Navegando por Palavras-chave "Ionic Liquids"

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    Aplicação de extratores verdes para obtenção de flavonoides da própolis vermelha
    (Universidade Federal de São Paulo (UNIFESP), 2020-06-25) Santos, Cintia Maria dos [UNIFESP]; Rosso, Veridiana Vera de [UNIFESP]; Universidade Federal de São Paulo
    Red propolis has been widely studied in recent years, mainly by their flavonoids, which are responsible for most of their biological actions. Red propolis was recently discovered in Brazil and it is derived from the species Dalbergia ecastophyllum, from the Leguminaceae family. There are some studies that have shown antiparasitic, antioxidant and anti-tumor activity of this natural product. In general, the main solvent used in the extraction of bioactive propolis is ethanol, however, in some regions of the world the consumption of this type of extract is not allowed for religious reasons, therefore, the objective of this work was to develop a new method for extraction of flavonoids from red propolis using ionic liquids (ILs) and / or eutectic solvents (SEs), in order to obtain a high performance extract in terms of flavonoids and antioxidant activity. For that, an experimental design (CCDR 23) and the response-surface methodology were used as a strategy to establish the best parameters for the obtation of an extract rich in flavonoids. Initially, four ILs were tested in this work: 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), 1-hexyl-3-methylimidazolium chloride ([C6mim]Cl), 1-butyl-3- chloride methylimidazolium ([C4mim]Cl) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]), in addition to three eutectic solvents: Choline chloride - glycerol (CH-GLY), choline chloride - butanediol (CH- BUT) and choline chloride - levulinic acid (CH-LEV). For the extracts obtation, 0.5 g of red propolis were mixed with the solvents in a solid-liquid ratio of 1: 3 and subjected to extraction in 80% amplitude ultrasound equipment (equivalent to 400W of power) for 5 minutes, followed by centrifugation at 4700 rpm for 15 minutes. An ethanolic extract (70 and 95% v: v) was prepared using the same experimental conditions to compare yields. The quantification of the total flavonoids present in the extracts was performed using the method of Zhishen, Mengcheng and Jianming (1999) and the results expressed in rutin equivalent (RuE.g-1). The extract obtained with the IL [C6mim]Cl in 10: 1 concentration (p:v) presented the best better performance, with 581.06 mg RuE.g-1, so it was selected for CCDR 23, considering the responses: flavonoid yield and antioxidant activity. In the response surface methodology, the following variables were evaluated: extraction time (Tmin), number of extractions and probe power (W). In this way, four extractions with [C6min]Cl, under the operational conditions set at 3.3 minutes and 300W were able to extract 394.39 ± 36,30 mg RuE.g-1 of total flavonoids and generate 7595.77 ± 5.48 mg TE.g-1 of dry biomass of antioxidant activity. Then, the antimicrobial evaluation of the optimized extract of red propolis, which showed the growth inhibition of Staphylococcus aureus and Salmonella enteritidis. In this way, the work contributed to the production of extracts, alcohol-free, of high performance in terms of flavonoids and antioxidant activity in comparison with conventional solvents.
