The study of coumarin dates back to 1820 when coumarin was first extracted from tonka bean by Vogel. Compounds containing coumarin backbone are a very important group of compounds due to their usage ...in pharmacy and medicine. Properties and biological activities of coumarin derivatives have a significant role in the development of new drugs. Therefore, many different methods and techniques are developed in order to synthesize coumarin derivatives. Coumarin derivatives could be obtained from different starting materials with various methods but with big differences in yield. This review summarized various methods, techniques and reaction conditions for synthesis of coumarins from different compounds such as aldehydes, phenols, ketones and carboxylic acids.
The Menshutkin reaction represents the alkylation of tertiary amines by alkyl halide where the reactants are neutral and the products, quaternary ammonium salts, are two ions with opposite signs. The ...most commonly used organic solvents in quaternization reactions are volatile organic solvents (VOSs), namely acetone, anhydrous benzene, dry dichloromethane (DCM), dimethylformamide (DMF) and acetonitrile (ACN). The purpose of this work was to examine eutectic solvents as a “greener” alternative to conventional solvents so that quaternization reactions take place in accordance with the principles of green chemistry. Herein, sixteen eutectic solvents were used as replacements for volatile organic ones in quaternization reactions of isonicotinamide with substituted phenacyl bromides. The reactions were carried out at 80 °C by three synthetic approaches: conventional (4–6 h), microwave (20 min) and ultrasound (3 h). Microwave-assisted organic reactions produced the highest yields, where in several reactions, the yield was almost quantitative. The most suitable eutectic solvents were based on choline chloride (ChCl) as the hydrogen bond acceptor (HBA) and glycerol, oxalic or levulinic acid as hydrogen bond donors (HBDs). The benefits of these three deep eutectic solvents (DESs) as a medium for quaternization reactions are the simplicity of their preparation for large-scale production, with inexpensive, available and nontoxic starting materials, as well as their biodegradability.
Seven pyridoxal dioxime quaternary salts (1–7) were synthesized with the aim of studying their interactions with human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The synthesis was ...achieved by the quaternization of pyridoxal monooxime with substituted 2-bromoacetophenone oximes (phenacyl bromide oximes). All compounds, prepared in good yields (43–76%) and characterized by 1D and 2D NMR spectroscopy, were evaluated as reversible inhibitors of cholinesterase and/or reactivators of enzymes inhibited by toxic organophosphorus compounds. Their potency was compared with that of their monooxime analogues and medically approved oxime HI-6. The obtained pyridoxal dioximes were relatively weak inhibitors for both enzymes (Ki = 100–400 µM). The second oxime group in the structure did not improve the binding compared to the monooxime analogues. The same was observed for reactivation of VX-, tabun-, and paraoxon-inhibited AChE and BChE, where no significant efficiency burst was noted. In silico analysis and molecular docking studies connected the kinetic data to the structural features of the tested compound, showing that the low binding affinity and reactivation efficacy may be a consequence of a bulk structure hindering important reactive groups. The tested dioximes were non-toxic to human neuroblastoma cells (SH-SY5Y) and human embryonal kidney cells (HEK293).
It is well known that carbohydrates are the main source of calories in most diets. However, by inhibiting carbohydrases, intake of calories is reduced and weight loss is improved. α-amylase is an ...enzyme that hydrolyses α-1,4 glycosidic linkages of α-linked polysaccharides, resulting in low-molecular-weight products such as glucose, maltose and maltotriose, while α-glucosidase catalyzes the hydrolysis of nonreducing α-1,4-linked glucose moieties from disaccharides or oligosaccharides. Currently, one of the most common nutritional disorders in the world is hyperglycemia. One of the new therapeutic approaches to treat this disease is the application of natural inhibitors, such as polyphenols, that control starch digestion and regulate blood glucose level. Dietary polyphenols showed potential inhibitory activity against α-amylase and α-glucosidase and this review summarizes the recently published literature that studied inhibition mechanisms and the structure–activity relationship between individual dietary polyphenols and mentioned digestive enzymes. It is known that higher binding interactions cause higher inhibitory activities; thus, different polyphenols can affect different steps in the digestion of polysaccharides. The aim of this review is to clarify these mechanisms and to introduce polyphenol-rich functional foods as potential tools for the inhibition of α-amylase and α-glucosidase.
Eleven pyridine derivatives were prepared by quaternization reactions by different synthetic routes: conventional, microwave, and ultrasound. Since acetone and other solvents used in conventional ...quaternization reactions are harmful, attempts were made to replace the organic solvents with more environmentally friendly alternative - deep eutectic solvents. The reactions were carried out using pyridine-3-aldoxime, pyridine-4-aldoxime, isonicotinamide and nicotinamide as nucleophiles and three different dihaloalkanes as electrophiles: diiodopropane, dibromopropane and diiodohexane. The results showed that the microwave method using acetone as solvent was significantly faster and gave higher yields than the conventional method. In contrast, synthesis in the eutectic solvents choline chloride: urea gave significantly lower yields. The structures of the synthesized compounds were confirmed by .sup.1H and .sup.13C NMR spectroscopy, mass spectrometry and elemental analysis. The antifungal activity of all compounds was tested at two different concentrations (10 and 100 microg mL.sup.-1) against Botrytis cinerea, Fusarium culmorum, Macrophomina phaseolina and Sclerotinia sclerotiorum in vitro. All tested compounds showed excellent inhibitory activity against the studied phytopathogenic fungal species at a concentration of 100 microg mL.sup.-1. Keywords: antifungal activity, dihaloalkanes, deep eutectic solvents, microwave synthesis, quaternization, pyridine derivatives, ultrasound synthesis.
