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  • Open access
  • 72 Reads
Bioavailability of rapeseed oil fortified with ethyl sinapate

Rapeseed oil is the most popular vegetable oil in Poland. It is a valuable source of bioactive compounds such as polyphenols, phospholipids, and sterols. Additionally, it contains a high amount of essential fatty acids. Unfortunately, oils containing a high amount of unsaturated acids are easily oxidized. Therefore, it is desirable to protect the oil from oxidation process. One of the ways to protect the oil from oxidation is supplementation with antioxidants.

For this reason, the aim of this work were (1) the enzymatic synthesis of ethyl sinapate and (2) the fortification of refined rapeseed oil with two concentrations 0.02 and 0.5% of the synthesized ester. Then in vitro gastrointestinal digestion was performed on the two-step model. Antioxidant activity of oil samples before and after digestion was analyzed by three spectrophotometric methods: 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Folin–Ciocalteu. The addition of synthesized ethyl sinapate caused an increase in antioxidant activity measured by each method, while increasing the ester concentration increased the antioxidant activity from two to ten times. An increase in antioxidant activity also was observed after two-step digestion. The enzymatically synthesized ethyl sinapate improved the antioxidant potential of refined rapeseed oil. Therefore it could probably be used as an efficient antioxidant in the oil industry.

  • Open access
  • 59 Reads
A New Approach for the Synthesis of N-Arylamides Starting from Benzonitriles

N-Arylamides are a ubiquitous component of a broad range of natural products and biologically active compounds. The significance of these motifs can be recognized from their presence in natural products (e.g., penicillin, paclitaxel), pharmaceuticals (e.g., atorvastatin, imatinib), agrochemicals, and in a large number of industrial materials including polymers, detergents and lubricants. More importantly, it constitutes the backbone of the biological crucial proteins and peptides. Among the several synthetic methods developed so far, the direct formation of the C–N bond through cross-coupling reaction of arylhalides (I, Br, Cl) or pseudohalides (OTf, OTs, OMs etc) with primary or secondary amides is one of the best method in terms of versatility. These amidation methods are mainly catalyzed by the transition metal such as palladium and copper catalysts; and it is necessary to install the leaving group beforehand on the aromatic coupling partner which finally ends up with undesirable waste. It is, therefore, highly desirable to develop an efficient and more environmental friendly method for the synthesis of N-arylamides.

N-Acetyl-para-aminophenol (APAP), commonly known as paracetamol or acetaminophen, is a representative of the N-arylamide class drug. This drug is one of the most consumed worldwide with a global production of more than 100,000 tons per year. Over the last century, many routes have been explored for the preparation of paracetamol but all those which have emerged industrially are based on the acetylation of para-aminophenol (PAP) in the final step. In this paper, we have demonstrated a new synthetic protocol for the preparation of acetanilides including paracetamol via hypervalent iodine mediated aza-Hofmann type rearrangement of amidines. The reaction proceeds smoothly at 100 °C in the presence of PhI(OAc)2 or PhINTs in toluene solvent. The requisite amidine substrates were prepared from amines and nitriles by applying Pinner reaction approach. Considering the easy access of amidines from nitriles, the overall process is the conversion of nitriles to acetanilides. As an application of the protocol, we have synthesized paracetamol from 4-cyanophenol.

  • Open access
  • 102 Reads
Green chemistry oriented synthesis of arylmethyl ethers by the reaction of phenol and its derivatives with dimethyl carbonate in the presence of FeHYmmm zeolite

In recent years, Green Chemistry methods have been intensively developed to reduce the harmful effects of chemical processes on the environment. Dimethyl carbonate is an effective substitute for toxic methyl halides and phosgene. We have developed for the first time a new catalytic method for the preparation of arylmethyl ethers based on the reaction of phenol and its derivatives, as well as α- and β-naphthols with dimethyl carbonate in the presence of FeHYmmm zeolite of a hierarchical micro-, meso- and macroporous structure with a high degree of crystallinity. The optimal molar catalyst and reagents, as well as the reaction conditions for the selective synthesis of arylmethyl ethers, have been found. The nature and position of the substituent in the phenol molecule do not significantly affect the selectivity of the reaction, but affect the yield of esters. The presence of meso- and macropores in the catalyst creates conditions for effective diffusion of reactant molecules to catalytically active sites.