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    Desenvolvimento de processos químicos sustentáveis para extração de carotenoides de Bactris gasipaes: aplicações tecnológicas e nutricionais
    (Universidade Federal de São Paulo (UNIFESP), 2021) Mesquita, Leonardo Mendes de Souza [UNIFESP]; De Rosso, Veridiana Vera [UNIFESP]; Universidade Federal de São Paulo
    Carotenoids are natural pigments present in vegetables, animals and algae. Due to their hydrophobicity, carotenoids are usually extracted and synthesized by volatile organic solvents (COSs), restricting their potential applications, since they have low extraction selectivity, and an inherent toxicological potential (even in a low residual level in the final extract). In the food industry, these pigments have a big important sensory role, attributing an orange-redish color to the products, and important health benefits, since they act in important anti-inflammatory and antioxidant biochemical pathways. Commercially, synthetic carotenoids are more used than natural ones. However, the current market trend predicts that synthetic dyes will be sooner replaced by natural ones. Thus, alternative strategies, mainly based on the sustainability and green chemistry principles are excellent ways to mitigating the toxicity of the extracts and to create new integrated benign extraction platforms. Therefore, non-volatile solvents, such as ionic liquids (ILs), can be considered a promising alternative for replacing (or decreasing) the use of non-benign solvents. ILs are molten salts formed by large cations and organic or inorganic anions that vary in their dimensions. ILs have high thermal and chemical stability, negligible volatility in most cases and are known to be high performance solvents, capable of improving the extraction yield of natural compounds when compared to VOS-mediated processes. As a model, Bactris gasipaes fruits (peach palm) were used. This biomass are from Amazonian region, rich in carotenoids, namely all-isomers of carotene and lycopene, little explored commercially, being wasted in many cultivation systems, since the main commercial target of the species is the palm heart, a food delicacy of high economic value, which represents a predatory farming system. In this work, based on the principles of green chemistry and the concepts of biorefinery and circular economy, the valorization of the peach palm fruit was carried out. In particular, two IL-mediated carotenoid extraction platforms were developed, with low environmental impact (assessed by low carbon footprint and E-factor metrics), with solvent and raw material recycling, with optimized extraction operational conditions, which provided carotenoid extracts with high antioxidant activity, high thermal stability, and high yield compared to VOSmediated processes. In addition, the extracts were evaluated for their bioaccessibility and cellular uptake, using in vitro digestion assays of Caco-2 cells. Bioproducts enriched with carotenoids were developed, namely a vegan mayonnaise sauce, and a biodegradable packaging film. Finally, the extracts (obtained by ILs and VOS) were compared in terms of their biological activity, by an in vivo experimental assay, using Wistar rats, submitted to a high-fat diet for 7 days. Pro- and antiinflammatory cytokines, as well as oxidative stress markers were analyzed, with extracts obtained by ILs capable of raising the levels of anti-inflammatory and antioxidant markers, contrasting with the results found for extracts mediated by VOS.
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    Líquidos iônicos como extratores verdes para obtenção de carotenoides da casca de laranja
    (Universidade Federal de São Paulo (UNIFESP), 2019-12-04) Murador, Daniella Carisa [UNIFESP]; Rosso, Veridiana Vera de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The increased concern about environmental and sustainability issues has encouraged the search for alternative strategies in several productive fields, in order to minimize the environment impacts and the risks to living beings. Ionic liquids are molten salts with low vapor pressure, and negligible toxicity compared to the conventional solvents, which have been successfully applied in the extractions of bioactive compounds. However, there are still scarce publications regarding the biological activity from these extracts. Brazil is responsible for 50% of worldwide orange juice production, implying in high amounts of waste, which could be harnessed as carotenoids source, a natural pigment with antioxidant properties, and mostly found as hydroxylated in the orange peel. The hydroxylated carotenoids can be naturally present in its free form or esterified to fatty acids, which increases the analysis complexity. There are few studies regarding the characterization of native carotenoids extracts, including esters and chlorophylls, especially after being submitted to bioaccessibility and bioavailability assays. Thus, the present study aimed to develop a new method of carotenoids extraction from orange peel, using ionic liquid; characterize saponified and nonsaponified extracts obtained with ionic liquid, comparing them to extracts obtained with conventional solvent; and evaluate their thermal stabilities, antioxidant activities and behavior after bioaccessibility and cellular uptake assays. The new extraction developed used 1-nbutyl-3-methylimidazolium ([C4mim]Cl) as ionic