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1.
Proc Natl Acad Sci U S A ; 119(18): e2201646119, 2022 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-35507892

RESUMO

Multiple membrane organelles require cholesterol for proper function within cells. The Niemann-Pick type C (NPC) proteins export cholesterol from endosomes to other membrane compartments, including the endoplasmic reticulum (ER), plasma membrane (PM), trans-Golgi network (TGN), and mitochondria, to meet their cholesterol requirements. Defects in NPC cause malfunctions in multiple membrane organelles and lead to an incurable neurological disorder. Acyl-coenzyme A:cholesterol acyltransferase 1 (ACAT1), a resident enzyme in the ER, converts cholesterol to cholesteryl esters for storage. In mutant NPC cells, cholesterol storage still occurs in an NPC-independent manner. Here we report the interesting finding that in a mutant Npc1 mouse (Npc1nmf), Acat1 gene (Soat1) knockout delayed the onset of weight loss, motor impairment, and Purkinje neuron death. It also improved hepatosplenic pathology and prolonged lifespan by 34%. In mutant NPC1 fibroblasts, ACAT1 blockade (A1B) increased cholesterol content associated with TGN-rich membranes and mitochondria, while decreased cholesterol content associated with late endosomes. A1B also restored proper localization of syntaxin 6 and golgin 97 (key proteins in membrane trafficking at TGN) and improved the levels of cathepsin D (a key protease in lysosome and requires Golgi/endosome transport for maturation) and ABCA1 (a key protein controlling cholesterol release at PM). This work supports the hypothesis that diverting cholesterol from storage can benefit multiple diseases that involve cholesterol deficiencies in cell membranes.


Assuntos
Longevidade , Doença de Niemann-Pick Tipo C , Acetil-CoA C-Acetiltransferase , Doença de Alzheimer , Animais , Colesterol , Ésteres do Colesterol , Modelos Animais de Doenças , Endossomos/genética , Camundongos , Proteína C1 de Niemann-Pick , Doença de Niemann-Pick Tipo C/genética , Esterol O-Aciltransferase
2.
Small ; 20(33): e2309651, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38530065

RESUMO

The scientific community is pursuing significant efforts worldwide to develop environmentally viable film materials from biomass, particularly transparent, high-performance regenerated cellulose (RC) films, to replace traditional plastics. However, the inferior mechanical performance and hydrophilic nature of RC films are generally not suitable for use as a substitute for plastics in practical applications. Herein, lignin homogenization is used to synthesize high-performance composite films. The esterified lignin nanoparticles (ELNPs) with dispersible and binding advantages are prepared through esterification and nanometrization. In the presence of ELNPs, RC films exhibit a higher tensile strength (110.4 MPa), hydrophobic nature (103.6° water contact angle, 36.6% water absorption at 120 min, and 1.127 × 10-12 g cm cm-2 s-1 Pa-1 water vapor permeability), and exciting optical properties (high visible and low ultraviolet transmittance). The films further display antioxidant activity, oxygen barrier ability, and thermostability. The films completely biodegrade at 12 and 30% soil moisture. Overall, this study offers new insights into lignin valorization and regenerated cellulose composite films as novel bioplastic materials.

3.
Small ; : e2402777, 2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-38934355

RESUMO

Lignocellulosic nanofibrils (LCNFs) isolation is recognized as an efficient strategy for maximizing biomass utilization. Nevertheless, achieving a 100% yield presents a formidable challenge. Here, an esterification strategy mediated by the equilibrium moisture in biomass is proposed for LCNFs preparation without the use of catalysts, resulting in a yield exceeding 100%. Different from anhydrous chemical thermomechanical pulp (CTMP0%), the presence of moisture (moisture content of 7 wt%, denoted as CTMP7%) introduces a notably distinct process for the pretreatment of CTMP, comprising the initial disintegration and the post-esterification steps. The maleic acid, generated through maleic anhydride (MA) hydrolysis, degrades the recalcitrant lignin-carbohydrate complex (LCC) structures, resulting in esterified CTMP7% (E-CTMP7%). The highly grafted esters compensate for the mass loss resulting from the partial removal of hydrolyzed lignin and hemicellulose, ensuring a high yield. Following microfluidization, favorable LCNF7% with a high yield (114.4 ± 3.0%) and a high charge content (1.74 ± 0.09 mmol g-1) can be easily produced, surpassing most previous records for LCNFs. Additionally, LCNF7% presented highly processability for filaments, films, and 3D honeycomb structures preparation. These findings provide valuable insights and guidance for achieving a high yield in the isolation of LCNFs from biomass through the mediation of equilibrium moisture.

