Intelligence Way from Eco-friendly Synthesis Strategy of New Heterocyclic Pyrazolic Carboxylic α-Amino Esters

The α-amino acid derivatives constitute a class of compounds of particular medicinal and synthetic attention and considerable interest has been devoted to their synthesis in recent years. In the present work, we develop the computational study of the synthesis reaction of new pyrazolyl α-amino esters derivatives using the Gaussian 09 based on the DFT/B3LYP density functional theory method, with the base 6-31G(d, p) to ensure the possibility of carrying out these reactions within the laboratory of synthesis. Indeed, this research has encouraged us to establish an economical synthesis strategy of these products in overall yields of 73.5% to 87% to have access to new active biomolecule through the O-alkylation reaction between methyl α-azidoglycinate N-benzoylated and primary pyrazole alcohols[(3,5-dimethyl-1H-pyrazol-1-yl)methanol, (1H-pyrazol-1-yl)methanol and (3-ethoxy-5-methyl-1H-pyrazol-1-yl)methanol] under different operating conditions. The structure of the prepared heterocyclic systems was characterized by conventional spectroscopic techniques, like ¹H NMR, ¹³C NMR, and MS. The results revealed that the experimental study is in good correlation with the computational one.     

Hydrogeochemical modeling for groundwater management in arid and semiarid regions using MODFLOW and MT3DMS: A case study of the Jeffara of Medenine coastal aquifer,South-Eastern Tunisia

The study of water quality and the quantification of reserves and their variations according to natural and anthropogenic forcing is necessary to establish an adequate management plan for groundwater resources. For this purpose, a modeling approach is a useful tool that allows, after calibration phase and verification of simulation, and under different scenarios of forcing and operational changes, to estimate and control the groundwater quantity and quality. The main objective of this study is to collect all available data in a model that simulates the Jeffara of Medenine coastal aquifer system functioning. To achieve this goal, a conceptual model was constructed based on previous studies and hydrogeological investigations. The regional groundwater numerical flow model for the Jeffara aquifer was developed using MODFLOW working under steady-state and transient conditions. Groundwater elevations measured from the piezometric wells distributed throughout the study area in 1973 were selected as the target water levels for steady state (head) model calibration. A transient simulation was undertaken for the 42 years from 1973 to 2015. The historical transient model calibration was satisfactory, consistent with the continuous piezometric decline in response to the increase in groundwater abstraction. The developed numerical model was used to study the system's behavior over the next 35 years under various constraints. Two scenarios for potential groundwater extraction for the period 2015–2050 are presented. The predictive simulations show the effect of the increase of the exploitation on the piezometric levels. To study the phenomenon of salinization, which is one of the most severe and widespread groundwater contamination problems, especially in coastal regions, a solute transport model has been constructed by using MT3DMS software coupled with the groundwater flow model. The best calibration results are obtained when the connection with the overlying superficial aquifer is considered suggesting that groundwater contamination originates from this aquifer. Recommendations for water resource managers

• The results of this study show that Groundwater resources of Jeffara of Medenine coastal aquifer in Tunisia are under immense pressure from multiple stresses.
• The water resources manager must consider the impact of economic and demographic development in groundwater management to avoid the intrusion of saline water.
• The results obtained presented some reference information that can serve as a basis for water resources planning.
• The model runs to provide information that managers can use to regulate and adequately control the Jeffara of Medenine water resources.

     

Retention of ionizable compounds on high-performance liquid chromatography: VII. Characterization of the retention of ionic solutes in a C18 column by mass spectrometry with electrospray ionization

The elution of ions from a C₁₈ column with mobile phases containing methanol (60%, v/v) and aqueous buffers is studied by mass spectrometry. It is demonstrated that the anions are excluded from the stationary phase by the ionized silanols. However, the ionized silanols interact strongly with cations, which are retained in the column. These cations are later eluted from the column by ion exchange with the cations present in the pH buffered mobile phase. The size of the ions, the mobile phase cation concentration and the mobile phase pH are the main parameters that affect elution of the retained cations. It is also demonstrated that there are at least two different types of ionizable silanols, with different acidities, that contribute to the retention of cations. An estimate of the pK_a values of these two groups of silanols in 60% methanol is given.     

Phytochemical Profile,Antioxidant Capacity, α-Amylase and α-Glucosidase Inhibitory Potential of Wild Moroccan Inula viscosa (L.) Aiton Leaves