liquid, ultrasonic-assisted, resulting in a total carotenoids content of 32.08 µg/g, while the conventional extraction using acetone achieved 7.88 µg/g. The major carotenoids detected by HPLC-DAD-MSn in the saponified samples from orange peel were: 9-cis-violaxanthin and all-trans-lutein, while in the native extracts (non-saponified) were: all-trans-lutein and all-trans-zeaxanthin. In the native extracts, it was found a total of 5 free carotenoids, being 1 apocarotenoid; 7 monoesters; and 11 diesters, being the esters derived from violaxanthin, lutein and anteraxanthin. The antioxidant activity against peroxyl radical found for the [C4mim]Cl extract was double compared to the acetone extract, and the half-live from [C4mim]Cl extract was higher than the acetone one, meaning that the first one also presented higher thermal stability. After the in vitro simulated digestion according to the INFOGEST adapted protocol, both extracts did not differ significantly; 26.2% and 22.0% of total carotenoids were bioacessible, and 69.7% and 45.9% of chlorophylls were bioacessible in [C4mim]Cl and acetone extracts, respectively. The bioacessibility of xanthophylls and carotenes were significantly higher than from mono- and diesters. The uptake by Caco-2 cells of the total carotenoids varied from 131.9 to 130.2 8 ng/mg of cellular protein, and for chlorophylls varied from 234.2 to 243.8 ng/mg of cellular protein, in [C4mim]Cl and acetone extracts, respectively. Overall, in both extracts, xanthophylls and esters were better absorbed by Caco-2 cells than carotenes. Summing up, this work resulted in the obtaining of a carotenoid extract from an orange sub-product, using ionic liquid. The saponified and non-saponified extracts were characterized, contributing to the elucidation of a better understanding about the biological effects from these compounds. The extracts obtained with [C4mim]Cl presented higher yield and thermal stability than the acetone extracts, besides maintaining their antioxidant activity, and showing to be potentially bioacessible and bioavailable, representing a viable alternative to substitute artificial pigments for natural ones.
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    Nanopartículas de ouro em líquidos iônicos: preparação, caracterização e imobilização em celulose não modificada
    (Universidade Federal de São Paulo (UNIFESP), 2021) Cabreira, Camila Rodrigues [UNIFESP]; Camilo, Fernanda Ferraz [UNIFESP]; Universidade Federal de São Paulo
    Gold nanoparticles (AuNPs) are attractive due to their interesting properties and applications such as therapeutic agents, sensors and catalysts. In view of these numerous applications, this thesis focused on the synthesis of AuNPs in ionic liquids (ILs), and their use in two different areas. The first goal was the study of the effects of AuNPs on cell membrane models, due to its application in medicine. The second aim was to immobilize AuNPs on cellulose and evaluate the catalytic activity of the material in the reduction of 4-nitrophenol. Thus, in this thesis AuNPs were prepared by Au3+ reduction using tetrabutylammonium borohydride (TBABH4) in different ILs containing imidazolium cations, such as 1-butyl-3- methylimidazolium (BMIm) or 1-octyl-3-methylimidazolium (OMIm) or 1-dodecyl-3- methylimidazolium (DMIm) chloride (Cl- ) and bis(trifluoromethanesulfonyl)imide (Tf2N- ). Dispersions of AuNPs at 3 mM, 10 mM and 20 mM concentrations were obtained in 1-butyl-3-methylimidazolium chloride (BMImCl) and 1-octyl-3-methylimidazolium chloride (OMImCl), and showed good stability over time. The dispersions contain nanoparticles with diameters around 5-20 nm. Increasing the alkyl chain length of the imidazolium cation from butyl to octyl led to the formation of smaller and more monodisperse AuNPs. Due to its high viscosity, AuNPs synthesis using 1-dodecyl-3- methylimidazolium chloride (DMImCl) was not performed. Also, stable dispersions were not obtained in ionic liquids containing Tf2Nanion. AuNPs synthesized in ILs and pure ILs were incorporated in monolayers of dipalmitoylphosphatidylcholine (DPPC) at the air-water interface as cell membrane model in a Langmuir trough. All the samples led to monolayer condensation and presented a homogeneous pattern, suggesting that both pure ILs and AuNPs in ionic liquids interact with the cell membrane model. A film of cellulose containing AuNPs synthesized in aqueous media was prepared efficiently by impregnation of an aqueous AuNPs dispersion in a regenerated cellulose film. It has cellulose type II structure and nanoparticles around 10 nm are homogeneously dispersed along the polymeric matrix. Cellulose films containing AuNPs prepared in BMImCl and OMImCl were also obtained by a simpler methodology than the one using AuNPs in aqueous medium. This method allowed the incorporation of higher concentrations of Au into the films. They have cellulose type II and spherical nanoparticles well distributed along the films. The films of cellulose and AuNPs were applied as heterogeneous catalysts for 4-nitrophenol reduction. The film containing AuNPs prepared in water showed great efficiency during 5 cycles. Films containing AuNPs prepared in ionic liquids were efficient for around 8 cycles, and the catalysts containing AuNPs in OMImCl showed the highest kapp values. The ease of removal of the films from the reaction medium makes the hybrid material very appealing in application as a catalyst.
