Phytochemical screening of Nepeta cataria extracts and their in vitro inhibitory effects on free radicals and carbohydrate-metabolising enzymes

This research was performed to investigate in?vitro the biological activities of successive as well as 70% ethanol extracts of Nepeta cataria on some biochemical parameters including oxidative markers and carbohydrate-hydrolysing enzyme activities (α-amylase, β-galactosidase and α-glucosidase). Powdered N. cataria and its successive extracts were screened for their phytochemical constituents. Tests for tannins, carbohydrates, glycosides and flavonoids were positive in ethanolic extract, but those for steroids and terpenoids were positive in petroleum ether and chloroform extracts. Also, different extracts were chromatographically investigated. The results obtained demonstrated that different successive extracts of N. cataria exhibited an inhibitory effect on oxidative stress indices and carbohydrate-hydrolysing enzymes. It is observed that 70% ethanol, petroleum ether and chloroform extracts showed, respectively, the most potent inhibitory activities, while ethyl acetate and ethanol successive extracts appeared with moderate or low reducing activities.     

Fragmentation reactions of phenoxide anions: deprotonated Dinoterb and related structures

Dinoterb (6-t-butyl-2,4-dinitrophenol), 1, Dinoseb (6-secbutyl-2,4-dinitrophenol), 2, TBP (2-t-butylphenol), 3, and DNP (2,4-dinitrophenol), 4, have been analyzed by electrospray ionization in the negative mode (ESI-N) - tandem mass spectrometry. Nominal laboratory collision energy was varied from zero to 60 eV during the experiments. Apparent fragmentation energies were estimated from a parametric fitting of the collision efficiency curves. In parallel, fragmentation mechanisms of the deprotonated molecules [M-H](-) were explored using quantum chemistry modeling at the B3LYP/6-31 + G(d,p) level. A major fragmentation of the [M-H](-) ions of Dinoterb and Dinoseb is elimination of an alcohol molecule. This reaction is shown to involve one oxygen atom originating from a nitro group rather than the phenoxide moiety. Eliminations of NO, C(4) and CH(2) = C(CH(3))(2), i.e. reactions involving significant rearrangements, constitute the major part of the other fragmentation pathways observed from [3-H](-) and [4-H](-) ions.     

The synthesis of (N2O2S2)-Schiff base ligands and investigation of their ion extraction capability from aqueous media

Two new Schiff bases (I) and (II) containing nitrogen-sulfur-oxygen donor atoms were designed and synthesized in a multi-step reaction sequence. The Schiff base (I) was used in solvent extraction of metal chlorides such as Cu2+ and Cr3+ as well as metal picrates such as Hg2+ and UO2(2+) from aqueous phase to the organic phase. The influences of the parameter functions, such as pH, solvent, ionic strength of aqueous phase, aqueous to organic phase and concentration of the extractant were investigated to shed light on their chemical extracting properties upon the extractability of metal ions. The effect of chloroform, dichloromethane and nitrobenzene as organic solvents over the metal chlorides extraction was investigated at 25±0.1 °C by using flame atomic absorption and the result is that the ability of extraction in solvents as follows: C6H5NO2>CHCl3>CH2Cl2 and the compositions of the extracted species have been determined. The metal picrate extraction was investigated at 25±0.1 °C by using UV-visible spectrometry. As well that the extraction of picrates metal such as UO2(2+) and Hg2+ with Schiff base(I) in absence and presence of 2-(2-aminoethyl) pyridine was investigated in chloroform. The extraction results revealed the presence of neutral donors 2-(2-aminoethyl) pyridine shifts the extraction percentage curves towards higher pH region, indicating a synergistic effect of this donors on extraction of UO2(2+) and Hg2+ by the studied Schiff base (I).     

Utilization of bromine azide to access vicinal-azidobromides from arylidene malononitrile

An efficient and facile approach for tetrachlorosilane as an in situ mediated transformation via a one-pot, synthesis of vicinal bromoazides through the generation of BrN₃ from azidochlorosilane and N-bromosuccinimide in acetonitrile as solvent at ambient temperature is achieved. This catalytic process represents a highly regioselective and high yielding method for the synthesis of 1,2-bromoazides. Thiamine pyrophosphate (TPP) riboswitches regulate essential genes in bacteria by changing conformation upon binding intracellular TPP. Molecular docking studies are conducted to understand the orientation and the interaction of each synthesized molecules with TPP riboswitches. 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.     

A novel modified screen-printed electrode with triazole surfactant assembled on silver nanoparticles for potentiometric determination of uranium

Journal of Radioanalytical and Nuclear Chemistry - Potentiometric modified screen-printed electrodes were developed for UO2(II) determination using a triazole-derivative alone (MSPE) or...     

Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated ketones with DIFLUORPHOS and SYNPHOS analogues

Applications of electron-deficient DIFLUORPHOS and SYNPHOS analogues in the rhodium-catalyzed asymmetric conjugate addition of boronic acids to α,β-unsaturated ketones afford the 1,4-addition adducts in yields up to 92% and with 99% ee. Particularly, a Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to nonsubstituted maleimide substrates using the (R)-3,5-diCF(3)-SYNPHOS ligand is also reported. This protocol provides access to various enantioenriched 3-substituted succinimide units of biological interest, in high yields and good to excellent ee up to 93%, which could be upgraded up to 99% ee, after a single crystallization.     