4.
Chembiochem ; 25(4): e202300843, 2024 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-38169079

RESUMO

Using lipases to catalyze the synthesis of the most differentiated type of compounds remains one of the major challenges among scientists. Seeking more economic and advantageous catalysts is a current goal of green chemistry. In this work, we demonstrate the potential of a chemically modified form of lipase from Thermomyces lanuginosus (cmLTL) for the synthesis of both hydrophobic (heptyl heptanoate, heptyl octanoate, heptyl decanoate, decyl heptanoate, decyl octanoate and decyl decanoate) and amphiphilic (2-(2-ethoxyethoxy)ethyl oleate and 2-(2-ethoxyethoxy)ethyl linoleate) esters, in bulk. The results were compared with its native (LTL) and immobilized (imLTL) forms. The data revealed that LTL showed poor activity for all reactions performed with n-heptane (η<20 %). ImLTL was able to synthesize all hydrophobic esters (η>60 %), with exception of the short ester, heptyl heptanoate. cmLTL was the only form of LTL capable of producing hydrophobic and amphiphilic esters, without compromising the yield when the reactions were performed under solvent-free conditions (>50 %). Molecular modeling showed that the active pocket of cmLTL is able to deeply internalize transcutol, with stronger interactions, justifying the outstanding results obtained. Furthermore, owing to the possibility of cmLTL filtration, the reusability of the catalyst is ensured for at least 6 cycles, without compromising the reaction yields.


Assuntos
Ésteres , Eurotiales , Lipase , Solventes , Esterificação , Lipase/química , Decanoatos , Heptanoatos , Enzimas Imobilizadas/metabolismo
5.
Bioorg Med Chem ; 99: 117601, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38278098

RESUMO

A series of cadasides analogues have been prepared via a combination of solid-phase peptide synthesis and solution-phase cyclization. Primary structure-activity relationship studies of cadasides have also been established and revealed the critical roles of unnatural amino acid residues, which will facilitate the further development of cadasides analogues with improved antimicrobial activities.


Assuntos
Anti-Infecciosos , Esterificação , Anti-Infecciosos/farmacologia , Relação Estrutura-Atividade , Ciclização
6.
Mar Drugs ; 22(5)2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38786615

RESUMO

A predigested product from arachidonic acid oil (ARA) and docosahexaenoic acid (DHA) oil in a 2:1 (w/w) ratio has been developed and evaluated in an in vitro digestion model. To produce this predigested lipid mixture, first, the two oils were enzymatically hydrolyzed up to 90% of free fatty acids (FFAs) were achieved. Then, these two fatty acid (FA) mixtures were mixed in a 2:1 ARA-to-DHA ratio (w/w) and enzymatically esterified with glycerol to produce a mixture of FFAs, mono-, di-, and triacylglycerides. Different glycerol ratios and temperatures were evaluated. The best results were attained at 10 °C and a glycerol-to-FA molar ratio of 3:1. The bio-accessibility of this predigested mixture was studied in an in vitro digestion model. A total of 90% of the digestion product was found in the micellar phase, which contained 30% monoacylglycerides, more than 50% FFAs, and a very small amount of triacylglycerols (3% w/w). All these data indicate an excellent bio-accessibility of this predigested mixture.


