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Associated Laboratory for Green Chemistry - Clean Technologies and Processes
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Structural diversity of marine anti-freezing proteins, properties and potential applications: a review
Publication . Ghalamara, Soudabeh; Silva, Sara; Brazinha, Carla; Pintado, Manuela; LAQV@REQUIMTE; Springer
Cold-adapted organisms, such as fishes, insects, plants and bacteria produce a group of proteins known as antifreeze proteins (AFPs). The specific functions of AFPs, including thermal hysteresis (TH), ice recrystallization inhibition (IRI), dynamic ice shaping (DIS) and interaction with membranes, attracted significant interest for their incorporation into commercial products. AFPs represent their effects by lowering the water freezing point as well as preventing the growth of ice crystals and recrystallization during frozen storage. The potential of AFPs to modify ice growth results in ice crystal stabilizing over a defined temperature range and inhibiting ice recrystallization, which could minimize drip loss during thawing, improve the quality and increase the shelf-life of frozen products. Most cryopreservation studies using marine-derived AFPs have shown that the addition of AFPs can increase post-thaw viability. Nevertheless, the reduced availability of bulk proteins and the need of biotechnological techniques for industrial production, limit the possible usage in foods. Despite all these drawbacks, relatively small concentrations are enough to show activity, which suggests AFPs as potential food additives in the future. The present work aims to review the results of numerous investigations on marine-derived AFPs and discuss their structure, function, physicochemical properties, purification and potential applications. Graphical Abstract: [Figure not available: see fulltext.].
How Can Deep Eutectic Systems Promote Greener Processes in Medicinal Chemistry and Drug Discovery?
Publication . Domingues, Luis; Duarte, Ana Rita C.; Jesus, Ana Rita; DQ - Departamento de Química; LAQV@REQUIMTE; Molecular Diversity Preservation International (MDPI)
Chemists in the medicinal chemistry field are constantly searching for alternatives towards more sustainable and eco-friendly processes for the design and synthesis of drug candidates. The pharmaceutical industry is one of the most polluting industries, having a high E-factor, which is driving the adoption of more sustainable processes not only for new drug candidates, but also in the production of well-established active pharmaceutical ingredients. Deep eutectic systems (DESs) have emerged as a greener alternative to ionic liquids, and their potential to substitute traditional organic solvents in drug discovery has raised interest among scientists. With the use of DESs as alternative solvents, the processes become more attractive in terms of eco-friendliness and recyclability. Furthermore, they might be more effective through making the process simpler, faster, and with maximum efficiency. This review will be focused on the role and application of deep eutectic systems in drug discovery, using biocatalytic processes and traditional organic chemical reactions, as new environmentally benign alternative solvents. Furthermore, herein we also show that DESs, if used in the pharmaceutical industry, may have a significant effect on lowering production costs and decreasing the impact of this industry on the quality of the environment.
Using Natural Deep Eutectic Systems as Alternative Media for Ocular Applications
Publication . Sarmento, Célia; Monteiro, Hugo; Paiva, Alexandre; Duarte, Ana Rita C.; Jesus, Ana Rita; DQ - Departamento de Química; LAQV@REQUIMTE; MDPI AG
The major goal of this work was to study the potential of natural deep eutectic systems (NADES) as new media for ocular formulations. In formulating eye drops, it is important to increase the retention time of the drug on the surface of eye; hence, due to their high viscosity, NADES may be interesting candidates for formulation. Different systems composed of combinations of sugars, polyols, amino acids, and choline derivatives were prepared and then characterized in terms of rheological and physicochemical properties. Our results showed that 5–10% (w/v) aqueous solutions of NADES have a good profile in terms of viscosity (0.8 to 1.2 mPa.s), osmolarity (412 to 1883 mOsmol), and pH (7.4) for their incorporation of ocular drops. Additionally, contact angle and refractive index were determined. Acetazolamide (ACZ), a highly insoluble drug used to treat glaucoma, was used as proof-of-concept. Herein, we show that NADES can increase the solubility of ACZ in aqueous solutions by at least up to 3 times, making it useful for the formulation of ACZ into ocular drops and thereby enabling more efficient treatment. The cytotoxicity assays demonstrated that NADES are biocompatible up to 5% (w/v) in aqueous media, promoting cell viability (above 80%) when compared to the control after 24 h incubation in ARPE-19 cells. Furthermore, when ACZ is dissolved in aqueous solutions of NADES, the cytotoxicity is not affected in this range of concentrations. Although further studies are necessary to design an optimal formulation incorporating NADES, this study shows that these eutectics can be powerful tools in the formulation of ocular drugs.
