A liquid chromatography-mass spectrometry assay for the quantification of nucleotide sugars in human plasma and urine specimens and its clinical application.

Nucleotide sugars and more specifically UDP-sugars, represent a major source of energy, key components of extracellular matrix, glycosylation and glucuronidation reactions, and emerge as important signaling molecules through P2Y14 purinergic receptor. Despite their pivotal role in a variety of physiological and pathological processes and their potential as biomarkers, UDP-sugar composition of biological fluids remains poorly studied. We developed a liquid chromatography electrospray ionization tandem mass spectrometry in multiple reaction monitoring mode for the simultaneous quantification of UDP-glucose, UDP-galactose, UDP-glucuronic acid, UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine in human blood and urine. Relative to existing methods, UDP-sugar recovery was enhanced with perchloric acid and ammonium formate during sample preparation that also significantly improved chromatographic stability. Performance of the assay was validated and allowed the absolute quantification of UDP-sugars with a wide dynamic range (0.1 to 200 ng/mL) using stable deuterated isotopes as internal standards. We report a fast (13 min run) and sensitive method (limit of detection: 10-30 pg/mL; lower limit of quantification ≤ 0.2 ng/ml) to simultaneously quantify five UDP-sugars in a low volume (100 µL) of plasma and urine. Findings identified sex-specific profiles in both plasma and urine of healthy subjects. Applicability was also successfully demonstrated in specimens collected from individuals displaying a variety of medical conditions. This validated method was optimized for a high-throughput assessment of UDP-sugars in specimens of clinical importance and enabled an accurate and reliable absolute quantification of important UDP-sugars in diverse clinical contexts.