Bio-activation of simeprevir in liver microsomes and characterization of its glutathione conjugates by liquid chromatography coupled to ultrahigh-resolution quadrupole time-of-flight mass spectrometry

Quantification of sixteen cephalosporins in the aquatic environment by liquid chromatography-tandem mass spectrometry

Antimicrobial agents are essential to protect human and animal health. During the COVID-19 pandemic, antimicrobials such as cephalosporins were widely used as prophylactics and to prevent bacterial co-infection. Undoubtedly, the prevalence of antibiotics in the aquatic environment will ultimately affect the degree of resistance against these bacteria in animals and the environmental systems. In order to monitor sixteen cephalosporins in the aquatic environment, we developed a new LC-MS/MS method that functioned simultaneously under positive and negative ESI switching modes. The chromatographic separation has been implemented using a pentafluorophenyl propyl column kept at 40°C. The limits of detection and quantitation for the studied cephalosporins ranged from (8 × 10^-4 ) to (7.11 × 10^-2 ) ng/mL and from (2.61 × 10^-3 ) to (2.37 × 10^-1 ) ng/mL, respectively. The percent extraction efficiency (apparent recovery) and relative standard deviations for the analyzed cephalosporins ranged from 61.69 to 167.67% and 2.45 to 13.48%, respectively. The overall findings showed that the effluent from the wastewater treatment plants that receive wastewater from pharmaceutical factories had a higher detected amount of cephalosporins than that of domestic sewage. Moreover, seven cephalosporins, including cefuroxime, ceftazidime, cefradine, cefprozil, cefixime, cefalexin, and cefadroxil (0.68-105.45 ng/L) were determined in the aquatic environment. This article is protected by copyright. All rights reserved.

A smartphone-integrated dual-mode nanosensor based on Fe3O4@Au for rapid and highly selective detection of glutathione

A simple, rapid and straightforward method for detecting reduced glutathione (GSH) was developed supported on smartphone analysis software package and a peroxide simulated catalyst nanoparticles (Fe₃O₄@Au) system. The nanocomposite was prepared by self-assembling technique, and the characterization was carried out using transmission electron microscopy, Fourier transforms infrared, and X-ray diffractometer. Fe₃O₄@Au materials have catalyzed the oxidation of a typical colorimetric substrate in the presence of H₂O₂, with the color changes from colorless to green oxidized. A smartphone with a free self-developed app referred to as "Color Capture" was accustomed live the RGB (red-greenblue) values of color intensity within the Fe₃O₄@Au system and computationally convert them GSH concentrations. The smartphone detection system showed high property and sensitivity of GSH detection. It gave a constant correlation (R² = 0.9973) between the colour intensity of I and the GSH concentration, with a linear vary of 0-0.25 mmol/L, and a detection limit of 0.013 μmol/L. The results obtained were most consistent with the results obtained in ultraviolet spectrophotometry. The colorimetric system is based on smartphone analysis software developed to detect GSH in actual samples with potential application values.

Unravelling the antifungal and antiprotozoal activities and LC-MS/MS quantification of steroidal saponins isolated from Panicum turgidum

Bioassay-guided investigation of Panicum turgidum extract resulted in the identification of seven steroidal saponins (Turgidosterones 1–7). They were evaluated for their in vitro antifungal, antileishmanial, and antitrypanosomal activities. Turgidosterone 6 was the most active antifungal against Candida albicans and Candida neoformans (IC₅₀ values of 2.84 and 1.08 μg mL⁻¹, respectively). Turgidosterones 4–7 displayed antileishmanial activity against Leishmania donovani promastigotes with IC₅₀ values ranging from 4.95 to 8.03 μg mL⁻¹ and against Leishmania donovani amastigote/THP with IC₅₀ values range of 4.50–9.29 μg mL⁻¹. Activity against Trypanosoma brucei was also observed for Turgidosterones 4–7 with an IC₅₀ values range of 1.26–3.77 μg mL⁻¹. Turgidosterones 1–3 did not display any activity against the tested pathogens. The study of structure–activity relationships of the isolated saponins indicated that the antifungal, antileishmanial, and antitrypanosomal activities are markedly affected by the presence of spirostane-type saponins and the elongation of the sugar residue at C-3. To quantitatively determine the most abundant active ingredient in Panicum turgidum extract, a single run, sensitive, and highly selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been applied under positive and negative modes. The obtained results showed that compound 5 was the most abundant (95.93 ± 1.10 mg per gram of dry Panicum turgidum extract), followed by 6 (52.51 ± 1.05 mg gm⁻¹), 4 (32.71 ± 0.48 mg gm⁻¹), and 7 (13.19 ± 0.50 mg gm⁻¹). Docking of these saponins against the Candida albicans oxidoreductases and Leishmania infantum trypanothione reductase active sites revealed their potential to effectively bind with a number of key residues in both receptor targets.

Bioassay-guided investigation of Panicum turgidum extract resulted in the identification of seven steroidal saponins (Turgidosterones 1–7).

Determination and structural characterization of ravidasvir metabolites by LC coupled to triple quadrupole linear ion trap MS: Application to pharmacokinetics and phase I metabolism in rats

Hepatitis C virus (HCV) is an infectious disease that has become a global clinical issue because of its significant morbidity and mortality. Novel anti-hepatitis C drugs are continuously developed to decrease the pervasiveness of the infection globally. A synthetic ravidasvir, benzimidazole-naphthylene-imidazole derivatives, has been used as an anti-HCV drug. This study determined the metabolites of ravidasvir and its pharmacokinetics in rats using information-dependent acquisition and multiple reaction monitoring scanning modes in linear ion trap LC-MS/MS instrument, respectively. Two time-programming linear-gradient chromatographic methods were employed using a Kinetex C₁₈ column (50 × 3 mm, 2.6 μm) and a Luna HILIC column (100 × 4.6 mm, 3 μm) for the qualitative and quantitative determination of ravidasvir and its metabolites, respectively. In silico prediction where sites in a molecule are susceptible to metabolism by cytochrome P₄₅₀ was implemented, which helped in proposing the metabolic pathway of ravidasvir. The most dominant metabolite in rat liver microsomal samples was oxidative ravidasvir, where one O-demethylated metabolite and eight isomers of the oxidative ravidasvir metabolites were identified. The study provides essential data for proposing the metabolic pathway and successfully applied it to determine the pharmacokinetics of ravidasvir in rat plasma.