Insights into the antimicrobial potential of acorn extracts (Quercus ilex and Quercus suber)

Acorns, frequently left uncollected in the fields, have been a part of the traditional medicine of different cultures. Among the different properties associated with them, their antimicrobial potential is of particular importance. However, this characterization has long been superficial and has not ventured into other topics such as biofilm inhibition. Thus, the current work aimed to characterize the antimicrobial and antibiofilm potential of an array of phenolic rich extracts attained from acorns, two different acorn varieties Q. ilex and Q. suber, considering the fruit and shell separately, fresh and after heat-treating the acorns to aid in the shelling process. To accomplish this, the extracts’ capacity to inhibit an array of different microorganisms was evaluated, the minimum bactericidal concentration (MBC) was determined, time-death curves were drawn whenever an MBC was found and the antibiofilm potential of the most effective extracts was drawn. The overall results showed that Gram-positive microorganisms were the most susceptible out of all the microorganisms tested, with the shell extracts being the most effective overall, exhibiting bactericidal effect against S. aureus, B. cereus and L. monocytogenes as well as being capable of inhibiting biofilm formation via the two S. aureus strains. The attained results demonstrated that acorn extracts, particularly shell extracts, pose an interesting antimicrobial activity which could be exploited in an array of food, cosmetic and pharmaceutical applications.info:eu-repo/semantics/publishedVersio

Reversible trans-cis photoisomerization of new pyrrolidene heterocyclic imines

A series of novel pyrrolidene imines bearing functionalized aryl or naphthyl moieties was synthesized and their photochromic properties studied by UV spectroscopy. UV irradiation of these heterocyclic Schiff bases at room temperature promotes the trans-cis photoisomerization of the C=N double bond with formation of a variable amount of the cis-isomer that, in the absence of light, returns thermally to the original form in few seconds. The thermal cis-trans re-isomerization of these molecular switches is much more slower than for the common benzylidene aniline-type imines, allowing the observation of the photochromic phenomena at room temperature. Strong electron-donor substituents in the para-position of the aniline part of the molecule decreases even more the kinetics of the thermal cis-trans re-isomerization leading to a manifest change in the UV spectrum.Fundação para a Ciência e a Tecnologia (FCT

Photoswitching in azo dyes bearing thienylpyrrole and benzothiozole heterocyclic systems

Dedicated to the Centenary of the Portuguese Chemical SocietyVisible light promotes the conversion of the E-isomer of benzothiazol-2-yl and benzothiazol-6-yl diazenes to the thermal unstable Z-isomer that reverts in few seconds to the initial form. The kinetics of the thermal Z / E process is strongly influenced by the linkage position of the N]N function to the benzothiazole heterocycle. Thienylpyrrole azo dyes functionalized with benzothiazol-6-yl groups are particularly interesting since they show an excellent compromise between the switching speed (rate constants: 0.068-0.12 s-1) and the amplitude of the absorbance variation (37-42%).Fundação para a Ciência e a Tecnologia (FCT

Fastest non-ionic azo dyes and transfer of their thermal isomerisation kinetics into liquid-crystalline materials

Push-pull bithienylpyrrole-based azo dyes exhibit thermal isomerisation rates as fast as 1.4 μs in acetonitrile at 298 K becoming, thus, the fastest neutral azo dyes reported so far. These remarkably low relaxation times can be transferred into liquid-crystalline matrixes enabling light-triggered oscillations in the optical density of the final material up to 11 kHz under ambient conditions.Financial support for this research was obtained from the Ministerio de Economía y Competitividad (Spain, CTQ2012-36074 and CTQ2015-65770-P). The authors thank Prof. Santi Nonell for his help with the flash photolysis measurements. Thanks are also due to: Fundação para a Ciência e Tecnologia (FCT) for a PhD grant to M. C. R. Castro (SFRH/BD/78037/2011); FEDERCOMPETE for financial support through the Centro de Quı ´mica – UM, PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT

