Forced degradation study of quinapril by UPLC-DAD and UPLC/MS/MS: Identification of by-products and development of degradation kinetics.

International audienceQuinapril undergoes a significant degradation in the solid state, specially in the presence of humidity, temperature and pharmaceutical excipients. Since dissolution increases the degradation, hydrolytic reactions are among the most common processes involved in drug degradation. Improving the knowledge regarding drug stability, particularly concerning the critical factors that can influence the stability of the active substance in solutions, such as the temperature, the pH and the concentration of catalytic species usually acids or bases are essential for pharmaceutical use. The aim of this study was therefore to develop a new chromatographic method for rapidly and accurately assessing the chemical stability of quinapril and to study the mechanism of quinapril degradation in acidic, neutral and alkaline media at 80°C according to the ICH guidelines. Ultra High Performance Liquid Chromatography (UPLC) coupled with electrospray ionization tandem mass spectrometry and/or diode array detector was used for the rapid and simultaneous analysis of quinapril and its by-products. Separation was achieved using a BEH C18 column and a mixture of acetonitrile-ammonium hydrogencarbonate buffer (pH 8.2; 10 mM) (65:35, v/v) at a flow rate of 0.4 mL/min as a mobile phase. This method allowed drug byproducts profiling, identification, structure elucidation and quantitative determination under stress conditions. The developed method also provides the determination of the kinetic rate constants for the degradation of quinapril and the formation of its major by-products. A complete model including degradation pathway observed under all tested conditions was proposed according to the kinetic study and the structure elucidation of by-products

Seasonal variation of plasma testosterone levels in Algerian male Arabia goats

The aim of the present work was to evaluate the general monthly averages of the testosterone hormone and the influence of  season and photoperiod on plasma testosterone levels in Arabia bucks of Algeria. Testosterone concentrations were determined throughout one year in blood samples collected every fortnight of the month from nine males of Arabia goat breeds, fed a constant diet, maintained without interactions with female goat. Plasma testosterone level was measured by radioimmunoassay. Analyses performed show that the monthly averages of the testosterone hormone vary during the year; higher levels were recorded during August (T=8.57±6.72, P=0.00***) however, bucks displayed the same change tendency during the same period (P=0.79). Plasma testosterone concentrations vary significantly between seasons (P=0.00***) being higher during autumn (6.15±3.81ng/ml) compared with spring (0.90 ± 1.27ng/ml) when hormone synthesis reaches its lowest levels. In conclusion, Arabia bucks of Algeria displayed a clear seasonality of plasma testosterone concentration with very low levels in winter and spring (from January to May) and high levels in summer and autumn (from July to November).Keywords: Arabia bucks, testosterone, season, photoperiod

Sustainable water treatment: Harnessing mining waste as catalysts for Sicomet green degradation

This paper presents a novel circular economy approach to water remediation that focuses oncreating sustainable systems by utilizing mining waste from El-Ouenza, Tebessa, in the east ofAlgeria. Waste materials are employed as catalysts in Fenton and photo-Fenton processes. Twocases were studied: the conventional and the modified heterogeneous photo-Fenton at a pH of 3and under modified pH conditions for degrading Sicomet Green food dye ZS120. Catalysts werecharacterized through various analyses. Catalyst performance and dye degradation were examinedfor raw and calcined waste at 500 ◦C. Parameters like catalyst amount, sodium sulfiteconcentration, oxalic acid, and pH were optimized for both systems, with and without ligand. Thefirst system achieved 91.5 % mineralization using 0.15 g L\u100000 1 catalyst, pH of 3, and 0.45 mMNa2SO3 in 90 min under sunlight. The second reached 78.5 % efficiency with variable conditions.Kinetic models demonstrated a first-order model for both photo-Fenton degradation and mineralizationunder sunlight. These findings guide eco-friendly dye degradation via mining wastebasedcatalysts in photo-Fenton systems, supporting sustainable wastewater treatment

Exploring the Influence of Sr Concentration on the Structural and Catalytic Properties of CuO/SrSO4 Nanocomposites for Organic Dye Degradation

