1 research outputs found
High-Resolution Twin-Ion Metabolite Extraction (HiTIME) Mass Spectrometry: Nontargeted Detection of Unknown Drug Metabolites by Isotope Labeling, Liquid Chromatography Mass Spectrometry, and Automated High-Performance Computing
The metabolic fate of a compound
can often determine the success
of a new drug lead. Thus, significant effort is directed toward identifying
the metabolites formed from a given molecule. Here, an automated and
nontargeted procedure is introduced for detecting drug metabolites
without authentic metabolite standards via the use of stable isotope
labeling, liquid chromatography mass spectrometry (LC/MS), and high-performance
computing. LC/MS of blood plasma extracts from rats that were administered
a 1:1 mixture of acetaminophen (APAP) and <sup>13</sup>C<sub>6</sub>-APAP resulted in mass spectra that contained “twin”
ions for drug metabolites that were not detected in control spectra
(i.e., no APAP administered). Because of the development of a program
(high-resolution twin-ion metabolite extraction; HiTIME) that can
identify twin-ions in high-resolution mass spectra without centroiding
(i.e., reduction of mass spectral peaks to single data points), 9
doublets corresponding to APAP metabolites were identified. This is
nearly twice that obtained by use of existing programs that make use
of centroiding to reduce computational cost under these conditions
with a quadrupole time-of-flight mass spectrometer. By a manual search
for all reported APAP metabolite ions, no additional twin-ion signals
were assigned. These data indicate that all the major metabolites
of APAP and multiple low-abundance metabolites (e.g., acetaminophen
hydroxy- and methoxysulfate) that are rarely reported were detected.
This methodology can be used to detect drug metabolites without prior
knowledge of their identity. HiTIME is freely available from https://github.com/bjpop/HiTIME