Browsing by Author "Mendes, M."
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- Antimicrobial activity and lipid profile of seaweed extracts from the North Portuguese coastPublication . Mendes, M.; Pereira, R.; Pinto, I. Sousa; Carvalho, A. P.; Gomes, A. M.Seaweeds or marine macroalgae are a potential renewable resource in the marine environment and can represent a source of new natural compounds for human nutrition. This experimental work focused on the selection of a suitable extraction method, using Gracilaria vermiculophylla as a model, followed by the characterization of the antimicrobial activity of different solvent extracts of Gracilaria vermiculophylla, Porphyra dioica and Chondrus crispus, both from wild and from an integrated multi-trophic aquaculture system (IMTA), collected in the north of Portugal. Additionally, the fatty acid profile of the seaweed extracts was also investigated. Extraction tests included the definition of the physical state of the seaweed, temperature and type of solvents to be used during the process. Results revealed that test organisms (Gram negative and Gram positive bacteria as well as one yeast species) were more sensitive to extracts obtained with dried algae, processed continuously at higher temperatures. Results from antimicrobial activity of wild and IMTA seaweed extracts showed stronger antimicrobial activity in extracts of ethyl acetate when compared with those from methanol and diethyl ether; furthermore, among the type of microorganisms tested, there was tendency for inhibition of the Gram positive ones. In general, there appears to be a higher antimicrobial activity for the microorganisms under study in extracts obtained from aquaculture species, when compared with the wild ones. The fatty acid profile of ethyl acetate extracts revealed a predominance of saturated fatty acids (SFA), especially palmitic acid (16:0), followed by polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA). A higher content of fatty acids in aquaculture extracts of Gracilaria vermiculophylla and Porphyra dioica was also observed.
- 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.
- Functional activity of extracts from goji berries (Lycium barbarum)Publication . Mendes, M.; Carvalho, A. P.; Barroso, M. F.; Magalhães, J. M. C. S.; Gomes, A. M.; Delerue-Matos, C.Lycium barbarum is a woody perennial plant that produces a berry commonly known as Goji. This fruit has been used for centuries in traditional Chinese medicine to control/prevent several diseases, and is also associated with longevity [1,2]. Currently, and mainly due to their antioxidant properties, Goji berries caught the attention of the Western food industry, since antioxidants can protect cells against damage effects caused by free radicals. Goji berries can be eaten fresh or dried, alone or in various culinary uses. Most of the commercially available Goji berries in Western countries are dried, because such procedure increases durability and facilitates transportation. Nevertheless, several compounds of interest may suffer numerous modifications during the drying process, e.g. degradation of heat-sensitive chemicals and losses of volatile compounds; on the other hand, other components may increase their concentration. The present study aims to investigate the differences in biological properties of dried Goji berries commercially available. As the selection of extraction methodologies is of extreme importance especially when it concerns the achieving of compounds of interest with functional properties, a method combining the use of microwaves and solvents was exploited, in order to obtain bioactive compounds available for the pharmaceutical and nutraceutical industries. A response surface methodology obtained from a multivariate study was used to investigate the performance of the extraction procedure, to study the relevance of the variables required in extraction and to determine the final optimal settings. Results revealed that temperature is of utmost importance during extraction process, whereas time and the polarity of the extracting solvent presented a decreased degree of influence.