Hepatic UDP-glucose 13C isotopomers from [U-13C] glucose: A simple analysis by 13C NMR of urinary menthol glucuronide

Ana C. Mendes, M. Madalena Caldeira, Claudia Silva, Shawn C. Burgess, Matthew E. Merritt, Filipe Gomes, Cristina Barosa, Teresa C. Delgado, Fatima Franco, Pedro Monteiro, Luis Providencia, John G. Jones

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Menthol glucuronide was isolated from the urine of a healthy 70-kg female subject following ingestion of 400 mg of peppermint oil and 6 g of 99% [U- 13C]glucose. Glucuronide 13C-excess enrichment levels were 4-6% and thus provided high signal-to-noise ratios (SNRs) for confident assignment of 13C-13C spin-coupled multiplet components within each 13C resonance by 13C NMR. The [U- 13C]glucuronide isotopomer derived via direct pathway conversion of [U-13C]glucose to [U-13C]UDP-glucose was resolved from [1,2,3-13C3]- and [1,2-13C2] glucuronide isotopomers derived via Cori cycle or indirect pathway metabolism of [U-13C]glucose. In a second study, a group of four overnight-fasted patients (63 ± 10 kg) with severe heart failure were given peppermint oil and infused with [U-13C]glucose for 4 hr (14 mg/kg prime, 0.12 mg/kg/min constant infusion) resulting in a steady-state plasma [U- 13C]glucose enrichment of 4.6% ± 0.6%. Menthol glucuronide was harvested and glucuronide 13C-isotopomers were analyzed by 13C NMR. [U-13C]glucuronide enrichment was 0.6% ± 0.1%, and the sum of [1,2,3-13C3] and [1,2- 13C2]glucuronide enrichments was 0.9% ± 0.2%. From these data, flux of plasma glucose to hepatic UDPG was estimated to be 15% ± 4% that of endogenous glucose production (EGP), and the Cori cycle accounted for at least 32% ± 10% of GP.

Original languageEnglish (US)
Pages (from-to)1121-1125
Number of pages5
JournalMagnetic resonance in medicine
Issue number5
StatePublished - Nov 2006


  • C-isotopomer
  • Cori cycle
  • Glycogen
  • Indirect pathway
  • Krebs cycle

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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