Assuntos
Ácido Araquidônico , Digestão , Ácidos Docosa-Hexaenoicos , Ácidos Docosa-Hexaenoicos/química , Ácido Araquidônico/metabolismo , Glicerol/química , Temperatura , Hidrólise , Triglicerídeos/química , Animais , Ácidos Graxos não Esterificados/metabolismo , Ácidos Graxos não Esterificados/química , Humanos
7.
Chem Biodivers ; : e202400652, 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38924342

RESUMO

Commonly isolated from plants of Celastraceae family, pentacyclic triterpenoids have a broad spectrum of biological activities, such as antitumor, anti-inflammatory, antinociceptive properties, among others. Structural modifications in these triterpenoids can enhance their biological activity, as well as their selectivity, while improving their physicochemical and pharmacokinetic aspects. In this study, eight novel esters were synthesized: four derivatives of 3α-friedelinol (friedelan-3α-yl p-bromobenzoate (1a); friedelan-3α-yl naproxenate (1b); friedelan-3α-yl pent-4-ynoate (1c); friedelan-3α-yl undec-10-ynoate (1d)) and four derivatives of 3ß-friedelinol (friedelan-3ß-yl p-bromobenzoate (2a); friedelan-3ß-yl naproxenate (2b); friedelan-3ß-yl pent-4-ynoate (2c); friedelan-3ß-yl undec-10-ynoate (2d)). Overall, 3α-friedelinol showed greater reactivity when compared to the ß-epimer. The esters 1b-d and 2b-c were tested for antileukemic activity against THP-1 and K-562 cells but showed low cytotoxicity for both cell lines. The most active against THP-1 cells was friedelan-3ß-yl naproxenate (2b, IC50=266±6 µM), and the most active against K-562 cells was friedelan-3α-yl pent-4-ynoate (1c, IC50=267±5 µM).

8.
Chem Biodivers ; : e202400799, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-39031575

RESUMO

Chalcones are a group of molecules with recognized biological potential against many diseases, including cancer. Thus, studies on this structure and derivatives have become an attractive chemical strategy to optimize their observed biological activities. One of the synthetic routes used to obtain chalcone derivatives is esterification using either commercial acid chlorides or carboxylic acids. This work focuses on preparing chalcone derivatives and investigating their biological potential against cancer cells. Compound 3'-hydroxychalcone (1) was synthetized by Claisen-Schmidt condensation followed by esterification of the 3'-OH, resulting in eight compounds named 1a-b and 2a-f. All structures were confirmed by 1H and 13C NMR and FT-IR, and cytotoxicity was evaluated in the HCT 116 (colon adenocarcinoma), MCF-7 (breast adenocarcinoma), and CCD-18Co (nontumoral colon fibroblasts) cell lines. Chalcone derivatives were generally more active toward the colon cancer cell line, and 1a and 2b were selected for IC50 determination, presenting IC50 values of approximately 10 µM in HCT 116 cells and above 20 µM in both MCF7 and CDC-18-Co cells, suggesting moderate selectivity. Additionally, we tested compounds 1a and 2b in combination with doxorubicin, but they did not act synergistically with this anthracycline. In conclusion, considering these compounds obtained by the esterification reaction, 1a and 2d showed better results against cytotoxic cells.

9.
Phytochem Anal ; 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38693046

RESUMO

INTRODUCTION: Pectin-oligosaccharides (POS) serve diverse purposes as a food ingredient, antimicrobial and biostimulant in plants, and their functionality is linked to the degree of esterification. Grape and broccoli wastes emerge as environmentally friendly alternatives to obtaining pectin, serving as a sustainable source to producing POS. For example, microwaves have proven to be an effective and sustainable method to extract polysaccharides from plant matrices. OBJECTIVE: This work aims to use grape and broccoli wastes as alternative sources for obtaining pectin by microwave-assisted extraction and biotransformation into POS, which possess biological properties. MATERIAL AND METHODS: The extraction conditions were identified at a power of 400 W, 300 s for the extraction of pectin from grape pomace and broccoli waste. Biotransformation of pectins into POS, using commercial enzyme preparations (Viscozyme L and Pectinase). Characterisation was carried out by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. RESULTS: Physicochemical analysis indicated grape pomace and broccoli waste pectins had galacturonic acid content of 63.81 ± 1.67 and 40.83 ± 2.85 mg 100 mg-1, low degree of esterification of 34.89% and 16.22%, respectively. Biotransformation of pectins into POS resulted in a 20% hydrolysis rate. The main enzymatic activity was polygalacturonase for the degradation of the main structure of the pectin. CONCLUSION: Production of POS from agro-industrial wastes by emerging technologies, such as the combined use of microwave-assisted extraction and enzymatic processes, represents an alternative method for the generation of bioactive compounds with distinctive properties suitable for different applications of interest.

