Combined use of filtered and edited 1H NMR spectroscopy to detect 13C-enriched compounds in complex mixtures

✍ Scribed by P. W. A. Howe; Z. Ament; K. Knowles; J. L. Griffin; J. Wright

• Publisher: John Wiley and Sons
• Year: 2012
• Tongue: English
• Weight: 560 KB
• Volume: 25
• Category: Article
• ISSN: 0952-3480
• DOI: 10.1002/nbm.2791

✦ Synopsis

In conventional metabolism and pharmacokinetic studies, radioactive isotopes are used to identify and quantify the breakdown products of xenobiotics. However, the stable isotope ^13^C provides a cheaper and less hazardous alternative. Metabolites of ^13^C‐enriched xenobiotics can be detected, quantified and identified by ^13^C‐filtered NMR spectroscopy. However, one obstacle to using ^13^C is its 1.1% natural abundance that produces a background signal in ^13^C‐filtered NMR spectra of crude biological extracts. The signal makes it difficult to distinguish between ^13^C‐enriched xenobiotics resonances from endogenous metabolites unrelated to the xenobiotic. This study proposes that the ^13^C background signal can be distinguished from resonances of ^13^C‐enriched xenobiotics by the absence of a ^12^C component in the xenobiotic. This is detected by combined analysis of ^13^C‐filtered and ‐edited NMR spectra. The theory underlying the approach is described and the method is demonstrated by the detection of sub‐microgram amounts of ^13^C‐enriched phenacetin in crude extracts of hepatocyte microsomes. Copyright © 2012 John Wiley & Sons, Ltd.