Fluorimetric determination of the enantiomers of vigabatrin, an antiepileptic drug, by reversed‐phase HPLC with a novel diastereomer derivatization reagent

Abstract

Herein, determination of an antiepileptic drug, (±)‐vigabatrin (VB), was performed by reversed‐phase HPLC with fluorimetric detection using a newly designed and synthesized fluorescence derivatization reagent, 2,5‐dioxopyrrolidin‐1‐yl (4‐{[(2‐nitrophenyl)sulfonyl]oxy}‐6‐(3‐oxomorpholino)quinoline‐2‐carbonyl)prolinate [Ns‐MOK‐(R)‐ or (S)‐Pro‐OSu]. During the derivatization of VB with Ns‐MOK‐(R)‐Pro‐OSu at 60°C, the nosyl (Ns) group, which was introduced to protect a phenolic hydroxy group, was released within 30 min to produce MOK‐(R)‐Pro‐VB, which was detected fluorimetrically at 448 nm with an excitation wavelength of 333 nm. The VB enantiomers were separated on an octadecylsilica (ODS) column with a resolution value of 5.57, because Ns‐MOK‐(R)‐Pro‐OSu bears an optically active D‐proline structure. A complete separation of MOK‐(R)‐Pro‐(R)‐ and ‐(S)‐VB enantiomers was achieved on the ODS column within 40 min using stepwise gradient elution, and the detection limits were ~0.80 and 0.37 pmol on the column, respectively. The proposed HPLC with fluorimetric detection method was successfully used for determining VB enantiomers in VB‐spiked human serum following solid‐phase extraction with an anion‐exchange cartridge.

Development of a Derivatization Reagent with a 2-Nitrophenylsulfonyl Moiety for UHPLC-HRMS/MS and Its Application to Detect Amino Acids Including Taurine

“…In our previous study, Ns-MOK-Pro-OSu was reacted with amino groups under heating conditions to eliminate the nosyl group [11]. In contrast, Ns-MOK-β-Pro-OSu reacted effectively with amino acids at room temperature, and no nosyl elimination product was observed.…”

“…For comparison with Ns-MOK-Pro-OSu, the derivatization reagent designed in our previous study [11], 2,5-dioxopyrrolidin-1-yl(4-(((2-nitrophenyl)sulfonyl)oxy)-6-(3-oxomorpholino)quinoline-2-carbonyl)pyrrolidine-3-carboxylate (Ns-MOK-β-Pro-OSu), a structural analogue, was synthesized.…”

“…Previously, we developed a diastereomer derivatization reagent, Ns-MOK-(R)-or -(S)-Pro-OSu (Figure 1a), which was used for derivatization with the amino group of an anti-epileptic drug, vigabatrin, which is a gamma-amino acid [11]. For ease of reaction with the amino group of the target drug, the phenolic hydroxyl group in the derivatization reagent was protected with a 2-nitrobenzenesulfonyl (nosyl) group.…”

Direct Fluorescence Evaluation of d-Amino Acid Oxidase Activity Using a Synthetic d-Kynurenine Derivative

“…We investigated the fluorescence properties of 6- or 6,7-substituted KYNA ethyl ester (KYNA-Et) derivatives synthesized from 4-substituted aniline . As shown in Figure , the KYNA-Et 2a revealed weak fluorescence intensity at 400 nm and an excitation wavelength of 342 nm.…”

Substituted kynurenic acid derivatives as fluorophore-based probes for d- and l-amino acid oxidase assays and their in vitro application in eels

“…A more intense KYNA-based fluorophore can expand its applications in biomedical research. We previously investigated the effect of acetyl, fluoro, methyl, methoxy, 2-oxomorphrino, and dimethylamino substituents on the fluorescence of KYNA-based fluorophores; 13,14 however, the effects of aromatic substituents have not yet been explored. Therefore, in this study, we analysed the substituent effects of mono and dimethyl phenyl groups at the 6-position of KYNA and monitored the consequent changes in its fluorescence.…”