Pure CuO and CuO/SrSO4 nanocomposites were synthesized via the hydrothermal method to explore their catalytic efficacy in degrading methylene blue (MB). CuSO4\ub75H2O, NaOH, and SrCl2\ub76H2O were used as primary reagents. XRD characterization unveiled the monoclinic structure (C2/c) of pure CuO NPs, exhibiting well-defined crystallinity with crystallite sizes ranging from 9.64 to 26.08 nm. Notably, samples with Sr concentrations exceeding 2wt% exhibited a secondary SrSO4 phase with an orthorhombic structure (Pnma). Infrared and Raman spectroscopy confirmed Cu-O, S-O, and Sr-O bond vibrations, validating CuO and SrSO4 synthesis. SEM micrographs depicted irregular platelet-like morphology with a surface area of up to 0.061 μm2 and nanometric thickness for pure CuO NPs, while this morphology varied for CuO/SrSO4 nanocomposites. BET analysis revealed a relatively large specific surface area (9.04 to 15.12 m2 /g), potentially advantageous for catalytic activity. Catalytic degradation of MB in aqueous solution by pure CuO NPs exhibited limited efficiency (19.77% in 60 min), markedly enhanced to 100% in 40 min with the addition of H2O2. Despite H2O2 presence, CuO/SrSO4 nanocomposites showed lower MB degradation efficiency due to sulfate SO4 2- ion poisoning. Monitoring the formation of SrSO4 phase is a synthesis strategy to adjust the poisoning effect by sulfate ions. The sample with a Sr concentration of 6 wt% demonstrated the highest degradation rate (83.78% in 40 min), attributed to its larger specific surface area. Furthermore, synthesized materials displayed satisfactory catalytic stability upon recycling for MB degradation

The Effect of the Stationary Phase on Resolution in the HPLC-Based Separation of Racemic Mixtures Using Vancomycin as a Chiral Selector: A Case Study with Profen Nonsteroidal Anti-Inflammatory Drugs

\ua9 2023 by the authors.Chiral resolution is a technique of choice, making it possible to obtain asymmetric and enantiomerically pure compounds from a racemic mixture. This study investigated the behavior of vancomycin when used as a chiral additive in high-performance liquid chromatography (HPLC) to separate enantiomers of nonsteroidal anti-inflammatory drugs (NSAIDs), including ketoprofen, ibuprofen, flurbiprofen, and naproxen enantiomeric impurities. We compared two achiral stationary phases (C18 and NH2) to assess the impact of mobile phase composition and stationary phase on the vancomycin retention time in the racemic resolution of drug enantiomers. Our results demonstrated the successful enantioseparation of all drugs using vancomycin in the mobile phase (phosphate buffer 0.05 M/2-propanol, 50/50) with an NH2 column. This enhanced separation on the NH2 column resulted from the chromatography system’s efficiency and vancomycin dimers’ stereoselective interaction on the NH2 surface. This study underscores the importance of stationary phase selection in the chiral resolution of NSAIDs with vancomycin as a chiral additive. It offers valuable insights for future research and development of NSAID chiral separation methods, highlighting potential vancomycin applications in this context

Modeling and Optimization of Hybrid Fenton and Ultrasound Process for Crystal Violet Degradation Using AI Techniques

\ua9 2023 by the authors. This study conducts a comprehensive investigation to optimize the degradation of crystal violet (CV) dye using the Fenton process. The main objective is to improve the efficiency of the Fenton process by optimizing various physicochemical factors such as the Fe2+ concentration, H2O2 concentration, and pH of the solution. The results obtained show that the optimal dosages of Fe2+ and H2O2 giving a maximum CV degradation (99%) are 0.2 and 3.13 mM, respectively. The optimal solution pH for CV degradation is 3. The investigation of the type of acid for pH adjustment revealed that sulfuric acid is the most effective one, providing 100% yield, followed by phosphoric acid, hydrochloric acid, and nitric acid. Furthermore, the examination of sulfuric acid concentration shows that an optimal concentration of 0.1 M is the most effective for CV degradation. On the other hand, an increase in the initial concentration of the dye leads to a reduction in the hydroxyl radicals formed (HO•), which negatively impacts CV degradation. A concentration of 10 mg/L of CV gives complete degradation of dye within 30 min following the reaction. Increasing the solution temperature and stirring speed have a negative effect on dye degradation. Moreover, the combination of ultrasound with the Fenton process resulted in a slight enhancement in the CV degradation, with an optimal stirring speed of 300 rpm. Notably, the study incorporates the use of Gaussian process regression (GPR) modeling in conjunction with the Improved Grey Wolf Optimization (IGWO) algorithm to accurately predict the optimal degradation conditions. This research, through its rigorous investigation and advanced modeling techniques, offers invaluable insights and guidelines for optimizing the Fenton process in the context of CV degradation, thereby achieving the twin goals of cost reduction and environmental impact minimization

Advanced green peel utilization for efficient methylene blue removal: Integrated analysis and predictive modeling

