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Open AccessArticle

Simultaneous Measurement of Urinary Trimethylamine (TMA) and Trimethylamine N-Oxide (TMAO) by Liquid Chromatography–Mass Spectrometry

by Xun Jia 1, Lucas J. Osborn 1,2 and Zeneng Wang 1,2,*
1
Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195, USA
2
Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
*
Author to whom correspondence should be addressed.
Academic Editors: Gavino Sanna and Stefan Leonidov Tsakovski
Molecules 2020, 25(8), 1862; https://doi.org/10.3390/molecules25081862
Received: 30 March 2020 / Revised: 15 April 2020 / Accepted: 16 April 2020 / Published: 17 April 2020
Trimethylamine (TMA) is a gut microbial metabolite—rendered by the enzymatic cleavage of nutrients containing a TMA moiety in their chemical structure. TMA can be oxidized as trimethylamine N-oxide (TMAO) catalyzed by hepatic flavin monooxygenases. Circulating TMAO has been demonstrated to portend a pro-inflammatory state, contributing to chronic diseases such as cardiovascular disease and chronic kidney disease. Consequently, TMAO serves as an excellent candidate biomarker for a variety of chronic inflammatory disorders. The highly positive correlation between plasma TMAO and urine TMAO suggests that urine TMAO has the potential to serve as a less invasive biomarker for chronic disease compared to plasma TMAO. In this study, we validated a method to simultaneously measure urine TMA and TMAO concentrations by liquid chromatography–mass spectrometry (LC/MS). Urine TMA and TMAO can be extracted by hexane/butanol under alkaline pH and transferred to the aqueous phase following acidification for LC/MS quantitation. Importantly, during sample processing, none of the nutrients with a chemical structure containing a TMA moiety were spontaneously cleaved to yield TMA. Moreover, we demonstrated that the acidification of urine prevents an increase of TMA after prolonged storage as was observed in non-acidified urine. Finally, here we demonstrated that TMAO can spontaneously degrade to TMA at a very slow rate. View Full-Text
Keywords: trimethylamine (TMA); trimethylamine N-oxide (TMAO); biomarker; urine; liquid chromatography–mass spectrometry (LC/MS) trimethylamine (TMA); trimethylamine N-oxide (TMAO); biomarker; urine; liquid chromatography–mass spectrometry (LC/MS)
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MDPI and ACS Style

Jia, X.; Osborn, L.J.; Wang, Z. Simultaneous Measurement of Urinary Trimethylamine (TMA) and Trimethylamine N-Oxide (TMAO) by Liquid Chromatography–Mass Spectrometry. Molecules 2020, 25, 1862.

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