Identification and Characterization of Kukoamine Metabolites by Multiple Ion Monitoring Triggered Enhanced Product Ion Scan Method with a Triple-Quadruple Linear Ion Trap Mass Spectrometer

Abstract

Kukoamines are a series of bioactive phytochemicals conjugated by a polyamine backbone and phenolic moieties. Understanding the structural diversity of kukoamine metabolites in plants is meaningful for drug discovery. In this study, an LC-MS/MS method was established for kukoamine profiling and characterization from lycii cortex (LyC) via a triple-quadrupole linear ion trap mass spectrometry (Q-TRAP). On the basis of the typical fragmentation of kukoamine, a diagnostic ion, which represents the features of the backbone and phenolic substitute, was chosen as the product ion for precursor ion scan, and then the screened precursor ions were applied to a successive multiple ion monitoring triggered enhanced product ion scan (MIM-EPI) to simultaneously present the profile survey and MS/MS acquisition. Because the MIM narrowed the ion scan range in Q1 and the ion trap enhanced the ion fragments passing through Q2, the qualitative capability of quadrupole MS can be greatly improved, especially for capture of the uncommon metabolites. There are 12 kukoamine metabolites identified from LyC, with either spermine or spermidine backbone and with conjugation of one to three dihydrocaffeoyls or other kinds of phenolic moieties. Except for kukoamines A and B, other metabolites were identified in LyC for the first time. This approach can be utilized for metabolite identification in other substrates.

Metabolism and Bioactivation of The Tricyclic Antidepressant Amitriptyline in Human Liver Microsomes and Human Urine

“…First, an MIM-EPI method was used to identify all potential metabolites of amitrptyline in vitro without the need of predicting molecular weights (MW) or fragmentation patterns. The Q1 (Q3) ranged from m/z 229 (MW + H -50, 50 Da was set as the largest dealkylated fragment) to 634 (MW +H + 3O + GSH, three oxygen atoms were decided as the largest molecular weight added), and in total 406 ion transitions were monitored [24][25][26].…”

Quality control of Lycium chinense and Lycium barbarum cortex (Digupi) by HPLC using kukoamines as markers

“…2. KA and KB were not stable in neutral solution (pH = 7), as they were found to decrease by about 30% after exposure in air for 21 h. This change might arise through oxidation of the o -dihydrocaffeoyl moieties into quinones [25]. In contrast, it was found that when the pH was adjusted to 2.5–3 by acetic acid, KA and KB remained constant within the investigated period.…”

Metabolic Demethylation and Oxidation of Caffeine during Uptake by Lettuce

“…Triple quadrupole mass spectrometry can quantify trace amounts of metabolites using the scan mode of multiple reaction monitoring (MRM) as long as the corresponding authentic standards are provided. 37,39 This study aimed to investigate uptake and distribution of caffeine in the leafy vegetable lettuce and to examine the metabolism of exogenous caffeine in the plant. A liquid chromatography coupled to a QTrap tandem mass spectrometry (LC-QTrap-MS/MS) was used to obtain the fragment patterns of metabolites for the elucidation of their chemical structures and to quantify caffeine and the metabolites using MRM mode.…”

“…Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) with various or hybrid mass analyzers (i.e., triple quadrupole, Orbitrap, linear ion trap, and time-of-flight) has become the major tool employed to identify metabolites derived from pharmaceuticals in environmental and plant matrices. ,− High-resolution time-of-flight (TOF) mass spectrometry provides accurate mass information for determination of metabolites. Ion trap mass spectrometry can achieve more enriched fragment ions for structure elucidation and quantification of metabolites.…”

“…Ion trap mass spectrometry can achieve more enriched fragment ions for structure elucidation and quantification of metabolites. Triple quadrupole mass spectrometry can quantify trace amounts of metabolites using the scan mode of multiple reaction monitoring (MRM) as long as the corresponding authentic standards are provided. , …”