Cheese whey fermentation with lactic acid bacteria (LAB) results in the production of lactic acid, but can also induce the proteolysis of the major whey proteins, therefore originating polypeptides with antibacterial activities. This work set out to determine if by using different types of whey (ovine, caprine and bovine), inoculated with three different LAB strains, could enhance proteolysis degradation of major whey proteins and improve antibacterial activity. Lactic acid production was monitored throughout time by using chromatographic techniques and protein variations were evaluated by electrophoretic techniques. Low Molecular Weight (LMW) polypeptides were isolated by ultra filtration and tested for their bioactivities against the model bacteria Listeria monocytogenes. Overall, results showed that consumption of whey proteins α-lactalbumin and β-lactoglobulin as well as antibacterial activities induced by fermentation were highly dependent on the bacterial strain, the type of whey used and the length of fermentation. Despite being little known by its proteolytic activity towards caseins and whey proteins, Lactobacillus casei proved to be a strain with high fermentative potential and the capacity to produce antibacterial polypeptides

O objetivo do presente estudo, foi avaliar a atividade antibacteriana dos extratos orgânico e aquoso de múkua e mulala. Para tal, foi utilizada uma metodologia modificada a partir de Vuyst, Callewaert & Pol (1996), utilizando como indicadores Pseudomonas aeruginosa, Salmonella Enteritidis, Staphylococcus aureus, Listeria monocytogenes e Escherichia coli. O extrato orgânico de mulala demonstrou ter efeito inibitório em P. aeruginosa, S. Enteritidis e S. aureus e não evidenciou nenhum efeito inibitório sobre L. monocytogenes e E. coli. No caso do extrato aquoso de múkua, observou-se um efeito inibitório em P. aeruginosa, S. Enteritidis e E. coli, não tendo sido registado efeito inibitório em S. aureus e L. monocytogenes. Posteriormente, realizou-se um ensaio experimental de aplicação dos extratos de múkua e mulala no fabrico de um preparado de carne tendo-se utilizado como modelo almôndegas. Para avaliar o efeito antimicrobiano sobre a microbiota da carne, adicionou-se 5%, de extrato de múkua e 1,5% de extrato de mulala. As almôndegas foram embaladas em atmosfera protetora e em aerobiose sendo conservadas a 4 ˚C durante 22 dias. Efetuaram-se contagens de microrganismos aeróbios totais a 30 ˚C, Brochothrix thermosphacta, bactérias ácido lácticas, Enterobacteriaceae e Staphylococcus coagulase-negativa ao longo do período de armazenamento (0, 4, 8, 12, 18 e 22 dias). Nas almôndegas adicionadas de 5% de múkua observou-se um maior efeito inibitório para todos os grupos de microrganismos estudados, sendo maior nas Enterobacteriaceae, Staphylococcus coagulase-negativa e B. thermosphacta. Realizou-se um segundo ensaio com a aplicação do extrato de 1% de múkua em salsichas embaladas em atmosfera protetora, conservadas a 7 ˚C durante 30 dias. Efetuaram-se contagens de microrganismos aeróbios totais a 30 ºC, Enterobacteriaceae e bactérias ácido lácticas ao longo do período de armazenamento (0, 5, 10, 20 e 30 dias). Os extratos vegetais utilizados, mostraram ser efetivos na inibição dos microrganismos patogénicos e de deterioração estudados, tendo-se revelado o extrato aquoso com adição de 5% de múkua o melhor candidato como aditivo natural a utilizar em produtos cárneos. Os resultados evidenciaram que a adição de múkua aos preparados de carne durante o armazenamento reduziu o pH do produto, o que favorece a inibição da multiplicação bacteriana. Os resultados demonstraram que a cor não foi influenciado significativamnete P>(0,05) pelos diferentes tipos de embalagem (aerobiose e atmosfera protetora) a que foram sujeitos os preparados de carne durante os dias de armazenamento. Nas salsichas adicionadas de 1% de múkua observou-se um efeito inibitório nas Enterobacteriaceae no dia 20 mas de modo geral não ocorreu qualquer inibição da microbiota presente.

This study aimed to analyse the chemical profile and biological activities of 29 accessions of Brassica rapa (turnips) and 9 of Brassica napus (turnips and seeds) collections, maintained ex situ in Por- tugal. HPLC-HRMS allowed the determination of glucosinolates (GLS) and polyphenolic compounds. The antioxidant and antimicrobial activities were determined by using relevant assays. The chemical profiles showed that glucosamine, gluconasturtiin, and neoglucobrassin were the most abundant GLS in the extracts from the turnip accessions. Minor forms of GLS include gluconapoleiferin, glucobrassicanapin, glucoerucin, glucobrassin, and 4-hydroxyglucobrassin. Both species exhibited strong antioxidant activity, attributed to glucosinolates and phenolic compounds. The methanol extracts of Brassica rapa accessions were assessed against a panel of five Gram-negative bacteria (Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serovar, and Yersinia enterocolitica) and three Gram-positive bacteria (Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus). The extracts exhibited activity against S. enterica and S. aureus, and two showed inhibitory activity against E. coli and Y. enterocolitica. This study provides valuable insights into the chemical composition and biological properties of Brassica rapa and Brassica napus collections in Portugal. The selected accessions can constitute potential sources of natural antioxidants and bioactive compounds, which can be used in breeding programs and improving human health and to promote healthy food systems.