Medicinal plants offer imperative sources of innovative chemical substances with important potential therapeutic effects. Among them, the members of the genus Inula have been widely used in traditional medicine for the treatment of several diseases. The present study investigated the antioxidant (DPPH, ABTS and FRAP assays) and the in vitro anti-hyperglycemic potential of aerial parts of Inula viscosa (L.) Aiton (I. viscosa) extracts through the inhibition of digestive enzymes (α-amylase and α-glucosidase), responsible of the digestion of poly and oligosaccharides. The polyphenolic profile of the Inula viscosa (L.) Aiton EtOAc extract was also investigated using HPLC-DAD/ESI-MS analysis, whereas the volatile composition was elucidated by GC-MS. The chemical analysis resulted in the detection of twenty-one polyphenolic compounds, whereas the volatile profile highlighted the occurrence of forty-eight different compounds. Inula viscosa (L.) Aiton presented values as high as 87.2 ± 0.50 mg GAE/g and 78.6 ± 0.55mg CE/g, for gallic acid and catechin, respectively. The EtOAc extract exhibited the higher antioxidant activity compared to methanol and chloroform extracts in different tests with (IC₅₀ = 0.6 ± 0.03 µg/mL; IC₅₀ = 8.6 ± 0.08 µg/mL; 634.8 mg ± 1.45 AAE/g extract) in DPPH, ABTS and FRAP tests. Moreover, Inula viscosa (L.) Aiton leaves did show an important inhibitory effect against α-amylase and α-glucosidase. On the basis of the results achieved, such a species represents a promising traditional medicine, thanks to its remarkable content of functional bioactive compounds, thus opening new prospects for research and innovative phytopharmaceuticals developments.     

Determination of flavonoid aglycones in several food samples by mixed micellar electrokinetic chromatography

The application of mixed micellar electrokinetic chromatography to the separation of ten flavonoid aglycones (catechin, epicatechin, naringenin, morin, fisetin, quercetin, kaempferol, galangin, apigenin, and chrysin) belonging to four different classes (flavanols, flavanones, flavonols, and flavones), and expected to be prominent in commonly consumed foods, has been developed. A micellar system composed of 25 mM SDS and 25 mM sodium cholate buffered at pH 7.0 provided a simultaneous separation of all compounds in less than 20 min. The procedure could be easily adapted to the determination of some flavonoids from each of these classes in real complex samples (propolis, Ginkgo biloba, etc.). The LODs of these compounds were in the range of 1.2-4 microg/mL, and the peak area and migration time repeatabilities were below 6.0 and 3.1%, respectively.     

Liquid–Liquid Equilibrium of the Quaternary Systems <Emphasis Type="Italic">n</Emphasis>-Octane or Decane + Toluene + Dimethyl Sulfoxide + Methanol or Ethanol at 298.15 K: Experimental Data and Correlation

In this work, the effect of addition of methanol or ethanol to dimethyl sulfoxide to extract toluene from alkanes was studied. Liquid–liquid equilibria data of the four quaternary systems: {methanol (1)?+?DMSO (2)?+?octane (3)?+?toluene (4)}, {ethanol (1)?+?DMSO (2)?+?octane (3)?+?toluene (4)}, {methanol (1)?+?DMSO (2)?+?decane (3)?+?toluene (4)} and {ethanol (1)?+?DMSO (2)?+?decane (3)?+?toluene (4)} were obtained at 298.15 K and 101.3 kPa. The thermodynamic consistency of the experimental data was verified using the Othmer–Tobias and Hand tests. Selectivities and distribution ratios of the four quaternary systems were calculated from experimental data to evaluate the capacity of these two mixed solvents to extract toluene from octane and decane. A comparison of the results obtained was carried out. The NRTL model was used to correlate experimental data and the correlated results are in good agreement with experimental data.     

Towards Understanding the Anticorrosive Mechanism of Novel Surfactant Based on Mentha pulegium Oil as Eco-friendly Bio-source of Mild Steel in Acid Medium:a Combined DFT and Molecular Dynamics Investigation

Today,due to the increasingly stringent European directives concerning the use of molecules with certain toxicities towards the environment or their users,the essential oils,extracts,and molecules derived from plants exhibiting the characteristic of being biodegradable can be considered as a source of green corrosion inhibitors instead of harmful synthetic chemicals.The present work was devoted to testing the essential oil extracted from Mentha pulegium leaves(M1) as a corrosion inhibitor for C-steel in 1mol/L HCl solution using both electrochemical techniques and gravimetric measurements for the evaluation of the inhibition efficiencies at different temperatures.The results obtained showed that the inhibition efficiency increased with an increase in Ml concentration to reach a maximum value of 92.21%.We sought to determine the molecule responsible for this high efficiency,starting with the analysis of oil chemical composition by gas chromatography coupled with mass spectrometry.This analysis revealed that menthol(M2)and isomenthol(M3)were the principal constituents.In order to identify the molecule responsible for the inhibition and explain the protection mechanism involved,quantum chemical calculations and Monte Carlo simulations were used to explain the interaction of menthol,the major constituent of M1 with the Fe-surface.To practically confirm these results,we studied the action of 1mol/L HCl on steel with and without the addition of M2 by both methods(gravimetric and electrochemical study).A very high efficiency was obtained,an efficiency of 94.90% at 10^-3 mol/L,which was retained for a long exposure time,and slightly decreased in function of temperature.Finally,a good correlation between the experimental data,theoretical calculations,and SEM studies was obtained,which denied that the Ml efficiency was only a result of a synergy effect and confirmed the high efficiency of Mentha oil and its main component(menthol)as a strong ecological inhibitor of corrosion.