Carotenoids diet: digestion, gut microbiota modulation, and inflammatory diseases

Several epidemiologic studies have found that consuming fruits and vegetables lowers the risk of getting a variety of chronic illnesses, including several types of cancers, cardiovascular diseases (CVDs), and bowel diseases. Although there is still debate over the bioactive components, various secondary plant metabolites have been linked to these positive health benefits. Many of these features have recently been connected to carotenoids and their metabolites’ effects on intracellular signalling cascades, which influence gene expression and protein translation. Carotenoids are the most prevalent lipid-soluble phytochemicals in the human diet, are found in micromolar amounts in human serum, and are very susceptible to multiple oxidation and isomerisation reactions. The gastrointestinal delivery system, digestion processes, stability, and functionality of carotenoids, as well as their impact on the gut microbiota and how carotenoids may be effective modulators of oxidative stress and inflammatory pathways, are still lacking research advances. Although several pathways involved in carotenoids’ bioactivity have been identified, future studies should focus on the carotenoids’ relationships, related metabolites, and their effects on transcription factors and metabolism.info:eu-repo/semantics/publishedVersio

Adaptation and convergence in circadian‐related genes in Iberian freshwater fish

The circadian clock is a biological timing system that improves the ability of organisms to deal with environmental fluctuations. At the molecular level it consists of a network of transcription-translation feedback loops, involving genes that activate (bmal and clock - positive loop) and repress expression (cryptochrome (cry) and period (per) - negative loop). This is regulated by daily alternations of light but can also be affected by temperature. Fish, as ectothermic, depend on the environmental temperature and thus are good models to study its integration within the circadian system. Here, we studied the molecular evolution of circadian genes in four Squalius freshwater fish species, distributed across Western Iberian rivers affected by two climatic types with different environmental conditions (e.g., light and temperature). S. carolitertii and S. pyrenaicus inhabit the colder northern region under Atlantic climate type, while S. torgalensis, S. aradensis and some populations of S. pyrenaicus inhabit the warmer southern region affected by summer droughts, under Mediterranean climate type.info:eu-repo/semantics/publishedVersio

Variations of Quality of Teacher–infant Interactions Across Play and Care Routine Activities

This study examined the extent to which the quality of teacher-infant interactions varies across play and routine care activities. In addition, the effects of the quantity of adult involvement in the quality of teacher-infant interactions were investigated. Participants were 90 infant classrooms in Portugal. Classrooms had, on average, 6 infants enrolled (M = 6.38, SD = 2.34), with the number of adults ranging from 1 to 3 (M = 2.00, SD = 0.60). Classrooms were observed by trained observers using the Classroom Assessment Scoring System–Infant (CLASS-Infant; Hamre et al., 2014). Research Findings: Multilevel models showed that interaction quality varied as a function of type of activity. The quality of interactions of all CLASS domains was lower in routine care activities compared to play activities. Findings further showed that adult involvement was positively associated with all CLASS domains. In addition, after adding adult involvement to the models, differences between play and routine care activities were no longer statistically significant for most CLASS domains. Practice or Policy: Findings suggest the importance of considering the context of the activity and the levels of adult involvement when assessing and improving the quality of teacher-infant interactions.info:eu-repo/semantics/publishedVersio

Photochromic properties of thienylpyrrole azo dyes in solution

The photochromic behaviour of thienylpyrrole azo dyes in THF solutions was studied for the first time. The photochromic properties are strongly dependent on the substitution pattern on the dyes. Nitro-substituted thienylpyrrole azo dyes are particularly interesting since they exhibit very fast colouration/decolouration processes. The activation energies of these compounds are among the lowest values reported for heterocyclic azo dyes. These compounds show aggregation phenomena in freshly prepared solutions of THF, which lead to variable photochromic behaviours. Only after 1–5 h the solutions reach equilibrium and then reproducible photochromic behaviour can be observed.Fundação para a Ciência e Tecnologia (FCT

