Enantioselective LC–ESI–MS/MS method for quantitation of (−)-lumefantrine and (+)-lumefantrine in mice plasma and application to a pharmacokinetic study

We developed and validated a simple, sensitive, selective, and reliable LC–MS/MS–ESI method for the direct quantitation of lumefantrine (LFN) enantiomers [(−)-LFN and (+)-LFN] in mice plasma as per regulatory guideline. LFN enantiomers and carbamazepine (internal standard) were extracted from mice plasma using Strata X SPE (solid-phase extraction) cartridges. Good resolution between enantiomers was achieved on a Chiralpak IA-3 column using an isocratic mobile phase (0.1% of diethyl amine in methanol), which was delivered at a flow rate of 0.8 mL/min. Detection and quantitation were performed using multiple reaction monitoring mode following the transitions m/z 530.27 → 512.30 and 237.00 → 194.00 for LFN enantiomers and the internal standard, respectively, in the positive-ionization mode. The proposed method provided accurate and reproducible results over the linearity range of 2.39–895 ng/mL for each enantiomer. The intra- and inter-day precisions were in the range of 1.03–6.14 and 6.36–8.70 and 2.03–4.88 and 5.82–11.5 for (−)-LFN and (+)-LFN, respectively. Both (−)-LFN and (+)-LFN were found to be stable under different stability conditions. The method was successfully used to delineate stereoselective pharmacokinetics of LFN enantiomers in mice after an oral administration of rac-LFN (20 mg/kg). The pharmacokinetic results indicated that the disposition of LFN enantiomers was stereoselective in mice.     

Validated LC–MS/MS method for quantitation of a selective JAK1 inhibitor,filgotinib in rat plasma,and its application to a pharmacokinetic study in rats

Filgotinib is a selective JAK1 (Janus kinase) inhibitor, filed in Japan for the treatment of rheumatoid arthritis. In this paper, we report a validated liquid chromatography coupled with tandem mass spectrometry for the quantification of filgotinib in rat plasma using tofacitinib as an internal standard (IS) as per the Food and Drug Administration regulatory guidelines. Filgotinib and the IS were extracted from rat plasma using ethyl acetate as an extraction solvent and chromatographed using an isocratic mobile phase (0.2% formic acid:acetonitrile; 20:80, v/v) at a flow rate of 0.9 mL/min on a Gemini C₁₈ column. Filgotinib and the IS were eluted at ~1.31 and 0.89 min, respectively. The MS/MS ion transitions monitored were m/z 426.3 → 291.3 and m/z 313.2 → 149.2 for filgotinib and the IS, respectively. The calibration range was 0.78–1924 ng/mL. No matrix effect and carryover were observed. Intra- and inter-day accuracies and precisions were within the acceptance range. Filgotinib was stable for three freeze–thaw cycles: on bench-top up to 6 h, in an autosampler up to 21 h, and at −80 ° C for 1 month. This novel method has been applied to a pharmacokinetic study in rats.     

Quantification of fenoprofen in human plasma using UHPLC–tandem mass spectrometry for pharmacokinetic study in healthy subjects

A rapid, simple and sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method has been developed to quantify fenoprofen, a nonsteroidal anti-inflammatory drug in human plasma for a pharmacokinetic study in healthy subjects. Owing to high levels of protein binding, protein precipitation followed by solid-phase extraction was employed for the extraction of fenoprofen and fenoprofen-d3 (used as internal standard) from 200 μL human plasma. Separation was performed on a BEH C₁₈ (50 × 2.1 mm, 1.7 μm) column using methanol−0.2% acetic acid in water (75:25, v/v) under isocratic elution. Electrospray ionization was operated in the negative mode for sample ionization. Ion transitions used for quantification in the selected reaction monitoring mode were m/z 241/197 and m/z 244/200 for fenoprofen and fenoprofen-d3, respectively. Under the optimized conditions, fenoprofen showed excellent linearity in the concentration range 0.02–20 μg/mL (r² ≥ 0.9996), adequate sensitivity, favorable accuracy (96.4–103.7%) and precision (percentage coefficient of variation ≤4.3) with negligible matrix effect. The validated method was successfully applied to a pharmacokinetic study of fenoprofen in healthy subjects. The significant features of the method include higher sensitivity, small plasma volume for processing and a short analysis time.     

First total synthesis and reassignment of absolute configuration of diosniponol A and B

Enantioselective first total synthesis of diosniponol A and B has been achieved starting from commercially available vanillin. Wittig reaction, Keck allylation, and Prins cyclization reactions are the key steps involved in the target synthesis.     

Synthesis,characterization & in vitro antimicrobial‐antioxidant studies of novel N,1‐diphenyl‐4,5‐dihydro‐1H‐1,2,4‐triazol‐3‐amine derivatives

A new series of 1,2,4‐triazole was designed, synthesized, and characterized as remarkable antimicrobial and antioxidant agents. These heterocycles have been prepared from the cyclization reactions of Schiff bases 3 ( a‐k ) with phenylhydrazine by refluxing under the alkaline medium. The Schiff bases in turn were realized in good yields from the condensation reactions of N‐phenylurea with different aromatic aldehydes. The structures of the intermediates 3 ( a‐k ) and final heterocycles 4 ( a‐k ) have been fully characterized through their spectral parameters.     

210Po in the environment: insight into the naturally occurring polonium isotope

Journal of Radioanalytical and Nuclear Chemistry - Polonium is rapidly emerging as an international environmental health concern primarily because of the recent rise in hydraulic fracturing...     

Nitrile Metabolizing Enzymes in Biocatalysis and Biotransformation

Nitrile metabolizing enzymes, i.e., aldoxime dehydratase, hydroxynitrile lyase, nitrilase, nitrile hydratase, and amidase, are the key catalysts in carbon nitrogen triple bond anabolism and catabolism. Over the past several years, these enzymes have drawn considerable attention as prominent biocatalysts in academia and industries because of their wide applications. Research on various aspects of these biocatalysts, i.e., sources, screening, function, purification, molecular cloning, structure, and mechanisms, has been conducted, and bioprocesses at various scales have been designed for the synthesis of myriads of useful compounds. This review is focused on the potential of nitrile metabolizing enzymes in the production of commercially important fine chemicals such as nitriles, carboxylic acids, and amides. A number of opportunities and challenges of nitrile metabolizing enzymes in bioprocess development for the production of bulk and fine chemicals are discussed.