European Journal of Chemistry
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Efficient, environment friendly and regioselective synthetic strategy for 2/3-substituted-8,8-dimethyl-8,9-dihydropyrazolo[1,5-a]quinazolin-6(7H)-ones and their structure elucidation
Get PDFAn efficient and regioselective synthetic reaction friendly to the environment has been described to synthesize various derivatives of pyrazolo[1,5-a]quinozolinone. Condensation of aminopyrazole (4a-m) with formylated dimedone (3) in the presence of KHSO4, under ultrasonic irradiation furnished 2/3-substituted 8,8-dimethyl-8,9-dihydropyrazolo[1,5-a]quinazolin-6(7H)-one (6a-m). This is a clean reaction, giving excellent yields with short reaction time. The structures were elucidated with the help of spectral and analytical data. X-ray crystallographic studies of a model compound 6a ascertained its structural configuration, crystal data for C12H12BrN3O (M =294.152 g/mol): Triclinic, space group P-1 (no. 2), a = 5.872(4) Å, b = 10.870(8) Å, c = 19.523(15) Å, α = 90.013(10)°, β = 90.009(11)°, γ = 93.838(11)°, V = 1243.3(16) Å3, Z = 4, T = 296.15 K, μ(Mo Kα) = 3.293 mm-1, Dcalc = 1.571 g/cm3, 37271 reflections measured (4.18° ≤ 2Θ ≤ 52.7°), 5073 unique (Rint = 0.2404, Rsigma = 0.2366) which were used in all calculations. The final R1 was 0.0596 (I≥2σ(I)) and wR2 was 0.1759 (all data)
The effect of different molecular weight chitosan on the physical and mechanical properties of plasticized films
Get PDFPackaging materials based on biodegradable polymers are a viable alternative to replacing conventional plastic packaging of fossil origin. The main two factors affecting functionality and performance are the molecular weight and the type of plasticizer used in these materials. The goal of this research was to modify unfractionated plasticized chitosan films to improve the physical and mechanical characteristics of the original unfractionated chitosan films. Chitosan extracted from local shrimp shells was zone-refined to produce five distinct chitosan fractions with molecular weights ranging from 1.089×105 to 5.605×105 g/mole. The unfractionated and fractionated chitosan films plasticized with 1:3 poly(vinyl alcohol) and 2:1 maleic acid were prepared by casting from their 2% acetic acid solutions. They were examined by FT-IR and were found to be comparable to the native chitosan spectrum, indicating that the primary backbone of the chitosan structure was unaltered. Therefore, the effects of molecular weight fractions and the type of plasticizer on the physical and mechanical properties were investigated. Examining the films’ surface topography by atomic force microscopy revealed that increasing the molecular weight of chitosan fractions from 2.702×105 to 5.605×105 g/mole affects the surface morphology of the chitosan: poly(vinyl alcohol) (1:3) film. This was accompanied by an increase in the surface roughness of the resulting film from 0.953 to 2.82, and for chitosan: maleic acid from 0.509 to 1.62. It was found that the tensile strength and Young’s modulus of the cast films decreased and the percent elongation at break of the plasticized fractionated chitosan films was increased, implying that less stiff films were obtained with fractionated chitosan. The outcome of this work suggests that the biodegradable fractionated chitosan blend film is a promising packaging material and that poly(vinyl alcohol) is the most suitable plasticizer for this formulation
Ultra-performance liquid chromatography determination of related compounds of molindone in drug substances
Get PDFEffective chromatographic separation was achieved on a phenyl-hexyl stationary phase (50×2.1 mm, 1.9 micron particles) with the economical and straightforward mobile phase combination delivered in isocratic mode at a flow rate of 0.6 mL/min at 254 nm using a ultra-performance liquid chromatography (UPLC) system. In the developed method, the resolution between molindone and its related compounds was more significant than 2.0. Regression analysis shows an r2 value (correlation coefficient) greater than 0.999 for molindone and its associated compounds. This method could detect related compounds of molindone at a level below 0.009% with respect to a test concentration of 500 µg/mL for a 2.0 µL injection volume. The method has shown good, consistent recoveries for related compounds (90-110%). The test solution was found to be stable in the diluent for 48 hours. The drug was subjected to stress conditions. The mass balance was found to be close to 99.3%
In vitro anticancer, antioxidant and DNA-binding study of the bioactive ingredient of clove and its isolation