Fast thermal cis-trans isomerization of heterocyclic azo dyes in PMMA polymers

Em publicaçãoA series of heterocyclic azo dyes were dispersed in poly(methyl methacrylate) (PMMA) matrix and the photochromic properties of the coloured films studied by UV-Vis spectroscopy. Visible irradiation of the coloured films lead to a fast decrease in the colour intensity due to the trans-cis photoisomerization reaction. When the light source was removed the spontaneous thermal cis-trans reverse isomerization occurred bringing the absorbance back to initial value with variable speed. Contrary to common azobenzenes that after photoisomerization with UV or visible light exhibit very slow thermal cis-trans back re-isomerization, that can last for hours or days, azo dyes bearing pyrrole, thiophene, thiazole or thiadiazole heterocycles display very fast switching between the two isomers (few seconds) even when dispersed in PMMA polymers.Fundação para a Ciência e a Tecnologia (FCT

Bithiophene azo dyes bearing thiazole, benzothiazole and thiadiazole heterocycles: synthesis and comparative study of their photochromic properties

Although a large variety of diarylazo compounds are used in the design of optical materials, only a few reports concerning the photoisomerization of heterocyclic azo dyes can be found in the literature. In the last years our group reported for the first time the synthesis and characterization of heterocyclic azo dyes bearing thiophene and pyrrole moieties as thermally stable conducting materials, solvatochromic probes and nonlinear optical systems. The E/Z isomerizable N=N double bond within a conducting chain can work as molecular switch, making these (hetero)aryl azo systems promising candidates as photochromic materials [1-6]. As part of our continuing interest in heterocyclic azo dyes for optical applications we report here the synthesis of dithiazole azo dyes 4 using as coupling components bithiophene and thiadiazolyldiazonium salts and the comparative study of the photochromic properties of 4 classes of bithiophene azo dyes 1-4. This study reveals that the kinetics of the E-Z transformation of these systems is strongly influenced by the electronic nature of the heterocyclic diazene moiety as well as its position on the bithiophene system. Moreover, for benzothiazole 3 and thiadiazole 4 azo dyes the switching between the two photoisomers can be performed in 3 seconds with a significant conversion of the trans-isomer to the thermal unstable cis-isomer (19-21%) showing that they could be used as efficient photochromic materials. Thanks are due to the Fundação para a Ciência e Tecnologia (Portugal) and FEDER-COMPETE for financial support through the Centro de Química - Universidade do Minho, Projects PTDC/QUI/66251/2006 (FCOMP-01-0124-FEDER-007429), PEst-C/QUI/UI0686/2011 (F-COMP-01-0124-FEDER-022716) and a PhD grant to M. C. R. Castro (SFRH/BD/78037/2011). [1] Coelho, P. J.; Castro, M. C. R.; Fonseca, A. M. C.; Raposo, M.M.M. Dyes Pigments 2012, 92, 745. [2] Raposo, M. M. M.; Castro, M. C. R.; Schellenberg, P.; Fonseca, A. M. C.; Belsley, M. Tetrahedron 2011, 67, 5189. [3] Raposo, M. M. M.; Fonseca, A. M. C.; Castro, M. C. R.; Belsley, M.; Cardoso, M. F. S.; Carvalho, L. M.; Coelho, P. J. Dyes Pigments 2011, 91, 62. [4] Raposo, M. M. M.; Castro, M. C. R.; Belsley, M.; Fonseca, A. M. C. Dyes Pigments 2011, 91, 454. [5] Coelho, P. J.; Carvalho, L. M.; Moura, J. C. V. P.; Raposo, M. M. M. Dyes Pigments 2009, 82, 130. [6] Coelho, P. J.; Carvalho, L. M.; Fonseca, A. M. C.; Raposo, M. M. M. Tetrahedron Lett 2006, 47, 3711