Pistacia lentiscus (var. chia), também conhecida como mastic tree, uma pequena árvore pertencente à família Anacardiaceae, é produzida exclusivamente no Sul da ilha de Chios, na Grécia. É usada há mais de 2500 anos em medicina tradicional Grega, mas as suas propriedades vêm descritas nas obras de Heródoto, Dioscórides e Galeno. Vários autores romanos, árabes, do período bizantino e europeus fazem extensas referências às propriedades de mastic, nome dado à resina produzida por P. lentiscus, conhecida por mastic tree. As suas propriedades antibacterianas, especialmente contra Helicobacter pylori, antifúngicas, antioxidantes, anti-inflamatórias, antineoplásicas e citoprotetoras, hepatoprotetoras e antidiabéticas, hipocolesterolémicas, a sua aplicação em Tecnologia Farmacêutica são abordadas nesta monografia no sentido de avaliar o potencial de Pistacia lentiscus como novo agente terapêutico de origem natural. A maioria das publicações existentes sobre Pistacia lentiscus L. refere-se à variedade Pistacia lentiscus var. chia. Num estudo recente realizado pelo Professor Kazim Browicz (Browicz, Plant Systematics and Evolution, 1987), este propõe a substituição de “var.” por “cv.”, uma vez que se trata de um clone cultivado, “cultivated clone”. Ainda assim, numa tentativa de harmonização, na proposta de revisão apresentada pela EMA à Grécia, sugere-se a aceitação de Pistacia lentiscus L., conforme a monografia constante na Farmacopeia Europeia, sem qualquer especificação de variedade ou cultivo (EMA, 2015).

O objetivo do presente projeto é o de aprofundar um estudo sobre a deposição de filmes finos de ZnO, para revestir superfícies hospitalares, a partir da técnica de pulverização catódica por radiofrequência. Utilizando esta técnica, e pela variação da potência de deposição, foram obtidas diferentes topografias superficiais destas superfícies de ZnO. Todos os filmes finos foram estudados através da utilização de várias técnicas de caracterização. Os resultados evidenciaram que quanto menor a densidade de potência durante a deposição menor a espessura dos filmes finos e a respetiva topografia apresentava-se menos angular, com diminuição de rugosidade. Numa fase posterior, as superfícies de ZnO foram utilizadas na realização de testes antimicrobianos, de modo a inferir qual das superfícies teria uma maior atividade em relação a três estirpes bacterianas usualmente encontradas em ambiente hospitalar: Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) e Pseudomonas aeruginosa (P. aeruginosa). Os testes decorreram com e sem irradiação dos filmes finos de ZnO com UV, de modo a analisar o impacto deste tipo de radiação na inibição bacteriana das superfícies. A partir destes resultados, foi selecionado um dos tipos de filmes finos para a realização de testes conjuntamente com um material natural, reportado na literatura como um agente antibacteriano: o óleo de limão. Os halos de inibição avaliados em meio de cultura sólido foram satisfatórios para as estirpes de S. aureus e E. coli em ambas as condições, com e sem irradiação de luz UV. No entanto, o diâmetro dos halos obtidos para os filmes expostos a radiação ultravioleta foram superiores. Este estudo demonstrou a viabilidade de utilizar filmes finos para o revestimento de superfícies não deformáveis de equipamentos presentes em ambiente hospitalar.

The preparation of photocrosslinkable bioadhesives synthesized from oligomers of lactic acid and polycaprolactone (PCL), both functionalized with 2-isocyanoethyl acrylate (AOI), were studied. The obtained modified macromers of LA-AOI (mLA) and PCL-AOI (mCL) were chemically characterized by 1H NMR and used to formulate polymeric blends with different mass proportions, 1:1, 1:2 and 2:1, respectively. Subsequently, the produced blends were crosslinked, considering two UV irradiation times: 30 and 120 s. After their production, the thermal and mechanical properties of bioadhesives were assessed, where upon the rheology, gel content, hydrolytic degradation and dynamic contact angles were determined. Furthermore, the cytotoxic profile of bioadhesives was evaluated in contact with human dermal fibroblasts cells, whereas their antibacterial effect was studied monitoring Escherichia coli and S. aureus growth. Overall, flexible and resistant films were obtained, presenting promising features to be used as surgical bioadhesives.

