Intact Endogenous Metabolite Analysis of Mice Liver by Probe Electrospray Ionization/Triple Quadrupole Tandem Mass Spectrometry and Its Preliminary Application to in Vivo Real-Time Analysis

Abstract

Probe electrospray ionization (PESI) is a recently developed ionization technique that enables the direct detection of endogenous compounds like metabolites without sample preparation. In this study, we have demonstrated the first combination use of PESI with triple quadrupole tandem mass spectrometry (MS/MS), which was then applied to intact endogenous metabolite analysis of mice liver, achieving detection of 26 metabolites including amino acids, organic acids, and sugars. To investigate its practicality, metabolic profiles of control and CCl4-induced acute hepatic injury mouse model were measured by the developed method. Results showed clear separation of the two groups in score plots of principal component analysis and identified taurine as the primary contributor to group separation. The results were further validated by the established gas chromatography/MS/MS method, demonstrating the present method's usefulness. In addition, we preliminarily applied the method to real-time analysis of an intact liver of a living mouse. We successfully achieved monitoring of the real-time changes of two tricarboxylic acid cycle intermediates, α-ketoglutaric acid and fumaric acid, in the liver immediately after pyruvic acid injection via a cannulated tube to the portal vein. The present method achieved an intact analysis of metabolites in liver without sample preparation, and it also demonstrates future possibility to establish in vivo real-time metabolome analysis of living animals by PESI/MS/MS.

Molecularly Imprinted Polymer-Coated Probe Electrospray Ionization Mass Spectrometry Determines Phorbol Esters and Deoxyphorbol Metabolites in Jatropha curcas Leaves

“…The needle touches the sample for analyte extraction, and subsequently, the needle is positioned in front of the mass spectrometer inlet orifice. A high voltage is applied to the needle, and an electrolytic spray is formed, followed by the ion analysis by MS. PESI has already been employed for direct MS analysis of foods [17], psychoactive drugs [18], plants [19], metabolites from mouse liver [20], and brain [21], including detection of metabolites at subcellular levels [22].…”

Fast Quantitation of Target Analytes in Small Volumes of Complex Samples by Matrix‐Compatible Solid‐Phase Microextraction Devices

“…As ap roof of concept, microprobes were used for the qualitative analysis of Allium cepa (red-onion) single cells.F lavonoids,l uteolin, and quercetin, previously reported on other food commodities,w ere successfully identified by comparing chromatographic retention times and fragmentation patterns with those of standards.As expected, target analytes could not be detected with the use of anon-coated tip;incontrast, good signal was achieved when the PPy-CTAB coated tip was exposed to the single cell (see Figure S19). However,a pplication of the current device cannot prevent disturbances to the equilibrium of the investigated object, nor the cell damage that results from penetration of the membrane.T hus,smaller sampling means, such as ac oated nano-tip [19] with custom-made nanoparticles, [20] are under development, with aims to minimize these effects and make SPME suitable for cells one order of magnitude smaller (e.g. red-cells or fibroblasts).…”

“…Unlike other reported approaches that are based on metal needles without coating, [6,7,19] SPME acts as achemical biopsy tool by enriching small molecules carrying chemical information about the investigated system without removing tissue,t hus providing am uch cleaner extraction. Currently,o ur group is working on the development of versatile biocompatible coatings for miniature devices that allow for the extraction of abroader range of compounds,with potential for avariety of applications in fields,s uch as plant biology and oncology, where small objects need to be scrutinized.…”

Direct detection of the psychoactive substance MT‐45 in human tissue samples by probe electrospray ionization‐tandem mass spectrometry

“…A new ionization method, probe electrospray ionization (PESI)–mass spectrometry (MS), which uses a solid needle as a sample probe and an ESI emitter, was developed by Hiraoka et al and can be applied not only to liquid and surface analyses, but also to the inside of samples. As PESI usually requires no pretreatment steps, PESI–MS has been used in several fields, such as food science, plant science, studies of chemical reaction mechanisms, medical and clinical diagnosis, and metabolomics . In this study, we used PESI–MS/MS for the direct detection of MT‐45, an opioid analgesic psychoactive substance, in human tissues in an actual forensic case.…”

“…As PESI usually requires no pretreatment steps, PESI-MS has been used in several fields, such as food science, plant science, studies of chemical reaction mechanisms, medical and clinical diagnosis, and metabolomics. [8][9][10][11][12][13][14] In this study, we used PESI-MS/MS for the direct detection of MT-45, an opioid analgesic psychoactive substance, 15,16 in human tissues in an actual forensic case.…”