Tài liệu miễn phí Hoá học
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Process optimization and mechanism study of acid red G degradation by electro-FentonFeox process as an in situ generation of H2O2
Dye-contaminated wastewaters are industrial wastewaters that are difficult to treat using traditional biochemical and physicochemical methods. In the present work, the acid red G was removed as a model pollutant by the electro-Fenton process for the first time. The anode and cathode used by the electro-Fenton process were iron plate and graphite felt, respectively. It was concluded that under the optimal conditions of current density = 20 mA cm–2, pH = 3 and initial Na2 SO4 concentration = 0.2 M, the removal rate of acid red G (ARG) with an initial concentration of 300 mg L–1 could reach 94.05% after 80 min of electrolysis.
4/3/2023 11:28:56 PM +00:00
Synthesis, antioxidant and antimicrobial properties of novel pyridyl-carbonyl thiazoles as dendrodoine analogs
Marine compound dendrodoine was first obtained from tunicate species (Dendrodo grossularia). It has a five-membered ring, namely, it is a heterocycle thiadiazole, which is found rarely in natural sources. Following its biological activities, novel analogs have been investigated recently. Synthesis of the analogs for this study is realized with uncommon thiazole closure, including methylene-carbonyl condensation. Structures are elucidated by NMR (1H, 13C) and HRMS spectrums. As an alkaloid derivative, antioxidant properties were evaluated with DPPH and FRAP assays and antimicrobial effect with microdilution method.
4/3/2023 11:28:47 PM +00:00
Fabrication and characterization of boric acid-crosslinked ethyl cellulose and polyvinyl alcohol films as potential drug release systems for topical drug delivery
In this study, boric acid (BA) is employed as a crosslinking agent to improve the characteristics of two commonly used polymeric films, ethyl cellulose (EC) and polyvinyl alcohol (PVA), for topical drug delivery applications. The developed films are characterized by FTIR spectroscopy and SEM analysis. The results show that the surfaces of the prepared films are even and transparent, except for the BA-modified EC sample. The initial cumulative release for erythromycin (EM) is found to be 0.30 and 0.36 mg/mL for EC and PVA films, which drops to 0.25 and 0.20 mg/mL after BA crosslinking, respectively, after 1 h at 25°C.
4/3/2023 11:28:39 PM +00:00
Highly luminescent water-dispersed silicon quantum dots for fluorometric determination of oxytetracycline in milk samples
A fluorescent probe based on silicon quantum dots (SiQDs) was developed for the selective and sensitive detection of oxytetracycline (OTC) via the inner filter effect (IFE). The water-soluble fluorescent SiQD was synthesized based on the reaction of 3-Aminopropyltriethoxysilane (APTES) and sodium citrate as precursors by the one-pot hydrothermal process. The strong fluorescence emission of quantum dots (QDs) was obtained at 440 nm when excited at 350 nm and OTC had a broad absorption band between 200 and 400 nm. The excitation spectrum of SiQDs was completely overlapped with the absorption spectrum of OTC.
4/3/2023 11:28:32 PM +00:00
Structural insights of two novel N-acetyl-glucosaminidase enzymes through in silico methods
The selectivity and the thermostability of EndoBI-1 and EndoBI-2 suggest that these enzymes may be useful for many scientific and industrial applications. In this study, the growing numbers of homologous sequences in different databases were exploited in a comparative approach to investigate structural properties of EndoBI-1 and EndoBI-2 enzymes. Moreover, the complete and partial homology models of these two enzymes were generated and evaluated. Selected models were used for docking studies of the plus subsite ligand of these enzymes for further understanding on the substrate selectivity of EndoBI enzymes.
4/3/2023 11:28:23 PM +00:00
Processing impact on tocopherols and triglycerides composition of soybean oil and its deodorizer distillate evaluated by high-performance liquid chromatography
In the present study, high-performance liquid chromatography (HPLC) was used for the separation of tocopherols and triglycerides of processed soybean oil and deodorizer distillate (DD). The results of normal and reversed-phase modes of HPLC revealed that concentrations of tocopherols and triglycerides content were decreased during the neutralization, bleaching, and deodorization processes. The loss of individual tocopherols ranged between 55.16% and 63.25%. During processing, triglycerides containing stearicoleic-linoleic (SOL) moieties and palmitic-palmitic-linoleic (PPL) fragments showed greater reduction up to 38.14% and 37.69%, respectively.