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    Síntese de nanopartículas de óxidos de manganês em líquidos iônicos e sua imobilização em celulose
    (Universidade Federal de São Paulo (UNIFESP), 2021) Oliveira, Larissa Verena Figueiredo De [UNIFESP]; Camilo, Fernanda Ferraz [UNIFESP]; Universidade Federal de São Paulo
    The development of synthetic methodologies for manganese oxide nanomaterials has been the subject of several studies due to the improved physical and chemical properties of these materials compared to those in micro and macro scales and their wide applicability. In this thesis, it was developed a new preparation method of MnO 2 nanoparticles in an exclusive medium of different ionic liquids, which acted simultaneously as a solvent, structure-directing agent, and reducing agent of a permanganate salt, the tetramethylammonium permanganate (TMAMnO 4 ). The synthesis was performed in a single step and under mild conditions. It was obtained, for all ionic liquids tested, MnO 2 in nanoscale with lamellar structural organization and with the cations of the ionic liquids in the interlamellar space. These materials were immobilized on non-modified cellulose films and used in discoloration tests of Indigo Carmine dye (IC). The immobilization of the nanoparticles at the films prevented the aggregation and/or agglomeration of the particles during use and it facilitated its recovery from the reaction medium and reuse for several cycles. The obtained films were amorphous and had around 5 wt.% of MnO 2 nanoparticles distributed homogeneously in the cellulosic film. These films were capable of efficiently discoloring an Indigo Carmine dye solution, decolorizing 5.00 mL of a 20 ppm IC solution between 35-50 minutes, depending on the film used. Besides, they could be reused for at least 5 cycles without significant loss of efficiency. These materials were easily removed from the solution using a tweezer. The use of a film instead of dispersion or powdered material allows straightforward isolation from treated water, avoiding the need for more complex separation methods, such as centrifugation or filtration.
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    Versatile interactions of boron fullerene b-80 with gas molecules
    (Univ Sao Paulo, Fac Saude Publica, 2016) Colherinhas, Guilherme; Fileti, Eudes Eterno [UNIFESP]; Chaban, Vitaly V. [UNIFESP]
    Stable all-boron fullerene B-80 supplements a family of elemental cage molecules. These molecules may initiate a drastic rise to intriguing new chemistry. The principal stability of B-80 was recently demonstrated using photoelectron spectroscopy. We report the systematic investigation of different aspects of B-80 interactions with small gas molecules-such as carbon dioxide, molecular hydrogen, hydrogen sulfide, hydrogen fluoride, ammonia and sulfur dioxide-employing density functional theory. We found peculiar interactions between B-80 and ammonia resulting in the formation of a weak boron-nitrogen covalent bond in one of their local-minimum configurations. Hydrogen fluoride maintains a weak hydrogen bond with B-80. The boron fullerene was found to be strongly polarizable, with its electron density distribution changing significantly even in the presence of low-polar gases. The binding energies of the gas molecules to B-80 are generally in direct proportion to their dipole moments. Valence bands are predominantly localized on B-80. According to the present findings, one of the prospective applications of B-80 in future may be gas capture and separation.