Development of a column-switching high-performance liquid chromatography for kynurenine enantiomers and its application to a pharmacokinetic study in rat plasma

Kynurenine (KYN), a tryptophan metabolite, is a precursor of kynurenic acid, which is an antagonist of N-methyl-D-aspartate receptor. In this study, an enantiomeric separation Of D,L-KYN derivatized with the benzofurazan fluorescence reagent 4-N,N-dimethylaminosulfonyl-7-fluoro-2,1,3-benzoxadiazole (DBD-F) (DBD-D,L-KYN) was first investigated by using a high-performance liquid chromatography (HPLC) with several chiral columns. As a consequence, DBD-D,L-KYN was enantiomerically separated on a cellulose-type chiral column (CHIRALCEL OJ-RH) with a mobile phase of H2O/CH3CN/MeOH (40/50/10) containing 0.1% acetic acid. Under this condition, the separation factor and resolution were 1.48 and 1.28, respectively. Next, a column-switching HPLC consisting of both octadecylsilica and chiral columns was developed and used to determine both D- and L-KYN enantiomers in 10 mu L of rat plasma following the intraperitoneal administration Of D,L-KYN to rats (10 mg kg(-1)). The result revealed that the concentration Of L-KYN was higher than that Of D-KYN, suggesting that D-KYN was eliminated faster than L-KYN. (c) 2007 Elsevier B.V. All rights reserved.