Simple Measurement of Gluconeogenesis by Direct

The contribution of gluconeogenesis to fasting glucose production was determined by a simple measurement of urinary menthol glucuronide (MG) H enrichment from H2O. Following ingestion of H2O (0.5% body water) during an overnight fast and a pharmacological dose (400 mg) of a commercial peppermint oil preparation the next morning, 364 mol MG was quantitatively recovered from a 2-h urine collection by ether extraction and a 125 mol portion was directly analyzed by H NMR. The glucuronide H-signals were fully resolved and their relative intensities matched those of the monoacetone glucose derivative. The pharmacokinetics and yields of urinary MG after ingestion of 400 mg peppermint oil as either gelatin or entericcoated capsules 1 h before breakfast were quantified in five healthy subjects. Gelatin capsules yielded 197 81 mol of MG from the initial 2-h urine collection while enteric-coated capsules gave 238 84 mol MG from the 2to 4-h urine collection. Magn Reson Med 54:429–434, 2005. © 2005 WileyLiss, Inc.