Identification of In Vivo Metabolites of Dictamnine in Mice Using HPLC-LTQ-Orbitrap Mass Spectrometry

Dynamic metabolic change of cancer cells induced by natural killer cells at single-cell level studied by label-free mass cytometry

Natural killer cells (NK cells) are important immune cells which have attracted increasing attention in cancer immunotherapy. Due to the heterogeneity of cells, individual cancer cells show different resistance to NK cytotoxicity, which has been revealed by flow cytometry. Here we used label-free mass cytometry (CyESI-MS) as a new tool to analyze the metabolites in Human Hepatocellular Carcinoma (HepG2) cells at the single-cell level after the interaction with different numbers of NK92 MI cells. A large amount of chemical information from individual HepG2 cells was obtained showing the process of cell apoptosis induced by NK cells. Nineteen metabolites which consecutively change during cell apoptosis were revealed by calculating their average relative intensity. Four metabolic pathways were impacted during cell apoptosis which hit 4 metabolites including glutathione (GSH), creatine, glutamic acid and taurine. We found that the HepG2 cells could be divided into two phenotypes after co-culturing with NK cells according to the bimodal distribution of concentration of these 4 metabolites. The correlation between metabolites and different apoptotic pathways in the early apoptosis cell group was established by the 4 metabolites at the single-cell level. This is a new idea of using single-cell specific metabolites to reveal the metabolic heterogeneity in cell apoptosis which would be a powerful means for evaluating the cytotoxicity of NK cells.

Label-free mass cytometry is utilized to study the dynamic metabolic change during apoptosis in HepG2 cells induced by NK92 MI cells at the single-cell level. The metabolic heterogeneity of individual HepG2 cells during apoptosis was revealed.

Identification and characterization of quinoline alkaloids from the root bark of Dictamnus dasycarpus and their metabolites in rat plasma, urine and feces by UPLC/Qtrap-MS and UPLC/Q-TOF-MS

Quinoline alkaloids are the main bioactive and potentially toxic constituents in the root bark of Dictamnus dasycarpus Turcz. (BXP), a widely used traditional Chinese medicine for the treatment of skin inflammation, eczema and rubella. However, the comprehensive analysis of the chemical components and metabolites of quinoline alkaloids remain unclear. In this study, an integrated strategy by combining UPLC/Q-TOF-MS and UPLC/Qtrap-MS was established to comprehensively profile the quinoline alkaloids from BXP and their metabolites in rat plasma, urine and feces. Q-TOF-MS (MS^E mode), Qtrap-MS (EMS, MIM, pMRM and NL mode) were performed for acquiring more precursor ions and clearer precursor product ions. A step-by-step manner based on the diagnostic fragment ions (DFIs), in-house database, ClogP value and dipole moment (μ) was proposed to overcome the complexities due to the similar fragmentation behaviors of the quinoline alkaloids. As a result, a total of 73 quinoline alkaloids were unambiguously or tentatively identified. Among them, 4 furoquinolines, 10 dihydrofuroquinolines, 2 pyranoquinolinones, 4 dihydropyranoquinolinones and 9 quinol-2-ones were characterized in BXP for the first time. Moreover, a total of 98 BXP-related constituents (including 57 prototypes and 41 metabolites) were detected in rat plasma, urine and feces. The metabolic pathways included phase I reactions (O-demethylation, hydroxylation and 2,3-olefinic epoxidation) and phase II reactions (conjugation with glucuronide, sulfate and N-acetylcysteine). In conclusion, the integrated strategy with the proposed stepwise manner is suitable for rapid identifying and characterizing more extensive quinoline alkaloids of BXP in vitro and in vivo. Moreover, the results will be helpful for revealing the pharmacological effective substances or toxic substances of BXP and provide a solid basis for further research.

Corrigendum to "Identification of In Vivo Metabolites of Dictamnine in Mice Using HPLC-LTQ-Orbitrap Mass Spectrometry"

[This corrects the article DOI: 10.1155/2018/3567647.].