10.
Int J Mol Sci ; 25(12)2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38928488

RESUMO

The oxidative esterification of aldehydes under mild conditions remains a significant challenge. This study introduces a unique defective UiO-66 to achieve gold nanoclusters (AuNCs) for efficient aldehyde oxidation under mild conditions. The construction and characterization of these materials are thoroughly investigated by techniques of XRD, SEM and TEM images, FT-IR, Raman, and XPS spectrum, emphasizing the unique microporous in defective UiO-66 are conducive to the fabrication of AuNCs. The catalytic performance of the prepared materials in aldehyde oxidation reactions is systematically evaluated, demonstrating the remarkable efficiency of dispersed Au@UiO-66-25 with high-content (9.09 wt%) Au-loading and ultra-small size (~2.7 nm). Moreover, mechanistic insights into the catalytic process under mild conditions (70 °C for 1 h) are provided, elucidating the determination of defective UiO-66 in the confined fabrication of AuNCs and subsequent furfural adsorption, which underlie the principles governing the observed enhancements. This study establishes the groundwork for the synthesis of highly dispersed and catalytically active metal nanoparticles using defective MOFs as a platform, advancing the catalytic esterification reaction of furfural to the next level.


Assuntos
Aldeídos , Ouro , Nanopartículas Metálicas , Oxirredução , Ouro/química , Nanopartículas Metálicas/química , Aldeídos/química , Catálise , Estruturas Metalorgânicas/química , Porosidade , Esterificação , Espectroscopia de Infravermelho com Transformada de Fourier
11.
Int J Mol Sci ; 25(10)2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38791124

RESUMO

The use of lipase immobilized on an octyl-agarose support to obtain the optically pure enantiomers of chiral drugs in reactions carried out in organic solvents is a great challenge for chemical and pharmaceutical sciences. Therefore, it is extremely important to develop optimal procedures to achieve a high enantioselectivity of the biocatalysts in the organic medium. Our paper describes a new approach to biocatalysis performed in an organic solvent with the use of CALB-octyl-agarose support including the application of a polypropylene reactor, an appropriate buffer for immobilization (Tris base-pH 9, 100 mM), a drying step, and then the storage of immobilized lipases in a climatic chamber or a refrigerator. An immobilized lipase B from Candida antarctica (CALB) was used in the kinetic resolution of (R,S)-flurbiprofen by enantioselective esterification with methanol, reaching a high enantiomeric excess (eep = 89.6 ± 2.0%). As part of the immobilization optimization, the influence of different buffers was investigated. The effect of the reactor material and the reaction medium on the lipase activity was also studied. Moreover, the stability of the immobilized lipases: lipase from Candida rugosa (CRL) and CALB during storage in various temperature and humidity conditions (climatic chamber and refrigerator) was tested. The application of the immobilized CALB in a polypropylene reactor allowed for receiving over 9-fold higher conversion values compared to the results achieved when conducting the reaction in a glass reactor, as well as approximately 30-fold higher conversion values in comparison with free lipase. The good stability of the CALB-octyl-agarose support was demonstrated. After 7 days of storage in a climatic chamber or refrigerator (with protection from humidity) approximately 60% higher conversion values were obtained compared to the results observed for the immobilized form that had not been stored. The new approach involving the application of the CALB-octyl-agarose support for reactions performed in organic solvents indicates a significant role of the polymer reactor material being used in achieving high catalytic activity.