  • Open access
  • 37 Reads
Development and validation of a multi-level computational protocol for Drug Re-purposing in the treatment of Bacterial Infections

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that causes acute and chronic infections that are very difficult to eradicate due to acquired drug resistance and since it can also be organized in structured microbial communities forming a biofilm.

Biofilms are structured microbial communities of surface-attached cells embedded in a self-produced matrix of extracellular polymeric substances (EPS) that can be formed in a variety of biological and industrial surfaces. Controlling biofilm formation and development might be the key to hinder bacterial growth without leading to acquired drug resistance.

A biofilms structural database was created to quickly assess all the structural information on different protein structures involved in biofilm formation, development, and virulence available.

Here we report the optimization of a methodology using docking and virtual screening to identify novel clinical uses for already approved drugs. PqsD and PqsR molecular structures were selected as targets due to their crucial role in the formation and development of biofilms.

The FDA approved subset of the ZINC database was screened after careful validation of the Virtual Screening protocol. Subsequently, molecular dynamics and free energy calculation methods were performed in the top 15 results of each target, to further validate the results, calculate the binding free energy, and have a better understanding of the protein-ligand interactions established.

  • Open access
  • 36 Reads
Multicomponent crystalline solid forms of pyridinecarboxamides and DL-2-Hydroxy-2-phenylacetic acid

We have prepared co-crystals of DL-2-Hydroxy-2-phenylacetic acid (H2ma) with picolinamide (pic), nicotinamide (nam) and isonicotinamide (inam). They have been characterized by elemental analysis, single crystal and powder X-ray, IR spectroscopy and 1H and 13C NMR. The crystal packing is stabilized primarily by hydrogen bonding and in some cases through π-π stacking interactions. The analysis of crystal structures reveals the existence of the characteristic heterosynthons with the binding motif of the characteristic heterosynthons with the binding motif R22(8) (primary amide-carboxilic acid) between pyridinecarboxamide molecules and the acid. Other synthons involve hydrogen bonds like (carboxyl)O-H···N(pyridine) and (hydroxyl)O-H···N(pyridine).

  • Open access
  • 39 Reads
Study on the effect of the ligand structure in palladium organometallic catalysts in the Suzuki˗Miyaura cross˗coupling reaction

In this communication we present the results obtained using a family of cyclometallated palladium compounds as catalysts for the Suzuki-Miyaura cross-coupling reaction between an aryl halide and phenylboronic acid.

We have studied the structural factors that enhance the catalysts efficiency for this process through the synthesis of a library of analogous compounds containing thiosemicarbazone ligands with substituted rings and ferrocene diphosphine (dppf). We found that the best conversion rates are obtained with ligands bearing methoxy-disubstituted aromatic rings; and that the process performance is improved when R2 is a methyl group bound to the thioamidic nitrogen.

These results lay the foundations for the design and development of novel and more efficient palladium catalysts based in thiosemicarbazones.

  • Open access
  • 284 Reads
QUANTITATIVE STRUCTURE-PROPERTY RELATIONSHIP FOR THE RETENTION INDEX OF VOLATILE AND SEMIVOLATILE COMPOUNDS OF COFFEE