Separation of <Superscript>125</Superscript>IBZM and <Superscript>125</Superscript>ILIS using polyacrylamide-acrylic acid resin

Radioiodination of both S(−)BZM and LIS was carried out using n-bromosuccimide(NBS) as a mild oxidizing agent. The factors affecting on the radiochemical yield such as pH, reaction time, substrate concentration and oxidizing agent have been studied. The chromatographic separation of both ¹²⁵IBZM and ¹²⁵ILIS was carried out using HPLC and poly(acrylamide-acrylic acid) resin P(AAm-AA). The copolymer was prepared by a template polymerization of AA in aqueous solution on PAAm as a template polymer and in the presence of N,N-methylenebisacrylamide (NMBA) as a crosslinker using gamma rays as initiator. The purifications of tracers were carried out using prepared resin compared with TLC and HPLC. The effects of pH buffer, variable elution volumes, flow rate and temperature on the separation process of the resin efficiency have been studied.     

Chlorosulfonation of Some Aldimine-Isocyanate Cycloadducts

Attempts to chlorosulfonate 1,4-diphenyl-1,3-diazetidin-2-one (1) failed, but the 3-methyl derivative (2) reacted with chlorosulfonic acid to give the bis-sulfonyl chloride (3), characterized as the sulfonamides 4 and 5. 2,3,6-Triphenyl-2,3-dihydro-1,3,5-thiadiazin-4-one (6) with chlorosulfonic acid suffered an acid-catalyzed ring-opening reaction forming the sulfonyl derivatives (8, 9) of N-phenyl-N′-thiobenzoylurea (7). Condensation of 8 and 9 with diethylamine afforded the diethyl-sulfonamide (10). Dibenzylideneethylenediamine (11) reacted with thiobenzoyl isocyanate at room temperature to yield the cycloadduct 12; however at 90°C, N,N′-di (thiobenzoylcarbamoyl)ethylenediamine (13) was obtained. The cycloadduct 12 with chlorosulfonic acid gave the ring-opened disulfonyl chloride 14 and the diethylsulfonamide 15. 1,6-Diphenylhexahydro-s-triazine-2,4-dione (17) was converted into the dimethyl derivative (18), which with chlorosulfonic acid afforded the bis-sulfonyl chloride (19), characterized as the sulfonamides 20–22.

     

Particle simulation of radio-frequency plasma discharges of methanefor carbon film deposition

Particle-in-cell/Monte Carlo (PIC/MC) simulations of capacitively coupled radio-frequency (RF) glow discharges were carried out for low pressure CH₄ plasmas. The present computational scheme includes the motions and collisions of both neutral and charged particles. The CH₄ plasma is modeled by combining a one-dimensional PIC/MC method with a polyatomic particle collision scheme. The model considers the motions of CH₄, CH₄⁺, CH₃, C₂H₅, H₂, H, and electrons. Space and time dependent results show ionization rate is high at the sheath region. The dissociation rate of CH₄ is found to be high at the sheath as well as in the plasma bulk. Deposition rate of carbon film is calculated by sampling impinging particles at at the powered electrode. The calculations show that neutral radicals are the major depositing species for the cases studied. Ion energy impinging to the electrode was found to be strongly dependent on the “imposed” dc bias (as opposed to self-bias) voltage for a given RF voltage. Deposition rate was found to be almost independent of the “imposed” dc bias voltage as the RF voltage remained constant     

Computational Studies of Atmospheric-Pressure Methane–Hydrogen DC Micro Glow Discharges

Atmospheric-pressure methane–hydrogen micro glow discharges were computationally investigated using a 2-D hybrid model. The plasma model was solved simultaneously with a model for the external circuit. Simulations were conducted for a pin-to-plate electrode configuration with an interelectrode separation of 400 ${rm mu}hbox{m}$. The spatiotemporal evolutions of electrons, species densities, electric field, and electron and gas temperatures were studied. A total of 81 reactions were considered, which included electron–neutral, electron–ion, ion–neutral, and neutral–neutral reactions. An 84-step reaction mechanism consisting of 15 surface species and four deposited bulk species was considered. A time-stepping technique was employed to address the time scales of plasma transport (in microseconds) and neutral and fluid transport (in milliseconds) in 2-D simulations with detailed volume and surface chemistry. The simulations indicated $hbox{H}_{3}^{+}$ and $hbox{CH}_{5}^{+}$ ions to be the most prominent hydrogen and hydrocarbon ions. The gas temperature predictions suggested the discharge to be operating as a nonthermal glow discharge. The effect of discharge current on both plasma and deposition characteristics was studied. The simulations predicted a flat voltage–current characteristic, indicating the discharge to be operating in normal glow mode. The predicted voltage–current characteristic was found to be in favorable agreement with the experimental measurements. With an increase in discharge current, the deposition rate profile expanded in the lateral direction, suggesting that deposition occurred at the cathode spot.