Assuntos
Biocatálise , Enzimas Imobilizadas , Proteínas Fúngicas , Lipase , Sefarose , Lipase/química , Lipase/metabolismo , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/química , Sefarose/química , Propionatos/química , Estereoisomerismo , Cinética , Esterificação , Temperatura , Estabilidade Enzimática , Candida/enzimologia , Solventes/química , Saccharomycetales
12.
Molecules ; 29(15)2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-39125055

RESUMO

Microstructured reactors offer fast chemical engineering transfer and precise microfluidic control, enabling the determination of reactions' kinetic parameters. This review examines recent advancements in measuring microreaction kinetics. It explores kinetic modeling, reaction mechanisms, and intrinsic kinetic equations pertaining to two types of microreaction: esterification and transesterification reactions involving acids, bases, or biocatalysts. The utilization of a micro packed-bed reactor successfully achieves a harmonious combination of the micro-dispersion state and the reaction kinetic characteristics. Additionally, this review presents micro-process simulation software and explores the advanced integration of microreactors with spectroscopic analyses for reaction monitoring and data acquisition. Furthermore, it elaborates on the control principles of the micro platform. The superiority of online measurement, automation, and the digitalization of the microreaction process for kinetic measurements is highlighted, showcasing the vast prospects of artificial intelligence applications.

13.
Molecules ; 29(10)2024 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-38792264

RESUMO

The study aimed to utilize MoO3 catalysts, produced on a pilot scale via combustion reaction, to produce biodiesel from residual oil. Optimization of the process was conducted using a 23 experimental design. Structural characterization of the catalysts was performed through X-ray diffraction, fluorescence, Raman spectroscopy, and particle size distribution analyses. At the same time, thermal properties were examined via thermogravimetry and differential thermal analysis. Catalytic performance was assessed following process optimization. α-MoO3 exhibited a monophasic structure with orthorhombic phase, whereas α/h-MoO3 showed a biphasic structure. α-MoO3 had a larger crystallite size and higher crystallinity, with thermal stability observed up to certain temperatures. X-ray fluorescence confirmed molybdenum oxide predominance in the catalysts, with traces of iron oxide. Particle size distribution analyses revealed polymodal distributions attributed to structural differences. Both catalysts demonstrated activity under all conditions tested, with ester conversions ranging from 93% to 99%. The single-phase catalyst had a long life cycle and was reusable for six biodiesel production cycles. The experimental design proved to be predictive and significant, with the type of catalyst being the most influential variable. Optimal conditions included α-MoO3 catalyst, oil/alcohol ratio of 1/15, and a reaction time of 60 min, resulting in high biodiesel conversion rates and showcasing the viability of MoO3 catalysts in residual oil biodiesel production.

14.
Molecules ; 29(8)2024 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-38675674

RESUMO

The water produced during the oxidative esterification reaction occupies the active sites and reduces the activity of the catalyst. In order to reduce the influence of water on the reaction system, a hydrophobic catalyst was prepared for the one-step oxidative esterification of methylacrolein (MAL) and methanol. The catalyst was synthesized by loading the active component Au onto ZnO using the deposition-precipitation method, followed by constructing the silicon shell on Au/ZnO using tetraethoxysilane (TEOS) to introduce hydrophobic groups. Trimethylchlorosilane (TMCS) was used as a hydrophobic modification reagent to prepare hydrophobic catalysts, which exhibited a water droplet contact angle of 111.2°. At a temperature of 80 °C, the hydrophobic catalyst achieved a high MMA selectivity of over 95%. The samples were characterized using XRD, N2 adsorption, ICP, SEM, TEM, UV-vis, FT-IR, XPS, and water droplet contact angle measurements. Kinetic analysis revealed an activation energy of 22.44 kJ/mol for the hydrophobic catalyst.

15.
Molecules ; 29(9)2024 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-38731482

RESUMO

An efficient palladium-catalyzed carbonylation of aryl fluorosulfates with aryl formates for the facile synthesis of esters was developed. The cross-coupling reactions proceeded effectively in the presence of a palladium catalyst, phosphine ligand, and triethylamine in DMF to produce the corresponding esters in moderate to good yields. Of note, functionalities or substituents, such as nitro, cyano, methoxycarbonyl, trifluoromethyl, methylsulfonyl, trifluoromethoxy, fluoro, chloro, bromo, methyl, methoxy, N,N-dimethyl, and [1,3]dioxolyl, were well-tolerated in the reactions, which could be kept for late-stage modification. The reactions employing readily available and relatively robust aryl fluorosulfates as coupling electrophiles could potentially serve as an attractive alternative to traditional cross-couplings with the use of aryl halides and pseudohalides as substrates.