4/3/2023 11:28:14 PM +00:00
Design, synthesis, cytotoxic activity, and apoptosis inducing effects of 4- and N-substituted benzoyltaurinamide derivatives
In this study, a group of 4-substituted benzoyltaurinamide derivatives were designed, synthesized, and investigated for their anticancer activity against three cancer cell lines and one nontumorigenic cell line by MTT assay. Among the final compounds, methoxyphenyl derivatives 14, 15, 16 were found to be effective against all the tested cancerous cell lines with promising selectivity. The most active compounds were further evaluated to determine the molecular mechanism of their anticancer activity by using western blot assay and the Annexin V-FITC/PI test. Compound 14 (in SH-SY5Y and MDA-MB-231 cell lines) and 15 (in SH-SY5Y cell line) were found to induce intrinsic apoptotic pathway by upregulating BAX, caspase-3, and caspase-9, while downregulating Bcl-2 and Bcl-xL expression levels.
4/3/2023 11:28:04 PM +00:00
Comparison of antioxidant capacities and antioxidant components of commercial bitter melon (Momordica charantia L.) products
In this study, the total phenolic contents and total antioxidant capacities of some commercial bitter melon products (powder, packaged powder, capsule, paste in olive oil), and of unripe and ripe fruits were determined by spectrophotometric and chromatographic methods. The total antioxidant capacities of unripe and ripe bitter melon samples, determined by using the CUPRAC (cupric reducing antioxidant capacity assay) and ABTS (2,2′-azino-bis(3-ethylbenzthiazolin-6-sulfonic acid))/HRP (horseradish peroxidase) methods, were 42.5 and 36.3 µmol TRE (Trolox equivalent) g–1, and 8.7 and 7.0 µmol TRE g–1, respectively.
4/3/2023 11:27:56 PM +00:00
Chemical composition, antimicrobial, and lipase enzyme activity of essential oil and solvent extracts from Serapias orientalis subsp. orientalis
The volatile components of essential oil (EO), SPME, and SPME of solvent extracts (n-hexane, methanol, and water) obtained from fresh Serapias orientalis subsp. orientalis(Soo) were analyzed by GC-FID/MS. EO of Soo gave 11 compounds in the percentage of 99.97%; capronaldehyde (37.01%), 2-(E)-hexenal (23.19%), and n-nonanal (19.05%) were found to be major constituents. SPME GC-FID/MS analyses of fresh plant and solvent extracts of Soo revealed 7, 12, 7, and 4 compounds within the range of 99.7% to 99.9%. Limonene (76.5%, 41.7%, and 61.3%) was the major compound in SPMEs of the n-hexane and methanol extracts. α-Methoxy-p-cresol (52.9%) was the main component in its water extract.
4/3/2023 11:27:48 PM +00:00
Blue TiO2 nanotube arrays as semimetallic materials with enhanced photoelectrochemical activity towards water splitting
In the past years there has been a great interest in self-doped TiO2 nanotubes (blue TiO2 nanotubes) compared to undoped ones owing to their high carrier density and conductivity. In this study, blue TiO2 nanotubes are investigated as photoanode materials for photoelectrochemical water splitting. Blue TiO2 nanotubes were fabricated with enhanced photoresponse behavior through electrochemical cathodic polarization on undoped and annealed TiO2 nanotubes. The annealing temperature of undoped TiO2 nanotubes was tuned before cathodic polarization, revealing that annealing at 500 °C improved the photoresponse of the nanotubes significantly.
