Title:Synthesis, Structure Confirmation of Deuterium-substituted Kynurenine
and the Conformation Analysis of Kynurenine in Daptomycin
Volume: 19
Issue: 4
Author(s): Hanzhi Zhang*, Feng Qin, Ning Sun, Mengmeng Zheng, Wenyan Luo, Ya Qiu, Hao Liu and Xiangmin Zhang*
Affiliation:
- Department of Antibiotics and Microorganisms, Shanghai Institute for Food and Drug Control, Shanghai 201203,
China
- Analytical Department, Abiochem Biotechnology Co., Ltd, Shanghai 200241, China
- Department of Chemistry,
Fudan University, Shanghai 200438, China
Keywords:
L-[β, 3’, 5’-2H3] kynurenine-d3, L-[β, β, 3’ , 5’-2H4] kynurenine-d4, H/D exchange, NMR, HPLC-Q/TOF-MS, daptomycin.
Abstract:
Background: After the hydrolysis of daptomycin in deuterated hydrochloric acid, the
deuterium-substituted kynurenine was found, but the structure of deuterium-substituted kynurenine
has not been reported.
Introduction: The deuterium-substituted kynurenines were simply synthesized and confirmed
to be tri- and tetra-substituted products by high resolution mass spectrum and NMR. In further,
the deuterium-substituted kynurenines were used to determine the conformation of kynurenine
to be L-type in daptomycin through conformation analysis combined with derivation and high
performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLCQ/
TOF-MS).
Methods: In the present study, a simple synthesis method was developed for deuteriumsubstituted
kynurenine, and its structure was confirmed by high resolution mass spectrometry and
NMR. L-kynurenine was mixed with the deuterated hydrochloric acid and heated at 110 °C for 7 h. The
hydrogen/deuterium exchange products of L-kynurenine were obtained through the hydrogen/deuterium
exchange method. After the derivation of deuterium-substituted L-kynurenine by Marfey’s reagent, the
conformation of kynurenine in daptomycin was deduced by HPLC-Q/TOF-MS.
Results: The deuterium-substituted kynurenines were confirmed to be tri- and tetra-substituted
products by high resolution mass spectrum. Further, Hydrogen NMR spectrum indicated that the
deuterium-substitution positions were β-position on amino acid and 3’ and 5’ positions on the
benzene ring. Thus, the tri-deuterium-substituted product was L-[β, 3’, 5’-2H3] kynurenine-d3,
while the tetra-deuterium-substituted product was L-[β, β, 3’, 5’-2H4] kynurenine-d4. Furthermore,
the deuterium-substituted kynurenines were used to determine the conformation of
kynurenine to be L-type in daptomycin through conformation analysis combined with derivation
and HPLC-Q/TOF-MS.
Conclusion: The synthesis, structures, and application of tri- or tetra- deuterium-substituted
kynurenine were reported in this study.