Waste lignocellulosic material, namely brewers' spent grain (BSG), was modified by quaternisation, where amino groups were introduced into BSG via the reaction with N,N-dimethylformamide (DMF) and ...epichlorohydrin. The applicability of the modified BSG (MBSG) for the removal of nitrate ions from model solutions and wastewater was evaluated in batch adsorption experiments. Adsorption of nitrate to the MBSG was confirmed by FTIR analysis of the saturated/spent adsorbent. Fixed bed adsorption column and regeneration studies were performed to determine the regeneration capacity of MBSG. The MBSG had a maximum nitrate adsorption capacity of 22.65 mg g−1 for model nitrate solution, 18.22 mg g−1 for model wastewater and 14.4 mg g−1 for the real wastewater effluent generated from dairy industry. The analysis of the equilibrium data showed that the Freundlich isotherm model provided a slightly better fit to the obtained data than the Langmuir model, indicating multilayer sorption. The data were further analysed by pseudo-first-order and pseudo-second-order kinetic models, and the results revealed that the adsorption followed pseudo-second-order kinetics. The intraparticle diffusion model was used to interpret the mechanism of adsorption, and the results suggest that intraparticle diffusion was not the only process that controlled the adsorption. The adsorption-desorption studies in fixed bed column indicated that MBSG could be regenerated and reused for more than three cycles when model nitrate solutions were used. However, when real dairy industry effluent was used in the fixed bed experiments, the clogging of the column occurred. The applied modification technique was found to be appropriate yielding an effective adsorbent for selective nitrate removal from water.
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•Lignocellulosic food industry waste, i.e. brewers' spen grain has been successfully modified for nitrate sorption.•The highest sorption capacity of 22.65 mg g−1 was achieved in model nitrate solution.•Good nitrate removal efficiencies were achieved in a broad pH range.•Column studies were performed suggesting that the sorbent could be successfully regenerated.
We evaluated the potential of nine vitamin B3 scaffold-based derivatives as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors, as a starting point for the development of novel ...drugs for treating disorders with cholinergic neurotransmission-linked pathology. As the results indicate, all compounds reversibly inhibited both enzymes in the micromolar range pointing to the preference of AChE over BChE for binding the tested derivatives. Molecular docking studies revealed the importance of interactions with AChE active site residues Tyr337 and Tyr124, which dictated most of the observed differences. The most potent inhibitor of both enzymes with
of 4 μM for AChE and 8 μM for BChE was the nicotinamide derivative 1-(4'-phenylphenacyl)-3-carbamoylpyridinium bromide. Such a result places it within the range of several currently studied novel cholinesterase inhibitors. Cytotoxicity profiling did not classify this compound as highly toxic, but the induced effects on cells should not be neglected in any future detailed studies and when considering this scaffold for drug development.
The synthesis of 14 hydrazone compounds derived from pyridoxal, pyridine-4-carbaldehyde, and quinoline-2-carbaldehyde using two methods, conventional method in deep eutectic solvents (DESs) and ...effective combination of ultrasound and DESs, is presented in this paper. In addition, the possibility of using 12 choline chloride (ChCl)-based DESs as an alternative to organic solvents was investigated. The results show that the application of ultrasound not only improves the reaction yield but also shortens the reaction time. The prepared compounds synthesized at room temperature were analyzed via NMR spectroscopy and MS spectrometry. The studies confirmed that the DESs ChCl:malonic, oxalic, levulinic, and trans-cinnamic acid can be excellent alternatives to classical organic solvents. By the combined use of DESs and the ultrasonic method, compound 11 was obtained in a nearly quantitative yield of 98% in DES ChCl:oxalic acid. The advantages of using DESs as reaction media are that they are biodegradable, nontoxic, recyclable, and can be easily prepared with inexpensive starting materials. The results of recycling DESs show that they can be used up to the fourth recycling cycle without significantly changing the reaction yield.
Foodomics and Food Safety: Where We Are Andjelkovic, Uros; Gajdosik, Ma; Gaso-Sokac, Dajana ...
Food technology and biotechnology,
07/2017, Letnik:
55, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The power of foodomics as a discipline that is now broadly used for quality assurance of food products and adulteration identification, as well as for determining the safety of food, is presented. ...Concerning sample preparation and application, maintenance of highly sophisticated instruments for both high-performance and high-throughput techniques, and analysis and data interpretation, special attention has to be paid to the development of skilled analysts. The obtained data shall be integrated under a strong bioinformatics environment. Modern mass spectrometry is an extremely powerful analytical tool since it can provide direct qualitative and quantitative information about a molecule of interest from only a minute amount of sample. Quality of this information is influenced by the sample preparation procedure, the type of mass spectrometer used and the analyst's skills. Technical advances are bringing new instruments of increased sensitivity, resolution and speed to the market. Other methods presented here give additional information and can be used as complementary tools to mass spectrometry or for validation of obtained results. Genomics and transcriptomics, as well as affinity-based methods, still have a broad use in food analysis. Serious drawbacks of some of them, especially the affinity-based methods, are the cross-reactivity between similar molecules and the influence of complex food matrices. However, these techniques can be used for pre-screening in order to reduce the large number of samples. Great progress has been made in the application of bioinformatics in foodomics. These developments enabled processing of large amounts of generated data for both identification and quantification, and for corresponding modeling.
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