16.
Molecules ; 29(11)2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38893561

RESUMO

The application of chemical operations in food processing, in which pure chemical compounds are used to modify food ingredients, often raises social concerns. One of the most frequently modified dietary substances is starch, e.g., E1401-E1404, E1412-E1414, E1420, E1422, E1440, E1442, and E1450-E1452. An alternative solution to chemical treatments seems to be the use of raw materials naturally containing substrates applied for starch modification. Heating starch with a lemon juice concentrate can be considered a novel and effective method for producing starch citrate, which is part of the so-called "green chemistry". The modified preparations obtained as a result of potato starch esterification with natural lemon juice had a comparable degree of esterification to that of the esters produced with pure citric acid. In addition, the use of the juice doubled their resistance to amylolytic enzymes compared to the preparations made with pure acid. Replacing citric acid with lemon juice can facilitate the esterification process, and the analyzed properties of both types of modified preparations indicate that starch esters produced with pure citric acid can be successfully replaced by those produced using natural lemon juice, which may increase the social acceptance of these modified preparations.


Assuntos
Ácido Cítrico , Citrus , Sucos de Frutas e Vegetais , Solanum tuberosum , Amido , Esterificação , Ácido Cítrico/química , Amido/química , Citrus/química , Sucos de Frutas e Vegetais/análise , Solanum tuberosum/química , Manipulação de Alimentos/métodos
17.
Molecules ; 29(16)2024 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-39203007

RESUMO

Antimicrobial resistance has emerged as a significant danger to global health, and the need for more effective antimicrobial resistance (AMR) control has been highlighted. Cinnamic acid is abundant in plant products and is a potential starting material for further modification, focusing on the development of new antimicrobial compounds. In the following review, we describe the classification of critical antibacterial-guided reactions applied to the main skeleton structure of cinnamic acid derivatives over the last decade. Of all of the main parts of cinnamic acids, the phenyl ring and the carboxylic group significantly affect antibacterial activity. The results presented in the following review can provide valuable insights into considerable features in the organic modification of cinnamic acids related to antibacterial medication development and the food industry.


Assuntos
Antibacterianos , Cinamatos , Cinamatos/química , Cinamatos/farmacologia , Antibacterianos/farmacologia , Antibacterianos/química , Testes de Sensibilidade Microbiana , Relação Estrutura-Atividade , Estrutura Molecular , Bactérias/efeitos dos fármacos , Humanos
18.
Molecules ; 29(4)2024 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-38398668

RESUMO

This article presents a thorough investigation into the synthesis of trimethylolpropane triacrylate (TMPTA) via the esterification reaction of trimethylolpropane (TMP) with acrylic acid using Amberlite™ 120 IR (H+), Amberlyst® 15, and Dowex™ 50WX8 resins as heterogeneous catalysts. Preliminary comparative tests explored the impact of air flow on water removal during the reaction and different acid-to-alcohol molar ratios (3:1, 6:1, or 9:1 mol:mol). The findings revealed that introducing air significantly enhances TMPTA yield and -OH group conversion, particularly at a 6:1 acid-to-alcohol molar ratio. Based on cost considerations, Amberlite™ 120 IR (H+) was selected as the preferred catalyst for further optimization. This included evaluating the effect of catalyst loading (10%, 5.0%, and 2.5% w/wtot) and assessing the impact of a pre-drying process on resin efficiency. The study concluded that optimal conditions did not necessitate drying, requiring 120 °C, a catalyst loading of 10% w/wtot, a 4 h reaction time, an acid:alcohol ratio of 6:1 mol:mol, the presence of MEHQ (0.1% mol/molAA), and air bubbling at 6 ± 1 Nl/h. Catalyst recycling was effectively implemented with a slight reduction in catalytic activity over consecutive runs. Furthermore, the study explored a scaled-up system with a mechanical stirrer, demonstrating the potential for multi-hundred grams scale-up. Considerations for optimizing the air flow stripping system are also highlighted. In summary, this study provides valuable insights into designing and optimizing the esterification process for TMPTA synthesis, laying the foundation for potential industrial applications.