4/3/2023 11:27:37 PM +00:00
Synthesis and molecular docking studies of quinoline derivatives as HIV non-nucleoside reverse transcriptase inhibitors
Quinoline moiety is an important scaffold in the field of drug discovery and drug development, with a wide range of pharmacological activities. Quinoline derivatives are potent inhibitors for reverse transcriptase, which is responsible for the conversion of single-stranded viral RNA into double-stranded viral DNA.In the present study, we have designed and synthesized 2 series, namely pyrazoline and pyrimidine containing quinoline derivatives as non nucleoside reverse transcriptase inhibitors (NNRTIs). Eleven compounds were synthesized and characterized by 1 H and 13C NMR and mass spectrophotometry.
4/3/2023 11:26:58 PM +00:00
Computational and biological studies of novel thiazolyl coumarin derivatives synthesized through Suzuki coupling
The current investigation presents the synthesis, computational molecular-docking and biological activity studies of arylated thiazole coumarins. Aryl substituted thiazolyl coumarin derivatives were synthesized via Suzuki cross-coupling reaction. A detailed reaction condition optimization revealed that the Pd-PEPPSI-IPent precatalyst in only 2 mol% loading resulted in the desired product with high yield. The aim of this study was to examine the antimicrobial behavior of thiazole coumarin derivatives through in vitro and in silico studies.
4/3/2023 11:26:48 PM +00:00
Synthesis and pharmacological effects of novel benzenesulfonamides carrying benzamide moiety as carbonic anhydrase and acetylcholinesterase inhibitors
N-(1-(4-Methoxyphenyl)-3-oxo-3-((4-(N-(substituted)sulfamoyl)phenyl)amino)prop-1-en-1-yl)benzamides 3a – g were designed since sulfonamide and benzamide pharmacophores draw great attention in novel drug design due to their wide range of bioactivities including acetylcholinesterase (AChE) and human carbonic anhydrase I and II (hCA I and hCA II) inhibitory potencies. Structure elucidation of the compounds was carried out by 1 H NMR, 13C NMR, and HRMS spectra. In vitro enzyme assays showed that the compounds had significant inhibitory potential against hCA I, hCA II, and AChE enzymes at nanomolar levels.
4/3/2023 11:26:39 PM +00:00
Biosynthesis of silver nanoparticles using Onosma sericeum Willd. and evaluation of their catalytic properties and antibacterial and cytotoxic activity
In this study, silver nanoparticle (AgNP) synthesis was carried out using Onosma sericeum Willd. aqueous extract for the first time, with a simple, economical, and green method without the need for any other organic solvent or external reducing or stabilizing agent. A variety of AgNPs, all of different particle sizes, were synthesized by controlling the silver ion concentration, extract volume, temperature, and pH. It was determined that the optimum conditions for AgNP synthesis were 1 mM AgNO3 , pH 8, 25 °C, 20 g/200 mL extract, silver nitrate, and extract ratio 5:1 (v/v). The AgNPs were defined using UV-Vis spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and X-ray diffraction (XRD).
4/3/2023 11:26:20 PM +00:00
Design of novel substituted phthalocyanines; synthesis and fluorescence, DFT, photovoltaic properties
The 4-(2-[3,4-dimethoxyphenoxy] phenoxy) phthalonitrile was synthesized as the starting material of new syntheses. Zinc, copper, and cobalt phthalocyanines were achieved by reaction of starting compound with Zn(CH3 COO)2 , CuCl2 , and CoCl2 metal salts. Basic spectroscopic methods such as nuclear magnetic resonance electronic absorption, mass and infrared spectrometry were used in the structural characterization of the compounds. Absorption, excitation, and emission measurements of the fluorescence zinc phthalocyanine compound were also investigated in THF. Then, structural, energy, and electronic properties for synthesized metallophthalocyanines were determined by quantum chemical calculations, including the DFT method.
4/3/2023 11:26:06 PM +00:00
Evaluation of carbonic anhydrase and paraoxonase inhibition activities and molecular docking studies of highly water-soluble sulfonated phthalocyanines
The investigation of carbonic anhydrase and paraoxonase enzyme inhibition properties of water-soluble zinc and gallium phthalocyanine complexes (1 and 2) are reported for the first time. The binding of p-sulfonylphenoxy moieties to the phthalocyanine structure favors excellent solubilities in water, as well as providing an inhibition effect on carbonic anhydrase (CA) I and II isoenzymes and paraoxonase (PON1) enzyme. According to biological activity results, both complexes inhibited hCA I, hCA II, and PON1. Whereas 1 and 2 showed moderate hCA I and hCA II (off-target cytosolic isoforms) inhibitory activity (Ki values of 26.09 µM and 43.11 µM for hCA I and 30.95 µM and 33.19 µM for hCA II, respectively), they exhibited strong PON1 (associated with high-density lipoprotein [HDL]) inhibitory activity (Ki values of 0.37 µM and 0.27 µM, respectively).