The only surviving Medieval codex of Galician-Portuguese secular poetry
Publication . Vieira, Márcia; Nabais, Paula; Hidalgo, Rafael Javier Díaz; Melo, Maria J.; Pozzi, Federica; DCR - Departamento de Conservação e Restauro; LAQV@REQUIMTE; SpringerOpen
The Ajuda Songbook is an exceptional illuminated manuscript being the only surviving codex of Galician-Portuguese secular poetry; it was produced in the end of the thirteenth century, beginning of the fourteenth century. The diversity of colors accentuated by the presence of lapis lazuli blue and brazilwood pink, demonstrates the desire to produce a sumptuous manuscript. Pink is, in this context, a luxury color and its identification attests to one of the earliest known occurrences of brazilwood in artworks. Scientific analysis showed, for the light pinks, a different formulation from that found in fifteenth-century books of hours and from all historical reconstructions of these colors prepared to date. This knowledge was used to further expand a database previously built in our laboratory and applied to the characterization of pink shades in the Ajuda Songbook. Thirteen brazilwood recipes were selected from seven Medieval treatises and reference materials were prepared based on such historical information. Three types of colors were achieved, defined as translucent rose, rose, and red. The translucent rose was obtained from recipes where egg white is used for extraction, and no other additives are present; rose from recipes with calcium carbonate; and red from a wider range of recipes, in which these ingredients are not mentioned. These colors were then prepared as paints, and analytical results were thus compared with data from the light pinks seen in the Ajuda Songbook’s architectural backgrounds. We were able to reproduce the pink very well using infrared spectroscopy, identifying its main ingredients: calcium carbonate as filler; lead white as the pigment that produces light pink; and the binder as a polysaccharide with a fingerprint similar to mesquite gum. For the chromophore color, the application of chemometrics approaches to molecular fluorescence spectra highlighted a high degree of similarity with the paint reconstructions.
BioH2 from Dark Fermentation of OFMSW
Publication . Martins, Inês; Surra, Elena; Ventura, Márcia; Lapa, Nuno; DQ - Departamento de Química; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
Food wastes represent one third of all food produced worldwide. It is crucial to both prevent the production of food waste and recover the wasted fraction with the aim to valorizing it. In this context, the conversion of the organic fraction of municipal solid wastes (OFMSW) into bioH2 by dark fermentation (DF) is an important technology to valorize these wastes into renewable fuel. Nevertheless, the DF of OFMSW needs to be optimized for critical operational parameters. The main purposes of this study were to investigate (i) the effect of HRT during continuous bioH2 production through DF and (ii) the effect of organic loading rate (OLR) ruled by HRT. In this work, three HRTs (4, 5, and 6 d) were tested in a mesophilic continuous stirred-tank reactor (CSTR). The HRTs of 4, 5, and 6 days, corresponding to OLRs of 23.6, 18.0, and 10.6 g volatile solids (VS) L-1 d-1, respectively, showed bioH2 yields of 8.48, 18.2, and 1.64 L kg-1 VSinfluent with an H2 content of approximately 25, 32, and 5% v/v, respectively. An accumulation of volatile fatty acids (VFAs) was registered with the decrease in HRT, causing a decrease in bioH2 production. The 5 d HRT was the most favorable condition.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UID/QUI/50006/2019