Textile staining: Toward a greener and functional solution

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Chitosan as an effective inhibitor of multidrug resistant Acinetobacter baumannii

Publication . 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.

2017Journal article

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Quercus based coffee-like beverage: effect of roasting process and functional characterization

Publication . Coelho, Marta; Silva, Sara; Rodríguez-Alcalá, Luis Miguel; Oliveira, Ana M.; Costa, Eduardo; Borges, André; Martins, Célia; Rodrigues, António S.; Pintado, Maria Manuela E.

Coffee is one of the world’s most widely consumed beverages but intake it is not encouraged in consumers with some health conditions. In this way, with the growing interest in developing healthier substitutes, a coffee-like beverage obtained from Quercus ilex and Quercus suber acorn´s species, was elaborates maintaining the flavor. Although, this beverage is a promising coffee alternative, little is known about effects of roasting process in its composition. To that end the antioxidant capacity and toxicity of the developed coffee were analyzed and phenolic compounds and fatty acids (esterified and free forms) were characterized through HPLC-DAD and GC-FID, respectively. The results showed that Quercus based beverages presented antioxidant capacity related to their phenolic content, mainly to ellagic acid as the primary phenolic compound identified. Due to this composition, the beverage also presented antimutagenic activity. The main fatty acids in the esterified lipids were mainly oleic, linoleic, palmitic, stearic and cis vaccenic. In the free fatty acids fraction (FFA) they were oleic, linoleic and palmitic acids. Heat processing produced a reduction in total fatty acid concentration in TG and FFA fraction of Q. ilex. Nevertheless, for Q. suber alterations were only found for FFA. Coffee production did not form genotoxic or cytotoxic compounds. Overall, these results show the feasibility of Quercus acorn-based foodstuffs and its potential to produce a functional coffee-like beverage.

2018Journal article

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Insights into chitosan antibioﬁlm activity against methicillin-resistant Staphylococcus aureus

Publication . Costa, E. M.; Silva, S.; Tavaria, F. K.; Pintado, M. M.

Aims: Chitosan is a natural compound that has been validated as a viable antimicrobial agent against Staphylococcus aureus. With this work we sought to evaluate the planktonic and sessile sensitivity of methicillin-resistant S. aureus to chitosan's activity and evaluate if methicillin-resistant S. aureus (MRSA) would be more or less sensitive to chitosan's activity than methicillin-sensitive S. aureus (MSSA). Methods and Results: A group comprised of reference strains and clinical multiresistant isolates of MSSA and MRSA were used. Methicilin resistance effect upon chitosan activity was assessed in planktonic setting and in different phases of sessile colonization, namely adhesion, biofilm formation and mature biofilm through biomass and metabolism inhibition. The results obtained showed that S. aureus methicillin resistance mechanism did not impair chitosan's activity as the highest bacterial susceptibility was registered for MRSA. Chitosan was highly effective in inhibiting MSSA and MRSA strains in both planktonic and sessile settings with biofilm inhibition percentages reaching as high as 90% for MRSA. Conclusions: Staphylococcus aureus methicillin resistance did not impair chitosan's antimicrobial and antibiofilm activities and MRSA and MSSA were inhibited both in planktonic and sessile settings at low concentrations with great efficacy. Significance and Impact of the Study: Considering the obtained results chitosan shows potential as an alternative for the control of biofilm-related recalcitrant MRSA infections.

2017Journal article

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Variation of anthocyanins and other major phenolic compounds throughout the ripening of four Portuguese blueberry (Vaccinium corymbosum L) cultivars

Publication . Silva, Sara; Costa, Eduardo M.; Coelho, Marta C.; Morais, Rui M.; Pintado, Manuela E.

Blueberries are widely recognised as one of the richest sources of bioactive compounds, among which are anthocyanins, though the ripeness of berries has been reported as affecting the phytochemical composition of fruits. Therefore, the present work aimed to evaluate the variation of anthocyanins, and other major phenolics, throughout five ripening stages in four blueberry cultivars. The results showed that the antioxidant capacity and anthocyanin content increased during ripening, reaching the highest values when the blueberries are collected from bunches comprised of 75% ripe blueberries. Antagonistically, the amount of phenolic acid decreases, while the quercetin-3-glucoside levels remain stable. Furthermore, Goldtraube blueberries appear to possess, systematically, higher amounts of phenolic compounds than the other cultivars studied. Thus, when seeking the highest yield of anthocyanins, the preferred harvest should occur in bunches that contain ca 75% of ripe blueberries and, considering the cultivars assayed, the Goldtraube cultivar appears to bethe richest in phenolic compounds.

2017Journal article

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Nutritional characterization of acorn flour (a traditional component of the Mediterranean gastronomical folklore)

Publication . Silva, Sara; Costa, Eduardo M.; Borges, André; Carvalho, Ana Paula; Monteiro, Maria João; Pintado, M. E.

Abstract Nowadays, acorns, the fruits of Quercus trees, are mostly associated with animal feed. However they are part of the traditional gastronomical folklore of severalMediterranean countries. Though several uses can be mentioned, one of the most common uses is powdering the acorns in order to produce a flour that can substitute regular corn flour in the manufacture breads and cakes. An example of this is acorn bread, a typical Portuguese loaf.However, to the best of our knowledge, there is no information about the nutritional value of these flours. As such, the main goal of this work was to describe the nutritional value of acorn flours from two different subspecies of Quercus abundant in Portugal (Quercus ilex and Quercus rotundifolia) obtained using two different traditional methods (drying and roasting). The results demonstrated that all flours possessed interesting nutritional properties, namely the absence of gluten and elevated values of both monounsaturated and polyunsaturated fatty acids. Because of these facts and it’s low production cost, acorn flour poses as an interesting alternative to traditional flours particularly for gluten intolerant individuals.

2016Journal article

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