Get PDFCancer cannot be ignored since it is the most dangerous disease because it is a major cause of death globally with 15% mortality. Researchers have been attracted to the plant-based solution of this havoc. Among all plants, Syzygium aromaticum has shown tremendous results in many aspects such as anticancer, antioxidant, and others. All the studies that took place, were done on the plant extract only. No one goes further than this. Hence, an advanced computational chemistry-based method for the characterization and identification of the bioactive ingredients isolated from cloves was developed for the first time. First, different extracts of Syzygium aromaticum plant buds were obtained using different solvents (Water, methanol, chloroform, ethyl acetate, 50% ethanol, and hexane), then each extract was evaluated for its anticancer activity against A549 and H1299 lung cancer cell lines. The fractionation of the most active extract was done using flash chromatography. After that, anticancer evaluation of every fraction was done again. One of the obtained fractions showed the highest anticancer activity. For the identification of the most active fraction the experimental IR and NMR data of it was taken and compared with the computational IR and NMR data of 19 compounds found in cloves. Furthermore, DNA binding affinity and antioxidant activity of the fraction showing the highest anticancer activity were also studied. The presented method of the isolation of the most bioactive ingredient will be the most helpful for all the scientists working in the field of separation science and phytomedicine
Development of a new highly sensitive and selective spectrophotometric method for the determination of cobalt at nanotrace levels in various complex matrices using N,N’-bis(salicylidene)-ethylenediamine
Get PDFA new spectrophotometric reagent, N,N'-bis(salicylidene)-ethylenediamine (Salen), has been synthesized and characterized through novel reaction techniques. A very simple, ultrasensitive, and nonextractive spectrophotometric method has been developed for the determination of the picotrace amount of cobalt (II) using Salen. Salen undergoes a reaction in a slightly acidic solution (0.001-0.003 M H2S04) with cobalt in 20% ethanol to give a light orange chelate, which has an absorption maximum at 459 nm. The reaction is instantaneous, and the absorbance remains stable for over 24 hours. The average molar absorption co-efficient and Sandell’s sensitivity were found to be 6.04×105 L/mol.cm and 5.0 ng/cm2 of Co, respectively. Linear calibration graphs were obtained for 0.001-40 mg/Lof Co with a detection limit of 0.1 µg/L and RSD of 0-2 %. The stoichiometric composition of the chelate is 1:1 (Co:Salen). A large excess of over 60 cations, anions and some common complexing agents such as chloride, azide, tartrate, EDTA, SCN- etc. do not interfere in the determination. The developed method was successfully used in the determination of cobalt in several Certified Reference Materials (Alloys, steel, bovine liver, human hair, drinking water, sewage sludge, soil, and sediments) as well as in some environmental waters (Potable and polluted), biological fluids (Human blood, urine, and milk), soil samples, food samples (Vegetables, rice, and wheat) and pharmaceutical samples and solutions containing both cobalt (II) and cobalt (III) as well as complex synthetic mixtures. The results of the proposed method for assessing biological, soil, food and vegetable samples were comparable with ICP-OES and AAS were found to be in excellent agreement. The method has high precision and accuracy (s = ±0.01 for 0.5 mg/L)
Phenazine and 10H-phenothiazine cocrystal stabilized by N-H···N and C-H···S hydrogen bonds
Get PDFA 1:1 co-crystal of phenazine and phenothiazine was prepared. The crystal structure was determined by using a single crystal X-ray crystallography technique. Analysis of the crystal revealed that the molecular complex crystallizes in monoclinic P21/n space group, C12H8N2·C12H9NS, a = 9.068(2) Å, b = 8.872(2) Å, c = 23.935(4) Å, β = 92.16(4)°, V = 1924.1(6) Å3, Z = 4, T = 293(2) K, μ(MoKα) = 0.182 mm-1, Dcalc = 1.310 g/cm3, 8057 reflections measured (3.4° ≤ 2Θ ≤ 46.54°), 2751 unique (Rint = 0.0559, Rsigma = 0.0618) which were used in all calculations. The final R1 was 0.0548 (>2sigma(I)) and wR2 was 0.1029 (all data). The molecules recognize each other through N-H···N and C-H···N hydrogen bonds, thus producing a tetramer unit. These units further interact with one another via C-H···S hydrogen bonds
Kinetically simulation of photo-Fenton process in removal of sulfamethazine, ciprofloxacin, sulfathiazole and amoxicillin by Monte Carlo modeling
Get PDFKinetic Monte Carlo modeling was employed to investigate the kinetics and photodecomposition mechanism of sulfamethazine, ciprofloxacin, sulfathiazole, and amoxicillin antibiotics by the photo-Fenton process (iron(III) citrate/hydrogen peroxide in the presence of UV irradiation). The reaction kinetic mechanisms of each photo-Fenton degradation mentioned above have been achieved. The rate constants values for each step of the reaction mechanisms (including photo-Fenton process of antibiotics) were obtained as adjustable parameters by kinetic Monte Carlo simulation. The optimized values of iron(III) citrate and hydrogen peroxide were investigated through the obtaining the effect of their initial amounts on the rate of antibiotic elimination utilizing kinetic Monte Carlo simulation. The perfect agreement is observed between the simulation results and the experimental photo-Fenton data for the systems above