4/3/2023 11:25:54 PM +00:00
Newly synthesized peripherally octa-substituted zinc phthalocyanines carrying halogen terminated phenoxy-phenoxy moiety: Comparative photochemical and photophysical features
This study reports the 3 new phthalonitrile derivatives, namely 4, 5 Bis-[4-(4-bromophenoxy) phenoxy] phthalonitrile (1), 4,5 Bis-[4-(4-chlorophenoxy) phenoxy]phthalonitrile (2), and 4, 5 Bis[4-(4-fluorophenoxy) phenoxy] phthalonitrile (3). Their octasubstituted zinc phthalocyanines (4, 5, 6) are reported for the first time in this study. The resulting compounds were characterized by utilizing some spectroscopic methods, such as UV-Vis, 1 HNMR, FT-IR spectroscopy, as well as mass spectraand elemental analysis. To show photosynthesizer’s potential, emission (FF ), singlet oxygen (1 O2 ), and photodegradation quantum yields (F∆, Fd ) of octaperipherally phthalocyanines (Pcs) were performed in the solutions, such as biocompatible solvent DMSO (dimethyl sulfoxide) as well as DMF (dimethylformamide) and THF (tetrahydrofuran).
4/3/2023 11:25:46 PM +00:00
Synthesis and electrochemical properties of copper(II), manganese(III) phthalocyanines bearing chalcone groups at peripheral or nonperipheral positions
In this study, new chalcone compound 1, new phthalonitrile derivatives 2 and 3, new copper(II), manganese(III) phthalocyanines bearing chalcone groups at peripheral or nonperipheral positions were synthesized. Electrochemistry of tetra-(4- {(2E)-3-[2-fluoro-4-(trifluoromethyl)phenyl]prop-2-enoyl}phenoxy) substituted Co(II)Pc and Mn(III)Pcs were studied with cyclic voltammetry (CV) to determine the redox properties of the phthalocyanines. According to the results, while the CuPcs 2a and 3a showed two Pc based reduction reactions and one Pc based oxidation reaction, MnPcs 2b and 3b gave two metal-based reduction reactions. All the redox processes are shifted toward positive potentials as a result of the increased electron-withdrawing ability of the trifluoromethyl substituents.
4/3/2023 11:25:38 PM +00:00
Chemical composition, and antibacterial and antioxidant activities of essential oils from Laggera tomentosa Sch. Bip. ex Oliv. et Hiern (Asteraceae)
Laggera tomentosa Sch. Bip. ex Oliv. et Hiern (Asteraceae), an endemic Ethiopian medicinal plant, is traditionally used to treat various ailments. Previously, the chemical constituents of the essential oil (EO) of its leaves and inflorescence were documented. However, no data about the chemical compositions of other parts of the EOs of the plant have been reported to date. Moreover, there are no previous biological activity reports on any parts of the EOs of this plant. Thus, in this study, the EOs were isolated from the stem bark and roots of this plant by hydrodistillation and analyzed using gas chromatography-mass spectrometry to identify their components. In addition, antibacterial potentials of the oils were evaluated using the disc diffusion and minimal inhibitory concentration (MIC) methods.
4/3/2023 11:25:31 PM +00:00
Effect of pH on lipid oxidation of red onion skin extracts treated with washed tilapia (Oreochromis niloticus) muscle model systems
The aim of the study was to investigate the effect of pH on the lipid oxidation of red onion skin extracts (ROSEs) treated with washed tilapia muscle model systems (WTMS). Minced and buffered washed samples were prepared at pH 6.3 and 6.8. The WTMS were treated with2 different concentrations of red onion skin prior to storage for 5 days. Lipid oxidation was investigated via peroxide values (PVs), thiobarbituric acid reactive substances (TBARS), and the formation of volatile compounds. Fatty acid profiles of the samples were also identified. The ROSEs were able to significantly suppress the PV (~71%) and TBARS (~42%) formation.