This study explores the adsorption of Methylene Blue (MB) onto Green Peel (GP) material, utilizing advanced analytical techniques and modeling approaches. Fourier-transform infrared spectroscopy (FT-IR) confirms GP\u27s effectiveness as an adsorbent. The study systematically examines the influence of key factors such as adsorbent dose, pH, MB concentration, and temperature on adsorption efficiency. Among the isotherm models analyzed, the monolayer with double energy (M2) model is identified as the most accurate for describing MB adsorption onto GP. Steric parameters provide insights into the adsorption mechanism, revealing temperature-dependent changes. Thermodynamic analysis indicates an exothermic adsorption process, with a decrease in adsorption capacity at elevated temperatures. Density Function Theory (DFT) analysis highlights the potential for electron transfer during adsorption, contributing to a deeper understanding of the process. Molecular Dynamic Simulation (MDS) uncovers stable adsorption configurations and reveals the significance of chemical interactions and Van der Waals forces. Gaussian Process Regression with L\ue9vy Flight Distribution (GPR_LFD) demonstrates exceptional predictive accuracy, closely aligning experimental and predicted MB uptake values. Optimal adsorption conditions (30 minutes contact time, 0.6 g adsorbent dose, 400 mg/L initial MB concentration, pH 6.6, and 10\ub0C) yield an adsorption capacity of 207.90 mg/g. The integration of LFD optimization and GPR prediction through a MATLAB interface further enhances the practical application of these findings. This comprehensive investigation not only advances the understanding of MB adsorption onto GP but also highlights GP\u27s potential as an efficient, reusable adsorbent

Elucidating Chiral Resolution of Aromatic Amino Acids Using Glycopeptide Selectors: A Combined Molecular Docking and Chromatographic Study

\ua9 2024 by the authors.An asymmetric synthesis is a favorable approach for obtaining enantiomerically pure substances, but racemic resolution remains an efficient strategy. This study aims to elucidate the chiral resolution of aromatic amino acids and their elution order using glycopeptides as chiral selectors through molecular docking analysis. Chiral separation experiments were conducted using Vancomycin as a chiral additive in the mobile phase (CMPA) at various concentrations, coupled with an achiral amino column as the stationary phase. The Autodock Vina 1.1.2 software was employed to perform molecular docking simulations between each enantiomer (ligand) and Vancomycin (receptor) to evaluate binding affinities, demonstrate enantiomeric resolution feasibility, and elucidate chiral recognition mechanisms. Utilizing Vancomycin as CMPA at a concentration of 1.5 mM enabled the separation of tryptophan enantiomers with a resolution of 3.98 and tyrosine enantiomers with a resolution of 2.97. However, a poor chiral resolution was observed for phenylalanine and phenylglycine. Molecular docking analysis was employed to elucidate the lack of separation and elution order for tryptophan and tyrosine enantiomers. By calculating the binding energy, docking results were found to be in good agreement with experimental findings, providing insights into the underlying mechanisms governing chiral recognition in this system and the interaction sites. This comprehensive approach clarifies the complex relationship between chiral discrimination and molecular architecture, offering valuable information for creating and improving chiral separation protocols

Silicon-Mediated Resilience: Unveiling the Protective Role against Combined Cypermethrin and Hymexazol Phytotoxicity in Tomato Seedlings

Insecticides and fungicides present potential threats to non-target crops, yet our comprehension of their combined phytotoxicity to plants is limited. Silicon (Si) has been acknowledged for its ability to induce crop tolerance to xenobiotic stresses. However, the specific role of Si in alleviating the cypermethrin (CYP) and hymexazol (HML) combined stress has not been thoroughly explored. This study aims to assess the effectiveness of Si in alleviating phytotoxic effects and elucidating the associated mechanisms of CYP and/or HML in tomato seedlings. The findings demonstrated that, compared to exposure to CYP or HML alone, the simultaneous exposure of CYP and HML significantly impeded seedling growth, resulting in more pronounced phytotoxic effects in tomato seedlings. Additionally, CYP and/or HML exposures diminished the content of photosynthetic pigments and induced oxidative stress in tomato seedlings. Pesticide exposure heightened the activity of both antioxidant and detoxification enzymes, increased proline and phenolic accumulation, and reduced thiols and ascorbate content in tomato seedlings. Applying Si (1 mM) to CYP- and/or HML-stressed seedlings alleviated pigment inhibition and oxidative damage by enhancing the activity of the pesticide metabolism system and secondary metabolism enzymes. Furthermore, Si stimulated the phenylpropanoid pathway by boosting phenylalanine ammonia-lyase activity, as confirmed by the increased total phenolic content. Interestingly, the application of Si enhanced the thiols profile, emphasizing its crucial role in pesticide detoxification in plants. In conclusion, these results suggest that externally applying Si significantly alleviates the physio-biochemical level in tomato seedlings exposed to a combination of pesticides, introducing innovative strategies for fostering a sustainable agroecosystem