Phytochemical analysis, investigation of antioxidant and anti-inflammatory activities of ethanolic and aqueous extracts of roots of Combretum glutinosum Perr. ex DC from Cote d'Ivoire
Get PDFThe phytochemical, antioxidant, and anti-inflammatory potential of root (ethanol and aqueous) extracts of Combretum glutinosum was investigated in this study. Their antioxidant activity was determined using an in vitro DPPH radical scavenging activity assay. The ethanol extract had the lowest IC50 (0.055 mg/mL), which is comparable to vitamin C. Phytochemical screening of extracts revealed the presence of sterols and polyterpenes, polyphenols, alkaloids, flavonoids, catechin tannins, gallic tannins, saponosides, terpenoids, mucilages, anthocyanins, volatile oils, and cardiac glycosides. The extracts significantly inhibit the development of paw edema induced by carrageenan. Anti-inflammatory studies showed that the inflammation inhibition potential of 200 mg/kg body weight of all extracts was significantly lower than the standard diclofenac (20 mg/kg) in the first hours. At the third hour, the inflammation inhibition potential of ethanolic and aqueous extracts was significantly higher than that of the standard. This study revealed that Combretum glutinosum extracts have anti-inflammatory effects and can act as an effective antioxidant
Molecular dynamics of fibric acids
Get PDF1H- and 13C-NMR chemical shifts were measured for four fibric acids (bezafibrate, clofibric acid, fenofibric acid, and gemfibrozil), which are lipid-lowering drugs. Correlation is found with DFT-computed chemical shifts from the conformational analysis. Equilibrium populations of optimized conformers at 298 K are very different when based on computed Gibbs energies rather than on potential energies. This is due to the significant entropic advantages of extended rather than bent conformational shapes. Abundant conformers with intramolecular hydrogen bonding via five-member rings are computed for three fibric acids, but not gemfibrozil, which lacks suitable connectivity of carboxyl and phenoxy groups. Trends in computed atom-positional deviations, molecular volumes, surface areas, and dipole moments among the fibric acids and their constituent conformations indicate that bezafibrate has the greatest hydrophilicity and fenofibric acid has the greatest flexibility. Theoretical and experimental comparison of chemical shifts of standards with sufficient overlap of fragments containing common atoms, groups, and connectivity may provide a reliable minimal set to benchmark and generate leads
Kinetic studies and adsorptive removal of chromium Cr(VI) from contaminated water using green adsorbent prepared from agricultural waste, rice straw
Get PDFWater pollution caused by heavy metals is of great concern because of rapid industrialization, lack of wastewater treatment, and inefficient removal of these metals from wastewater. The present project was designed to develop a green adsorbent from rice straw and to investigate it for the removal of chromium from chromium-contaminated water. Rice straw biochar was prepared and then modified with FeCl3·6H2O and FeSO4·7H2O to enhance its Cr removal efficiency. Modified and unmodified biochar were characterized by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR). Batch sorption experimentations were performed to inquire about adsorption kinetics, isotherms, and Cr(VI) adsorption mechanism onto iron-modified rice straw biochar (FMRSB). The results specified that the apex adsorption capability of the adsorbent for chromium was 59 mg/g and the maximum removal efficacy was 90.9%. Three isotherm models, Sips, Freundlich, and Langmuir models were applied to the experimental data. Among them, the Sips isotherm model reveals the most excellent fitting with a maximum correlation coefficient (R2 = 0.996) that was adjusted to the experimental data. Regarding kinetic studies, the Pseudo second-order (PSO) exhibits the best fitting with a higher correlation coefficient (R2 = 0.996). The kinetic equilibrium data expressed that the adsorption of Cr(VI) on the FMRSB surface was chemisorption. The mechanism of adsorption of Cr(VI) on FMRSB was predominantly regulated by anionic adsorption through adsorption coupled reduction and electrostatic attraction. The present study demonstrated that the use of modified biochar prepared from agricultural wastes is an environmentally safe and cost-effective technique for the removal of toxic metals from polluted water