4/3/2023 11:25:24 PM +00:00
Catalytic activity of novel thermoplastic/cellulose-Au nanocomposites prepared by cryomilling
Due to environmental concerns, increasing attention has been focused on the application and preparation of biobased polymers and their blends. In this study, cellulose, the most spread biopolymer on Earth, was used in the preparation of novel cotton/polypropyleneAu and cotton/polyethylene-Au nanocomposites via a green mechanochemical approach. First, mechanoradicals were generated by ball milling of the cotton and thermoplastics under cryo conditions, and then, these radicals were used in the reduction of Au ions to Au nanoparticles (Au NPs). Nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS).
4/3/2023 11:25:13 PM +00:00
Innovational combination of hetero-bifunctional N-PEG quinoline scaffolds derivatives with improved anticancer activity against breast and colon cancer cell lines and P-glycoprotein, cytochrome p450 enzyme activity prediction
Polyethylene glycol (PEG) is a polymer that is widely used as a carrier for drug delivery systems (DDS). A library of N-PEGylated quinoline derivatives of PEG molecular weight 200 was prepared rapidly after the activation of PEGs using maleic anhydride. Quinoline with a polymer backbone is essential as new material. PEG is a water-soluble nonionic polymer approved by food and drug organizations for medicine applications. Because of its nontoxic grapheme, it is widely utilized in numerous biochemical, cosmetic, pharmaceutical, and industrialized applications. The modern SwissADME is a web tool that stretches free admittance to a pool of hasty, yet solid, clarifying models for physicochemical properties, pharmacokinetics, and therapeutic science.
4/3/2023 11:25:01 PM +00:00
Characterization and kinetics analysis of the thermal decomposition of the humic substance from hazelnut husk
A humic substance was obtained from hazelnut husk using an alkali extraction. The chemical and morphological structure of the humic matter was characterized via elemental analysis, Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance, Brunauer-Emmet-Teller (BET) analysis, scanning electron microscopy (SEM), and thermogravimetric-FTIR (TG-FTIR). In addition, thermal analysis measurements TG analysis-differential thermogravimetry/differential scanning calorimetry (TGA-DTG/ DSC) were performed under dynamic air conditions to better determine the origin, physical and chemical structure, and decomposition process of the humic matter.
4/3/2023 11:24:53 PM +00:00
Synthesis and characterization of hexagonal boron nitride used for comparison of removal of anionic and cationic hazardous azo-dye: Kinetics and equilibrium studies
The purpose of this study was to compare the adsorption behavior of cationic and anionic dyes onto a hexagonal boron nitride (hBN) nanostructure that was rich in a negative charge. Herein, the hBN nanostructure was synthesized using boric acid as a precursor material. The characteristic peaks of the hBN nanostructure were performed using Fourier transform infrared (FT-IR) and Raman spectroscopies. The morphology and the particle size of hBN nanostructure were determined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). During the studies, various essential adsorption parameters were investigated, such as the initial dye concentration, pH of the dye solution, adsorbent dose, and contact time.
4/3/2023 11:24:44 PM +00:00
Synthesis and structural analysis of nonstoichiometric ternary fulleride K1.5Ba0.25CsC60
The existence of cation-vacancy sites in fullerides might lead to long-range ordering and generate a new vacancy-ordered superstructure. The purpose of this work is to search whether or not long-range ordering of vacant tetrahedral sites, namely superstructure emerges in nonstoichiometric K1.5Ba0.25CsC60 fulleride. Therefore, K1.5Ba0.25CsC60 with cation-vacancy sites is synthesized using a precursor method to avoid inadequate stoichiometry control and formation of impurity phases within the target composition. For this purpose, first, phase-pure K6 C60, Ba6 C60 and Cs6 C60 precursors are synthesized. Stoichiometric quantities of these precursors are used for further reaction with C60 to afford K1.5Ba0.25CsC60.
