Browsing by Author "Silva, S."
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- Anthocyanin extraction from plant tissues: a reviewPublication . Silva, S.; Costa, E. M.; Calhau, C.; Morais, R. M.; Pintado, M. E.Anthocyanins have gathered the attention of the scientific community mostly due to their vast range of possible applications. They have been the center point of the research in many different fields, among which is food development, where their innate coloring, antioxidant capacity, and biological potential open interesting venues to the development of new food additives and functional foodstuffs. As the range of application grows, so does the necessity to obtain these compounds, and since they are naturally occurring, the most common way to obtain anthocyanins is to extract them from different plant sources, such as fruits and flowers. Several efforts have been made to develop methods that allow for better extraction yields and higher purification rates therefore this review aims to compile the information regarding extraction and purification procedures in a comprehensive manner.
- Antimicrobial activity of an anthocyanin rich blueberry extract, purified using SPEPublication . Silva, S.; Costa, E. M.; Morais, R. M.; Pintado, M. M.
- Behavioural approaches to the strategic partner selectionPublication . Silva, S.; Silva, F.; Vlacic, B.; Meneses, R.
- Bioavailability of phenolic compounds from brewer’s spent grain extractsPublication . Bonifácio-Lopes, T.; Batista, P.; Silva, S.; Teixeira, José A.; Pintado, Manuela
- Chitosan as an effective inhibitor of multidrug resistant Acinetobacter baumanniiPublication . Costa, E. M.; Silva, S.; Vicente, S.; Veiga, M.; Tavaria, F.; Pintado, M. M.Over the last two decades worldwide levels of antibiotic resistance have risen leading to the appearance of multidrug resistant microorganisms. Acinetobacter baumannii is a known skin pathogen which has emerged as a major cause of nosocomial outbreaks due to its capacity to colonize indwelling medical devices and natural antibiotic resistance. With chitosan being an effective antimicrobial agent against antibiotic resistant microorganisms, the aim of this work was to access its potential as an alternative to traditional antimicrobials in the management of A. baumannii growth. What the results showed was that both chitosan MW’s tested were active upon A. baumannii’s planktonic and sessile growth. For planktonic growth MICs and MBCs were obtained at relatively low concentrations (0.5–2 mg/mL) while for sessile growth chitosan proved to be an effective inhibitor of A. baumannii’s adhesion and biofilm formation. Considering these results chitosan shows a high potential for control of A. baumannii infections.
- Chitosan effect upon biofilm formation of multiresistant Staphylococcus aureus strainsPublication . Costa, E. M.; Silva, S.; Tavaria, F. K.; Pintado, M. M.
- Chitosan mouthwash: toxicity and in vivo validationPublication . Costa, E. M.; Silva, S.; Costa, M. R.; Pereira, M.; Campos, D. A.; Odila, J.; Madureira, A. R.; Cardelle-Cobas, A.; Tavaria, F. K.; Rodrigues, A. S.; Pintado, M. M.A previous study showed that a chitosan mouthwash would be a valid alternative to current mouthwashesas it demonstrated, in vitro, significantly higher antibiofilm activity than two commercial mouthwashes.As such, the aim of this work was to verify the safety of the developed product and to validate, in vivo, thebiological activity ascertained in vitro. Chitosan mouthwash safety was evaluated through Ames, MTT andV79 chromosomal aberration assay while antimicrobial activity was evaluated through in vivo assays. Theresults showed that the chitosan mouthwash was safe, presenting lower cytotoxicity than a commercialmouthwash, and that it effectively reduced viable counts of Streptococcus spp. and Enterococcus spp. by ca.5.5 log of CFU. Furthermore, in direct comparison with a commercial mouthwash the chitosan mouthwashpossessed significantly higher antimicrobial activity. The conjunction of these results proves that thechitosan mouthwash is a safe, effective, natural alternative to the existent chemical mouthwashes.
- Chitosan nanoparticles as alternative anti-staphylococci agents: bactericidal, antibiofilm and antiadhesive effectsPublication . Costa, E. M.; Silva, S.; Vicente, S.; Neto, C.; Castro, P. M.; Veiga, M.; Madureira, R.; Tavaria, F.; Pintado, M. M.Chitosan is a biocompatible, bioactive, non-toxic polymer that due to these characteristics has been widely used as a carrier for targeted delivery of bioactive molecules. In recent years, and considering that chitosan has a strong antimicrobial potential, the scientific community's focus has shifted onto the possible antimicrobial activity of chitosan nanoparticles. With this in mind, the aim of this work was to produce low molecular weight chitosan nanoparticles, through the ionic gelation method and characterize their potential biological activity against three staphylococci (MSSA, MRSA and MRSE) in planktonic and sessile environments. The chitosan nanoparticles produced had an average size of 244 ± 12 nm, an average charge of 17.3 ± 1.4 mV and had a MIC of 1.25 mg/mL for all tested microorganisms. Bactericidal activity was only registered for MSSA and MRSA with the time-inhibition curves showing bactericidal activity within 1 h. Assays regarding chitosan nanoparticles' impact upon sessile populations showed that they were effective in preventing MRSE adhesion and highly effective in reducing MRSA and MSSA biofilm formation.
- A comparative analysis of the antibiofilm properties of crude blueberry extracts against MRSA and MSSAPublication . Silva, S.; Costa, E. M.; Costa, M. R.; Pereira, M. F.; Morais, R. M. S. C.; Pintado, M. E.
- Comparison of bioactive compounds in four blueberry cultivars throughout the years: selection of the best cultivars to be used in health promoting foodstuffsPublication . Silva, S.; Costa, E. M.; Coelho, M. C.; Pereira, M. F.; Costa, M. R.; Pintado, M. M.Blueberries are known as rich in phenolics and possessing a considerable antioxidant capacity. In recent decades, Portuguese blueberry production has increased greatly with several new blueberry producers appearing every year and, considering the amount of factors that can affect the overall fruit composition it is important to systematically study each matrix in order to understand the phenolic compounds profile, and therefore allow both the industry and consumers to maximize the potential benefits. Therefore the present work aimed to characterize four blueberry cultivars (representative of Portuguese blueberry production); Duke, Bluecrop, Goldtraube and Ozarkblue throughout a period of 3 years. Antioxidant activity, total phenolic compounds and anthocyanins were assessed. The results obtained illustrated, as could be expected, significant differences throughout the years studied for all parameters assessed, with values ranging from ca. 205 to 770 g of ascorbic acid equivalents per 100 g of fresh fruit for the total antioxidant capacity, ca. 115 to 630 g of gallic acid equivalents per 100 g of fresh fruit for the total phenolics content and ca. 56 to 263 mg of cianidin-3-glucoside equivalents per 100 g of fresh fruit for the total anthocyanin content. Despite the large variations, the cultivar Goldtraube proved to possess systematically higher contents of anthocyanins and antioxidants than all other cultivars though the same cannot be said for the total phenolics were, despite possessing higher values for 2 years, in both Duke and Bluecrop significantly higher content of phenolic compounds were observed. In conclusion, as it stands Goldtraube appears to be the better cultivar to be used in the development of blueberry based matrices and foodstuffs with higher potential health benefits.
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