of p-iodonitrotetrazolium chloride (INT) dye, after application of the microdilution method. Results and discussion: The açaí aqueous extract showed antimicrobial activity against all the tested Gram-positive bacteria. The lowest MICs (0.25 mg/ml) were obtained against Methicillin Susceptible Staphylococcus aureus (MSSA) and Methicillin Resistant S. aureus (MRSA), followed by the MIC 0.5 mg/ml correspondent to Streptococcus agalactiae and Enterococcus faecalis. Regarding the inhibition of the growth of Gram-negative bacteria, the extract was active against Morganella morganii, Pseudomonas aeruginosa and Acinetobacter baumannii with MICs 1 mg/ml e 2 mg/ml, respectively. The results were better for Gram-positive bacteria in comparison with Gram-negative bacteria. Conclusion: However, even at low concentration (2 mg/ml) the results are very promising for Gram-negative bacteria with high resistance profiles and commonly related with health care-associated infections, namely Pseudomonas aeruginosa and Acinetobacter baumannii.
- Antibiofilm potential of medicinal plants against Candida spp. oral biofilms: a reviewPublication . Guimarães, Rafaela; Milho, Catarina; Liberal, Ângela; Silva, Jani; Fonseca, Carmélia; Barbosa, Ana Carolina; Ferreira, Isabel C.F.R.; Alves, Maria José; Barros, LillianThe use of natural products to promote health is as old as human civilization. In recent years, the perception of natural products derived from plants as abundant sources of biologically active compounds has driven their exploitation towards the search for new chemical products that can lead to further pharmaceutical formulations. Candida fungi, being opportunistic pathogens, increase their virulence by acquiring resistance to conventional antimicrobials, triggering diseases, especially in immunosuppressed hosts. They are also pointed to as the main pathogens responsible for most fungal infections of the oral cavity. This increased resistance to conventional synthetic antimicrobials has driven the search for new molecules present in plant extracts, which have been widely explored as alternative agents in the prevention and treatment of infections. This review aims to provide a critical view and scope of the in vitro antimicrobial and antibiofilm activity of several medicinal plants, revealing species with inhibition/reduction effects on the biofilm formed by Candida spp. in the oral cavity. The most promising plant extracts in fighting oral biofilm, given their high capacity to reduce it to low concentrations were the essential oils extracted from Allium sativum L., Cinnamomum zeylanicum Blume. and Cymbopogon citratus (DC) Stapf.
- Antifungal activity of Chamomilla recutita L. and Foeniculum vulgare Mill. aqueous extracts in cottage cheesePublication . Alves, Maria José; Heleno, Sandrina A.; Caleja, Cristina; Oliveira, Joana; Pimentel, Vanessa; Kostić, Marina; Soković, Marina; Ferreira, Isabel C.F.R.Introduction: The use of natural substances with fungicide, insecticide and herbicide properties is the focus of intensive research in order to develop sustainable foodstuff. Objectives: To assess the inhibition effect of Chamomilla recutita and Foeniculum vulgare aqueous extracts, against yeasts and fungi directly in cottage cheese along storage at 4ºC (t0, after 7 days (t7) and after 14 (t14) days). Methodology: Cottage cheese was incorporated with aqueous extracts of C. recutita and F. vulgare. Yeasts and molds were grown in Dichloran Rose Bengal Chloramphenicol medium (Agar-DRBC). The antifungal activity was evaluated by the microdilution method in plate. Results: After observation of the cottage cheese cultures in specific medium at t0, it can be stated that it was not verified any growth neither in control nor in the samples incorporated with the plant extracts. However, at t7 and t14 it was observed growth of yeasts and fungi in control, while the samples with C. recutita and F. vulgare revealed no growth of yeasts in Agar-DRBC. Thus, we note that both C. recutita and F. vulgare inhibited the growth of yeasts and fungi directly in the cottage cheese. Fungal colonies present in curd control were identified and verified as being the yeast Candida krusei and filamentous fungus Cladospoirium herbarum. C. recutita and F. vulgare showed antifungal activity against C. krusei (MIC = 50 mg/ml and 25 mg/ml, respectively) and C. herbarum (MIC = 100 mg/ml in both cases). Conclusion: The two tested plant extracts were able to inhibit the growth of the mentioned yeast and fungi, being able to increase the shelf life of the cottage cheese.
- Antimicrobial activity of natural extracts and commercial elixirs in oral pathogensPublication . Alves, Maria José; Pereira, Marta; Fraga, Sara; Ferreira, Isabel C.F.R.; Dias, Maria InêsAlthough Streptococcus mutans has been responsible for decades as the etiological agent of dental caries, recent evidence indicates a high prevalence for S. mutans in dental biofilms where Candida albicans resides; which suggests that the interaction between these two species may mediate cariogenic development [1].