4/3/2023 11:24:33 PM +00:00
Effective synthesis of bicyclodienes via palladium-catalyzed asymmetric allylic alkylation and ruthenium-catalyzed cycloisomerization
[n.3.0]Bicycles (n = 3–6) can be synthesized using palladium-catalyzed asymmetric allylic alkylation followed by rutheniumcatalyzed cycloisomerization. New types of triarylphosphino-1,2-diaminooxazoline ligands show the same high levels of enantioselectivity observed with Trost ligand when employed in Pd-catalyzed allylic alkylation reactions. The enyne products of these allylic alkylation reactions were further elaborated using a Ru-catalyzed redox isomerization process, for which a mechanism is proposed.
4/3/2023 11:23:46 PM +00:00
Tuning the mechanical properties and degradation properties of polydioxanone isothermal annealing
Polydioxanone (PPDO) is synthesized by ring-opening polymerization of p-dioxanone, using stannous octoate as the catalyst. The polarized optical micrograph (POM) shows thes pherulite growth rate of PPDO decreases with an increase in the isothermal crystallization temperature. PPDO is compression-molded into bars, and PPDO bars are subjected to isothermal annealing at a range of temperatures (Ta = 50, 60, 70, 80, 90, and 100 °C), and correspond to three different annealing times (ta = 1h, 2h, 3h). The effect on PPDO is investigated by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM).
4/3/2023 11:23:33 PM +00:00
Mathematical modeling of a continuous-flow packed-bed reactor with immobilized lipase for kinetic resolution of (R,S)-2-pentanol
In this study, the kinetic resolution of (R,S)-2-pentanol via transesterification to achieve S-2-pentanol, a key intermediate required in the synthesis of anti-Alzheimer drugs, was investigated in continuous-flow packed-bed reactors. The effects of residence time, substrate concentration, and operation time of the enzyme were investigated. Under steady state conditions, 50% conversion and enantiomeric excess of the substrate (eeS )>99% were achieved at a residence time of 0.04 min. Productivity of the continuous-flow process (1.341 mmol/min/g)was about 4 times higher than that of the corresponding batch process (0.363 mmol/min/g).
4/3/2023 11:23:26 PM +00:00
Design, synthesis, and spasmolytic activity of thiophene-based derivatives via Suzuki cross-coupling reaction of 5-bromothiophene-2-carboxylic acid: Their structural and computational studies
In the current research work, a facile synthesis of a series of novel thiophene-based derivatives of 5-bromothiophene-2- carboxylic acid (1) have been synthesized. All analogs (5a-5e, 10a-10f) were obtained from the coupling reaction of 5-bromothiophene2-carboxylic acid (1) and different arylboronic acids with moderate-to-good yields under controlled and optimal conditions. The structures of the newly synthesized compounds were characterized through spectral analysis and their spasmolytic activity, and most of the compounds exhibited potentially good spasmolytic effect. Among the synthesized analogs, compound phenethyl 5-(3,4-dichlorophenyl)thiophene-2-carboxylate (10d) particular showed an excellent spasmolytic effect with an EC50 value of 1.26.
4/3/2023 11:23:18 PM +00:00
Synthesis, characterization and evaluation of antidengue activity of enantiomeric Schiff bases derived from S-substituted dithiocarbazate
A series of Schiff bases have been successfully synthesized through the acid-catalyzed condensation of S-substituted dithiocarbazates and three enantiomerically pure monoterpenes, (1R)-(+)-camphor, (1S)-(-)-camphor, (1R)-(-)-camphorquinone, (1S)- (+)-camphorquinone, (R)-(-)-carvone and (S)-(+)-carvone. Spectroscopic results revealed that the Schiff bases containing camphor or carvone likely adopted an E-configuration along the characteristic imine bond while those containing camphorquinone assumed a Z-configuration. The antidengue potential of these compounds was evaluated based on DENV 2 caused cytopathic effect (CPE) reduction-based in vitro evaluation.
4/3/2023 11:22:59 PM +00:00