Preparation of [1′‐13C]citric acid as a probe in a breath test to evaluate tricarboxylic acid cycle flux

Abstract

[1′‐13C]Citric acid (1) was efficiently prepared from dimethyl 1,3‐acetonedicarboxylate in two steps as a probe for a breath test. The synthetic method was selected because of the yield and reproducibility. Compound 1 was orally administrated to rats, and the time course of the increase of 13CO2/12CO2 ratios (Δ13CO2) in their breath was successfully followed, indicating the metabolism of 1. Thus, the 13C‐breath test using 1 is a promising method to evaluate tricarboxylic acid (TCA) cycle flux.