19.
Molecules ; 29(16)2024 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-39202957

RESUMO

Pectin is a natural polymer that is found in the cell walls of higher plants. This study presents a comprehensive analysis of pectin extracted from lemon in two different geographic regions (Peddie and Fort Beaufort) in two consecutive years (2023 and 2024) named PP 2023, PP 2024, FBP 2023, and FBP 2024. The dried lemon peels were ground into a powder, sifted to obtain particles of 500 µm, and then subjected to pectin extraction using a conventional method involving mixing lemon peel powder with distilled water, adjusting the pH level to 2.0 with HCl, heating the mixture at 70 °C for 45 min, filtering the acidic extract, and precipitating pectin with ethanol. The yield of these pectin samples was statistically significant, as FBP 2024 had a maximum yield of 12.2 ± 0.02%, PP 2024 had a maximum yield of 13.0 ± 0.02%, FBP 2023 had a maximum yield of 12.2 ± 0.03%, and PP 2023 had a maximum yield of 13.1 ± 0.03%, The variation in yield could be due to the differences in the growing conditions, such as the climate and soil, which could have affected the pectin content in the lemons. The physicochemical characterization of all samples proved that our pectin samples could be used in the pharmaceutical and food industries, with anhydrouronic acid content which was greater than 65%, as suggested by the FAO. The scanning electron microscope analysis of all extracted pectin was rough and jagged, while the commercial pectin displayed a smooth surface morphology with a consistent size. FTIR confirmed the functional groups which were present in our samples. Thermogravimetric analysis was employed to investigate the thermal behavior of the extracted pectin in comparison with commercial pectin. It was found that the extracted pectin had three-step degradation while the commercial pectin had four-step degradation. Additionally, pectin samples have been shown to have antioxidants, as the IC50 of PP 2024, PP 2023, FBP 2023, FBP 2024, and Commercial P was 1062.5 ± 20.0, 1201.3 ± 22.0, 1304.6 ± 19.0, 1382.6 ± 29.9, and 1019.4 ± 17.1 mg/L, respectively. These findings indicate that lemon pectin has promising characteristics as a biopolymer for use in biomedical applications.


Assuntos
Antioxidantes , Citrus , Pectinas , Pectinas/química , Pectinas/isolamento & purificação , Antioxidantes/química , Antioxidantes/farmacologia , Citrus/química , Extratos Vegetais/química , Frutas/química
20.
Molecules ; 29(4)2024 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-38398664

RESUMO

Medium- and long-chain triacylglycerol (MLCT), as a novel functional lipid, is valuable due to its special nutritional properties. Its low content in natural resources and inefficient synthesis during preparation have limited its practical applications. In this study, we developed an effective Pickering emulsion interfacial catalysis system (PE system) for the enzymatic synthesis of MLCT by trans-esterification. Lipase NS 40086 served simultaneously as a catalyst and a solid emulsifier to stabilize the Pickering emulsion. Benefitting from the sufficient oil-water interface, the obtained PE system exhibited outstanding catalytic efficiency, achieving 77.5% of MLCT content within 30 min, 26% higher than that of a water-free system. The Km value (0.259 mM) and activation energy (14.45 kJ mol-1) were 6.8-fold and 1.6-fold lower than those of the water-free system, respectively. The kinetic parameters as well as the molecular dynamics simulation and the tunnel analysis implied that the oil-water interface enhanced the binding between substrate and lipase and thus boosted catalytic efficiency. The conformational changes in the lipase were further explored by FT-IR. This method could give a novel strategy for enhancing lipase activity and the design of efficient catalytic systems to produce added-value lipids. This work will open a new methodology for the enzymatic synthesis of structured lipids.

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