The synthesis and structural modulation of five pro-ligand salts was achieved using alternative sustainable synthetic strategies, the use of microwaves being the method of choice, with an 81% yield and an E factor of 43 for 3d. After complexation with Fe3(CO)12 by direct reaction with the appropriate pro-ligands at 130 °C, a set of iron(II) N-heterocyclic carbene (NHC) complexes were isolated and fully characterized (via 1H and 13C NMR and IR spectroscopy and elemental analysis). The antibacterial activities of the iron(II)-NHC complexes were tested against standard World Health Organization priority bacterial strains: Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922. The results showed a significant effect of the Fe(II)-NHC side-chain on the antibacterial activity against both Gram-negative and Gram-positive bacteria. Among all compounds, the most lipophilic iron complex, 3b, was found to be the most active one, with a minimum inhibitory concentration of 8 µg/mL. Pioneering mechanistic studies suggested an alternative mechanism of action (OH· formation), which opens the way for the development of a new class of antibiotics.

Metal-based nanoparticles have been extensively investigated for a set of biomedical applications. According to the World Health Organization, in addition to their reduced size and selectivity for bacteria, metal-based nanoparticles have also proved to be effective against pathogens listed as a priority. Metal-based nanoparticles are known to have non-specific bacterial toxicity mechanisms (they do not bind to a specific receptor in the bacterial cell) which not only makes the development of resistance by bacteria difficult, but also broadens the spectrum of antibacterial activity. As a result, a large majority of metal-based nanoparticles efficacy studies performed so far have shown promising results in both Gram-positive and Gram-negative bacteria. The aim of this review has been a comprehensive discussion of the state of the art on the use of the most relevant types of metal nanoparticles employed as antimicrobial agents. A special emphasis to silver nanoparticles is given, while others (e.g., gold, zinc oxide, copper, and copper oxide nanoparticles) commonly used in antibiotherapy are also reviewed. The novelty of this review relies on the comparative discussion of the different types of metal nanoparticles, their production methods, physicochemical characterization, and pharmacokinetics together with the toxicological risk encountered with the use of different types of nanoparticles as antimicrobial agents. Their added-value in the development of alternative, more effective antibiotics against multi-resistant Gram-negative bacteria has been highlighted.

Macroalgae have been seen as an alternative source of molecules with promising bioactivities to use in the prevention and treatment of current lifestyle diseases. In this vein, the lipophilic fraction of short-term (three weeks) cultivated Bifurcaria bifurcata was characterized in detail by gas chromatography-mass spectrometry (GC-MS). B. bifurcata dichloromethane extract was composed mainly by diterpenes (1892.78 ± 133.97 mg kg-1 dry weight (DW)), followed by fatty acids, both saturated (550.35 ± 15.67 mg kg-1 DW) and unsaturated (397.06 ± 18.44 mg kg-1 DW). Considerable amounts of sterols, namely fucosterol (317.68 ± 26.11 mg kg-1 DW) were also found. In vitro tests demonstrated that the B. bifurcata lipophilic extract show antioxidant, anti-inflammatory and antibacterial activities (against both Gram-positive and Gram-negative bacteria), using low extract concentrations (in the order of µg mL-1). Enhancement of antibiotic activity of drug families of major clinical importance was observed by the use of B. bifurcata extract. This enhancement of antibiotic activity depends on the microbial strain and on the antibiotic. This work represents the first detailed phytochemical study of the lipophilic extract of B. bifurcata and is, therefore, an important contribution for the valorization of B. bifurcata macroalgae, with promising applications in functional foods, nutraceutical, cosmetic and biomedical fields.

Chitosan oligomers (OQ) have deserved particular attention due to their low viscosity and high solubility at neutral pH. Different studies have emphasized their ability to improve food quality and human health. Chemical and enzymatic methods have been widely used for the production of OQ but the chemical hydrolysis is more commonly used in the industrial-scale. The objective of this work was to prepare OQ from brown crab (Cancer pagurus) chitosan by an oxidative degradation method involving hydrogen peroxide (H2O2) and microwave radiation and to evaluate their antioxidant and antibacterial properties. Chitin was extracted from brown crab exoskeleton and deacetylated to chitosan. Several OQ with different molecular weight (MM) were prepared by making a mixture of chitosan and H2O2 followed by irradiation with microwave for different periods. The reducing power, the antiradicalar capacity (DPPH and ABTS) and the antibacterial activity of OQ were measured. The highest radical scavenging ability was recorded in OQ with the lowest MM (500 Da). Conversely the highest antibacterial activity was achieved by OQ with the highest MM (3 000 Da). It may be concluded that OQ can be conveniently and effectively obtained by oxidative degradation of chitosan with H2O2 and microwave radiation