Percorrer por autor "Pereira, Adriana"
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- Chitosan nanoparticles loaded with 2,5-dihydroxybenzoic acid and protocatechuic acid: Properties and digestionPublication . Madureira, Ana Raquel; Pereira, Adriana; Pintado, M. E.Research efforts on the production of chitosan nanoparticles (NP) as delivery systems of bioactive compounds such as polyphenols have been made along the last decade. Nevertheless, the effect of the phenolic compound structure in the production of these NP was never evaluated so far. Low and high molecular weights chitosan (LMWC and HMWC) NP loaded with the phenolic acids, protocatechuic (PA) and 2,5-dihydroxybenzoic acids (2,5-DHBA) were produced by ionic gelation. Antioxidant activities were determined by ORAC assay. Physical and thermal properties were evaluated by dynamic light scattering (DLS) and differential scanning calorimetry (DSC), respectively. Stability and release of phenolic acids during simulation of gastrointestinal tract (GIT) conditions were also assessed. Nanoparticles sizes ranged from 300 to 600 nm and maintained stable during storage at 4 C during 30 d. Antioxidant activities of the phenolic acids decreased when loaded in the NP. High molecular weight chitosan NP adsorbed higher energy and melted at lower temperatures than LMWC NP. Nanoparticles produced with HMWC released higher phenolic acids % at GIT simulated conditions and with slight increases in their sizes. The most proper systems for delivery of PA and 2,5-DHBA were found to be LMWC and HMWC NP, respectively. These NP could be used to as functional food ingredients or as models for production of phenolic acids-rich extracts NP for future incorporation in food matrices.
- Current state on the development of nanoparticles for use against bacterial gastrointestinal pathogens: focus on chitosan nanoparticles loaded with phenolic compoundsPublication . Madureira, Ana Raquel; Pereira, Adriana; Pintado, ManuelaGastrointestinal diseases have a huge impact especially in third world countries, making it urgent to seek new effective antimicrobial therapies. Thus, the development of nanoparticles (NPs) with bioactive compounds having antimicrobial activity has been the target of research over the past years. The development of antimicrobial drug NPs may be promising to overcome the problems associated with antibiotic resistance caused by many pathogenic bacteria. Moreover, the NPs administration of antimicrobial agents has advantages associated therewith, as use of low cost materials, contribution to the improvement of the therapeutic index and a controlled release drug by increasing the pharmacokinetics. These systems can be used to specific strains of bacteria, and to release interesting antimicrobial compounds. The phenolic compounds (PC) are a class of such bioactive compounds for which their antimicrobial activity was already tested on the production of NPs. Polymeric or lipidic NPs systems have been investigated to deliver these compounds. Chitosan is a polymer widely known for their properties, especially the antimicrobial activity and its ability to adhere to intestinal epithelium. This review article aims to evaluate and discuss recent developments in PC new delivery systems with antimicrobial activity against gastrointestinal pathogens, their production processes, activities, focusing on NPs produced using chitosan as the main structural and functional material.
- Production of antimicrobial chitosan nanoparticles against food pathogensPublication . Madureira, Ana Raquel; Pereira, Adriana; Castro, Pedro M.; Pintado, ManuelaChitosan nanoparticles (NPs) may be a promissory delivery system of polyphenols. The main objective of this study was to produce chitosan NPs encapsulated with polyphenols with antimicrobial and antioxidant activity against food pathogens. The NPs produced with low and high molecular weight chitosan (LMWC and HMWC) were successfully obtained showing slight variations in the particle size, in the range 300-600 nm, and zeta potential values in the range 20-30 mV, exhibiting a moderate stability. The best encapsulation performance was obtained for NPs produced with LMWC and the polyphenol rosmarinic acid. The antimicrobial studies proved that all free and encapsulated compounds have inhibitory activity upon the tested bacteria (Bacillus cereus, Escherichia coli O157, Listeria innocua, Staphylococcus aureus, Salmonella typhimurium and Yersinia enterocolitica). The images obtained by electronic microscopy showed that it was possible to obtain NPs capable of affecting the cellular structure of bacteria reinforcing their antimicrobial activity.
- Production of chitosan nanoparticles with polyphenols for incorporation in bioactive food formulationsPublication . Pereira, Adriana; Campos, Débora; Madureira, Ana Raquel; Pintado, Manuela