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- Health promoting properties of blueberries: a reviewPublication . Silva, Sara; Costa, Eduardo M.; Veiga, Mariana; Morais, Rui M.; Calhau, Conceição; Pintado, ManuelaWith the strengthening of the link between diet and health, several foodstuffs have emerged as possessing potential health benefits such as phenolic rich fruits and vegetables. Blueberries, along with other berries, given their flavonoid and antioxidant content have long since been considered as a particularly interesting health promoting fruit. Therefore, the present work aimed to compile the existing evidences regarding the various potential benefits of blueberry and blueberry based products consumption, giving particular relevance to in vivo works and epidemiological studies whenever available. Overall, the results demonstrate that, while the evidences that support a beneficial role of blueberry and blueberry extracts consumption, further human based studies are still needed.
- Antimicrobial, antiadhesive and antibiofilm activity of an ethanolic, anthocyanin-rich blueberry extract purified by solid phase extractionPublication . Silva, Sara; Costa, Eduardo M.; Mendes, M.; Morais, R. M. S. C.; Calhau, Conceição; Pintado, M. E.Aims: The present work aimed to characterize the impact of an anthocyaninrich blueberry extract upon the growth, adhesion and biofilm formation of several pathogens including some multiresistant bacteria. Methods and Results: A group comprised of reference strains and clinical multiresistant isolates of Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, Acinetobacter baumannii and Staphylococcus aureus, were used to screen for antimicrobial activity. Microbial growth was determined through the measurement of the optical density while adhesion and biofilm formation was determined using the standard crystal violet staining procedure. The results showed that, while blueberry extract was only effective in hindering the growth of Staph. aureus and E. coli, it was capable of significantly inhibiting biofilm formation and bacterial adhesion for all micro-organisms tested. Conclusions: The extract demonstrated a considerable potential as a natural, alternative antimicrobial capable of either interfering with microbial growth or hamper the adhesion to surfaces, with Staph. aureus proving to be the most susceptible micro-organism. Significance and Impact of the Study: The overall study demonstrates the potential of anthocyanin extracts as natural effective alternative antimicrobial agents. Additionally, the extract’s capacity to reduce adhesion without reducing bacterial growth reduces the likeliness of resistance development while reducing the probability of infection.
- Production of a food grade blueberry extract rich in anthocyanins: selection of solvents, extraction conditions and purification methodPublication . Silva, Sara; Costa, Eduardo M.; Calhau, Conceição; Morais, Rui M.; Pintado, M. Manuela E.Blueberries are recognized, by the scientific community and consumers, for their health promoting potential. This fact makes blueberries, and blueberry derived products, prime candidates to aid in the development of healthier foodstuffs that are easily recognized as such by consumers. As blueberries health promoting properties are frequently associated with their phenolic, particularly anthocyanins, composition the present work aimed to establish a simple, food safe, approach to extract these compounds. One that, while being food safe also allowed for a relatively easy scale up process. To accomplish this, four different solvents (water, ethanol, methanol and acetone) acidified or not, were evaluated for their extraction capabilities. The results obtained demonstrated that ethanol acidified with 0.01% HCl was an effective extractant of both phenolic compounds and anthocyanins. Acetone was significantly more effective in extracting phenolic compounds but it was almost unable to extract anthocyanins, with the addition of acid allowing for an increase of anthocyanin yield but reducing the overall phenolic yield. The extraction of anthocyanins may be further improved with the addition of an ultrasound treatment to the extraction process, though no significant differences were observed when considering the overall phenolic content. Furthermore, if seeking a condensed extract, purification using solid phase extraction columns allowed the production of an extract comprised of ca. 40% (w w(-1)) anthocyanins.
- DNA agarose gel electrophoresis for antioxidant analysis: Development of a quantitative approach for phenolic extractsPublication . Silva, Sara; Costa, Eduardo M.; Vicente, Sandra; Veiga, Mariana; Calhau, Conceição; Morais, Rui M.; Pintado, Manuela E.Most of the fast in vitro assays proposed to determine the antioxidant capacity of a compound/extract lack either biological context or employ complex protocols. Therefore, the present work proposes the improvement of an agarose gel DNA electrophoresis in order to allow for a quantitative estimation of the antioxidant capacity of pure phenolic compounds as well as of a phenolic rich extract, while also considering their possible pro-oxidant effects. The result obtained demonstrated that the proposed method allowed for the evaluation of the protection of DNA oxidation [in the presence of hydrogen peroxide (H2O2) and an H2O2/iron (III) chloride (FeCl3) systems] as well as for the observation of pro-oxidant activities, with the measurements registering interclass correlation coefficients above 0.9. Moreover, this method allowed for the characterization of the antioxidant capacity of a blueberry extract while demonstrating that it had no perceived pro-oxidant effect.
- Anti-biofilm potential of phenolic acids: the influence of environmental pH and intrinsic physico-chemical propertiesPublication . Silva, Sara; Costa, Eduardo M.; Horta, Bruno; Calhau, Conceição; Morais, R. M. S. C.; Pintado, M. E.Phenolic acids are a particular group of small phenolic compounds which have exhibited some anti-biofilm activity, although the link between their activity and their intrinsic pH is not clear. Therefore, the present work examined the anti-biofilm activity (inhibition of biomass and metabolic activity) of phenolic acids in relation to the environmental pH, as well as other physico-chemical properties. The results indicate that, while Escherichia coli was not inhibited by the phenolic acids, both methicillin resistant Staphylococcus aureus and methicillin resistant Staphylococcus epidermidis were susceptible to the action of all phenolic acids, with the pH playing a relevant role in the activity: a neutral pH favored MRSE inhibition, while acidic conditions favored MRSA inhibition. Some links between molecular polarity and size were associated only with their potential as metabolic inhibitors, with the overall interactions hinting at a membrane-based mechanism for MRSA and a cytoplasmic effect for MRSE.