This study describes the development of a quantitative structure-property relationship (QSPR) to predict the retention index (I) of volatile and semivolatile compounds identified in Arabica coffee samples from different geographical origin. The analytical method utilized rapid headspace solid-phase microextraction (HSSPME)-gas chromatography-time-of-flight mass spectrometry (GC-TOFMS) data measured in the divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber. A total of 102 molecules were optimized with the PM6/ZDO level of theory using Gaussian 09 Rev D.01, in order to calculate 3006 molecular descriptors in the alvaDesc software. Initially, the number of descriptors was reduced to 1237 by means of the V-WSP unsupervised variable reduction to be submitted to the model development. The ordinary least squares were coupled to the genetic algorithms supervised variable subset selection to find the best three descriptors for the QSPR model. For model validation, the dataset was split into a training set (70%) and a test set (30%). The quality of the model was evaluated by means of the coefficient of determination (R2) and the root mean square error (RMSE) for the training set (R2train=0.920 and RMSEtrain=71.8) and the test set (R2test=0.897 and RMSEtest=81.5). Other cross validation criteria were used such as leave-one-out (R2loo=0.869 and RMSEloo=91.7), leave-many-out (R2lmo=0.876 and RMSElmo=93.1) and bootstrap (R2loo=0.863 and RMSEloo=94.2). The computational model accomplished the five principles defined by the OECD to be applicable as a tool for the identification of other volatile and semivolatile constituents in other coffee varieties.

  • Open access
  • 71 Reads
Comparative study of eco-friendly methoximation of aldehydes and ketones using MnCl2.4H2O and CeCl3.7H2O as catalysts

Methoximes are a special group among oxime ethers; they are notoriously the most widely used oxime derivatives both in chemical synthesis and in the pharmaceutical industry. For this reason, there is a continuous and permanent interest in the synthesis of methoximes.

Conventional methods towards their synthesis mostly rely on the reaction between methoxylamine and aldehydes or ketones; however, despite the significance of these protocols, most of them require hard conditions, which may be incompatible with highly functionalized or sensitive compounds.

We have recently advanced the state of the art by demonstrating that the methoximation of aldehydes and ketones with various substituents can be accelerated by CeCl3.7H2O as a suitable promoter. As part of our ongoing research program, we are interested in developing simple, efficient and eco-friendly transformations. Therefore, in pursuit of these interests, here we report an efficient approach for the methoximation of aldehyde and ketones using MnCl2.4H2O, MeONH2.HCl and NaOAc in EtOH at 50 °C as solvent and compare the results with the previous approach. Under these mild conditions, expedient processes and good to excellent product yields were achieved.

More than 20 reactions were carried out with different aldehydes and ketones, generally in shorter reaction times and in some cases, even better yields were obtained when compared to the cerium-based catalysis. This is also advantageous, since manganese salts represent an even greener and inexpensive alternative, because manganese is of great abundance on Earth.

  • Open access
  • 64 Reads
Synthesis of α-acyloxycarboxamides via Passerini reaction.

The one-pot synthesis of α-acyloxycarboxamides is described. The products were obtained in 63 to 80% overall yields via a facile, efficient, and environmentally friendly strategy under catalyst-free conditions. We study the effect of the carboxylic acid component in the scope of the strategy

  • Open access
  • 35 Reads
On synthesis and determination in silico of the biological activity of new hybrid molecules with fragments of thieno[2,3-b]pyridine and 2- iminothiazoline

α-Thiocyanatocarbonyl compounds are the reagents with both electrophilic and nucleophilic reactivity useful as building blocks for many important
chemicals and bioactive molecules. These compounds are useful intermediates in the synthesis of sulfur-containing heterocycles such as thiazoles. Starting from alpha-thiocyanatocarbonyl compounds , we succeded to prepare 2-iminothiazolines and chloroacetamides . Chloroacetamides are of interest as reagents for fine organic synthesis, as well as promising agrochemicals or their precursors. Further, compounds were reacted in the presence of bases with a couple of 3-cyanopyridine-2(1H)-thionts. As a result, the new products of direct S-alkylation were synthesized in high yields (85-96%). When the reaction mixtures were treated with a second equivalent of base followed by warming, the Thorpe-Ziegler isomerization occurs to afford previously undescribed polyheterocyclic ensembles bearing both thieno[2,3-b]pyridine and thiazoline core units.

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